Watch out 'cause this time, it's for real! ...and this time you have a 1-in-3200 chance of being a human casualty...
RE-ENTRY ALERT: UARS, a NASA satellite the size of a small bus, will re-enter the atmosphere later this week. Best estimates place the re-entry time during the late hours of Sept. 23rd over a still-unknown region of Earth. "It is still too early to predict the time and location of re-entry," says NASA. "Predictions will become more refined over the next two days."
The disintegration of UARS is expected to produce a fireball that could be visible even in broad daylight. Not all of the spacecraft will burn up in the atmosphere, however; according to a NASA risk assessment, as many as 26 potentially hazardous pieces of debris could be scattered along a ground track some 500 miles long. The same report puts the odds of a human casualty at 1 in 3200.
On Sept. 15th, astrophotographer Theirry Legault video-recorded the doomed satellite during one of its last passes over France:
Photo details: Celestron 14" EdgeHD, Takahashi EM400 mount modified for fast tracking. Range to UARS: 252 km.
"The satellite appears to be tumbling, perhaps because a collision with satellite debris a few years ago," notes Legault. "The variations in brightness are rapid and easily visible to the human eye." (Other observers have reported UARS flashes almost as bright as Venus.)
For last-chance sightings of this brightly flashing satellite, please check the Simple Satellite Tracker or download the Satellite Flybys app for your smartphone.
NASA Update #6
Tue, 20 Sep 2011 02:00:29 PM MDT
As of Sept. 20, 2011, the orbit of UARS was 127 mi by 140 mi (205 km by 225 km). Re-entry is expected Sept. 23, plus or minus a day. It is still too early to predict the time and location of re-entry. Predictions will become more refined over the next two days.
As of Sept. 20, 2011, the orbit of UARS was 127 mi by 140 mi (205 km by 225 km). Re-entry is expected Sept. 23, plus or minus a day. It is still too early to predict the time and location of re-entry. Predictions will become more refined over the next two days.
U.S. Reentry Predictions
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The official source of reentry predictions for uncontrolled space objects isUSSTRATCOM’s Joint Space Operations Center (JSpOC).
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be prepared and released to the public (via the Space-Track.org website) at
the following intervals:
T – 3 days
T – 2 days
T – 1 day
T – 12 hours
T – 6 hours
T – 2 hours
TIP messages provide the best estimates of reentry time and location but– 2 hours, the uncertainty of reentry
Number of potentially hazardous objects expected to survive: 26NASA conducted a detailed reentry risk assessment for UARS in 2002.A final, post-reentry assessment message is normally issued within a few
T – 4 days•
have large uncertainties. Even at T
time is on average +/- 25 minutes for nearly circular orbits. This equates to
+/- 12,000 km on the Earth.
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hours of reentry.National Aeronautics and Space Administration
UARS Casualty Risk Assessment
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–
–
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No NASA or USG human casualty reentry risk limits existed when UARS
NASA, the USG, and some foreign space agencies now seek to limit human
UARS is a moderate-sized space object. Uncontrolled reentries of objects
Combined Dragon mockup and Falcon 9 second stage reentry in June 2010 was more
Since the beginning of the space age, there has been no confirmed report
http://www.nasa.gov/mission_pages/uars/index.html
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NASA, DoD, and the IADC will be monitoring the decay and reentry of UARSEstimated human casualty risk (updated to 2011): ~ 1 in 3200
Total mass of objects expected to survive: 532 kgNational Aeronautics and Space Administration
Summary
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was designed, built, and launched.
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casualty risks from reentering space objects to less than 1 in 10,000.
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more massive than UARS are not frequent, but neither are they unusual.
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massive.
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of an injury resulting from reentering space objects.
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carefully.http://www.nasa.gov/mission_pages/uars/index.html
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| The Upper Atmosphere Research Satellite hangs in the grasp of the Remote Manipulator System during deployment from Space Shuttle Discovery, September 1991. CREDIT: NASA Marshall Space Flight Center |
With a massive dead NASA satellite due to plunge back to Earth this week, the Federal Emergency Management Agency (FEMA) is laying the groundwork for a fast response in case the 6 1/2-ton spacecraft falls over American soil.
The defunct spacecraft, called the Upper Atmosphere Research Satellite (UARS), is projected to make and uncontrolled, fiery fall on Sept. 23, plus or minus a day, according to NASA.
Odds are that nobody will be beaned by any remaining chunks of the nearly $750 million spacecraft, with NASA experts forecasting a remote 1-in-3,200 chance of a possible injury from the satellite's debris.
National Aeronautics and Space Administration
