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Introduction:
After multiple incidents of space debris potentially colliding with the International Space Station last year, a recent incident that has now brought back the attention to this deep threat is from last week. Four spherical metal balls fell from the sky in some villages of Gujarat over the past few days, which as per some experts are most likely the debris of a Chinese rocket or fuel storage tanks of space launch vehicles. US-based astronomer Jonathan McDowell has claimed in a tweet that these metal spheres are likely debris of the Chinese rocket Chang Zheng 3B. He says the debris might have fallen over Gujarat during the re-entry of the rocket. While retired ISRO scientist B S Bhatia has been quoted as saying that these metal balls might be the fuel tanks used in rockets and satellites to store hydrazine, which is a type of liquid fuel. As scientists determine the specific nature of the objects that fell from the sky in Gujarat – whether the debris belonged to a satellite or a fuel tank or some other object – the larger concern is incidents like these pose multiple threats – to the Earth and its inhabitants, to functional satellites and other numerous space objects. With more & more space launches and events like space tourism kicking off, the space above Earth is overcrowded – calling for urgent attention from countries to declutter it.
- Space debrisposes a global threat to the continued use of space-based technologies that support critical functions like communication, transport, weather and climate monitoring, remote sensing.
- Predicting collision probability from these space objects is crucial from the national security perspective as well as for the protection of public and private space assets of Indian origin.
- The real amount of space debris is said to be between 500,000 and one million pieces as current sensor technology cannot detect smaller objects.
- They all travel at speeds of up to 17,500 mph (28,162 kmph) fast enough for a relatively small piece of orbital debris to damage a satellite or a spacecraft.
Causes
- Sources of space debris are dead spacecrafts, spent rocket stages, lost equipment, boosters, weapons etc.
- Space debris has become a pressing issue, with objects in orbit flying out of control, posing a risk to satellites and to astronauts.
Impacts
- Space debris poses a global threat to the continued use of space-based technologies that support critical functions like communication, transport, weather and climate monitoring, remote sensing.
- Space junk is a threat to active satellites, unmanned spacecrafts and spaceships.
- International space station:
- Although the ISS uses Whipple shielding to protect itself from minor debris, portions (notably its solar panels) cannot be protected easily.
- There is also the risk, known as the Kessler Syndrome or Kessler Effect, where one piece of debris breaks off and hits another so that it becomes a cascade, which could end up polluting an entire orbit for satellites.
- Earth:
- Although most debris burns up in the atmosphere, larger objects can reach the ground intact. According to NASA, an average of one catalogued piece of debris has fallen back to Earth each day for the past 50 years
Technologies:
- Nasa’s Space Debris Sensororbits the Earth on the International Space Station. REMOVEdebris, satellite contain two cubesats that will release simulated space debris so that it can then demonstrate several ways of retrieving them.
- Deorbit mission:There are two emerging technologies being developed under what’s known as the e.Deorbit mission to grasp the wayward space junk, or to catch it.
- Other technologies includemoving objects with a powerful laser beam. It is important to start doing that soon, current scientific estimates predict that without active debris removal, certain orbits will become unusable over the coming decades.
Way forward
- An old-fashioned bridge-building between spacefaring nations would help.
- The 1967 Outer Space Treaty, negotiated during an earlier space race with little input from China, is badly in need of an update.
- In particular, provisions that grant countries permanent property rights to their objects in space may complicate efforts to clean up debris.
- Space agencies should fund research into debris-removal technologies—such as those recently demonstrated by Astroscale, a Japanese startup, which hold promise— and consider partnerships with companies developing them.
- The US should also seek to expand the Artemis Accords, a framework for space cooperation that includes (so far) 11 other countries.
- As more nations join, debris-mitigation protocols, such as a requirement to specify which country has responsibility for end-of-mission planning, should become routine.
Conclusion:
- Space debris are a point of concern due their large momentum despite small size. The debris of Mission Shakti Anti-satellite mission was generated at an altitude much below the orbit of ISS. So, as the possibilities of them hitting ISS are seen quite low by Indian experts. But NASA is keeping a track on them for its own safety concerns
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