It’s Getting Busy Up There

This month life on the International Space Station got a little busier, as it welcomed three new crew members, but the space around our planet is getting busier by the day. With each new launch, and even collisions between objects in orbit, the amount of Earth-produced debris is increasing at an impressive and potentially concerning rate.

The scale of our space junk problem was revealed this week, with The European Space Agency releasing its assessment of orbital debris, the annual Space Environment Report, this week.

According to the report there are currently more than 8,800 tonnes of Earth debris in space, of which over 25,000 objects are regularly tracked by Space Surveillance Networks, including our very own RAF Fylingdales on the North Yorkshire Moors.

But the true picture of space debris, estimated by statistical models, is far higher and shows just busy it really is in space:

• 34,000 objects larger than 10 cm across
• 900,000 objects between 1cm and 10 cm
• 128 million objects between 1 mm and 1 cm

The debris is largely made up of non-functional spacecraft and abandoned launch vehicle stages, including fragments left over from the breakup of derelict rocket bodies and spacecraft. This includes paint flecks, metallic chips, solidified liquid propellants expelled from spacecraft, fragments left over from collisions between derelict spacecraft and unburned particles from solid rocket motors.

Could any of this orbital space junk pose a threat to us? Well, so far this has not affected us here on Earth. Since we sent the first rockets into space no human has been killed or even hurt by an artificial object falling from space, and NASA has said there’s generally little danger of death by space debris, but with another potential collision projected to happen this week, and an ever increasing amount of material populating the popular orbital altitudes of our planet, the potential problems are always increasing.

Unfortunately, defunct spacecraft colliding in orbit is not a new occurrence. The first major collision happened on February 10, 2009, when two communications satellites, Iridium 33 and Kosmos 2251, accidentally collided at a speed of 11,700 m/s. By July 2011, the US Space Surveillance Network had catalogued over 2,000 large debris fragments from the collision. NASA determined the risk to the International Space Station to be low but, just in case, there are things that the crew can do to avoid a space junk catastrophe. Thrusters can boost the orbit of the Space Station to avoid large debris, and specialised Whipple shielding protects vulnerable areas from smaller fragments. In addition to this, a Soyuz capsule similar to that on display at the National Space Centre is always docked and on standby to evacuate the crew.

One of the most controversial space debris incidents happened in 2007 when China conducted an anti-satellite missile test. The Chinese FY-1C polar orbit weather satellite was destroyed by a kinetic kill vehicle, creating an estimated 150,000 debris particles, of which more than 2,000 pieces were of trackable size (golf ball size and larger). As of April 2019, 3000 pieces of space debris routinely tracked by the US Military as a threat to the International Space Station were known to have originated from this 2007 satellite shoot down.

While some pieces of space debris will de-orbit, burning up in the atmosphere in an impressive meteor-like display, larger pieces of space junk at certain altitudes may remain in orbit for decades or even centuries.

Some space debris is so large, it has even tricked astronomers into thinking it is an asteroid! In September, following observations made through the 71-inch Pan-STARRS1 telescope in Hawaii, astronomers catalogued asteroid ‘2020 SO’. However, its unusual acceleration, that cannot be explained purely by the effect of the Earth’s gravity, suggests that this is not a natural asteroid, but actually a relic of human space explorations – likely to be the Surveyor 2 Centaur rocket booster launched in 1966. Scientists believe it will continue to orbit Earth until spring, 2021. So, something else to look out for in the night sky.

Scientists and engineers across the world are working on ways to clear up our orbits, with giant space nets and harpoon systems both being investigated as ways to declutter our local space. There is a lot of work to keep our astronauts and space technology safe, and to make sure that future generations will be able to launch their own technology into orbit, and beyond.