Why in News:

• With space junk posing an increasing threat to Indian assets in space, the Indian Space Research Organisation (ISRO) is building up its orbital debris tracking capability by deploying new radars and optical telescopes under the Network for Space Objects Tracking and Analysis (NETRA) project.

What NETRA hopes to achieve?

• The primary goal of Netra is to monitor, track, and defend national space assets while also serving as a centre for all space situational awareness (SSA) activities.
• The initiative would provide India with its own space situational awareness (SSA) capabilities, similar to that of other space powers, which is used to ‘predict’ dangers to Indian satellites from debris.
• The ultimate purpose of NETRA is to capture the GEO (geostationary orbit) landscape at 36,000 kilometres, where communication satellites operate.
• The initial SSA will be for remote-sensing spacecraft in low-earth orbits, or LEO.
• A space debris tracking radar with a range of 1,500 km and an optical telescope will be inducted as part of establishing an effective surveillance and tracking network under NETRA.
• The radar, which will be capable of detecting and tracking objects 10 cm and above in size. It will be indigenously designed and built.
• A high-precision, long-range telescope in Leh and a radar in the North East are both in the works.
• To acquire a comprehensive SSA picture, ISRO will also employ the Multi-Object Tracking Radar (MOTR) that has been set up at the Satish Dhawan Space Centre in Sriharikota, as well as the telescopes at Ponmudi and Mount Abu.

What is space debris?

• Space junk or debris consist of spent rocket stages, dead satellites, fragments of space objects and debris resulting from ASAT. Hurtling at an average speed of 27,000 kmph in LEO, these objects pose a very real threat as collisions involving even centimetre-sized fragments can be lethal to satellites.
• Much of the debris is in low Earth orbit, within 2,000 km of Earth’s surface, though some debris can be found in geostationary orbit 35,786 km above the Equator.
• As of 2021, more than 15,000 pieces of space debris larger than 10 cm (4 inches) is being tracked. It is estimated that there are about 200,000 pieces between 1 and 10 cm (0.4 and 4 inches) across and that there could be millions of pieces smaller than 1 cm.

Why has ISRO started Project NETRA?

• Radars and optical telescopes are vital ground-based facilities for keeping an eye on space objects, including orbital junk.
• To protect our space assets, we need to augment our capabilities.
• For protecting its space assets, the ISRO was forced to perform 19 collision avoidance manoeuvres (CAM) in 2021, of which 14 were in Low Earth Orbit (LEO) and five in the geostationary orbit.
• The number of CAMs jumped from just three in 2015 to 12 in 2020 and 19 in 2021.

Other measures taken by ISRO

• The Cryogenic Upper Stage of ISRO’s GSLV is passivated(The passivation process is a method of improving the corrosion resistance)
• ISRO’s communication satellites are built with enough propellant margins to re-orbit to a higher graveyard orbit after the end of their useful lives.

Why has Space Debris to be removed?

• • Even the smallest particles of debris can deactivate an operable satellite at orbital speeds.
  • The space stations might be in danger of colliding.
  • It might make it more difficult to use weather satellites and, as a result, monitor weather changes.
  • Approximately 20,000 items, including satellites and space trash, are now crammed into low-Earth orbit.

• Active satellites and spacecraft may be at risk.

• If the chance of collision becomes too great, Earth orbit may become impenetrable.
• Could endanger the astronauts  who do space walk

What could be done

• After a spacecraft’s mission is over, it can be moved to a more secure orbit. That is, a high-altitude “graveyard orbit” over low-Earth space.
• Carrying out ‘collision avoidance manoeuvres.’
• As a disposal technique, bringing it down via a laser into Earth’s atmosphere, where it will burn up on re-entry.
• Reusable spacecraft can be developed.
• Debris reduction strategies by  international collaboration.
• De-orbit old satellites or capture debris.
• Creating spaceships that can endure the harsh conditions of space without dissolving;

Related Information

Similar International measures

• The North American Aerospace Defense Command, or NORAD, is a joint US-Canadian programme that provides selected debris data with a number of nations.

Kessler syndrome

• This is a concept suggested by NASA scientist Donald Kessler in 1978, which states that if there is too much space junk in orbit, it might cause a chain reaction in which more and more objects crash, creating additional space junk in the process, until Earth’s orbit becomes useless — a Domino Effect.
• For the previous two decades, 12 fragmentation incidents have occurred per year.

References:

1. https://www.thehindu.com/news/national/kerala/isro-to-step-up-tracking-of-space-debris/article65274219.ece
2. https://www.nasa.gov/mission_pages/station/news/orbital_debris.html
3. https://www.britannica.com/technology/space-debris