Although we weren’t sure about this earlier this week, NASA has said that UARS, a 6-ton bus-sized satellite expected to break into more than a hundred pieces, issuing forth a 500-mile debris footprint as it falls (which it is expected to do sometime Friday afternoon), will NOT be passing over North America. New Yorkers can rest assured that they will not be hit by a piece of flying space junk and have to cancel their Friday night plans, at least, not if NASA knows what it’s talking about. Update: NASA has changed their mind!
As of last night: According to current calculations, the satellite won’t be passing over the U.S., Canada, or Mexico for its fall. Most scientists seem to think it will end up in the ocean — though they’ll know more as re-entry time, Friday afternoon, Eastern Daylight time — gets closer. (The Aerospace Corporation, a private firm tracking UARS, currently thinks the satellite will come down off the coast of Chile at 6:06 p.m..)
Revised, as of this a.m., from NASA: North America is back in the picture! The satellite re-entry time has also been pushed back.
As of 10:30 a.m. EDT on Sept. 23, 2011, the orbit of UARS was 100 miles by 105 miles (160 km by 170 km). Re-entry is expected late Friday, Sept. 23, or early Saturday, Sept. 24, Eastern Daylight Time. Solar activity is no longer the major factor in the satellite’s rate of descent. The satellite’s orientation or configuration apparently has changed, and that is now slowing its descent. There is a low probability any debris that survives re-entry will land in the United States, but the possibility cannot be discounted because of this changing rate of descent. It is still too early to predict the time and location of re-entry with any certainty, but predictions will become more refined in the next 12 to 18 hours.
If anyone does get hit, it will be a historic event. A 1 in 21 trillion kind of event. The AP reports:
Since the dawn of the Space Age, no one has been injured by falling space debris. The only confirmed case of a person being hit by space junk was in 1997 when Lottie Williams of Tulsa, Okla., was grazed in the shoulder by a small bit of debris from a discarded piece of a Delta rocket.
(She was okay. In fact, it felt like being tapped on the shoulder, apparently.)
However, note: “it is still too early to predict the time and location of re-entry with any more certainty.” Check back with NASA for more refined predictions over the course of the day. In the meantime, here’s some oddly soothing video of the satellite’s orbit and projected re-entry.
NASA says there’s nothing radioactive on UARS — the “main reason NOT to touch anything that you think could be debris: sharp metal cuts.”