Junk in Spaaaaace!

Somehow, I don't think those free crack repair places are up to this job.
Last week, we talked about space junk, how much there is and why it's a problem.  I think the photo above kind of sums that up.  This is the seventh shuttle mission's windshield after getting hit by pea-sized debris at about 15,000 miles per hour.  And you thought hitting a bird with your car was bad!

LDEF.  Kind of looks like a trailer in space, doesn't it?
Fortunately, space junk does not act like the common animal who just has to cross the road in front of that big shiny thing. However, satellites do get hit by miniscule stuff all the time.  NASA sent up a satellite to study this problem--the LDEF.  It was hit millions of times in eight years in orbit, but stayed operational.  (Some of the impacts could only been seen through an electron microscope, to give some perspective.)

So we can agree this is not an optimal situation.  In truth, for the most part, active satellites and space missions are relatively safe.  But the problem is increasing.  In fact in less than three years, the amount of space debris increased by 50 percent, mainly because of two incidents:  the Chinese testing of an anti-satellite weapon, and the crash of an Iridium satellite with a defunct Russian Satellite that together added nearly 5000 pieces of trackable space junk.  (from High Frontier article in Feb 2010)  So what do we do now--and what will we do later--about this problem?

1. Shields.  We need these anyway because of all the naturally occurring space debris--micrometeoroids and dust.  The most common shielding, as I'd mentioned before, are thin strips of aluminum or other material.  The reason these work is because of the speed it's hitting.  When the debris hits, there's so much energy in the force that it  flares into plasma and spreads across the shield.  Thus, you can use a lighter material, and have more layers, and it protects as well as the heavy material.
Here's a shield being tested at NASA.  It uses Kevlar

2. Avoidance.  Air Force Space Command tracks the orbital debris that's bigger than two inches.  (Rob did this for awhile.)  They put out reports and warn NASA and others when a piece of debris looks to be in danger of hitting a functioning satellite.  A more accurate space radar, called the "Space Fence" is in development to better track even smaller pieces of debris.  Of course, other nations do this as well...but we do it best.  (Here's a link to Space Command's website, but it's a 2006 page, so the data is OLD.)
3. Get out of the way!  Satellites, manned vehicles and even the ISS have maneuvering power and fuel planned for collision avoidance maneuvers.  NASA, for example, uses a 1 mile by 30 mile by 30 mile "pizza box" zone around the shuttle.  If something is going to enter that zone, they plan for a maneuver.  Problem is, while it only takes a couple of hours to plan a move on the shuttle, it takes 30 hours to plan and execute one by the ISS if they need the Russian rockets.  (Remember in July, Atlantis nudged it out of the way while docking.)  If they can't plan in time, they prep for collision and hang out in the Soyuz escape pods until the all clear.
4.  Clean up!  This is the one we're working on now.  There are several ideas for cleanup of space junk., and we'll hit on those in another blog.

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Caprice Hokstad said...

So why is the avoidance zone a pizza box instead of a cube? Which direction is the less important one mile radius? Great article as always, Karina.

Karina Fabian said...

Because the objects are going to be coming at them along the plane in which they're moving rather than from directly above or below, is my guess. I'll ask Rob, though, to be sure.

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