Space station ISS had to swerve last night for a rapidly approaching piece of space debris. According to the American space agency NASA, the debris threatened to pass through the station at a distance of 1.4 kilometres, which is minimal in terms of space.
NASA did not disclose the size of the debris. As a precaution, however, the three astronauts did move to the Russian part of the ISS, so that they could quickly leave the station in distress via a Soyuz capsule. According to NASA, the crew was not in any danger at all.
After the evasive manoeuvre, NASA top man Jim Bridenstine twittered that it was the third time this year that the ISS had had to change course for debris, whereas that is on average once a year. “It gets worse with space debris”, skew Bridenstine. He called on the US House of Representatives to quickly approve additional millions, including space debris.
The Dutch astronaut André Kuipers, who stayed twice in the ISS, thinks it is a justified call. “It is becoming a problem,” he says. Most waste in orbit lower than 600 kilometres above the earth will burn back into the atmosphere within 25 years. This is outweighed, however, by the many objects that are shot into space today and scrape through decades-old satellites, rocket stages and other space debris at speeds of around 10 kilometres per second.
“Satellites are also getting smaller and smaller,” says Kuipers. “They’re about the size of a milk carton these days. That’s all potential space debris too. There’s a lot of space in space, but it’s starting to get a little full.”
That‘s why he’s not surprised by last night‘s incident at the station that flies some 400 kilometres above the Earth. “It happens all the time,” he says. “In my missions we have had to make three such evasive manoeuvres. You don’t notice much of it, you see some cables moving.”
The fact that the crew had to stay near the Soyuz capsule as a precaution is rarer. Kuipers also experienced this during his second trip to the Space Station in 2012. He even had to take shelter in the escape pod because of a debris from an old Russian satellite with a course that was difficult to predict, which eventually skimmed some 15 kilometres along the ISS.
“We were woken up in the middle of the night to close the hatches,” says Kuipers. “I immediately packed up my personal belongings and looked out of the window of the Soyuz to see if there was anything left of the debris. But that wasn‘t the case”, he says laughing.
NASA is currently tracking more than 22,000 objects larger than 10 centimetres. Of those, 21,000 have been identified as space debris. The space organisation also estimates that there are about half a million particles between 1 and 10 centimetres in an endless orbit around the Earth, and tens of millions of pieces of debris smaller than a centimetre probably flying around.
Beware of cascade effects
Those smallest particles, such as paint splinters, can already cause damage, says Kuipers. “This can be seen in the ISS from small pits in the windows The station is therefore protected with a kind of bulletproof jacket, on which particles can burst and then be captured by several layers. “But it is going to happen one day that there will be a serious leak in the ISS”, Kuipers predicts.
In fact, astronauts are also prepared for this in their training by means of all kinds of procedures, he explains. “Such a leak does not have to be fatal right away. There are tools on board to plug holes and close off compartments”
It does not alter the fact that a collision with a large piece of space debris can end “very badly”. Kuipers: “It can destroy the station, but it can also hit the Soyuz. In that case, you are completely screwed. And we have to watch out for a cascade effect. In other words, all that space debris will collide with each other, leading to even more debris and collisions”
He refers to the seven Oscars award winning Hollywood film Gravity from 2013, in which two astronauts get into trouble because of a huge cloud of space debris from a satellite blown up by a rocket. The cloud eventually destroys the ISS in the film as well. “There are some artistic liberties in that film and it’s not all right from a physical point of view either, but theoretically this can happen,” says Kuipers.
In order to keep this chance as small as possible, Kuipers argues, just like NASA and the European Space Agency (ESA), for better agreements and the removal of as much waste as possible. For example, the ESA is currently investing in a kind of ‘space tow truck’.
The project involves a kind of inverted umbrella which, when folded shut, should grab the space debris:
Kuipers: “You can also, for example, oblige satellites to carry extra fuel in order to be placed in a graveyard orbit or to be given points of contact with which they can be removed more easily. Such rules are necessary