Near Earth Space Is A Very Crowded Place!

 

From The Washington Post

Space Junk's Reaching A Critical Danger Point

Mankind has a way of plunging into an endeavor without thinking about the consequences of its actions. That was done with the environment here on the planet, and now we are faced with destroyed environments, vanishing species, dirty and unsafe water & air, and the prospect of global climate change which could easily hurt the lives (and possible existence) of future generations. And unfortunately, man seem to be doing the same in space.

For the last 50 years or so an ever growing list of nations has been shooting a wide variety of things into space, and most of those things are still up there -- about 22,000 of them. And that's just the bits of space junk that are large enough to be detected from Earth. There are thousands and thousands more that are only 1 centimeter in diameter or slightly larger that can't be detected -- and these, in spite of their small size, could pose a real danger to spacecraft (which could hit them while traveling at enormous speeds).

A new report by the United States National Research Council (NRC) says that the enormous amount of space junk is reaching a critical "tipping point", and now poses a significant risk of causing fatal leaks in spacecraft or damaging valuable satellites. The report called for international regulations to limit future space junk and more research on how to reduce the amount of space junk that is already orbiting above the Earth.

Some might think we could just blow up the large space junk, but that would just exacerbate the problem rather than solve it. Back in 2007 the Chinese tested an anti-satellite weapon on a decommissioned weather satellite -- and the result was a disaster. They were able to blow up the satellite, but now instead of having one large piece of space junk there are thousands of much smaller pieces.

Then in 2009, two satellites crashed in orbit, creating thousands more tiny bits of space junk. Scientists believe the Chinese explosion and the satellite crash together may have doubled the amount of space junk. Donald Kessler, a retired NASA scientist, believes the situation is getting out of control since there is no doubt there will be further space junk collisions, and each collision makes the problem worse. He says, "We've lost control of the [space] environment."

It is obvious that the international community must get together and solve the space junk problem -- and soon. But what can be done? The NRC report didn't offer any solutions, but it did reference a previous report from a Pentagon think-tank, the Defense Advanced Research Projects Agency (DARPA). The DARPA report talked about ideas like a space harpoon, space nets, or an umbrella-like device. These could round up space junk and either send it to burn up re-entering Earth's atmosphere or push them much farther out into space.

But whatever the international community decides to do needs to be done quickly. Time is running out, and we may soon have another space disaster that takes human lives and destroys valuable property.

Satellites With Sails

Each year, various governments send several new satellites into orbit around our planet. These satellites have a variety of purposes, and operate from one to many years. But eventually, they all outlive their usefullness and become just more space junk, cluttering up the space around Earth.

A piece of space junk can orbit the planet for many decades before its orbit decays enough that it falls back toward Earth and burns up in the atmosphere. That is why the space junk is piling up around our planet, and soon it may start to pose a danger for any new satellites being launched. With much of our new technologies being dependent upon satellites, a solution to the problem of the proliferation of space junk must be found.

One solution is to save some power for the end of the satellites usefulness, and use that to ignite an engine to send it plummeting back to Earth. There are a couple of drawbacks to this. First, it is very expensive to outfit every satellite this way. Second, there is no guarantee that even if the money is spent, the satellite will have enough power left to power the re-entry engine.

Fortunately, there is a cheaper and more reliable solution being developed. Scientists are now working on a system they call the Innovative DEorbiting Aerobrake System (IDEAS). Basically, it is a sail that can be deployed at the end of a satellite's usefullness.

Even at heights of 470 miles above the Earth's surface, there are residual air molecules. The sail would catch these molecules and provide a drag effect on the satellite. While it would not send the satellite instantly plunging toward Earth, it would significantly cut the amount of time it would take for its orbit to decay enough to send it plummeting back.

For example, a French scientific satellite is to be launched soon. It is called Microscope, and will complete its mission in about a year. If left to decay and fall on its own, it could remain in orbit for between 50 and 100 years. However, it is being fitted with a deployable sail which is expected to bring the satellite down within 25 years.

While this may not be the complete solution to space junk, it can be of immense value in controlling the lifespan of future such space junk. Imagine how much it would help to cut the space lifetime of a piece of space junk by 50% to 75%.

A piece of space junk that has burned up falling back to Earth, poses no danger to the launch and orbit of a future satellite.