There are about 70,000 pieces of space junk larger than a softball flying around the Earth, and some of it is burning up as it enters the atmosphere. Luckily, we haven’t had any big incidents yet. But as the population of space junk increases, collisions between orbiting objects have become more common, and nobody’s sure what will happen if we reach the point of critical mass. Do we have any control over it? And what would happen if that critical mass was breached?
One serious concern is that something could go very wrong with space debris, creating a scenario in which the friction between the debris and the air leads to a chain reaction of destruction. That’s what happened in 1989, and it was witnessed by satellites, spacecraft and human observers. But it turns out that this wasn’t the first such incident.
Kopff and Adams write that NASA’s Visual Monitoring Explorer and Omega satellites were launched in 1974, and could both be traced to the second of three space debris collisions. Those satellites, along with two other satellites launched around the same time, were all spotted in November 1989. They observed that the debris was moving towards Earth at 4.7 miles (7.3 kilometers) per second. A large part of this was due to the end of the Cosmos 2251 anomaly, the disappearance of a pair of aging Russian satellites. But many of the debris pieces themselves were from the Cosmos 2251 incident, and if the two satellites had collided, a chain reaction would have happened, melting both satellites and spreading the debris around the Earth.
What makes this even stranger is that there was a Spacecraft Composition Record for the Cosmos 2251 satellites in place, which is considered an official flight-control source. NASA had very little information about the spacecraft, and the closest they could get to the debris was from Vanguard TV2, which was a different design. Of course, this was before all the information was online, so the US Government was clearly in the dark on several points.
The result is an interesting but uncomfortable example of how the typical observation is often just an early warning system. On this occasion, NASA didn’t have much more than that. While the existence of this fourth collision event represents a serious concern and was a much larger event than our historical knowledge of the Cosmos 2251 fleet at the time would suggest, at this time there is little reason to be alarmed about the cause of the collision or how to avoid the event in the future, the NASA report said.
The debate over this issue has been going on since the two satellites collided. The Air Force was quick to blame the Soviets for the accident, and more than once raised the possibility of a satellite strike, although the lack of space suits for the Soviets is a serious consideration. Other officials have tried to temper that, and not got anywhere. Others have tried to point out that if the Russians had an error-correcting digital clock, we wouldn’t have seen the event at all.
As technology improved and satellite designs grew more complex, though, these collisions could happen more often. Just last year, an orbiter containing a radio beacon for tracking purposes was destroyed when a piece of space junk collided with it. Orbital debris can also destroy spacecraft when it collides with them, and the Space Shuttle, even more than the other major spacecraft, had to deal with this problem. One study found that of the 20 human deaths caused by space debris, nearly half were caused by space junk.
Comments / 0