The hole punched by debris in the International Space Station’s robotic arm. Photo: NASA/ Canadian Space Agency
New Delhi: A fragment of space debris that was too small to be tracked hit a robotic arm of the International Space Station (ISS), punching a hole in it.
Experts from the Canadian Space Agency (CSA) and NASA have assessed the impact and found that the arm’s “damage is limited to a small section of the arm boom and thermal blanket. A hole approximately 5 mm in diameter is visible,” CSA said in a statement. The hit was discovered on May 12, during a routine inspection.
According to Business Insider, the Canadarm2, formally known as the Space Station Remote Manipulator System (SSRMS), is used to transport spacewalking astronauts outside the station and deploy science experiments in orbit. It has been in use for 20 years.
CSA said that over 23,000 objects the size of a softball or larger are tracked 24/7 to detect potential collisions with satellites and the ISS. However, a number of tiny objects – such as rocks, dust particles and flecks of paint from satellites – “are also too small to be monitored”.
“The threat of collisions is taken very seriously. NASA has a long-standing set of guidelines to ensure the safety of Station crew. The safety of astronauts on board the orbiting laboratory remains the top priority of all Station partners,” CSA added.
The damage may have been caused by a small metal fragment “no bigger than the width of an eyelash”, according to Business Insider.
Science Insider reported that although the ISS seems to have “gotten lucky this time”, concern about space debris is increasing. “Last year, the ISS had to perform emergency manoeuvres three times in order to avoid collisions with space debris at its altitude of around 400 kilometres (250 miles),” the report said.
A European Space Agency report published last year estimated that there are 130 million fragments of anthropogenic material smaller than a millimetre orbiting the Earth. A majority of debris is not caused by collisions between satellites, but “explosions in orbit, caused by left-over energy – fuel and batteries – onboard spacecraft and rockets”.
CSA said that robotics operations on the ISS using the Canadarm2 will continue as planned for the near future. CSA and NSA gather data to perform an analysis of the event, which will help them understand how it occurred and also assess future risk.
In March 2019, India conducted an anti-satellite (ASAT) test, shooting down a low-orbit satellite and generating debris. Space scientists – including the NASA director – criticised the test, saying that some pieces of debris have climbed to the upper reach of the low-Earth orbit and potentially endangered other satellites.
In a 2016 article for The Wire Science, Ronak Gupta delineated the dangers posed by space junk. The problem was first outlined by NASA astrophysicist Donald Kessler, who published a paper in 1978 and predicted that said the density of space debris will rise to such an extent that “one crash would not only be inevitable but also ultimately deadly”. Gupta described the Kessler syndrome as thus:
“He projected that a single collision would be able to kick off a chain of further collisions, each singularly catastrophic, exacerbated by the high speeds obtained by debris in orbit around Earth. The end result: a ring of space debris continuously circling the planet, dense and energetic, rendering future satellite launches completely infeasible.”
This possibility was ignored until 2009, when two satellites collided at a height of 789 km over Siberia. That same year, NASA and the Defence Advanced Research Project Agency organised the International Conference on Orbital Debris Removal to draw the attention of scientists and engineers to the space-junk problem and hope to find new solutions.