Got this from our own astrophysicist to the (radio) stars, Summer Ash. She blogs regularly at Newtonianism for the Ladies.
Special to the BPP from Summer Ash:
Heads Up, Earth!
The Return of Chicken Little
The Sky Is Falling, the Sky Is Falling — U.S. Spy Sat to Splat
That last one is my favorite, and it's the only real headline — used by Satnews Daily. But it's all real news, of a sort. A large U.S. spy satellite really has lost power and is now falling back to Earth.
Government officials aren't saying much, just that the satellite can be expected to re-enter the Earth's atmosphere by late February or early March and that the appropriate government agencies are monitoring the situation. My guess is that would include the DoD, NSC, NSA, and NASA — all of which would want to keep its intelligence hardware under wraps.
This particular satellite was launched by the Department of Defense, not NASA, but that doesn't preclude the space agency's involvement now. Both the Air Force and NASA maintain tracking stations across the globe to identify, track and monitor all Earth-orbiting objects down to sizes in tens of centimeters. They're even tracking handtools accidentally let go by astronauts. Of course, any object in orbit without its own propulsion system will eventually lose altitude, encounter the upper atmosphere and begin to break up. The vast majority of space debris is doomed to disintegrate.
However, as witnesses to Skylab, Mir, and Columbia will attest, when the object re-entering the atmosphere is above a certain size, many pieces can survive the intense heat and come out the other side more or less intact. When Skylab fell back to Earth, an oxygen tank the size of a large desk landed on the coast of Australia — the U.S. was charged for littering. Mir's de-orbiting was controlled by onboard rockets, so that any pieces surviving the re-entry process fell harmlessly in the Pacific Ocean. And most recently, the Columbia accident left sizeable debris across the southwestern United States.
According to the Associated Press, defense and intelligence expert John Pike estimates this spy satellite to weigh around 10 tons (20,000 pounds) and approach the size of a small bus. That's a lot smaller than any of the three spacecraft above, but still large enough to do some damage were it to come down in a populated place. You may remember from Geography 101 that 70 percent of the Earth's surface is covered by water. The odds favor a harmless splashdown. But secrecry, understandably, surrounds government satellites, so it's impossible to know where the folks in charge expect the particular bit of space junk to land.
A quick scan of the Web brought up some international coverage of the situation. It's interesting to note the different perspectives:
CTV in Canada mention the possible fuel on board as hydrazine and raise the concern of toxic exposure to the chemical should it re-enter in a populous area. They don't allude to it, but Canada was the victim of nuclear space debris once before at the hand of a Russian satellite that crashed in the skies over the Northern Territories in 1978.
Moscow released a tersely worded statement via Interfax-AVN, declining any alarm over the situation.
And India Daily hypes the idea that China and Russia would jump at the chance to hijack the satellite to steal our spy technology, if it were possible.
For the rest of us, at this point, there's not much to do but wait and keep one eye on the sky.