Ever since the launch of Sputnik 1 in 1957, we have been launching debris into space. Everything from space stations and large communication satellites to small CubeSats. With each launch, we also add things such as rocket parts and paint chips to the orbital pile. Right now there are more than a million objects orbiting Earth wider than a centimeter, and at least 130 million millimeter-sized objects. Most of it isn’t going to deorbit any time soon.
On one particular day in 2021, astronauts and cosmonauts aboard the ISS must have felt a pin-prick of fear and uncertainty. On November 15th of that year, Russia fired an anti-satellite missile at one of its own defunct military satellites, Tselina-D. The target weighed about 1,750 kg, and when the missile struck its target, the satellite exploded into a cloud of hazardous debris.
NASA woke the crew on the International Space Station in the middle of the night and told them to take precautions and prepare for a possible impact. The Chinese space station Tiangong was also in danger, and multiple countries and space agencies condemned Russia’s foolhardy behaviour.
The statistics of how people die offer a gruesome but informative way to understand both how humans perceive threats and how they react to fear. For example, you are more likely to be crushed by a falling vending machine (~13 people killed per year) than be eaten by a shark (~10 per year). However, there is one currently statistically unlikely cause of death that has a real risk of increasing dramatically in likelihood over the coming decades – falling space debris. According to a new study, there’s a 6-10% chance that someone will die from debris falling from space over the next ten years.
“You can’t hit what you can’t see” is a common phrase in sports and was originally derived to describe baseball pitcher Walter Johnson’s fastball. But the same goes for things with a more serious spin, such as some of the millions of pieces of debris floating in Low Earth Orbit (LEO). Now, a team of researchers have come up with a new imaging system that will allow agencies and governments to closely track some of the debris that is cluttering LEO and potentially endangering humanity’s future expansion to the stars.
Update. It looks like we didn’t roll a 1 on the d20, and the satellites passed each other without an impact. But this will probably become a more common occurrence as the skies get more crowded.
Over sixty years of space exploration have left their mark in Low Earth Orbit (LEO), where thousands of objects create the risk of collisions. These objects include the spent first stages of rockets, fragments of broken-up spacecraft, and satellites that are no longer operational. As Donald Kessler predicted, the growing presence of “space junk” could result in regular collisions, leading to a cascading effect (aka. Kessler Syndrome).
This evening – on Wednesday, Jan. 29th – such a collision might take place. These satellites are the Infrared Astronomical Satellite (IRAS), an old space telescope launched by NASA, the Netherlands, and the UK; and the GGSE-4 gravitational experiment launched by the US Air Force. These two satellites run the risk of colliding when their orbits cross paths at 06:40 p.m. EST (03:40 p.m. PST) about 900 km (560 mi) above Pittsburgh, Pennsylvania.