Junk in Spaaace 2--removal method one: Foam balls!

Looks like the UARS satellite pretty much ditched into the ocean, despite the Twitter rumor that the satellite crashed in the Canadian town of Okotoks.

So sorry to my friend, who lost the 1 in who-knows-how-many chance that the satellite would take out her roof, causing NASA to expends some chump change to fix her a new house ("Would $300,000 do ma'am?  Pull that out of the discretionary funds, Lewis, and make sure she signs the "It wasn't Obama's fault/I support government space" disclosure.)

But never fear!  Your chance may come again!  According to the European Space Agency, there are thousands of defunct satellites just puttering around waiting for their turn at firey demise:

Between 1957 and 2008, approximately 4600 launches have placed some 6000 satellites into orbit. Among these, about 400 were launched beyond Earth into interplanetary trajectories, but of the remaining ones only about 800 are operational. This means that roughly 85% of space objects belong to the uncontrolled satellite class, namely dead spacecrafts.

The ESA has proposed giving these guys a helping hand...in this case a "helping" satellite to coat the derelict one in spray foam.

Cozy!

 The idea is that the foam increases its area, causing atmospheric drag which slows it down and eventually causes it to plunge to the earth.  They would launch a satellite filled with this foam, and it would spray defunct satellites.  The resulting ball-shaped objects would then get pulled slowly and naturally back to earth.

...in 10 to 25 years.

So, it's an easy method, but not an especially fast one.  Of course, it's faster than what's going on now.  (Many of these satellites will take centuries to deorbit.)  The method itself calls for a relatively simple spacecraft, and there's no need to control the descent of the satellite itself.  You're not adding any more equipment to the satellite, like a sail to slow it down, so there's less threat of collision between the defunct craft and the deorbiter and less stuff to become space junk should the deorbit fail.


Of course, people are concerned that the deorbiter craft might cause space junk itself; it might break the craft while trying to grapple to it for the foaming process, or the foam itself might be a problem.  And, of course, there's the natural suspicion that this might not just get used on defunct satellites.

You can read more abut this on an ESA PDF available online.  Next time, I have a treat for you:  A very cool anime exploring the idea of humans collecting space trash.

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.

Falling Satellites and orbiting Space Junk

Look out below!

This is a great video.  Despite the enthusiastic introduction, where it describes the pieces shrieking to the earth, it does give some perspective: about one satellite a year falls to the Earth, and even with the UARS satellite not having fuel to control its descent, you have about a one in 3600 chance of getting hit. They expect about 26 pieces, the largest being around 300 pounds, to make it through the atmosphere--but it's all guesswork at this point. (My friend is actually hoping her house gets hit--she's mightily sick of her dilapidated house.  Can you imagine trying to convince your insurance that "satellite impact" is covered under your homeowners?)

Hyuk hyuk.  I just sold her the satellite impact policy.  What a maroon!

Because the satellite has no fuel left, it can't control its descent, and no one's quite sure where it will come down, so take an umbrella with you on the 23rd just in case.  (And have your cell phone camera charged!)

Anyway, this is a good time to address the issue of Space Junk.  Spcce junk is a pretty simple concept:  we lunch stuff into orbit, and not all of it comes back to earth or goes out into space.  Not only is the useful stuff up there, but the defunct stuff (satellites like the UARS that run out of fuel or malfunction); broken bits from collissions, even little flecks of stuff.

It's all potentially bad news.  Size is not as much an issue when you're traveling 17,000 mph. Back in the 80s, pea sized paint chip once impacted the windshield of the space shuttle.  It put a gouge in it.  During the last flight of the shuttle Atlantis, the ISS was in danger of being hit by a piece of a broken Soviet satellite--the docking of the Atlantis nudged the station just enough for a miss.  Even when lives are not threatened, satellites still have to maneuver at times to avoid junk.  Spacecraft ofteh have multiple layers of thin aluminum shielding.  It actually works better than a thick piece of metal.

So how much is out there?  According to NASA scientist Nicholas Johnson, there are roughly 22,000 objects bigger than 4 inches (some as big as car-sized rocket boosters weighing 9 tons), and perhaps 500,000 smaller ones, down to 0.4 inches across, in orbit.  (taken from USA TODAY--definitely go check this article out.)

Here's what it looks like in space.  Keep in mind that the dots are not to scale and space, as the Hitchhiker's Guide to the Galaxy says, "is big. Really big. You just won't believe how vastly, hugely, mindbogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space..."  However, as we add more stuff and stuff bumps into stuff and stuff breaks into smaller stuff and well, stuff happens, this will become an even more serious problem.

So what are we doing about it?  That's another blog.