Space is getting more dangerous as NASA dodges deadly debris

About once a The International Space Station takes evasive action to avoid colliding with a piece of space debris.

The latest maneuver took place last week as the ISS upgraded itself to a higher orbit to avoid debris from a Russian anti-satellite missile test in 2021. It’s likely that such near misses will only become more common as humanity continues to clutter the space tracks with old satellites and debris from collisions and rocket tests. Here’s what you need to know about space junk and how to avoid it.

How does the International Space Station dodge space debris?

It’s tempting to imagine astronauts piloting the ISS as if it were the Millennium Falcon, relying on their lightning reflexes (and perhaps the Force) to skirt portions of obliterated spacecraft, often by just inches to spare. Reality, like much in space travel, is much slower and takes place over much greater distances than Hollywood’s version. But it can still be extremely tense as lives are at stake and when things go wrong, help isn’t on the way.

Nobody sits in a cockpit on the ISS with a joystick and turns the entire station left or right out of the way of an approaching piece of debris. That’s not how space maneuvers work. Instead, if you’re heading for another object in space, you’re either accelerating, which puts you into a higher orbit, or slowing down, which puts you in a lower orbit. To avoid Russian satellite fragments last week, a Russian Progress cargo ship docked at the station and fired its engines for about five minutes, putting the ISS in orbit a little less than a mile above its old one.

Mission Control, a few hundred miles away on Earth, plans maneuvers like the Oct. 24 boost days in advance. How long does it take to calculate a new trajectory: what safe orbit is the ISS aiming for? How much boost does it take to get there? Is this orbit in the path of other satellites? Formally, it is called a predetermined debris avoidance maneuver.

“We have a flight control position at Mission Control Houston called TOPO (Trajectory Operations Officer) that manages the orbit of the space station,” said a NASA spokesman. “They work directly with US Space Command (USSPACECOM), which is responsible for tracking and cataloging satellites and debris in orbit around Earth. USSPACECOM compares the ISS path to their object catalog several times a day, and if anything is scheduled to pass by the space station within a range of ±2 km x 25 km x 25 km in the coming days, they will send a notification to TOPO along with the time of the greatest approach.”

What if there isn’t enough time to plan evasive maneuvers?

Then the crew has to prepare for a possible emergency. For most ISS crew members, this means gathering essential items and closing the hatches between the pressurized sections of the station so that if one module is damaged, the others will not be depressurized. It is the spaceflight version of a naval ship that closes all of its watertight hatches before sailing into battle.

A few minutes before potential impact, crews make their way to the lifeboats — in other words, the docked spacecraft that will take them home (and their only shelter) if the ISS is damaged beyond repair.

In his book Endurance, Scott Kelly describes a close encounter with a defunct Russian satellite in 2015, during which he took shelter with cosmonauts in a Russian Soyuz capsule Gennady Padalka and Mikhail Kornienko. Kelly and his crewmates stared out the windows of the Soyuz capsule at the darkness, although they all know the approaching satellite will be moving too fast to see if it hits them or not.

Mission Control had calculated to the second when the satellite would zoom past the ISS, and as the moment of truth approached, Kelly’s focus shifted from the window to the watch.

“Once the time ticks down to seconds, I feel myself tense up and start grimacing. We are waiting. Then … nothing,” he writes. “Thirty seconds pass. We watch each other with one last heartbeat of expectation of disaster. Then our grimaces slowly turn into expressions of relief.

What happens if something hits the ISS?

in the persistenceKelly describes how cosmonauts Padalka and Kornienko waited in the dark of their Soyuz capsule in 2015.

“‘You know,’ Gennady says, ‘it’s going to really suck if we get hit by that satellite.’

“There,” agrees Mischa. ‘Will suck.’”

According to NASA, most crew compartments and pressure tanks that make up the International Space Station “will typically be able to withstand impact from debris up to 1 centimeter in diameter.” That includes about a million tiny bits of floating debris: splatters of paint, the tiniest bits of debris from orbital glitches, small bits of stray hardware, and so on.

Anything larger than an inch is potentially much more dangerous. We think of space junk – and often the ISS itself – as just floating sluggishly in space, but they are actually moving very quickly, at around 25,000 to 50,000 kilometers per hour. At that speed, a centimeter-sized object would hit the ISS with about ten times the force of a similar-sized bullet fired from a weapon here on Earth.

And anything even bigger – any of the 25,000 known pieces of debris more than 10 centimeters wide, including things like the crew of the defunct satellite Kelly passed by in 2015 – would be devastating. Had the satellite struck the ISS in 2015, it likely would have vaporized most of the station upon impact, according to Kelly, who found closing the station’s hatches a futile exercise given the possibility.

This is why ISS crews and their mission controllers on Earth steer clear of space debris, keeping several kilometers between the station and potential collisions.

“The ISS normally maneuvers away from the object when the probability of a collision exceeds 1 in 10,000,” says NASA.

How often does the ISS have to avoid space debris?

With the Oct. 24 maneuver, the ISS shifted its orbit 32 times to avoid a piece of space junk or a dead satellite. That’s an average of about 1.5 evasive maneuvers a year since 2000, but a NASA spokesman says the actual frequency varies.

“For example, in calendar years 2014-2015 we had to do 9 maneuvers and then by 2020 we had zero,” they say. Two of those maneuvers — one on Oct. 24 and one in June 2021 — evaded parts of Cosmos 1408, the satellite that Russia blew up in its 2021 missile test.

The station’s biggest orbital debris problem right now is a connection between the scattered remains of a Pegasus rocket upper stage (the same type of rocket that launched NASA’s NuSTAR telescope) and those of a Chinese satellite, Fengyun 1C, in which China was blown up Anti-satellite missile test in 2007. NASA narrates Vice versa that the ISS had to avoid parts of each of these spacecraft three times.

The 2015 Shelter-in-Place episode that Kelly describes in persistence was the fifth such incident since 2000.

Is the space debris problem getting worse?

Right now there are about 9,000 tons of junk orbiting our planet, ranging from patches of paint to entire satellites that have run out of fuel or are otherwise malfunctioning – and we’re adding more all the time. That’s what happens when space agencies or private companies don’t ensure their satellites fall back into Earth’s atmosphere at the end of their lives, when a rocket stage or an entire spacecraft explodes, when two satellites collide (like an Iridium communications satellite and a Russian Cosmos satellite in the 2009) or when a country blows up one of its own satellites to demonstrate that it has the power to blow up another’s satellites.

This is exactly the kind of test that destroyed Cosmos 1408 and forced the ISS to dodge the debris for at least a few more years. A few weeks before the station’s latest evasive maneuver on October 24, Britain became the latest country to ban such anti-satellite missile tests – alongside Canada, Germany, Japan, New Zealand, South Korea and the United States. Russia and China in particular are missing from this list.

An Indian anti-satellite missile test in 2019 also produced a huge plume of debris, but most of it was burned up in Earth’s atmosphere within about a month of the test. Debris in lower orbits (below about 600 kilometers, according to NASA) tends to fall back into Earth’s atmosphere within a few months or years, as the weak upper remnants of Earth’s atmosphere create just enough drag to slow things down and destroy their orbits. so they succumb to gravity.

But as long as they persist, these fragments are still a potentially big problem, especially immediately after a missile test, collision, or missile accident.

“In the first days after the event you always have a dark risk because you know that you are surrounded by fragments and you don’t know where they are,” said Holger Krag from ESA’s Space Debris Office back in 2019.

But even without intentionally blasting old satellites into thousands of space junk, the few hundred kilometers of space around our planet are becoming ever more cluttered. New space missions add about 40 to 50 objects a year to the ever-expanding cloud of flotsam and jetsam in Earth orbit, usually in the form of metal slag from solid-fuel rocket engines or new satellites that just keep orbiting the planet once their fuel runs out or their communications systems run out on them make unmanageable.

And each of these junk satellites is made up of a thousand or more little pieces of debris just waiting to be passed. Currently, the single largest source of space debris is still a collision between the Iridium-33 satellite and the Cosmos-2251 satellite in 2009, which the ISS has already avoided three times.