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There are plenty of hazards in space travel. One that’s of our own making is what’s called Space Junk, a term for the remnants and debris of old satellites and other spacecraft that’s lost in orbit around the planet. While potentially damaging, larger space junk usually isn’t much of a real threat, because it can be tracked, and is. Flights to space can plot the location of these larger pieces of debris and maneuver around them. The smaller junk, however, is much more potentially hazardous.
What is the small stuff? Well, there are actually many kinds of small and even microscopic man made objects lost in orbit, the most common being flecks of paint from spacecraft, as well as frozen coolant (and other spacecraft waste) that has solidified and become a hazard. These items can and do hit spacecraft and have the potential to severely damage them. In fact, these items are so common and so dangerous to machinery that a special shield, called a Whipple Shield, was developed to combat it. There are currently an estimated 170 million pieces of space junk in orbit around the earth. Some will eventually suffer from a decay in orbit and burn up on reentry to the Earth’s atmosphere, but as long as we continue to go into space, the amount of small debris will not decrease-- more likely, it will increase. It takes many years for a piece of junk’s orbit to decay, but it takes only seconds for new junk to be lost in space. There is an official tracking system for all large objects in orbit. Currently there are around 18,000 items being tracked. While these items are mostly satellites (some now defunct), there are also many space boosters, used rockets and other defunct spacecraft that have themselves remained in orbit. There are also military items, some highly secretive, that are also tracked. Space junk that is large enough can eventually fall back to the earth, and can sometimes be a threat to humans. There have been at least two documented cases of space debris hitting people-- one of the events happened at sea in 1969, where several Japanese sailors were injured from reentered space debris; and the other occurred in 1997 in Oklahoma, when a woman was also hit, but not injured. There have likely been other unreported instances as well. Skylab, the United States’ first space station, suffered a decay in orbit and fell back to earth in 1979. It was a media sensation at the time, with news outlets reporting endlessly on the potential hazard of its falling debris. There were even Skylab watching parties held across the world (as no one knew exactly where Skylab would reenter the atmosphere). Skylab did finally fall back to earth on July 11, 1979, breaking up mostly above Australia, in what was a fiery but decidedly non-lethal conclusion to the media frenzy-- no one was hurt, and very little damage was done. Since we will continue to journey into space for many decades and millennia to come, there will likely have to be a more viable solution for the space junk problem (that will only get worse) to ensure the safe journey of future astronauts. There may be special flights in the future that will vacuum space to remove the smaller space junk, and use special machines to retrieve the larger items. This would help prevent a possible Kessler Event-- an event proposed by NASA scientist Donald Kessler in 1978 that suggested there could be multiple collisions of space junk that would cause larger junk to break up into smaller junk; these new smaller pieces of junk would collide, leading to even smaller junk; which would collide, leading to EVEN smaller junk; and on and on. This could lead to a scenario where there is SO MUCH space junk orbiting the planet’s Low Earth Orbit, that it would significantly increase the risk of space travel. Unfortunately, we’ve always left trash in our wake and space has been no different; but one day-- and one day soon-- we may have to solve this trash problem for good-- or else lose our access to space. |
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GLOSSARY
Kessler Event the Kessler syndrome, proposed by the NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in orbiting the Earth in low Earth orbit is high enough that collisions between objects could generate space debris that increases the likelihood of further collisions.
Low Earth Orbit a low Earth orbit is defined by Space-Track.org as an Earth-centered orbit with at least 11.25 periods per day and an eccentricity less than 0.25. Most of the man made objects in space are in LEO orbits.
Skylab skylab was a United States space station launched and operated by NASA, and occupied for about 24 weeks between May 1973 and February 1974. It’s also the only space station the U.S. has operated exclusively without the aid of other nations.
Space Junk initially, the term space junk referred to the natural debris found in the solar system, like asteroids, comets, and meteoroids. However, with the beginning of the NASA Orbital Debris Program, the term also refers to the junk from the mass of defunct, artificially created objects in space, especially Earth orbit.
Whipple Shield the Whipple shield or Whipple bumper, invented by Fred Whipple, is a type of hypervelocity impact shield which is used to protect manned and unmanned spacecraft from collisions with micro-meteoroids and other orbital space junk.
Low Earth Orbit a low Earth orbit is defined by Space-Track.org as an Earth-centered orbit with at least 11.25 periods per day and an eccentricity less than 0.25. Most of the man made objects in space are in LEO orbits.
Skylab skylab was a United States space station launched and operated by NASA, and occupied for about 24 weeks between May 1973 and February 1974. It’s also the only space station the U.S. has operated exclusively without the aid of other nations.
Space Junk initially, the term space junk referred to the natural debris found in the solar system, like asteroids, comets, and meteoroids. However, with the beginning of the NASA Orbital Debris Program, the term also refers to the junk from the mass of defunct, artificially created objects in space, especially Earth orbit.
Whipple Shield the Whipple shield or Whipple bumper, invented by Fred Whipple, is a type of hypervelocity impact shield which is used to protect manned and unmanned spacecraft from collisions with micro-meteoroids and other orbital space junk.
