A First Step to better Space Situational Awareness

It was three years after the Kargil war in 1998. It was more than a month after the deadly attacks of September 11. A Polar Satellite Launch Vehicle (PSLV) carrying a satellite with possible military applications was launched from India’s space port, Sriharikota.

Cover of the Jan-Mar 2003 edition of Space India. Source: ISRO.

The armed forces wanted a way to watch the border with Pakistan. The satellite launched on-board the PSLV-C3 mission had a capability to see vehicles on the ground (1 m resolution) and could hence help spot infiltration bids by military or terrorists from across the border from Pakistan.

This was the Technology Experiment Satellite (TES). The launch took place without much fanfare.

But, this mission had a more lasting impact than just this important near-term national security mission. Flying with TES, were the Belgian PROBA and the German BIRD satellites. The PSLV after placing TES and BIRD in circular orbits, moved using its yaw RCS thrusters to place PROBA in an elliptical orbit. Each of these customers paid India $1 million for the mission. This was a big deal then, being just the second commercial mission that India was flying.

PSLV-C3 sequence of satellite separation. Illustration in the Space India edition Oct-Dec 2001.

This demonstrated PSLV capability to place multiple satellites in multiple orbits. So, the primary satellite could be placed in one orbit while the ride-share satellites could fly to the same or other orbits.

Within a couple of months of the launch, the fourth stage of the satellite broke-up on 19 December, 2002. A paper written for the 34th Committee on Space Research (COSPAR) Scientific Assembly held in Houston, USA, by P Bandopadhyay, R Sharma and V Adimurthy identified the cause as explosion. They predicted that 75% of the debris would decay in the Earth’s atmosphere by end-2002.

In the Space Situational Assessment 2021 that ISRO released yesterday, they shared that 76 (almost 20%) of the 386 debris pieces from the PSLV-C3 fourth stage explosion still remain in orbit.

Although ISRO knew that passivation was important, this mission seems to have prompted active ISRO efforts towards passivation of upper stages of launch vehicles and spacecrafts of ISRO. This 2019 paper by Santosh Kosambe throws light on these efforts to reduce the contribution of space debris because of ISRO launches.

A K Ganeshan, then with the Flight Dynamics Center at ISRO Satellite Center (now, U R Rao Satellite Center) wrote a piece about space debris in the January to the March 2003 edition. This, seems to be one of the first public write-ups on the issue published by ISRO.

Ganeshan and Adimurthy (from the 2002 COSPAR paper above) wrote a paper together in Acta Astronautica in February 2006. This seems to be a seminal paper in the active efforts ISRO took in reducing space debris.

The Space Situational Assessment shares important information about Indian assets (spacecraft and Indian space debris) in orbit broadly. It shares the methods by which ISRO tracks these objects (optical telescopes and radar). It also shares the debris avoidance maneuvers it has performed to protect Indian space assets (satellites and even the Chandrayaan-II orbiter).

Sharing this important information publicly is an important first step. Transparently sharing this information with data (two-line elements) would be the logical next step.

ISRO has been building this capability with a series of optical telescopes and radars to be installed for monitoring. This would be the basic institutional infrastructure required since India is responsible, as per international law, for accidents in space caused due to Indian space assets (spacecraft and debris).

My former colleague at Takshashila, Aditya Pareek and I had written a piece in The Wire Science asking for more involvement from the open-source intelligence community. ISRO must encourage the growth of this talent in India. The sharing of the data with two-line elements will help the development and growth of an Indian community.

India has also begun the process of opening up the space sector for private companies. As private companies build spacecraft and launch vehicles, there would be an increase in the number of space assets to be monitored. While ISRO built infrastructure can monitor these, Indian companies should also become part of the solution. Companies like LeoLabs show how private companies can help solve this problem.

As the number of Indian assets in space grows, it will become increasingly important to work with other space-faring nations which may endanger Indian assets or vice-versa.

In short, we will need institutional capability, amateur enthusiasts, private companies and collaboration with other space-faring nations to keep Indian assets in space safe and to reduce Indian liability in case of any space accidents.

Leave a Comment

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.