Debris from Mission Shakti

In March 2019 India had successfully test-fired an anti-satellite missile by shooting down a live satellite. The project named as Mission Shakti led by the Defence Research and Development Organisation (DRDO) was aimed at strengthening India’s overall security.

Mission Shakti

• DRDO-developed anti-satellite system (A-SAT) successfully destroyed a live satellite in the Low Earth Orbit.
• India is only the fourth country after the U.S., Russia and China to have the A-SAT technology.
• The PM in his address has made clear that the intent of DRDO’s “Mission Shakti” is to defend India’s space assets and not to start any arms race in space.
• The indigenous development of the A-SAT technology will have many spin-offs that India can exploit for civilian commercial use.
• The test was carried out from the Dr A.P.J Abdul Kalam Islandlaunch complex by the DRDO.
• Since the test was done in the lower atmosphere, whatever debris that is generated will decay and fall back onto the earth within weeks.
• Mission Shakti does not violate the 1967 Outer Space Treaty of which India is a signatory. The treaty prohibits only weapons of mass destruction in outer space, not ordinary weapons.

Unintended Advantage

The ASAT test was not directed against any country. India’s space capabilities neither threatens any country nor are they directed against anyone. But as an added advantage the capability achieved through the anti-satellite missile test provides credible deterrence against threats to our growing space-based assets from long-range missiles and proliferation in the types and numbers of missiles.

Space Debris from the Mission

DRDO which was the nodal agency for the mission had stated in April 2019 that most of the debris generated from the anti-satellite test conducted by India in March has decayed and that the rest of it will dissipate in a short period of time.

India has no means of tracking the debris on its own yet and it is dependent on NASA’s ODQN report for the credible estimate of the remaining debris.

NASA, via the US Air Force, had initially claimed it was tracking 400 pieces of debris from the ASAT test, suggesting that they could even collide with the Space Station. But later it was able to catalogue only 101 of those pieces due to the low-altitude the test was carried out in and the rapid decay of the remaining fragments.

Recent Quarterly Report

• The recent quarterly report has revealed that out of the 19,524 catalogued pieces in total orbiting the Earth, a mere 254 belong to India (1.3 per cent).
• The US and the Commonwealth of Independent States (including Russia) have the highest fraction of (spacecrafts+rocket+debris) fragments, roughly 6,500 in all, followed by China with 4,000+.

Unusually Long Period

An explanation to the “unusually long” period of time the debris is taking to fall through the atmosphere is now being offered.

On an average day, the Earth’s upper atmosphere is heated and puffed up by ultraviolet (UV) radiation from the sun. Orbiting satellites in low-Earth orbit experience friction as they skim over the edges of the atmosphere, producing drag. The satellites, therefore, lose speed over time and eventually fall back to Earth.

Drag is good as far as space junk in concerned, as it helps keep low-Earth orbit more or less debris-free.

The Earth is currently in the middle of a ‘solar minimum’ phase, which some experts are citing as the reason for the slow disintegration of the debris. There is little to no solar activity during this period. Sunspot and solar flare activity diminish to a minimum for days during this period.

This affects the Earth’s upper atmosphere, too, where the natural heating mechanism by UV radiation subsides. The upper atmosphere cools, and to some degree, collapse. With lesser drag than on an average day, space junk, too, tends to linger in low-Earth orbit for longer.