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India is returning to Space: The Second Indian Astronaut after Rakesh Sharma, Shubhanshu Shukla, is flying onboard SpaceX's Dragon capsule. He is piloting the Axiom-4 mission to the International Space Station (ISS). The mission, currently scheduled for June 11th, 2025, marks an important milestone in India’s space history. However, there is a controversial sentiment within the space community because ISRO/India paid for a seat on this mission. This has resulted in limited coverage by the Indian media. I, on the other hand, believe an Indian in space deserves a lot more attention. So, as a self-proclaimed aerospace nerd, I am going to share my thoughts and some highlights on the Ax-4 mission.

Mission Details

Axiom Space has taglined the mission: “realize the return”, as three of the four crew members are realizing the return to space for their respective countries. Ax-4 mission will be the second human space mission for each of India, Poland, and Hungary, while also being their first mission to the International Space Station.

India’s last human spaceflight happened back in 1984 in a collaboration with Roscosmos onboard Soyuz T-11.

The mission is stated to launch on June 11th with upto 14 days stay at ISS. Pilot Shubanshu Shukla will be performing many experiments on behalf of ISRO as well as part of the ISRO-NASA collaboration to increase our understanding of life and humans in space.

Along with Shubanshu Shukla, Prasanth Balakrishnan Nair is another Indian astronaut who has trained as a backup crew member. Both of them would bring a wealth of experience for India’s Gaganyaan programme with its first stated flight in 2027. The Indian Astronaut Cadre was trained in Russia under an agreement with Roscosmos. Now, with this mission, Shubanshu Shukla and Prasanth Nair are receiving training from NASA and SpaceX. Such collaborations to start our Human Space Programme remind me of ISRO’s early days, where we got assistance from the USA, France, and Russia.

Why is it Important?

While the Space Community acknowledges the experiments and the experience gained, the lack of engineering is one of the reasons for the muted engagement on the mission. For a space programme that has only recently started venturing beyond low-earth orbit, everyone is more excited by the ‘firsts’ and new technologies.

The community is forgetting why we are exploring all these new avenues: SCIENCE!

In India, everyone talks about new technologies and building industries, which can be seen through programmes like ‘MADE IN INDIA’ and ‘STARTUP INDIA’. Science, research, and development get overlooked too often. While Ax-4 may be the second Indian space mission, it is our first micro-gravity experiments mission. The science itself would have long-term ripples in the scientific community. While I haven’t researched the experiments and their implications to share them in detail, I can safely say that any science has the potential to trigger scientific discoveries. Just look at a small experiment onboard Chandrayaan-1 that triggered the current Lunar age as we know it by discovering traces of water.

Along with science, another equally important aspect of the Axiom-4 mission is INSPIRATION!

Rakesh Sharma inspired my Dad and his generation, including Shubhanshu Shukla. Kalpana Chawla, even when she wasn’t an Indian citizen, while she ventured into space, inspired me and my generation. Now, Shubhanshu Shukla will be the face of Indian Space for kids and students. Seeing a person who looks and talks like them in space would enable so many to start dreaming of the stars. Forget all the experience and science, just this fact is enough of a reason to cover this mission in detail. I will try my best to do so because I strongly believe that the Human Space Programme’s most significant implication is towards galvanizing hundreds of young minds, which is the need of the hour for our fast-growing space industry.

All the very best to Shubhanshu Shukla and the Axiom 4 crew for their mission.
Ad Astra!

EDIT: The mission has been delayed after a leak was found during the pre-launch check-up.

Background: A legacy of Aryabhata, Bhaskara and APPLE

Over the next few years, to continue Vikram Sarabhai's vision, the agency built two more experimental satellites called Bhaskara 1 and Bhaskara 2. While Aryabhata was a scientific satellite, Bhaskara(s) were remote sensing satellites in some sense. They had camera payloads but lacked the strict parameters of operational remote sensing satellites like a fully stable satellite. The Bhaskara satellites, therefore, were a step forward in the right direction. ISRO tested some key technologies while leaving out some advanced ones.

On the communication satellites front, APPLE again was an experimental satellite, whereas the first operational satellites INSAT-1 series were procured. Therefore, when the design and development of the first operational satellite, IRS-1A, started, ISRO ventured into unknown territory on many fronts: control systems, deployable solar panels, ground station, quality control protocols and data utilisation, to name a few.

The Bhaskara satellites launched in 1979 and 1981, respectively. Around the same time, the idea of an operational remote sensing satellite was going around in ISRO. The National Natural Resources Monitoring and Management System (NNRMS) of Govt of India considered essential areas of application of satellite-based remote sensing data as

1. Agriculture, where the extent of crops and their yields were required to be monitored over the growing seasons,

2. Monitoring of the different types of land/land use,

3. Monitoring of water resources,

4. Monitoring of drought and floods,

5. Monitoring of the forestry in the country, and

6. Geological applications like mineral prospecting.

The agricultural applications gained priority over other areas. In India, a typical agricultural field had a 30 m length. Therefore, a 36 m resolution payload was selected for the satellite. Other applications could work with a course resolution which resulted in the inclusion of a separate 72 m resolution payload.

With these payloads finalised, the Space Commission submitted a proposal to the Government of India, giving full details of the mission. ISRO included a list of new technologies to be developed, specifications of satellite and ground segment, budget, import requirements, schedule and project management aspects in the report. Finally, the GOI approved the IRS-1A satellite in 1981.

IRS-1A Development: Realising new technologies

The imaging systems, along with fine resolutions, require multispectral data. Different frequency range channels help classify various features such as water bodies, green covers, and construction. Therefore, ISRO included four bands (blue, green, red, and infrared) in each of the two cameras.

Next came the decision of orbit selection. To observe the growth of crops in a season, a repetitiveness of 22 days was set. This requirement meant ISRO selected a 900 km Polar Sun-synchronous orbit. Therefore, two LISS (Linear Self Scanning Scanner) payloads were developed for the IRS-1A satellite.

The satellite needed a lot of new technologies to support the imaging system.

• A three-axis stabilised satellite with cameras mounted appropriately to take images of the Earth's surface with pointing accuracies of ± 0.3 degrees about pitch and roll axis and ± 0.4 degrees about the yaw axis,

• Power system to provide the required conditioned power,

• Telemetry, Tracking and Command (TT&C) system working in S-band,

• Data handling and radiofrequency transmit systems for transmitting the camera data, and

• The mechanical system consisting of a structure, thermal control and solar panel deployment mechanism.

Mechanical Subsystem

An aluminium honeycomb structure was realised to support different instruments. Special considerations meant that the satellite bus was compatible with different launch vehicles, including the upcoming PSLV. A passive (no electrical power needed) thermal system evolved where the cameras remained at the standard room temperature.

All prior ISRO satellites had permanent mounted solar panels. An imaging satellite like IRS-1A needs high power. Therefore deployable solar panels are required. The team developed a mechanism that underwent more than 50 tests, including zero-gravity testing.

Control Sub-System

Being the first three-axis stabilised satellite, IRS-1A needed many new control systems. Attitude sensors, dynamically tuned gyroscope, reaction wheels and mono-propellant based propulsion system were developed. Digital microprocessors was a new technology in the world. This lead ISRO to use a hardware-based control system with a safe mode inbuilt.

Communication Subsystem

The imaging camera data was beamed back to Earth in real-time. There was no recorder onboard. This meant that the payload data needed an Earth-pointing antenna while the Telemetry and Telecommand antenna had to be omnidirectional.

Power Subsystem

ISRO imported Solar cells and Ni-Cd Batteries. A power system tested and qualified for space was designed around these imported components. The team developed power conditioners to convert raw power into regulated power voltage.

IRS-1A also paved the path for managerial aspects

By that time, ISRO had expanded a lot. There were multiple centres of the space agency spread throughout the country. IRS-1A became one of the first inter-departmental efforts. ISRO satellite centre (URSC) lead the project and coordinated with all other centres. The Project Management Council (PMC) chaired by Dr UR Rao and a Project Management Board (PMB) chaired by Dr K Kasturirangan were formed at URSC to guide the project and conduct higher-level mission analysis.

The Space Applications Centre, Ahmedabad, developed the imaging system and even the data products to analyse the remote sensing data. Teams developed the control systems and solar panel deployment at ISRO Inertial Systems Unit (IISU), VSSC. Liquid Propulsion Systems Centre (LPSC), Bangalore, developed the propulsive system needed to control the satellite.

While this inter-departmental effort was undergoing, ISRO formed a new centre. Until now, ISRO utilised a ground station at the Sriharikota Launch Range as a command station for its satellites. ISRO Telemetry Tracking and Command Network (ISTRAC) was developed as a Control Centre for IRS-1A and all upcoming Indian Remote Sensing (IRS) satellites. Bearslake station in Moscow, Fairbanks station in Alaska, Weilheim station in Germany, Malindi station located in Kenya, operated by ESA, were the stations identified for the network.

The National Remote Sensing Agency, Hyderabad (now NRSC), was already receiving payload data from NASA Landsat and French SPOT satellites. New ground systems evolved to receive IRS-1A satellite data.

Quality Assurance and Testing

The inter-departmental effort and multiple industries involved meant uniform quality assurance norms was needed across all centres. ISRO constituted a Product Assurance Board which catered to reliability apportionment of the satellite. The teams required to get every component checked with the board through checklist documents.

Each and every subsystem of the satellite was thoroughly tested through newly developed testing setups. The teams even developed multiple models such as a structural model for vibration testing, qualification model for testing and final flight model. ISRO first used this multiple model philosophy for the IRS-1A mission.

Launch and Operations

ISRO's Polar Satellite Launch Vehicle (PSLV) was still under development. This limited the agency to use a foreign launcher for the satellite. After the Soviets helped India launch the first satellite, Aryabhata, ISRO decided to approach them again. Soviet Union agreed to launch IRS-1A onboard a VOSTOK rocket at a "reasonable price tag".

There were multiple visits by Soviet Scientists to assist ISRO to design a compatible satellite. Even ISRO scientists AD Dharma S Kalyana Raman visited Baikonur Cosmodrome. A few days before launch, the satellite was flown onboard an Aeroloft IL-76 cargo aircraft on 24th January 1988.

After conducting some more tests, such as solar panel deployment and fuel loading, the satellite was integrated with the launch vehicle. IRS-1A launched at 12:13 IST on 17th March 1988.

The solar panels deployed without any hiccups after a few minutes. On 18th March, the satellite had acquired stabilisation, and the LISS-1 was switched on. A few more days later, the LISS-2 payload started sending images as well. Within three weeks, the satellite was operationalised and data made available to the scientists.

UR Rao had become the ISRO chairman by then. He constituted the Antrix Corporation to sell the IRS series data internationally commercially. Hence, the commercial arm of ISRO was formed. IRS-1A worked for almost nine years, much more than its three-year design life.

IRS series: The Road Ahead

IRS-1A had a paved path for numerous facilities and procedures at ISRO. Riding on the first remote sensing satellite's success, ISRO designed IRS-1B/C/D satellites in the coming years. In 1993, PSLV became operational, and India now launched the satellites on our own launch vehicle. The Indian Remote Sensing network is one of the largest nationally operated around the world. IRS programme has evolved to include many satellites such as Resourcesat, Cartosat and the latest EOS series satellites.

References

• https://www.isro.gov.in/Spacecraft/irs-1a

• https://directory.eoportal.org/web/eoportal/satellite-missions/i/irs

• https://www.vssc.gov.in/VSSC/index.php/irs-1a

• From Fishing Hamlet to Red Planet Ebook

The Genesis of Indian Lunar Mission – Chandrayaan-1

In the year 1998, India carried out the Pokhran nuclear tests in the month of May. The tests were a technological and strategic feat, for that they were done hidden from the whole world. To commemorate this accomplishment, PM Atal Bihari Vajpayee, declared 11th May as the National Technology Day. You may be wondering how some nuclear tests done by the military and DRDO are relevant to the non-military Indian Space agency. You’ll know in a minute.

On 11th May 1999, the first Technology Day was celebrated. At a function in New Delhi, Dr K Kasturirangan indicated the possibility of India undertaking a lunar mission using the PSLV. This was the first mention of an Indian Lunar Mission. He even said that such a mission could take time and ‘if all goes well, it could be a reality by 2008.’ I wonder if he knew how he had just predicted the future!

Soon after, in 2000, a National Lunar Mission Task Force was set up with an aim to prepare a report and submit for parliamentary approval. In 2003, the report was unanimously recommended to the government by a pool of hundred scientists. The idea of a lunar mission picked up parliamentary support and the Prime Minister mentioned, “… now I think there is a political interest in this; there is a general societal interest in this. I would certainly make an announcement.” On 15th August 2003, he declared the Chandrayaan-1 mission. There is an interesting story behind the announcement.

ISRO had recommended Mr Bajpayee to call the mission Somayaan, but he announced it as Chandrayaan-1. When asked later, he replied that he consulted some Sanskrit scholars and Chandrayaan was a better name. He also added that he put it as Chandrayaan-1 because India is not going for one mission; we need to have a long-term planetary exploration programme. Perhaps, this is the kind of attitude that a nation requires from its Political leaders. Finally, in November 2003, Chandrayaan-1 got parliamentary approval.

The mission is Approved! What to pack for the Journey?

Parliament approved Chandrayaan-1. The budget was allotted. We were ready to go to the Moon, but what to take along? To understand the science (payloads) chosen for Chandrayaan, let’s look at the history of Lunar Exploration.

A brief history of Lunar Exploration

The Soviets and Americans utilized every trick in the book to explore the lunar surface back in the cold war era. With the advent of space-age by Sputnik-1 launch, both the nations were engaged in a space war. The Soviets reached the Moon first with their Luna satellites and even landed rovers called ‘Lunakhods’ to explore the surface. To top it all off, the USA sent humans to the Moon. Apollo was a huge success. We not only did experiments on the Moon, but the astronauts also brought lunar regolith (soil) samples back to the Earth. Even, India got some of these samples (thanks to Dr Sarabhai’s connections) to undertake experiments.

But after Luna and Apollo, the Moon got sidelined. There was no dedicated mission to Moon for the next 14 years. Finally, with the advent of Asian space nations like Japan, China, and India came the Renaissance of Lunar Exploration. Clementine, a NASA spacecraft, detected the presence of water ice in the south polar region of Moon in 1994. This renewed interest about the Moon and 21st Century saw a burst of missions. ESA launched SMART-1 in 2003, Japan Kaguya in Sept 2007, China Chang’e-1 in Oct 2007 and finally, India Chandrayaan-1 in October 2008.

The Search for Payloads for Chandrayaan-1

After the parliamentary approval in 2003, a Science Advisory Board (SAB) was established by ISRO. They took the National Lunar Mission Task Report as a starting point while comparing the planned missions by ESA, Japan, China, and the USA. Finally, they decided on five Indian payloads. The spacecraft configuration zeroed in on a model with had some margins in mass, power and space. ISRO, therefore, decided to accommodate another payload of maximum 10 Kgs and 10 W power consumption. SAB then called an Announcement of Opportunity for any lab outside ISRO.

The Indian Space Agency received a whopping 26 number of proposals from across continents. The SAB liked two of NASA’s instruments, but they both together exceeded the 10 Kg requirement. After some discussions and deliberations, ISRO optimized Chandrayaan-1 to accommodate 25 Kg. NASA and ISRO optimized the two instruments, and suddenly, Chandrayaan-1 had a total of extra six science payloads.

In 2004, a scaled model of Chandrayaan-1 with four Indian and six foreign payloads was presented at ‘Sixth International Conference on the Exploration and Utilization of the Moon’. The conference was held in Udaipur, Rajasthan, in November 2004. But a veteran space scientist’s suggestion added a vital payload to the spacecraft.

Dr APJ Abdul Kalam, the then President of India, suggested adding a lander/ impactor to Chandrayaan-1. And hence, an 11th payload, Moon Impact Probe was added.

Overview of the Spacecraft

Goals

1. To further enhance the already acquired knowledge about the Moon.

2. To achieve further progress in India’s capacity to build more efficient rockets and satellites, especially through miniaturization.

3. To provide challenging opportunities for young scientists of India to do research in new and exciting areas like the study of planets.

Objectives

1. To photograph the surface of the Moon in such a way that length, breadth, and height of the surface features of the Moon can be found out accurately. This is called 3D imaging and can lead to the preparation of a more accurate map of the Moon.

2. To prepare a map of the Moon accurately showing the way in which various elements and minerals are distributed over its surface.

3. To prepare a map of the Moon that shows different geological areas there clearly

Specifications

• Size and Shape: 1.5 m cuboid with 600 Kg mass in the Lunar Orbit

• Control: 3-axis stabilized using reaction wheels and attitude control thrusters;

  sun sensors, star sensors, and miniaturized DTGs for orientation reference.

• Power: 700 W Solar Panel with 36Ah Li-Ion Battery

• Propulsion: Bi-propellant Liquid Apogee Motor

• Communication: S-band for Telemetry and X-band for Payload data transmission

Payloads

Chandrayaan-1 Launch

PSLV’s new variant (launching for the first time) PSLV-XL launched Chandrayaan-1 on 22nd October 2008. The launch vehicle placed the spacecraft in a 250 km X 23,000 km initial Earth Parking Orbit. This was followed by a series of perigee manoeuvres to raise the apogee to 380,000 km in 17 days. Finally, Chandrayaan-1 was placed in 100 km circular orbit around Moon on 12th November 2008.

The trajectory to reach Moon was a special one. It took a long time but less fuel. A whole different article is planned on understanding this trajectory.

Ground Segment

Chandrayaan-1 was India’s first mission above the 36,000 km Geosynchronous range. This required better and more efficient ground segments to be built. After surveying several possible sites, ISRO finalized to set up two large dish antennas at Byalalu, about 40 km from Bangalore. This established the Indian Deep Space Network. L&T was one of the industrial partners involved in setting up this facility.

Along with IDSN, Indian Space Science Data Centre was established. It aims to store, retrieve and distribute scientific data from Indian Space Science Missions.

Finding Water on the Moon

Over its short mission life, Chandrayaan-1 achieved some great science. Listing all the achievements of scientific data in a single article may not be even possible because scientists are conducting research based on the data even today. But one discovery by India’s maiden lunar mission deserves its story to be told. The discovery of water molecules on the Moon!

NASA’s Moon Mineral Mapper (M3) could detect the presence of H2O molecule and OH by looking at the absorption spectrum of the lunar surface. This meant M3 could look for water in the sunlit areas of the Moon. But it was earlier conjectured that if there is water on the Moon, it’ll be in the dark areas. Therefore, when M3 found traces of hydroxyl in the reflected sunlight, it was a happy surprise for the whole team.

When M3 continued to find traces for months, the team decided it was indeed a breakthrough in lunar science. They decided to try and validate their discovery by using some other spacecraft which had the same capability. NASA’s Deep Impact mission on its return journey from the Comet 9P/Tempel was perfect for this validation. After some discussion and a few months, the team was able to get Deep Impact to look at Moon and there it was. Same features were present in Deep Impact data as well.

To add to all these scientific data, some scientists of M3 team, remembered that Cassini, NASA’s Saturn Exploration Spacecraft, had calibrated its instruments by looking at Moon. They got hold of the Cassini archived data and indeed, the hydroxyl and water signatures were present there as well. Chandrayaan-1 had indeed discovered water on the Moon, and it was published in the Science journal along with Cassini and Deep Impact data.

Other instruments onboard Chandrayaan-1 like the Chandrayaan-1 Altitude Compositional Experiment (ChACE), a part of the Moon Impact Probe (MIP), revealed signals of water (H2O) and carbon dioxide (CO2) molecules as it descended to the lunar surface. Even NASA’s mini-SAR found the presence of sub-surface ice in permanently shadowed areas of the lunar south pole. NASA confirmed this discovery with its LCROSS and LRO missions.

India’s maiden moon shot became the beacon for the discovery of water on the Moon!

End of the Mission

Chandrayaan-1 was overall a highly successful mission. But undertaking a maiden planetary mission with no surprises would be impossible. For us, the DC/DC converters onboard the spacecraft failed earlier in the mission. These failures disabled the spacecraft to utilize the star sensor for orientation referencing. The spacecraft team came up with a unique process of operating the spacecraft using the data from all the science payloads. Therefore Chandrayaan-1 was able to achieve great science, including finding water on the Moon. Finally, on 29th August 2009, all contact was lost subsequent to the failure of redundant DC/DC converters.

References

• Mission Moon: The Story of Chandrayaan by Biman Basu

• Chandrayaan-1: India’s Giant Leap to Moon by B R Guruprasad

• From Fishing Hamlet to Red Planet

• isro.gov.in

• https://www.issdc.gov.in/

• https://www.jpl.nasa.gov/missions/moon-mineralogy-mapper-m3/

• https://solarsystem.nasa.gov/missions/chandrayaan-1/in-depth/

• https://earth.esa.int/web/eoportal/satellite-missions/c-missions/chandrayaan-1

• https://www2.mps.mpg.de/en/projekte/chandrayaan/

Conceptualisation of PSLV

PSLV, the third generation launch vehicle, is the successor of India's SLV-3 and ASLV launch vehicles. ISRO's orbital flight journey started with the SLV-3 rocket on 10th August 1979. Even before this SLV launch, Dr Satish Dhawan, then Chairman of ISRO, formed a study group responsible for defining a configuration for a vehicle capable of placing a 600 kg satellite in Sun-synchronous orbit (500–1,000 km). S. Srinivasan was the head of this group targeting the first experimental launch in 1984–85.

The study group initially considered three configurations for PSLV, to be launched from the Sriharikota Range. At one time, ISRO even toyed with the idea of establishing another range down south from where PSLV could be launched due south. Such a sight will enable straight launch into polar orbit instead of azimuth constraints of the SHAR launch site.

• 2 × S80 + S80 + L30 + PAS (Perigee–Apogee System)

• 9 × S10 + L45 + L15 + PAS

• 4 × S80 + S80+ S20 + PAS

In the meantime, the French Space Agency, CNES, and ISRO came together into an agreement where CNES would transfer the knowledge for their liquid engine, and India would supply 10,000 space-qualified transducers. This agreement resulted in a breakthrough for ISRO. ISRO then developed the Vikas engine, the indigenous version of Viking (French counterpart). Now, a new configuration was considered for PSLV:

• 6 X S9 + S125 + L33 + S7 + S2

In simpler words, six solid strap-on boosters with 9 tonnes propellant loading for PS0 with a single solid core of 125 tonnes for the first stage, PS1, followed by a 33 tonnes propellant loaded liquid second stage, PS2. And finally, 7 tonnes and 2 tonnes of solid cores for the third and fourth stages, respectively. ISRO received the sanction for this configuration in 1982.

Lesson-1: Liquid over Solid for Forth Stage

Over the next few years of the development phase, many new technologies evolved, but a few critical changes in the configuration were done quite early. The final solid stage would have resulted in an inaccurate injection of the satellite. The liquid stage's ability to be switched off or on mid-operation and change the flow rates makes wins here. This ability can help in the design of a closed-loop control system as compared to the solid stage. Therefore, the final and fourth stage became liquid as well. The propellant loading of PS2 was also increased to 37.5 to augment payload capacity. Thus the configuration of the first PSLV flight, PSLV-D1, was 6 X S9 + S125 + L37.5 + S7 + L2.

PSLV-D1 Mission Objectives

• Realisation of the complex integrated mission involving many new technologies related to vehicle, range, and ground stations.

• Flight testing the integrated flight system and to inject IRS-1E satellite into a polar sun-synchronous orbit.

• Evaluation of the in-orbit performance of IRS-1E carrying multispectral LISS and MEOSS payloads.

PSLV-D1 Vehicle details

• Height: 44 m

• Diameter: 2.8 m

• Lift-Off Weight: 280 tonnes

• Number of Stages: 4

• Payload Weight: 846 Kgs (IRS-1E)

• Launched on 20th September 1993

Lesson 2: Change designs mid-course | Lessons Learnt from ASLV flights

While the development phase of PSLV had started after the sanction from GOI in 1982, the ASLV launch vehicle project was still in the testing phase. Therefore, the first two failures of ASLV necessitated ISRO to review and rework the PSLV Mission Design. Without going into the details of the ASLV flights, I would list a few significant guidelines incorporated. While all these guidelines are lessons learnt, the more important lesson for me is the change of Mission Design during the development phase.

• Aim for peak dynamic pressure as low as possible.

• Provide for the seasons' worst-case peak wind angle of attack, wind shear and gust values.

• Ensure availability of control force during the entire atmospheric phase of the flight.

• Introduce real-time decision making during critical regimes of flight.

• Aim for positive or neutral static stability margins.

• Take into account reliable estimates of dynamic pressure, tail-off thrust, wind and angle of attack while setting the jettisoning energy for stage separation.

In case you have doubts regarding the reasoning behind any of these guidelines, please comment below, and I would revert.

The Bold Decision to Work with Digital Systems

Today, the world around us revolves around digital systems. We work on embedded systems right from our undergraduate levels, and binary coding is taught even in high-schools. Three decades ago, the scenario was different. Space agencies in the USA, Russia and Europe were using analog techniques for control loop design. ISRO decided to go with digital implementation, and that too with a processor with severe performance limitations. They were doing everything in binary arithmetic and programming in machine language. This bold decision became of the reasons for the failure of PSLV-D1.

I should add that the decision itself was not wrong, but the implementation required something extra. This will be indeed clear by the end of this article, so read on.

There were many more design decisions, trade-offs and discussions. Some of these are listed in the article, 'PSLV: The Workhouse of ISRO', by N. Narayanamoorthy in the book, From Fishing Hamlet to Red Planet. I have inspired most of this blog post from the article only.

PSLV-D1 Launch | The Maiden Flight of PSLV

The launch campaign for PSLV-D1 took 115 days as opposed to the expected 90 days. This delay was okay being the first attempt. Finally, the countdown for the PSLV-D1 mission commenced on 16th September 1993. A minor snag on the launch day, 19th September, pushed the launch to the next day 20th September. Overall, the countdown performing for the first time was satisfactory.

The PSLV-D1 lifted off majestically on 20th September 1993 through thunderous applause and a sense of relief. The strap-on boosters, first stage and second stage, performed nominally. Though the mission control room was anxious for the stage separation events, they also went quite satisfactorily. But the mission was not over yet. Immediately after the ignition of the third stage, though control force being available, the pitch error went beyond limits, and the vehicle started tumbling. The result was a mission failure, even though the third and fourth stage propulsion system performed normally.

The post-flight analysis of the telemetry identified three issues, namely the following:

• During the second stage separation, two of the retro rockets has not functioned as the initiators were not commanded, indicating a break in the pyro chain electrically.

• During the second stage regime, yaw error build-up was excessive and was not being corrected due to specific autopilot problems.

• The pitch error was increasing due to an error in software implementation during the third stage regime.

Lesson 3: The Bane of Digital Systems

Further detailed investigations pointed towards an overlook during the in the software implementation. To understand this error better, we need it to understand the mounting of the electromechanical actuators of the third stage (PS3) flex nozzle control system. These actuators were mounted in such a way that the pitch command signal needed polarity inversion before being fed to the control electronics.

Now, the error computation by the Digital Autopilot (DAP) as implemented in the GCP (Guidance and Control Processor) was done in 32-bit fixed-point arithmetic using 2's complement representation and truncated 16 bits and then to effect the inversion. The following article can help in understanding the fixed-point binary arithmetic: https://inst.eecs.berkeley.edu/~cs61c/sp06/handout/fixedpt.html

The overlook was that no one foresaw the possible danger in this scheme during design and simulation. The software, as implemented, had no provision to limit the signal to a predetermined value or to recognise overflow condition. This meant that in case the error became large enough, the bits will not be enough and there will be an overflow. This overflow will then result in no inversion, which in turns lead to the flight going beyond control. All this happened during the PSLV-D1 mission, and it ended in tragedy.

Lesson 4: Quality control and assurance

ISRO realised the above error and corrected it. But such as error should have been detected and solved on the ground before the flight itself. The space agency acknowledged that the concepts of quality control, quality assurance, configuration control are to be applied as much to software as to hardware. This realisation resulted in setting up of an exclusive mission software testing and validation group which would evaluate the entire flight software on different simulation testbeds to eliminate any errors due to singularity, scale factor overflow and other parameters. Also, the documentation process and code walkthrough reviews were made mandatory before the commencement of any software testing.

Learning from the Failure: PSLV-D2

The next flight of PSLV after the PSLV-D1, PSLV-D2, performed flawlessly. Narayanamorrthy Ji describes this achievement as "We can also say that for the first time we successfully orbited an application satellite of the IRS class with a precision of which any advanced spacefaring nation could be proud." The learnings from SLV-3, ASLV, and PSLV-D1 mission, were all responsible for this success and all 47 subsequent successful PSLV flights. Even our interplanetary missions, Chandrayaan-1 and Mars Orbiter Mission, were launched using PSLV-XL. It has been nine months since the last PSLV launch. Hopefully, we will see one before the year ends.

Writing this article gave me the idea to write an article comparing the PSLV-D1 configuration with the current PSLV launch vehicle and list what all has been improved. Let me know if you want me to write such a blog post.

References:

• https://www.isro.gov.in/launchers/pslv

• https://www.isro.gov.in/launchers/aslv

• https://www.isro.gov.in/sites/default/files/pdf/pslv-brochures/PSLVD1.pdf

The Spacecraft

EDUSAT was a communication satellite and is also known as GSAT-3. It was the first dedicated tele-education satellite of India, which provided two-way communication to classrooms.

Mass: 1950.5 Kg (Lift-Off) & 819.4 (Dry Mass)

Bus: I-2K (I-2000)

Payload:

• Six upper extended C - band transponders

• Five lower Ku band transponders with regional beam coverage

• One lower Ku band National beam transponder with Indian mainland coverage

• Ku beacon

• 12 C band, high power transponders with extended coverage, covering southeast and northwest region apart from the Indian mainland using 63 W radiatively cooled Ku-band Travelling Wave Tube Amplifiers

Antenna: Multiple spot beam antenna with 1.2 m reflector

Thermal: Dual-core bent heat pipe

Power: Total four solar panel of size 2.54 M x 1.525 M generating 2040 W (End Of Life), two 24 AH NiCd batteries for eclipse support

Stabilization: Three-axis body stabilized in orbit using sensors, momentum and reaction wheels, magnetic torquers, and eight 10 N & 22N reaction control thrusters

Propulsion: 440 N Liquid Apogee Motor (LAM) with MON - 3 and MMH for orbit raising

Launch:

GSLV's first operational flight, GSLV-F01, launched EDUSAT (GSAT-3) on September 20, 2004, from SHAR, Sriharikota, India. The satellite, initially placed in Geo-Transfer Orbit (GTO), was later shifted to Geostationary (74°E longitude) orbit using the LAM motor.

Mission Life: 6 Years

EDUSAT Utilisation Programme

In 2002, ISRO/ Department of Space made the first proposal for a dedicated exclusive education satellite during a meeting with the Space Commission and Ministry of Human Resources Development. The following factors formed the basis for the recommendation:

• An acute shortage of qualified teachers both at the school level and higher education, including engineering and other technical subjects.

• A massive drop out of students at the school level.

• A need for formal and non-formal and continuing education to the vast masses of the country through satellite, viz., EDUSAT given an enormous population of illiterates and rural literacy.

• Need to supplement curriculum-based teaching, provide practical teacher training, facilitate community participation, and enable interaction between scholars and research.

• Need to provide a quantum jump in providing access to education to remote areas and improving education quality.

Subsequently, in August 2002, the Space Commission approved Rs 85 crore's budget to develop an exclusive education satellite. However, to harness the true potential of the satellite, a network was to be developed. This EDUSAT network would have a hub and studio facility at state capital/designated place of users, Satellite Interactive Terminals (SITs) at universities/colleges, and Receive Only Terminals (ROTs) at schools. Establishing all this ground hardware demanded a separate allocation of resources. Therefore, the Space Commission established the EDUSAT Utilisation Programme (EUP) with a Rs 98 crore budget.

EDUSAT Utilisation Programme (EUP) was to be utilized by various national and regional users. The national users were to be Indira Gandhi National Open University (IGNOU), National Council of Education Research and Training (NCERT), Integrated Disease Surveillance Programme (IDSP), and National Council of Science Museums (NCSM). The regional users were to be state governments, universities, colleges, and schools. ISRO established the national ground network and also provided one hub and ten terminals to each State/Union Territory free of cost.

Objectives of EUP

The EUP was established with long-term goals in mind. Even after the decommissioning of EDUSAT in 2010, EUP still worked with networks shifted to other satellites. In September 2011, there were 47 hubs available in EUP. One hub was capable of supporting eight networks. These networks could support a maximum of 500 SITs, primarily for universities/colleges, and many ROTs, mainly to schools. Therefore, EUP could support 376 networks, and in turn, 1.88 lakh SITs and any number of ROTs. The following were the objectives of EUP.

• To provide support to education through the low-cost ground segment and reach the unreached people of India in every nook and corner

• To provide sustainable distance education service and support formal and non-formal education in India

Three Phases of EDUSAT Utilisation Programme (EUP)

Department of Space organized the EUP in three phases. These were the pilot phase, semi-operational phase, and operational phase. INSAT 3A/3B satellites were used in the pilot phase to ensure that the technology worked with a satellite-based solution. In the semi-operational phase, EDUSAT was used to establish national and regional networks. In the operational phase, the users were to procure ground segments with technical support from ISRO, and the network was to become fully functional.

Lacks and Recommendations for Further Missions

EDUSAT Utilisation Programme had many issues and lacked in some significant aspects. A 2013 union audit report listed all these shortcomings with recommendations to ISRO for further missions. The report is over 35 pages long, listing all the lapses won't be feasible for this article. I will, therefore, list major recommendations of the audit.

Issues in Planning of EUP

Lapses:

There were issues in the planning phase itself. ISRO did not fix the target dates and action plans for the establishment of the ground network. The dates for the start and end of the three phases were not decided, nor were fixed number of hubs established in each phase. The plan of action for running educational programs was also inadequate.

Recommendation:

DOS/ISRO need to plan their satellite-based application programs only after ensuring that definite plans in terms of finances and infrastructure are in place to fully utilize the satellites.

Issues in Execution of EUP

Lapses:

As opposed to the operationalization of ground networks in March 2005 (6 months after the launch), there was a delay in establishing ground networks in at least 14 states. Overall these delays resulted in a considerable underutilization of EDUSAT capacity. There was a massive disparity in allotment of satellite capacity amongst states for both colleges & schools. Even thefts for the free hardware given by ISRO were reported. A full-time education program channel would require 6,570 educational programs per year with three repeat programs at a rate of 18 hours a day. Inadequate planning resulted in deficiencies of content generation as well.

Recommendations:

• In satellite-based application programs wherein stakeholders other than DOS/ ISRO were to be involved, DOS/ISRO may constitute a management structure to sort out issues that would come up during the program's implementation.

• ISRO should allocate bandwidth to all users most objectively and transparently to avoid differential treatment and subjectivity in bandwidth allocation.

• ISRO also needs to impress upon users to improve bandwidth utilization by creating an appropriate management structure so that the precious national resource is utilized optimally for the benefit of unreached masses and the rural population.

Deficiencies in replacement planning of EDUSAT

Lapses:

EDUSAT was decommissioned in September 2010, due to power constraints on the satellite. This failure resulted in shortening the satellite's mission life from seven (2011) to only six years. But, ISRO had planned replacement to EDUSAT transponders in GSAT-14 only in the 12th Five Year Plan period (2012-2017). Therefore, it was evident that ISRO could not schedule a replacement for EDUSAT transponders in time to provide continuity to operational EDUSAT networks. Some of the networks were shifted to other satellites but impacted the services of those INSAT series satellites.

Recommendation:

In satellite-based application programs of DOS/ISRO, it should implement a replacement strategy for the existing satellite in advance to avoid interruption to its satellites based operational programs.

In conclusion, the objectives of the implementation of EDUSAT could not be achieved. Despite all these lapses, the EDUSAT program served as a significant learning ground for ISRO. All the data mentioned in the articles were only valid as per the 2013 report. I hope that the EDUSAT Utilization Program is currently serving its potential, and the full capacity is reached. If you have any comments or updates on Tele-Education in India, please comment below or contact us through the form on the About Us page.

References

1. https://www.isro.gov.in/Spacecraft/edusat

2. https://en.wikipedia.org/wiki/GSAT-3

3. https://www.isro.gov.in/applications/tele-education

4. https://cag.gov.in/sites/default/files/audit_report_files/Union_Compliance_Scientific_Department_Audit_22_2013_chap_3.pdf

First Dedicated Meteorological Satellite

Indian Space Programme focused to cater to civil applications such as telecommunication, television, weather and remote sensing since its inception. This vision resulted in the INSAT series of satellites. The series began as telecommunication satellites but expanded to television, meteorological and remote sensing applications. Generally, the mission served multiple applications in a single spacecraft. MetSat-1 became the first dedicated weather satellite.

At the dawn of the 21st Century, two operating meteorological payloads in orbit stopped operating. The VHRR/2 payload onboard the INSAT-2E satellite failed just after launch in 1999. Now, only the INSAT-2B satellite launched in 1993 remained. But it was limited in the station-keeping fuel. On Nov. 4, 2000, ISRO retired the satellite after it completed its mission life in July. It was, therefore, essential to launch another weather satellite soon.

Developing a multi-purpose satellite would take a lot of resources. Therefore, ISRO planned and designed the MetSat-1 satellite as a cost-effective alternative solution. This mission would serve exclusively in GEO for meteorological payloads and services. While it was definitely important to have a cost-effective and quick solution, the satellite did provide other advantages. The performance of the meteorological payload gets constrained in the environment of high power transponders.

Objectives

Major MetSat-1 / Kalpana-1 mission objectives are:-

• To establish a small satellite I-1000 bus system that can meet the exclusive service requirements of a meteorological payload for earth imageries

• Collection of weather data from low-cost unattended data collection platforms to configure Metsat spacecraft within the lift-off mass constraints of the upgraded existing polar satellite launch vehicle for deployment in geo-synchronous transfer orbit (GTO) mission.

Kalpana-1 / MetSat-1 Spacecraft

Bus: I-1000

The UR Rao Satellite Center (URSC) designed the new I-1000 bus employing lightweight structural elements like CFRP (Carbon Fibre Reinforced Plastic). A central structural thrust cylinder provides mounting interfaces with structural brackets.

Propulsion Subsystem

• Fuel: Bi-propellant - mono-methyl hydrazine (MMH) and mixed oxides of nitrogen (MON3).

• Thrusters: One 440 N LAM for orbit raising manoeuvres and eight 22 N thrusters for orbit and attitude control

Control Subsystem

• Type: Three-axis stabilized (momentum biased control subsystem)

• Sensors: Gyroscopes, Earth sensors, digital sun sensor, coarse analog sun sensors, and solar panel sun sensor

• Actuators: Magnetic torquers and active thrusters

Thermal Subsystem

• Passive: Multi-layer insulation blankets, optical solar reflectors, heat sinks, paints, thermal grease, thermal shields

• Active: 112 heaters spread over the satellite maintain the temperature of individual subsystems

EPS (Electrical Power Subsystem)

• Power: 550 W

• Solar Panel: Single panel solar array of 2.15 m x 1.85 m using GaAs solar cells

• Battery: Single NiCd battery (18 Ah capacity) provides power for eclipse phases

Communication Subsystem

• Downlink Frequency: C-band (4503.05 MHz)

• Downlink Data Rates: Up to 526.5 kbit/s

• Uplink Frequency: 402.75 MHz

• EIRP: 18 dBW

• Antenna: Planar array antenna

Other Properties

• Launch Mass: 1055 kg

• Propellant Mass: 560 kg of propellant

• Design Life: 7 years with an operational goal of 10 years

Payloads

VHRR Instrument

The VHRR observes in VIS, water vapour and TIR bands providing a spatial resolution of 2 km in VIS band and 8 km for the rest. SAC (Satellite Application Center), Ahmedabad developed the instrument.

DRT (Data Relay Transponder)

The DRT (Data Relay Transponder) is part of a DCS (Data Collection System) of ISRO. The objective is to collect data from unattended meteorological platforms in the ground segment.

Launch and Status

• Launch: PSLV-C4 launched the MetSat-1 spacecraft on 12th September 2002 from the Satish Dhawan Space Center, SHAR.

• Status: The MetSat-1 / Kalpana-1 satellite operated for more than 15 years as compared to its seven years of mission life. Until 2018, it kept providing essential data needed for weather predictions and other meteorological applications.

Renaming to Kalpana-1

After the Columbia Space Shuttle (STS-107) Disaster, Prime Minister Mr Atal Bihari Vajpayee announced that India's meteorological series of satellites, MetSat, will be named as KALPANA. The announcement was made during the condolence meeting to honour Astronaut Kalpana Chawla, born in Karnal (1961), India in the Columbia disaster.

References

1. https://directory.eoportal.org/web/eoportal/satellite-missions/k/kalpana-1

2. https://www.mosdac.gov.in/satellite-catalog

3. https://www.isro.gov.in/Spacecraft/kalpana-1

4. https://www.mosdac.gov.in/kalpana-1-objectives

The Department of Space of the Government of India has recently been in the news for opening the Indian Space Industry for private players. Their recent webinar, hosted live on YouTube gained a lot of praise and positivity. While the webinar overall provided the DOS and ISRO suggestions to make IN-SPACe better, it was an eye-opener for me. Many of the industries invited to participate were unknown to me. On a further quick search of ISRO's website also didn't provide much insight into the Industry Partners of ISRO. In all these times subreddit r/ISRO comes to the rescue. Based on the inputs, I have compiled this list of ISRO Partners.

As I searched more, the list of Industry partners kept getting longer. Even many scientists have said that there are over 150 ISRO partners spread all over India. Therefore, it was essential to categorise them for ease of handling and understanding all the data. Through my research based on their company websites and various presentations, I have classified them according to their central subsystem area. You'll also get a summary of future plans of companies involved in the 'Unlocking India's Potential in Space Sector' Webinar.

25 Mechanical/Propulsion ISRO Partners

Godrej Aerospace

Godrej Aerospace had been involved in the Indian Space Programme since its inception back in 1985. It provides Hi-Tech Aerospace Manufactories Services. Vikas engine, used in the PSLV, was the first engine manufactured by Godrej and they followed onto cryogenic and semi-cryogenic engines. As described on their website, they are involved in 'Precision machining, Precision fabrication, (Welding & Brazing), Heat Treatment, Surface Treatment, Assembly, Testing & Supply of Complex & Airworthy Systems'

In the recent webinar, they discussed their future goals. Complete satellite propulsive system is one of the technologies that they want to take forward. The Vikas engine is manufactured in a pre-assembled mode by Godrej. They now plan to learn and move into the assembly of engines with the help of hand-holding by ISRO.

HAL-Aerospace

Hindustan Aeronautics Limited is a Defence Public Sector Undertaking under the Department of Defence. While, it is India's flagship national aerospace company, proving helicopters and trainers for the defence sector, the association with the space sector began in the early 1970s.

ISRO partnered with HAL for providing light alloy structures. It has since been involved in both satellite as well as launch vehicle structures. From Aryabhata to Chandrayaan 2, they have been contributed to almost all satellite missions. On the launch vehicle front, it participates in the assembly and integration of engines. They plan to expand their facilities for stage integration of PSLV and GSLV. You can find more about their association in the second link references mentioned in the end.

MTAR Technologies Private Limited

Founded in 1970, to indigenously develop and manufacture components and equipment for the space sector, MTAR Technologies Private Limited also is a pioneer in Precision Machining, Testing and Assembly Facilities. It has made its foray into Aerospace, Oil & Energy and Ball Screw sectors.

MTAR has been involved with ISRO since the past 34 years. It is one of the partners of Godrej Aerospace to make engines for PSLV and GSLV. They also plan to expand to stage integration of ISRO launch vehicles.

AVASARALA Technologies Limited

Avasarala was started in 1986 as a project consultancy company. It has since diversified into the precision assembly of various products for nuclear, space, defence and other R&D sectors. It was in 2001 that the company advanced into space industry with the manufacturing of heat pipes for satellites such as GSAT, INSAT and CARTOSAT series, AstroSat, Chandrayaan, RISAT and many more. It also provided complete thermal systems which have been used onboard satellites such as INSAT-3D and CARTOSAT-2B satellites.

Apart from thermal management systems, Avasarala provides high precision manufacturing and Ion Beam polishing service. The company also offers heaving machinery like thermovac chamber, conformal coating system, CNC performing machine, spill collection systems. They also re-furbished the W2M transport container of ISRO.

BrahMos Aerospace

Another company which partners with ISRO on the Precision Machining, BrahMos Aerospace was established in India after an inter-governmental agreement with The Russian Federation. They partner with other ISRO partners in the development of Vikas Engine and also manufacture propellant tanks.

Larsen & Toubro Limited

Larsen & Toubro is an Indian multinational engaged in technology, engineering, construction, manufacturing and financial services. L&T has partnered with ISRO for close to 50 years in the area of Launch Vehicles. Even the Deep Space Network Antenna at ISTRAC was installed and commissioned by L&T. Like all other industries involved in Launch Vehicle technology, they also plan to expand into PSLV integration and operations.

Walchand Industries Limited

Walchandnagar Industries Limited (WIL), is a Heavy Engineering Company with a presence in Strategic Sectors like Defence, Nuclear & Aerospace. ISRO and WIL started their association with the manufacturing of motor cases for SLV-3 in 1973. Since then WIL has participated in all launch vehicle programs in providing motor casing. As per their website, they have provided 141 strap-on boosters for PSLV/GSLV Mk II, 134 core boosters for PSLV/GSLV Mk II and 16 core boosters for GSLV Mk III till now.

ASACO

ASACO was founded in 1969 with a vision to revolutionise the Indian Metal Forming and Cable Industries by introducing the World's best European Equipment in India. The PSLV Stage Four Engine - PS4, a liquid propulsion engine is manufactured by this company alone. No other ISRO partner manufactures this engine. The engine is also used in the first stage for roll.

Paras Defence and Space Technologies Limited

PDSTL is a Mumbai based company which manufactures optics for space and defence sectors. As per their website, they have been involved in Chandrayaan 2, Mars Orbiter Mission, ResourceSAT 3S and Aditya-L1 missions. They also provided gratings for the HySIS and GSAT 29 satellites.

Other ISRO Partners in Space Industry working in Mechanical Sector

• Linde Group: Integrated Fluid Service System for C-25 Thrust Cryogenic Engine Test facility and Fluid System of Cold Test Facility at LPSC-ISRO, Mahendragiri, India

• MECON Limited: Execution of Second Launch Pad at Sriharikota

• CCTC Bhubaneswar: High Precision Manufacturing

• Microtech Precision, Hyderabad: High Precision Manufacturing

• Amado Tools, Bangalore: High Precision Manufacturing

• Craftsman Automation, Coimbatore: High Precision Manufacturing

• Microfine Bushings: Umbilical Cords

• Metallic Bellows Private Limited: Bellows and Metallic Flexible Hoses

• MIL Industries Limited: PTFE Flexible Hoses

• KCP Limited: Mobile Launch Platform at Sriharikota

• Kerala Automobiles Limited: High Precision Manufacturing

• Microtech Engineering, Bangalore: High Precision Manufacturing

• K max industries, Chennai: High Precision Manufacturing

• Jojo Industries, Ettumanoor: High Precision Manufacturing

• AIS, Nazareth: High Precision Manufacturing

• Mech VACC, Mumbai: High Precision Manufacturing

15 Electronics/Communications ISRO Partners

Keltron

Keltron is a government of Kerala undertaking, producing a wide range of products from discrete electronics components to complex equipment and systems. Right from the beginning of launch vehicle technology in India from SLV program to GSLV Mk III, Keltron provides avionics packages for these launch vehicles. About 40 to 50 Keltron packages fly onboard each PSLV and GSLV.

They plan to expand to sub-assemblies and subsystem fabrication. A reflow soldering facility and clean room for sub-assembly fabrication have recently commissioned at the Keltron Equipment Complex. VSSC has also identified the company as a nodal centre for training and certification in high-reliability soldering and inspection of satellite/launch vehicle electrical packages.

Ananth Technologies Limited (ATL)

Ananth Technologies Limited, incorporated in 1992, offers the manufacturing of critical aerospace systems and high-value geospatial services. According to their website, they have been 'integral in about 50 launch vehicles and close to 100 space crafts'. Also, their Geospatial services are widely used for town planning and infrastructure building.

Ananth has been one of the ISRO Partners since 1998. They are involved in launch vehicle and onboard satellite systems along with the ground checkout systems. Their range of products is quite wide from telemetry systems, OBCs, RF boards, control sensors and actuators, antenna and optical systems. They are also involved in the launch vehicle integration activities at Sriharikota. A detailed list of their products and services can be found on the second link in references mentioned in the end.

Electronics Corporation of India Limited (ECIL)

ECIL was set up under the Department of Atomic Energy in 1967 intending to generate a strong indigenous capability in the field of professional grade electronics. ECIL works on three major technology lines viz. Computers, Control Systems and Communications.

Company's association with the Indian Space Programme dates back to 1968 when they developed and commissioned India's 1st INTELSAT Class-A Earth Station Antenna at ARVI, Pune. Since then, ECIL is involved in developing various satellite ground station antennas.

Centum

Centum was founded in 1994 in Bangalore, India. There are four central business units: Centum Adeneo Engineering, Centum Strategic Electronics, Centum Adetel Transportation Solution and Centum Electronics Manufacturing Services.

They have been associated with ISRO since 2002. They provide satellite bus systems, test tools, power management system and data recorders for satellites. Recently a complete payload was built by Centum. A detailed list of their products and services can be found on the second link in references mentioned in the end.

Astra Microwave Products Limited (AMPL)

Astra Microwave Products Limited (AMPL), incorporated in 1991, work in the fields of RF, Microwave, and Digital electronics. Their space group started back in 2004. AMPL also has a wide range of products for both flight and ground-based applications. They also provide INSAT MSS (mobile satellite system) Terminals. Their specialisation is in RF systems. A detailed list of their products and services can be found on the second link in references mentioned in the end.

Alpha Design Technologies Private Limited

Established in Bangalore during 2004, ADTL specialises in R&D, manufacture, assembly, testing, qualification, integration & installation of Defence Electronics, Avionics & Space Satellites systems. They provide ground, navigation and satellite equipment such as Navic and GPS receiver and Antenna Control Systems. Satellite services ranging design, development, assembly, integration, testing, site planning and maintenance is also provided by alpha.

ADTL has been recently involved in the assembly, integration and testing of two launched satellites 1.5-ton IRNSS-1I and 3.5-ton GSAT-30 as a consortium. Currently, they are working on the RISAT-2BR2 to be launched in November 2020. In future, the small satellite market is their target. A detailed list of their products and services can be found on the second link in references mentioned in the end.

Data Patterns

Data Patterns is one of India's leader in indigenously developed electronic systems in the Defence and Aerospace domain. It started ISRO partnership around 20 years back by making checkout systems for ISRO such as the Second Launch Pad Count Down Checkout System.

In the past five years, they have expanded into small satellite domain. Data Patterns has designed and developed standard off-the-shelf products for Nanosatellite bus suitable for Low Earth Orbit (LEO) satellite missions. Most of the subsystems are proven in space, flown on NIUSAT, INS-1A, INS-1B & INS-1C satellites.

Currently, they are developing two complete satellites for the private industry, one to be launched by Russia and one probably with ISRO. They plan to expand more to provide full small satellite service right from development to ground station capabilities.

VCB Electronics

The Pune-based company started in 2001 to provide a dedicated facility for fabrication, testing and evaluation of avionics packages. VCB Electronics has been associated with all centres of ISRO right from inception.

They are involved in providing thick-film hybrid micro-circuits and wiring, assembly, integration and testing (WAIT) of modules for launch vehicle applications. To test all systems in-house, VCB has established Full-fledged Environmental Testing Facilities including thermo-vac, shock and vibration.

Lakshmi Technology and Engineering Industries (LTE)

LTE was incorporated in the year 1968 and ventured into Aerospace industry in the year 2004. This company provides components such as control valves, DC motors, transducers for launch vehicle as well as spacecraft systems.

Other ISRO Partners in Space Industry working in Electronics and Communications Sector

• ITI Limited: VSSC Flight Package Assembly Plant at Pallakad

• Bharat Heavy Electronics Limited (BHEL): space-grade solar panels and batteries, technology transfer of space-grade Li-Ion Batteries

• Bharat Electronics Limited (BEL): NavIC Messaging Receiver Technology Transfer, S-band Polarimeter Doppler Weather Radar (DWR)

• Electronics Regional Test Laboratory (ERTL): Electronical, Environmental and Component Testing

• Andhra Electronics: Indigenous Crystal filters

• Tata Consultancy Services (TCS)

10 Materials/Chemical ISRO Partners

Heavy Engineering Corporation Limited

Heavy Engineering Corporation Limited is one of the leading suppliers of capital equipment in India for steel, mining, railways, power, defence, space research, nuclear and strategic sectors. According to their website, they have provided Folding cum Vertically Repositionable Platforms (FCVRP) for space vehicle integration, Horizontal Sliding Door (HSD), Mobile Launch Pedestal (MLP), Development of Special grade of steel for ISRO and more.

TATA Advanced Materials Limited (TAML)

TAML is composite manufacturing and solutions company which caters to the aerospace, space, defence and industrial sectors. It has had a fifteen-year long journey with VSSC, ISRO. Their website states that they provide Solar Panel Substrates (SPS), Yokes, Interstage Assemblies (PLA, PS3A & IS3/4 components) and Deck Plates. It is one of the leading providers of materials to ISRO.

ANABOND Limited

Anabond Limited is one of the leading manufacturers of Engineering Adhesives & Sealants, Paints, Speciality Coatings & other chemical formulations in India since 1979. They started providing adhesives for aerospace applications in 1992.

Other ISRO Partners in Space Industry working in Chemicals and Materials Sector

• Advanced Systems Laboratory (ASL): Propellant Production

• Hindustan Organic Chemicals Limited: Propellant Production

• Bharat Aluminium Company Limited (BALCO): Manufacturing AA2014, AA2219, AA7075 and AA6063 alloys for VSSC

• Mishra Dhatu Nigam Limited (MIDHANI): Materials for Vikas Engine and Motor Casing

• Berger Paints: Fire Retardant Paint Technology Transfer

• Performance Polymers: PC 10 TPS Technology Transfer

• Surmit Enterprises, Procyon Technology, Pardhan Engineering: Black Anodizing on Aluminum 6061-T6 and Chromating Technology Transfer

References

1. S Somanath's 'Access to Space' presentation from 2009 at BSX

2. ESSRI 2017 presentations from ISRO's spacecraft subsystem suppliers

3. 'Unlocking India's Potential in Space Sector' Webinar

4. SAC Industry Portal

5. Company Websites and Brochures

SLV-3 Rocket | India's First Launch Vehicle

Specifications

• LEO Payload: 40 kg to 400 km Orbit

• Lift-off Thrust: 454.93 kN

• Total Mass: 17,610 kg

• Core Diameter: 1.0 m

• Total Length: 24.0 m

• Horizontal Integration

Primary Objectives of SLV-3 E1 Mission

1. Realize the SLV-3 launch vehicle system ready for flight after qualification and acceptance tests of its various subsystems

2. Flight-test the SLV-3 vehicle and to evaluate the performance of the stage motors and performance of the stage control systems and all other vehicle subsystems

3. Realize the launch complex and ground station facilities for the launch operations

Electrostatic Discharge over Payload Fairing | A lesson in Design Engineering

We all know that the rocket payload fairings are metallic. But the Indian SLV-3's payload fairing used phenol-glass honeycomb sandwich materials. The Rohini Technology Payload (RTP) had to communicate the telemetry for the in-flight monitoring during the launch phase. This requirement had led to the decision of using the insulating material for the ascent fairing.

While the use of insulators solved the requirement issue, it brought its own—the problem of electrostatic charge build-up. There were many risks associated with charge accumulation, such as arc-overs. The solution was simple. Use several longitudinal metallic wires embedded in the fairing. But now, these wires could compromise the radio transparency of the original requirement. Therefore, they tested the system by creating a particular test setup.

The similar problem of unequal electrostatic discharge on different stages was also solved using thin connecting wires between the stages. These wires would snap when the separation between the stages increased to about a meter.

An explosion during RCS testing | A lesson in Safety Procedures

The second stage of the SLV-3 launch vehicle used a bi-propellant reaction control system (RCS). Red Fuming Nitric Acid (RFNA) and Hydrazine were the two propellants used. The combination of these fuels results in a Hypergolic Propellant, which means it ignites simultaneously as the two fuels come into contact with each other.

On 18th May 1978, the second-stage control system was ready for the first hot test. But before the test could begin, a minor leak was noticed in the RFNA line. To rectify the leaking joint, the team removed the protective garments. The hot and humid weather was the culprit behind this decision. Suddenly, the fuels burst into an explosion. Fortunately, no-one got killed, but six individuals sustained critical burns.

The incompatibility between the fibreglass tank and the internal rubber lining was identified as the cause of the leak and subsequent explosion. ISRO then decided to use a stainless steel tank for RFNA and Teflon for bladder material. Also, better protective garments with forced air cooling were made available.

Perfection is not the Key to Success | A lesson in Systems Engineering

One of the significant configuration and status reviews of SLV-3 ended with everyone understanding the importance of 'Good-Enough' rather than 'Perfect'. The review meeting started on 23rd October 1978 with participation from Prof Dhawan and Dr Brahm Prakash. Once the starting remarks ended, and the meeting went into free-for-all mode, differences rose related to time-schedules and readiness of subsystems. Every subsystem wanted more time to improve its specifications. While the overall system required systems which fulfilled the requirements, subsystem teams were so motivated, that they were trying to accomplish more. This was resulting in delays and mismatches.

Dr Brahm Prakash concluded the meeting on 24th October (yes, it took two days). He ended with a humorous story, as described by Ved Prakash Sandlas, 'Once, a professor selected two PhD students. After a couple of years, one student completed his work quickly and submitted the thesis. The other student had not even finalized his choice of problem, and had been changing his ideas continuously, prompting the professor to say, 'My friend, where would you have been if your father had waited for the last suitable girl?"

During my time at the IIT Bombay Student Satellite Team, I have also realized this critical aspect of systems engineering. We often undertake a journey to achieve the best possible. While as an overview, it seems a great idea, it leads to delays. Any system has a time when it should be designed, manufactured and deployed. If you strive to go a few extra steps, it may lead to losing these deadlines. And the competitors take over with less but good-enough products.

The Final 'Partially Unsuccessful' Launch | A lesson from the Failure

SLV-3-E-01 launched on 10th August 1979 at 0758 hours. The lift-off was flawless, followed by the perfect first stage burn. At about T+50 seconds, the second stage had taken over. The tracking radars started announcing lower range and altitude, indicating underperformance, followed by loss of telemetry signals and splash into the Bay of Bengal at T+317 seconds, about 560km south-east of SHAR. The whole excitement for the last few years ended into despair within 300 seconds. As Dr APJ Abdul Kalam described, 'It is something like a pleasant dream suddenly turning into a frightening nightmare!'

The detailed post-flight analysis identified the problem with the second-stage Reaction Control System (RCS). The RFNA had leaked and depleted before the lift-off itself. While the SLV-3 was still on the launchpad, a series of warm-up pulses successfully opened the solenoid valve. But the valve, designed to close after the pulses, did not close.

The reason for the valve not closing as scheduled was to be found next. There could be two significant reasons. Contamination of the valve during the integration of the launch vehicle or an Electrical problem leading to continuous pulses rather than just for the warm-up duration. Because the battery voltage remained constant throughout the countdown, the electrical problem was ruled out

There were multiple indications as well, which had pointed to the RFNA leak. The only colour camera footage clearly showed orange-coloured fumes emanating from one of the control thrusters. There were even visible yellow spills on the floor of the launch pad. There was also a computerized hold before the lift-off indicating the reducing pressure in the gas bottles. But, this hold was quickly overridden manually, since the residual pressure was considered adequate by the concerned specialists.

The solution to the problem was simple. Put appropriate filters to block contaminant particles. For the subsequent flights, it was decided to carry out the final assembly of control system components in a clean tent, and by introducing micron-level filters in the fuel and oxidizer lines.

Though the flight failed, it was termed as a 'Partially Unsuccessful' Flight and rightly so. Thirty-six out of the forty-four significant subsystems of the SLV-3 performed satisfactorily. Also, the flight proved that all the launch complex facilities and ground stations were fully operational. And the team showed its resilience and commitment by starting work immediately for the next flight. Finally, on 18th July 1980, the SLV-3 E2 demonstrated the successful flight of the SLV-3 launch vehicle.

Also check out the article on SLV-3 second experimental flight, which was also India's First Orbit Flight.

This article was based on a chapter from the book The Leapfroggers: An Insider's Account of ISRO.

The First Partially Unsuccessful Flight

The first flight of the SLV-3 launch vehicle on 10th August 1979 was unsuccessful. The lift-off was flawless, followed by a perfect performance of the first stage. The rocket started underperforming due to a leak (detected later) once the second stage took over and ended up in the Bay Of Bengal. ISRO received a lot of backlash from the Media. It was even dubbed as the Sea-Loving Vehicle.

Prof Satish Dhawan (Chairman of ISRO) and Dr Brahm Prakash (Director of VSSC) made sure Dr APJ Abdul Kalam (Mission Director of SLV-3) and his team don’t lose their mantle and start working on the next launch.

Special Arrangements for the Second Flight

For the second flight, scheduled on 18th July 1980, Dr Dhawan decided to allow Doordarshan to telecast the launch. But DD was not yet equipped with the technology for a live telecast. Engineers at Space Applications Centre, Ahemdabad tethered a balloon with a transponder in between SHAR and Madras. Experts from TIFR’s ballon facility at Hyderabad came in specially for this project.

Prof. Yash Pal and Dr Aravamudan were roped in to do the commentary. But alas, the blimp designed for low-speed breezes flew off in strong winds when the tether broke. Madras Station then telecasted a recorded launch with commentary.

Stubborn Remote-Controlled Cable

There were two sets of umbilical cords attached to the Satellite Launch Vehicle (SLV-3). One set came off automatically at the launch while the heavier set was detached remotely. A few minutes before the take-off, the sequence had to be put on ‘hold’ because the cable refused to come off. A technician named Bapiah came to the rescue.

The launch vehicle was armed and hence very unsafe for anyone to come near. The technician volunteered to climb the 60 m launch tower and remove the cable. It was highly risky, but with no other option, safety was put on hold. Bapiah climbed the tower and kicked the cable, coaxing it to come off!

The Over-Performing Launch

On 19th July 1980, the SLV-3 launch vehicle lifted off with the RS-1 satellite making India the seventh nation to conduct an Orbital Flight. The launch as tracked by the SHAR ISTRAC station indicated slight overperformance, but the Down Range Station (DRSN) at Nicobar missed the visibility. Prof Dhawan and all other senior scientists were waiting for the news on-orbit insertion and health of the satellite. The insertion point was not within the ISTRAC station range. Therefore, it was the Trivandrum station that would hear the first communication from the RS-1.

Dr Ved Prakash maintained real-time contact with the station. At about 5-10 degree elevation, the sudden emergence of background hissing sound of RS-1 telemetry was heard. The satellite pass continued for around half a minute, indicating over performance and significantly higher perigee. Prof Dhawan called Prime Minister Indira Gandhi, who announced the news to the nation as the first item of the day in the Parliament.

Welcome AeroSpace Nerds to the Vikram Sarabhai Centenary Celebrations.

Dr Sarabhai was a scientist, industrialist, manager, institution builder, visionary – all rolled into one. While a lot of us AeroSpace nerds recognise his prowess in building the ISRO, you would be astonished to know the vast diversity of institutions he established. Indian Institute of Management (IIM), Community Science Centre, Darpan Academy for Performing Arts, Operations Research Group, Ahmedabad Textile Industry's Research Association are a few of the institutions which are outside the realm of Science and Technology Research. Although this wide array of institutions would have verified the first statement, let us delve a little deeper into the life of the father of the Indian Space Programme.

Celebrations at AeroSpace Nerds

I post a fact or a quote from Sarabhai's life thrice a week until his birthday on 12th August 2020. Let us revisit the Vikram Sarabhai History via multiple posts.

Childhood

1. The Retreat: Childhood Home

2. Montessori Home School

Education

3. Birth of the Physicist

4. The Cosmic Ray Researcher

5. Devotion towards PhD Research

Institution Builder

6. Institution Builder: An overview

7. PRL: The Cradle of Space Science in India

8. IIM Ahemdabad

Indian Space Programme

9. Beginning of the Indian Space Programme

Other Dignitaries on Dr Sarabhai

10. Dr APJ Abdul Kalam

Miscellaneous

11. 5+ Interesting Facts on Vikram Sarabhai

12. 20 Unique Notable Vikram Sarabhai Quotes

Vikram A Sarabhai Centenary Program

Indian Space Research Organisation (ISRO) is also having Vikram Sarabhai Centenary Celebrations. Vikram A Sarabhai Centenary Program is the name given to the celebrations. Events are lined up for the whole year ending on 12th August 2020. But the biggest resource is the compilation books, brochures, and newly designed stickers and posters. These resources have served as a valuable resource for the above series of articles.

Let us know about any other resources you know about!

Dr Vikram Sarabhai was a visionary. After dedicating the Thumba Equatorial Rocket Launching Station (TERLS) to the United Nations in 1968, Sarabhai requested Prof UR Rao to write a proposal to justify a satellite programme for India. Prof UR Rao responded in 2 weeks and was asked to lead the programme. After almost a year of continuous nudging by Sarabhai, Professor accepted the responsibility in 1971 and hence the story of Aryabhata commenced.

Team and Institution Building

UR Rao, along with 25 of his colleagues at PRL, Ahmedabad started working. Shri PP Kale had returned from NASA after a training programme and working on satellite electronics at Space Science and Technology Centre (SSTC), Trivandrum. Around 25 scientists and engineers from this group along with 25 experts from PRL, joined and formed the Satellite Systems Division (SSD). The specialists in the field of structures were requested from the Structures Group at SSTC. Finally, the team started designing a 100-Kg satellite to be launched by Scout launch vehicle of the USA.

This team worked at SSTC, Trivandrum until the project was approved in 1972. After the approval, the SSD needed a location for the satellite project. Prof UR Rao suggested Bangalore and Hyderabad as possible locations to the ISRO chairman MGK Menon. Two scientists sharing the last name, AS Rao (of Electronics Corporation of India Limited) and UR Rao, researched Hyderabad and Bangalore respectively. They only had one week to explore the facilities and make a final decision. The dedication and enthusiasm of scientists resulted in this fast speed of work.

At Peenya, on the outskirts of the Bangalore, there was a skeleton of a few industrial sheds under construction. Professor UR Rao asked for the first four sheds, each with 5,000 sq feet area. That is where our Indian Scientific Satellite Project (ISSP) started. ISRO remodelled the sheds, built sophisticated electronic laboratories, clean room, thermovac chamber and so on. Until this time Aryabhata had no name.

Indo-Soviet Agreement

When the team had started the design of satellite, it was meant to be launched by the American Scout launch vehicle. But in 1971, the Indian Ambassador to the Soviet Union informed PM Indira Gandhi that the Soviet Academy of Sciences wants to assist launching our first satellite. Sarabhai immediately contacted UR Rao, and an urgent meeting with USSR Ambassador was arranged. Another meeting took place in August 1971, at Moscow. A team of twenty Soviet scientists and four ISRO scientists, after four days of discussion, finalised a free launch for India's first satellite. The dedication of scientists is proven by the fact that Professor UR Rao landed back in Mumbai, briefed Dr Sarabhai at the airport and took a flight to Sydney to attend the Cosmic Ray Conference.

While final details were being laid out with Soviets, the nation was shaken with the news of Vikram Sarabhai's demise in December 1971. The follow-up meeting got delayed. Finally, in February 1972, a meeting was held at Trivandrum. Before the meeting, Mrs Gandhi asked for the justification of such a project. UR Rao told Interim Chairman MGK Menon,

"If we want to go into space, this is the first real opportunity we have. As we are getting a free launch, we can start with minimum amount of money and then build upon it. You just can't go straight to operational communication satellites or remote sensing satellites till you have successfully built at least a couple of experimental satellites and established your capability to build complex satellites."

Prof UR Rao on Justification of Aryabhata for India

Mrs Gandhi asked for the budget for the mission. UR Rao asked for 2 hours to get back with it. A team of four engineers and scientists, S.P. Kosta, K. Kasturirangan, Ashiya, and Tarsem Singh, estimated the total cost to be around about Rs 60 lakh. Prof UR Rao increased it to Rs 3 crore, with a foreign exchange component of Rs 1 crore after accounting for space-grade components. And PM Gandhi approved the mission, "Go ahead and sign the agreement!".

The Satellite

Objectives

The primary objectives of the Aryabhata mission (as explained in a paper by Prof UR Rao) were

1. Indigenous design and fabrication of a space-worthy system and evaluation of its performance in orbit;

2. Evolving the methodology of conducting a series of complex operations on the satellite in its orbital phase;

3. Setting up the necessary ground-based receiving, transmitting and tracking systems; and

4. Establishing the relevant infrastructure for the fabrication, testing and qualification of such sophisticated spacecraft systems.

To provide Indian scientists with an opportunity to conduct investigations in space sciences, suitable payloads were also included.

Payloads:

• X-ray Astronomy

• Aeronomy

• Solar neutron and Gamma Rays Studies

Technical Details

• Quasispherical shape, with 26 flat faces

• Mass: 358 kg

• Equivalent diameter: 1.59 m in the equatorial plane

• Height of 1.19 m

• Passive Thermal Control

• Body-mounted silicon solar panels with a total surface area of 36,800 cm sq

• Rechargeable Ni-Cd chemical batteries with 10 A hr capacity

• 137.44 MHz PCM/FM/PM downlink at 256 bits/s data rate

• 148.25 MHz PDM/AM/AM uplink

• Spin Stabilised

Launch and Orbital Performance

Aryabhata was successfully launched into a near-earth orbit at 1300 hr IST, on 19 April 1975. The orbital parameters immediately after the injection were apogee height 620 km, perigee height 562 km, and inclination 50.7 degrees.

In the initial phase, the ground station at Bears Lake, USSR controlled the satellite. While during the normal phase the SHAR ground station took over. Aryabhata tumbled initially, and regulator voltage to aeronomy experiment was absent. All other subsystem functioned very well as indicated by 91 different health monitoring parameters. In 45 orbit, the scientific operations were switched off, and the satellite was spin stabilised at 50 rev/min.

Aryabhata orbited for nearly seventeen years ending the story. The experience gained through this experimental satellite was valuable for future programmes in designing operational satellites.

Reddit Post for different papers on Aryabhata

INSAT-1 series had a total of four missions. The first satellite, INSAT-1A was launched on Delta 3910 vehicle on 10 April 1982. To mark the anniversary of this launch tomorrow, let us delve into the archives and learn how this programme came into being.

Initial Studies for INSAT-1 Payloads

The father of the Indian Space Programme, Dr Vikram Sarabhai was a great visionary. As early as 1964, he had the idea of an Indian satellite for telecommunications and television purposes. India, therefore in the year 1965, joined INTELSAT: an intergovernmental consortium owning and managing a constellation of communications satellites providing international broadcast services. In 1970, Dr Sarabhai presented the paper 'INSAT- A Strategy for Development' at the National Conference on Electronics held in Bombay. The article discussed applications as broad as Railways, Defence, Aviation and Computer Data Handling. This paper gives insight into many INSAT-1 origins.

The requirements for data transmission and inter-connection of large computer facilities have not yet come up in our country. However, one can visualise that such needs will arise for inter-connecting large computers on a timesharing system. Such communications could be handled very effectively by the satellite.

Excerpt from the paper: 'INSAT- A strategy for development'

Within the next few years, many joint studies between DAE (Department of Atomic Energy) and organisations such as NASA, MIT, General Electric and Hughes Aircraft Corporation were conducted regarding a broadcasting satellite for India. All these studies resulted in a lot of action. In the year, 1967, the first Experimental Satellite Communication Earth Station (ESCES) at Ahmedabad became operational. NASA and DAE signed the Satellite Instructional Television Experiment (SITE) memorandum of understanding in September 1969.

The studies conducted in 1968-70, explored various payloads which could be included for INSAT satellites. While almost all studies accepted the inclusion of television and telecommunications payloads, there was a discussion over the incorporation of meteorological ones. With SITE, India planned to get experience in receiving and using such data. But the VHRR payload responsible for the meteorological earth observations failed onboard the ATS-F satellite before SITE was commissioned in 1975. Therefore, the use of INSAT satellites for meteorological applications again became questionable. It was P R Pisharoty, the father of remote sensing in India, who convinced the stakeholders of the use of Met data for an agricultural society like India.

Request for Proposals (RFPs)

Later, ISRO invited Request for Proposals for the development of satellites with the following payloads.

• Two high-power transponders for television broadcasting to community TV sets, distribution of TV programmes for rebroadcasting and radio networking.

• Twelve transponders for telecommunications.

• Meteorological Earth Observation (EO) instrument (VHRR) for imaging the Earth in the visible and thermal infrared bands.

• Data relay transponder for meteorological data collection from unattended data collection platforms.

Hughes Aircraft Corporation (HAC) and Ford Aerospace Communication Corporation (FACC) of the USA submitted proposals. Experts from ESA, COMSAT corporation and INSAT-1 Space Segment Project Office, evaluated the proposals separately. In the end, along with technical experts from the Project Office, Department of Telecommunications (DOT), Doordarshan (the national TV), AIR and India Meteorology Department (IMD), selected FACC to award the contract for INSAT-1A and INSAT-1B satellites. And hence INSAT-1 series originated.

Different Launch Vehicles for INSAT-1 series

All four satellites in the INSAT-1 program were launched onboard different launch vehicles. INSAT-1A satellite failed in September 1982 after a series of problems post-launch in April 1982. Department of Space (DOS) received compensation for a total loss of satellite from Insurance Companies. INSAT-1B had an initial deployment problem. Later, after resolving the issue, the spacecraft functioned for more years than designed seven-year life. While INSAT-1C also failed, INSAT-1D was a total success. INSAT-1, along with APPLE, helped ISRO in developing INSAT-2 and all further satellites.

PRL - The Cradle of Space Sciences

Let us go back a few years. Dr Vikram Sarabhai founded the Physical Research Laboratory (PRL) at the M.G. Science College Ahemdabad. Research on cosmic ray studies was conducted by eminent scientists such as E. V. Chitnis. Dr Sarabhai himself sat only on a table at the end of a corridor. Despite a meagre start, the laboratory invited many lectures from many scientists. Even Nobel Laureate S Chandrashekar inspired the students and faculty there. Many scientists from PRL visited NASA, MIT, Harvard and many recognised institutions and acquired knowledge in the space background. Within a few years, PRL gained recognition in the science world and became the cradle of the Indian Space Programme.

Search for a Sounding Rocket Site

In around 1961, Dr Sarabhai started thinking of a space programme. INCOSPAR (Indian Indian National Committee for Space Research) was created as an autonomous body under the Department of Atomic Energy in February 1962. In July, the search of the site for a sounding rocket was conducted. Prof. E V Chintis decided Thumba to be the most suitable place after considering the Magnetic Equator and safety of fishers around the region.

I went in July 1962 in search of the site. We had several rounds of searches and the Kerala government cooperated extremely well. Bhabha himself came for final site selection. We stayed with the Governor at his guest house and a fleet of fifteen cars was available to go for site inspection. Bhabha, Sarabhai, Goveas, Chief Architect R.B. Patel and I – all five of us stayed as guests of Governor V.V. Giri and he hosted a dinner for us. So we had no difficulty in approaching anybody. INCOSPAR was working as an organisation.

C V Chintis (An excerpt from the book From Fishing Hamlet to Red Planet)

The locality was inhabited around a beautiful church, St. Mary Magdalene Church. Dr Sarabhai met the Bishop and requested for transfer of property. He was asked by the Bishop to meet on Sunday during the morning service. Dr APJ Abdul Kalam beautifully describes the congregation on Sunday in his book Ignited Minds.

The church has been converted to a space museum. The following link can help to plan a visit: https://www.vssc.gov.in/VSSC/index.php/outreach/space-measeum-visit-request.

Cold War Enemies Come Together

Within 100 days, the fishermen were relocated around a newly built church. NASA, the Soviet Union and CNES came together to help prepare the rocket range. The USA provided the rocket. The Minsk gave a computer while a helicopter came from USSR. The payload for the rocket-based experiment, known as the sodium vapour payload, was personally brought by Prof. Jacques Blamont from France, who has recently (2015) been honoured with a Padma Shri by the Government of India. This was the personality of Dr Sarabhai that the cold-war enemies together assisted for the beginning of the Indian Space Programme.

Many things also went awry. The hydraulic crane malfunction, therefore, the rocket was shifted into the position manually. The payload and rocket were incompatible. Consequently, a very young engineer spent the night working with a file to fit the payload within the Nose Cone. The engineer was none other than our beloved ex-president Dr APJ Abdul Kalam.

Beginning of Indian Space Programme

After all this hard work, at 6:25 PM, the Nike Apache Rocket sailed through the sky creating a sodium cloud and beginning the Indian Space Programme. The orange cloud, visible to the naked eye created a lot of interest. Even the Legislative Assembly of Kerala was suspended for 20 minutes to observe the phenomena. As described by Prof. Jacques Blamont, a child was born on 21 November 1963, and we watch its achievements with admirations (today).

Read more about the beginning of the Indian Space Programme.

The Launch

The MOM spacecraft was launched onboard PSLV C-25 on 5th November 2013. PSLV is the workhorse of ISRO hence it was chosen to launch the satellite. This meant placing the vehicle in orbit around Earth and then subsequently increasing the apogee (highest point of the orbit) in various manoeuvres followed by Trans Mars Injection which set the Mangalyaan on a 300-day journey to Mars.

To achieve the required parameters for Trans Mars Injection, the PSLV C-25 had to perform differently than regular PSLV missions. The fourth stage of the rocket ignited after a long coasting time. To give you an idea, a routine flight takes about 1200 seconds, PSLC C-25 had a flight duration of 2530 seconds. All this meant that by the time the fourth stage ignited, the rocket would be far away from the communication ground segment in India.

ISRO deployed two ship-borne tracking terminals in the Pacific ocean to overcome this challenge.

The Spacecraft - Mars Orbiter Mission

Power Subsystem

Mangalyaan had to survive the conditions of a near-Earth Orbit, followed by a heliocentric orbit and finally a Martian orbit. This meant different temperature conditions as well as different solar flux. A single solar array had to be designed which could power the spacecraft with varying flux of 1380 W/m2 in near-Earth to 590 W/m2 in Martian orbit. Moreover, the solar array must generate full power in operating temperatures of +65 ℃ to -20 ℃.

Communications Subsystem

The communications had to be maintained for four segments, Earth-based phase, cruise phase, MOI phase and Mars Orbit phase. The maximum range for communications was 374 million km (during MOI). To achieve this, precise tracking of the spacecraft is needed. ISRO tracked orbiter with 2m in position, 1mm/s in velocity and 0.4 nanosecond angle precision using Doppler and ranging methods.

First Full Disk Image of Mars taken by MOM

Propulsion Subsystem

The Liquid Engine of 440 N thrust was isolated after the geocentric phase and had to be restarted after 300 days of cruise with its Flow Control Valves (FCV) seats in wetted condition. Extensive ground tests were conducted to ensure this restart burn successfully places MOM into the Martian orbit on 24th September 2019.

MOM onboard the PSLV Stage 4

There were many other challenges associated with this mission; all were overcome within one year to launch in the nearest launch window to Mars. If ISRO missed this launch window, the next one would have come after nearly 2.5 years. The then chairman of ISRO: Dr K. Radhakrishnan states a few of the reasons for achieving this feat:

• Thorough Feasibility Study Leading to Robust Mission Planning

• Resolve to Contribute Might for National Pride

• Learning from Others' Failures

• Rigorous Execution

• Team Preparedness for Contingencies

In all, the Mangalyaan mission pushed ISRO into the limelight for both the scientific community and the general Indian public. China referred to the mission as "Pride of Asia". The Mars Orbiter Team won US-based National Space Society's 2015 Space Pioneer Award. The new ₹2000 note features an illustration of the orbiter at the back. The sole space-based Bollywood movie is loosely based on this mission. With a planned mission life of 6 months, Mangalyaan has long overlived its life and giving in relevant scientific data even today.

SOURCE: From Fishing Hamlet to Red Planet book