Space Debris Left By India's Mission Shakti Continues To Threaten The ISS After 4 Months

About four months ago, India carried out an anti-satellite weapon test. 'Mission Shakti' as it was called was meant to demonstrate we can take out spy satellites and the like in orbit. Unfortunately, though the test was successful, it may have created another serious problem.

ISRO

When we fired the ground-based missile on March 27, the mission was simple. We had to destroy a test satellite in low-Earth orbit. Which we did. Except destroying that also threw a bunch of shrapnel into orbit around our planet.

At least 400 pieces to be exact.

The United States Air Force has been tracking that debris since, and they say the pieces are still moving at thousands of miles an hour around the Earth. We can't do anything to stop that either, all we can do is monitor it. And if they were to collide with another satellite, they could damage it or even render it completely useless.

Shutterstock

According to the European Space Agency (ESA), our orbit is already filled with more than 22,000 pieces of debris. Each of these is about the size of a cricket ball, but they can still deal incredible damage considering the velocity they're travelling at. They're all tracked by the USAF's 18th Space Control Squadron, but there's a hitch. When we conduct ASAT tests, exploding satellites can create debris that's even smaller, perhaps even impossible to track, but just as dangerous.

The complication

We did of course try to minimize the shrapnel released by targetting an object in low orbit, just under 300 km up. The good news is that this way, most of the debris is pulled downward and drops out of orbit, burning up in the atmosphere. G Satheesh Reddy, the DRDO chief, even went so far as to suggest that all the debris would be eliminated this way in about 45 days. But that may not have been the case.

NASA

The USAF has specified that most of the debris is gone. "We can confirm more than 300 of the 400 plus objects we tracked from this event have reentered the Earth's atmosphere," a spokesperson told US publications. However, in ASAT tests some of this debris is thrown higher into orbit, meaning it takes longer for them to be pulled downward to burn up in the atmosphere, and therefore are a danger to the International Space Station and other satellites even longer.

The truth is harsher

Harvard astrophysicist Jonathan McDowell has been tracking the debris using data from the US Air Force. He compares India's ASAT test to one carried out by the US in 2008. When they destroyed a satellite 247 km, it created 173 larger debris objects, many of which were thrown well into satellite operational orbits. In fact, 64 percent of these objects were well above the ISS at their highest points. And it took months, in some cases even up to two years, for them to fully descend.

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The USA 193 intercept was at 247 km (compare 283 km for the Indian ASAT), yet a lot of the larger fragments ended up in eccentric orbits with apogee at much higher altitudes, well into the operational satellite range. 64% of the depicted sample had apogee above the ISS orbit.

¡ª Dr Marco Langbroek (@Marco_Langbroek) April 2, 2019

India's ASAT test meanwhile was intercepted at a height of 283 km. That could potentially mean debris well above where we were expecting it all to reach, and that's incredibly dangerous. Especially when some of it is so small we can't even track it.

NASA

More than 130 days later, the USAF can still track over 50 pieces of debris in orbit, well over the 45 day time frame we had estimated. This poses a danger to other satellites, the ISS which has six astronauts currently on board, and even other launches in the next couple of years. This floating debris may even jeopardize a future Indian space mission, if we aren't careful. It's not by any means a guarantee of danger, but it's certainly a considerable risk.