India’s ASAT test created debris, raised risk for International Space Station: NASA

The debris created by the anti-satellite test carried out by India last week had increased the risk to the International Space Station, NASA administrator Jim Bridenstine said on Monday.

The International Space Station, or ISS, is the world’s only permanent facility in space, and is always manned by one or more astronauts. The ISS serves as a platform to carry out a variety of experiments in space, especially those that require zero gravity, and also for testing new space systems and technologies.

Speaking at a townhall on Monday, Bridenstine, in a response to a question from a colleague, said that the risk to the ISS (due to possible collision with the space debris) had gone up by 44 per cent after the Indian anti-satellite test, though he added that both the ISS and the astronauts were safe.

“Here is what we know about the most recent direct ascent anti-satellite test done by India. We know that we have identified 400 pieces of orbital debris from that one event. That is what has been identified. Now, all of it cannot be tracked. What we are tracking right now, objects big enough to track and we are talking about objects 10 cm or bigger … about 60 pieces have been tracked. They have got tracking number… Out of those 60, we know that 24 of them are going above the apogee of ISS. That is a terrible terrible thing to create an event that creates debris that goes above the apogee of ISS,” Bridenstine said.

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Apogee is that point in the parabolic path of a spacecraft that is furthest from the earth. The ISS has an apogee of 408 km, and a perigee (closest point from earth) of 403 km. India had said its anti-satellite test had targetted a satellite that was orbiting at an altitude of about 300 km from earth’s surface. After the hit, the fragments of the satellite fly in all directions. The Indian government has not given any estimate of the number of pieces of space debris created by the hit, or whether it posed any threat to ISS or any other satellite in space.

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Bridenstine said NASA’s analysis showed that the threat to ISS from possible collisions had increased by 44 per cent.

“We are learning more and more every hour that goes by about this orbital debris that has been created from this anti-satellite test. Where we were last week, from an assessment that comes from NASA experts … was that the risk to the ISS was increased by 44 per cent. The risk, and I am talking about small debris impact to the ISS, risk went up 44 per cent over a period of ten days,” he said.

But he also said that the threat from the Indian test was much smaller compared to that created by a similar test by China in 2007, and that no harm was likely to be done to the ISS or the astronauts.

Explained Why space debris, anti-sat tests are dangerous The International Space Station is at constant risk of collision from space debris, and once in a while needs to navigate away in order to avoid collisions. Since it was established in 1999, it has had to make such delivery avoidance manouevres 25 times, the last one in 2015. Anti-satellite missile tests are a threat to peaceful activities in the space. The NASA, as Bridenstine puts it, is “charged with enabling more activities in space than we have ever seen before for the purposes of benefiting the human condition”. All of those activities are placed at risk when such space debris is generated. “When one country does it, other countries feel like they have to do it as well — it is unacceptable,” he says.

“The good thing is that it is low enough and over time this will all dissipate. You go back in time, 2007, (the) direct ascent anti-satellite test by the Chinese, a lot of the debris is still in the orbit,” he said.

“While the risk went up 44 per cent, our astronauts are still safe. The ISS is still safe. If we need to manoeuvre it, we will. But probability of that, I think, is low. But at the end of the day we have to clear also that these activities are not sustainable or compatible with the human space flight,” he said.

“We are charged with commercialising LEO. We are charged with enabling more activities in space than we have ever seen before, for the purposes of benefiting the human condition… all of those activities are placed at risk when this kind of events happen. And when one country does it, other countries feel like they have to do it as well… It is unacceptable,” Bridenstine said.

India had said that the test was done in the lower atmosphere to ensure that there was no space debris. “Whatever debris that is generated will decay and fall back on to the earth within weeks,” an Indian government statement had said.

The US government, in a statement the day after the test, said the issue of space debris was an “important concern” for it. It said it had taken “note of Indian government statements that the test was designed to address space debris issues”.