Re: more on space junk

Have a look at the link for some photos of space junk that has come back down to earth, and some of the damage this stuff does. Its also interesting that we can now track space junk as it orbits over our homes.

spud




http://www.smh.com.au/technology/sci-tech/space-the-final-frontier-of-junk-20...




Space: the final frontier of junk
Scott Casey
October 19, 2009



It's home to everything from gloves to tool kits, spatulas to disused rockets, urine bags to relic Cold War satellites.

Space is quickly becoming a floating scrap heap, with more than 14,000 pieces of space junk larger than 10cm currently being tracked orbiting the Earth.
But despite the potential safety hazard - both on land and to satellites in space - some scientists are calling for the space junk of yesteryear to be protected.

Australia: prime landing destination
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Click on Image for Full Size This is the main propellant tank of the second stage of a Delta 2 launch vehicle which landed near Georgetown, TX, on 22 January 1997. This approximately 250 kg tank is primarily a stainless steel structure and survived reentry relatively intact. Click for more photos
Space junk takes its toll

Click on Image for Full Size This is the main propellant tank of the second stage of a Delta 2 launch vehicle which landed near Georgetown, TX, on 22 January 1997. This approximately 250 kg tank is primarily a stainless steel structure and survived reentry relatively intact. Photo: NASA

* Click on Image for Full Size This is the main propellant tank of the second stage of a Delta 2 launch vehicle which landed near Georgetown, TX, on 22 January 1997. This approximately 250 kg tank is primarily a stainless steel structure and survived reentry relatively intact.
* Solar Max satellite repair. Several metal louvers and thermal blankets were returned from the Solar Max satellite. Returned surfaces are a source of information on sub-millimeter sized orbital debris.
* This 30 kg titanium pressurant tank also survived the reentry of the Delta 2 second stage on 22 January 1997 but was found farther downrange near Seguin, TX.
* A close-up view of a panel from the Long Duration Exposure Facility (LDEF) spacecraft.
* Mir Environmental Effects Payload (MEEP) Orbital Debris Collector (ODC) was exposed to the space environment for 18 months. The ODC utilized an aerogel capture medium. Aerogel is a very low density material that can slow small particles down from orbital velocities and capture them without destroying them.


Australia is a prime landing destination for space junk that may plummet towards Earth.

Early last year, James Stirton found a 57-centimetre wide, 20-kilogram chunk of rocket on his property near Charleville in south-western Queensland after it re-entered the Earth's atmosphere over Indonesia and burnt up.

"I was just riding along on my bike and it was beside the road, beside a track out in the paddock," Mr Stirton told AAP.

"I just wondered what it was so I went over and had a look at it and I figured it must have fallen from the sky because there's no tracks or traffic or anything out here."

Mark Rigby, curator of The Sir Thomas Brisbane Planetarium, was called upon to identify the piece of space junk at the time and says due to our landmass Australia attracts much waste falling from space. "Because we are such a large land mass we do tend to collect space junk coming down," Mr Rigby said.

"The best example of that is Skylab in 1979, NASA announced it came down in the Indian Ocean then we heard all the reports from Perth and Esperance of blazing bits of space junk coming down.

"Over the years we've had bits of Russian satellites, spherical tanks, a number of those sorts of things have been found in the outback."

It's crowded up there

Mr Rigby said the build up of clutter in near Earth orbit - about 3279 of the pieces are former payloads such as defunct satellites or probes - was beginning to become a massive problem for space agencies across the world.

"We've made the near Earth environment quite hazardous - it is a growing concern and there are international bodies looking at what we can do to clean this up and try and prevent it in the future," he said.

"Things like the International Space Station need to be manoeuvred every now and then to avoid the possibility of a collision, they don't like anything coming with in a few kilometres of it."

The threat of collisions is real with NASA saying on the website of its Orbital Debris Program Office an average of two windows on the Space Shuttle are needed to be replaced after every launch due to debris and micrometeorite impacts.

In the private sector a US communications company Iridium found out in February the danger of space debris when one of their satellites collided with a disused Russian military satellite, Kosmos 2551.

Such collisions produce more small particles of space junk which then pose the threat of further collisions.

"Those pieces of debris will be up there for many many years," Mr Rigby said.

Recently an elderly British couple had a two-kilogram chunk of metal, part of a booster rocket, smash into their home.

"We heard this sound and went outside and saw this hole in the roof. The lump had destroyed two tiles and made an absolute mess," Mair Welton, 62, from Hull in north-east England told The Telegraph.

"My granddaughter's boyfriend had to put on some oven gloves to fetch it because it was so hot."

In January of this year China drew the ire of all countries which operate satellite programs by shooting a missile at one of its own disused satellites, destroying it and producing hundreds of thousands of tiny pieces of debris.

In 2001, the MIR space station was, as part of a controlled re-entry program, crashed into the southern Pacific Ocean.

Looking ahead, Mr Rigby said the world's space agencies have future problems not just in cleaning up space but carefully negotiating the destruction of the biggest and most valuable object in orbit, the International Space Station.

"That will be trying to bring down several hundred tonnes of stuff and it's going to be tricky," he said. "One of the things which made Skylab unpredictable was solar panels which tended to allow it to skim along the atmosphere and instead of landing in the Atlantic, as they were predicting, it came down over Australia."

Call to save space rubbish

But Dr Alice Gorman, an archaeology lecturer at Flinders University in Adelaide, believes there is a duty to protect space junk for its cultural significance.

"It comes back to that basic thing in archaeology that the objects themselves have a significance not captured by written material," Ms Gorman told the magazine Archaeology in 2007.

"It's difficult this early on to get a sense of what kinds of questions people are going to want to ask of the orbital record, but early telecommunications satellites, for example, are the artefacts that created the modern world.

"We should keep spacecraft that are unique, or ones that represent a nation. Indonesia sent up a few satellites early on, and they're quite rare. Satellites that represent major leaps in technology are also notable, like the first geosynchronous satellite."

Professor Fred Watson, Astronomer in Charge at the Anglo-Australian Observatory, said Ms Gorman's comments were important to consider for the future of space travel.

"You might want to declare the Apollo landing sites on the Moon a heritage site because they are of great historical interest, the same is true of spacecraft but whether you should take something which is a hazard and make it heritage-listed is a different issue," Dr Watson said.

"Some of the spacecraft need to be actively boosted in orbit to keep them up there because otherwise they will come back down to Earth and that means you have to put energy and effort into that and you might not want to do that for the sake of history."

Dr Watson said due to the time it takes for some older objects to degrade, we still have time up our sleeve to assess their historical significance.

"The oldest is spacecraft in orbit is Vanguard One which was launched in 1958 and that is expected to remain in orbit for about 200 years before it naturally comes back to Earth, so it means we've got some time to find out if we want to save it as a heritage listed item," he said.

"By then we might have the wherewithal to bring these things down with something like the space shuttle but at the moment we just don't have that capability."

Spotting junk from home

Mr Rigby said it was not too difficult for amateur astronomers to observe space junk from their own backyard.

"To see a satellite or a piece of space junk you need to be in twilight or darkness and it needs to be in sunlight," he said.

"Morning twilight or evening twilight are good times but if you're trying to look in the middle of the night you won't see satellites and they'll be in the Earth's shadow.

For help spotting space junk, Mr Rigby recommended heavens-above.com, where users can set their location and see a map of all object currently passing over their area. Tweet