There is growing appreciation that outer space has become a trash bin, with the Earth encircled by dead or dying spacecraft, along with menacing bits of orbital clutter - some of which burns up in the planet's atmosphere. The big news of late was a smashup of a commercial Iridium satellite with a defunct Russian spacecraft earlier this year. Then there was that 2007 anti-satellite test by China, purposely destroying one of its aging weather satellites. These events produced large debris fields in space – adding to the swamp of cosmic compost. But I sense a line of research that needs exploring: The overall impact of human-made orbital debris, solid and liquid propellant discharges, and other space age substance abuse that winds up in a 2 high-speed dive through Earth's atmosphere. There's a convenient toss away line that is in vogue: that such space refuse simply "burns up" – a kind of out of sight, out of mind declaration. What chemistry is involved given the high heating during reentry of space leftovers made of tungsten, beryllium, aluminum and lots of composite materials? The impact of these materials on Earth's atmosphere - top to bottom – would seem worthy of investigation.
Ozone depletion - As for total mass of uncontrolled objects that re-enter each year – it's in the range of 70 – 80 metric tons. And that's the trackable, big stuff – never mind smaller bits of orbital jetsam like bubbles of still-radioactive coolant that has been leaked from old nuclear-powered Soviet satellites. One study team that looked into the impact of de-orbiting space debris on stratospheric ozone issued their findings back in 1994. The work was done by an aerospace industry firm for the Environmental Management Division of the Space and Missile Systems Center. They reported that objects re-entering the atmosphere can affect ozone in several ways, but not on a significant level globally. Indeed, as an object plows through the Earth's stratosphere...
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