NASA has narrowly canceled a spacewalk scheduled for today.

Actually, the two astronauts Thomas Marshburn and Kayla Barron should have put on their spacesuits for a spacewalk this morning. But the chance to stretch one’s legs—and, of course, do some odd jobs—passed Marshburn’s and Barron’s noses. This morning NASA decided to postpone the spacewalk. The reason? Space debris (see box).

In orbit around the Earth, in addition to the International Space Station and numerous satellites, there is also quite a bit of space debris orbiting. This concerns, for example, dead satellites and discarded rocket stages. But also literally for debris: fragments of satellites that have collided with each other, exploded accidentally or were deliberately blown to smithereens. According to ESA, some 36,000 objects larger than a tennis ball are currently orbiting the Earth. In addition, another 1 million objects that are between 1 and 10 centimeters in size and 330 million objects that are between 1 millimeter and 1 centimeter in size orbit the Earth. These small objects may seem harmless, but when, for example, the International Space Station or a high-speed satellite encounters such a small fragment, it can still cause considerable damage. Moreover, it is very difficult to follow those smaller particles.

Shortly before the spacewalk, the US space agency received a warning that space debris was in danger of approaching the International Space Station, according to a short statement on the NASA site. Normally, an extensive analysis follows to determine how great the risks actually are, but there was no time for that so shortly before the spacewalk. And that’s why NASA has decided to postpone it – for the safety of the astronauts.

Delay

It often happens that a spacewalk is moved. In August, for example, this happened because of a minor medical problem with one of the astronauts. However, a delay due to space debris is new.

Dodge

That space debris can pose a threat to the ISS is not new. In the past, astronauts have had to take regular measures to protect themselves and the space station. For example, sometimes the orbit of the space station is slightly adjusted to avoid a collision. And if that doesn’t work out in time, astronauts could also be ordered to take a seat in a spacecraft docked to the ISS. They can then quickly escape if a collision turns out to be really unavoidable. The last time the astronauts were asked to sit in the spacecraft because of space debris was exactly two weeks ago. Then the Russians blew up one of their own satellites, creating 1,500 relatively large debris that soon became a real threat to the ISS. Fortunately it went off with a sizzle; the ISS was not hit and the astronauts were soon able to leave the spacecraft again.

Whether the delay of the spacewalk has to do with the same debris is unclear. It is also still unknown when the postponed spacewalk – which was aimed at replacing a deteriorating antenna on the ISS – will take place. Incidentally, the postponement of the spacewalk and planned work will not affect the functioning of the space station.

Space debris is unfortunately a growing problem. Earlier this month, ESA announced that hundreds of larger pieces of space debris will be added in 2021 alone. Two weeks ago, an estimated 1,500 new objects were added as a result of the above-mentioned action by the Russians. In an effort to combat the space debris, missions are underway that can take that debris out of orbit. The first should start in 2025. However, partly in view of the large number of satellites that various companies are currently putting into orbit around the earth, it is still very doubtful whether this approach is sufficient to keep space safe and accessible.