We seem to have skipped a close call involving two satellites–yet how close did we get to a disastrous space event?
It all started with a set of LeoLabs posts, an organization that uses radar to monitor satellites and waste in space. Two unreliable Earth-orbiting satellites were estimated to be 1 in 100 odds, with potentially dangerous effects, of an almost inevitable head collision at 9:39, am AEST on January 30th (23:39 UTC, January 29th).
LeoLabs predicted that within 15 to 30 meters (50-100 feet) of each other, the satellites could pass No one could control or move either of the spacecraft. So we just had to watch anything happening over us.
Space collisions can be devastating, and high-speed fragments can scatter in all directions. The threat jeopardizes existing satellites, potential launches, and space missions ferrying crew members in particular.
Other agencies such as Aerospace began offering equally alarming predictions following LeoLabs ‘ alert. In comparison, publicly available calculations were much more positive. No warning came from either the US Air Force or NASA.
This situation was necessary because the US had a part to play in launching the two near-miss satellites. The first one is the Infrared Astronomical Satellite (IRAS), a considerable space telescope of weight about a tonne launched in 1983. It completed its mission successfully later in the year and has since been lying dormant in space.
A slightly different story comes from the second satellite. The spacecraft, previously known as GGSE-4, was launched in 1967 by the government in secret. It was an inclusion of a much bigger project to seize Soviet Union radar emissions. This satellite also included a test to establish how satellites can stabilize under the influence of gravity.
It is considerably smaller than the IRAS with a weight of 83 kilograms (182 pounds), but its design is very odd and unfortunate. It has an overhead arm of 18 meters (60 feet) with a weight at the end, thus a much broader target.
The major problem is that we don’t understand the satellites’ locations. The situation suggests that we need to be highly conservative, precisely due to the cost and relevance of most operational satellites and the drastic effects of high-speed crashes.
Space-object tracking is known as Space Situational Awareness and is a very challenging task. Radars, which are costly to build and run, are one of the best approaches. Telescopic visual observation is cheaper but poses many problems, such as the climate and many moving parts that may break down.
The remedy starts with creating better methods of tracking satellites and space disposal. It is a crucial next stage to eliminate the junk, but that can happen if we know precisely where it is.