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I remember watching man’s first tentative steps into space with the launch of NASA’s manned space probes in the early 1960s.
The Soviets were first, but their program was shrouded in secrecy, with only successful missions announced. The Americans, in contrast, did everything live on television. At the time, TV was just starting to become the medium of choice, replacing radio as the source of information and entertainment for many people.
There was nothing so dramatic as listening to a countdown to zero and seeing a huge blast of flame as the primitive rockets of the day slowly dragged themselves away from the Earth. Many such launch attempts ended with a “rapid, unscheduled disassembly” of a rocket in a tremendous ball of flame.
Little did we know that just this kind of accident could endanger our access to space in the future.
Last May 12, a routine inspection of the Canadarm, a robotic manipulation device on the International Space Station, revealed a five-millimetre hole in the insulation that wraps the high-tech arm. This was caused by a collision with a micro-meteoroid, or small piece of debris, that was orbiting Earth from some other space mission.
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We don’t really know what hit the Canadarm. It is not like a car crash were you can look at the vehicles involved and determine what happened. At these speeds, the objects are likely to be vapourized in the collision, leaving nothing but a huge crater relative to the size of the object that caused it.
As of the beginning of last year, the U.S. Space Surveillance Network, or SSN, was tracking about 23,000 objects larger than 7.5 centimetres. The total mass of these objects is a staggering 8,000 tonnes. This total does not include smaller or natural objects, such as meteoroids.
With so much junk orbiting Earth, you would expect that such collisions would be a regular occurrence. Well, such collisions are not exactly rare, but the risk is manageable for the single reason that space is big. The chances of a collision are small, but not negligible.
The problem is compounded by the fact that, as of 2020, there were more than 6,000 satellites orbiting the Earth and we are adding to that total at a great rate. Worse, only about 40 per cent of these satellites are still operational. We have even seen collisions between satellites. On Feb. 10, Kosmos-2251, a Russian communications satellite and Iridium 33 smashed into each other at a combined speed of 42,000 km-h. More than 1,000 pieces of debris larger than 10 centimetres were created and the SSN reported that more than 2,000 pieces spread through space as a result of the collision. It is not always easy to predict such collisions. These two satellites were predicted to miss each other by at least a half-kilometre.
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Collisions are not the only source of such debris. Sometimes rockets and satellites malfunction and explode. This mostly happens to rockets as they are highly energetic devices filled with volatile fuel and oxidizer. When they explode, rockets always spread debris like firing a shotgun. The only saving grace of this is that it usually happens in low orbit and the pieces often will be in highly unstable orbits that will decay and the pieces will burn up in the atmosphere removing them from orbit.
The biggest danger is to astronauts who are working outside of the space station. They are not nearly as well protected as people inside the station. Even a grain of sand travelling at these hyper-velocities could cause damage worse than getting shot. The energies involved could easily kill a space-suited human.
Given the amount of debris in orbit, it is probably not just a mater of if but when this will happen. The danger is not the big stuff that we can track but the small objects moving at incredible speed. Unless we find a way to keep our orbital environment clean, we risk being cut off from space for years until the worst of the debris falls back to Earth.
Tim Philp has enjoyed science since he was old enough to read. Having worked in technical fields all his life, he shares his love of science with readers weekly. He can be reached by e-mail at: tphilp@bfree.on.ca or via snail mail c/o The Expositor.
https://news.google.com/__i/rss/rd/articles/CBMiTWh0dHBzOi8vd3d3LmJyYW50Zm9yZGV4cG9zaXRvci5jYS9uZXdzL3NwYWNlLWp1bmstcG9zZXMtdGhyZWF0LXRvLWV4cGxvcmF0aW9u0gF7aHR0cHM6Ly93d3cuYnJhbnRmb3JkZXhwb3NpdG9yLmNhL25ld3Mvc3BhY2UtanVuay1wb3Nlcy10aHJlYXQtdG8tZXhwbG9yYXRpb24vd2NtL2EzOWRmYmU1LTlmMTQtNGE1My1hYjY3LWRjZDdlYzk1MGFhNi9hbXAv?oc=5
2021-06-03 15:54:03Z
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