Number of posts : 4389 Registration date : 2009-02-01
Subject: get a hard hat Sat Sep 17, 2011 8:48 pm
and don't be looking up..they say your chances of being hit are slim..but , who knows, it just may be your day... oh and by the way...anything falling from the sky is just old space junk..so no worries
NASA: Satellite Pieces To Hit Earth In A Week
WASHINGTON -- U.S. space officials say they expect a dead satellite to fall to Earth in about a week.
NASA has been watching the 6-ton satellite closely. On Friday officials moved up their prediction for its arrival to Sept. 23, give or take a day.
NASA scientists have calculated the satellite will break into 26 pieces as it gets closer to Earth. The odds of it hitting someone anywhere on the planet are 1 in 3,200. The heaviest piece to hit the ground will be about 350 pounds, but no one has ever been hit by falling space junk in the past.
NASA space junk experts have refined the forecast for the anticipated death plunge of a giant satellite, with the U.S. space agency now predicting the 6 1/2-ton climate probe will plummet to Earth around Sept. 23, a day earlier than previously reported.
The defunct bus-size spacecraft is NASA's Upper Atmospheric Research Satellite (UARS), which launched in 1991 and was shut down in 2005 after completing its mission. The satellite was expected to fall to Earth sometime this year, with experts initially pegging a weeks-long window between late September and early October, then narrowing it to the last week of this month. http://www.space.com/12982-dead-nasa-satellite-falling-earth-sept-24.html
"We simply will not know where it's going to come down until it comes down," said Air Force Maj. Michael Duncan of the U.S. Strategic Command last week.
http://www.space.com/12928-falling-satellite-crash-late-september-nasa.html The spacecraft, an old NASA climate probe called the Upper Atmosphere Research Satellite (UARS), was decommissioned in 2005 and has been slowly losing altitude since. Soon, the 6 1/2-ton satellite will make a final uncontrolled plunge through Earth's atmosphere.
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sky otter Senior Member
Number of posts : 4389 Registration date : 2009-02-01
Subject: Re: get a hard hat Wed Sep 21, 2011 7:32 pm
By Alan Boyle NASA says its derelict Upper Atmosphere Research Satellite is expected to make its final fiery plunge sometime on Friday afternoon ET and notes that "the satellite will not be passing over North America during that time period."
This afternoon's update suggests that Americans are not at any risk for injuries or property damage due to satellite debris. It also means they'll miss out on the fireworks.
For two weeks, experts on orbital debris have been telling people that the 20-year-old, bus-sized spacecraft would soon fall through the atmosphere and drop about two dozen pieces of debris on Earth — but until today, there was too much uncertainty to say exactly which day that would happen. In the morning update, NASA narrowed the time frame down to Friday. The forecast was refined further at 6:35 p.m. ET. But NASA said it couldn't yet be any more precise than to say it'll be Friday afternoon, Eastern Daylight Time.
"It is still too early to predict the time and location of re-entry with any more certainty, but predictions will become more refined in the next 24 to 48 hours," NASA said The six-ton satellite's orbit is limited to between 57 degrees north latitude and 57 degrees south, spanning the width of the world between northern Canada and the tip of South America. In the past, Nicholas Johnson, the head of NASA's Orbital Debris Program Office, has estimated that the chances that any of the UARS debris would hit anybody were 1 in 3,200 — which translates into a 1-in-20 trillion risk for any particular person.
NASA's Johnson told me today that he won't be recalculating the odds as the prediction becomes more precise. "At that point, we don't compute odds," he said.
NASA and its partners at the U.S. Strategic Command will be issuing updates on the timing at 24 hours before the expected fall, then at T-minus-12 hours, T-minus-6 hours and T-minus-2 hours — and we'll be passing those predictions along. But even two hours before re-entry, experts won't be able to project exactly where the debris will end up.
When UARS' predicament first came to light a couple of weeks ago, Johnson said the margin of error for the 500-mile (800-kilometer) fall zone would be somewhere around 6,000 miles, or a quarter of the way around the planet. The uncertainty arises because of a couple of factors: Solar outbursts, like the ones we've been getting over the past few weeks, lead to a faster decay of orbits for low-flying spacecraft. Also, the satellite is tumbling, which leads to unpredictable atmospheric-drag effects. Because there's no fuel left for orbital maneuvering, no one has any control over UARS' orbital course.
Most of the satellite will burn up in the atmosphere, but NASA estimates that about a half-ton's worth of fragments will survive re-entry and fall to Earth. The computer models suggest that the biggest chunk would weigh about 300 pounds (150 kilograms), or as much as a refrigerator. Anyone who happened to be in the vicinity of the debris fall would see bright streaks in the sky, much like the fireworks seen when pieces of Russia's Mir space station fell to Earth in 2001.
The most likely outcome is that the remnants of the UARS satellite would fall into a desolate patch of ocean or an uninhabited stretch of land, far away from any witnesses or potential victims. "Throughout the entire 54 years of the Space Age, there has been no confirmed report of anybody in the world being injured or severely impacted by any re-entering debris," Johnson noted two weeks ago.
UARS was deployed from the shuttle Discovery in 1991, beginning a $750 million mission to study the upper atmosphere and its interaction with the solar wind. In 2005, it was shut down and placed into a disposal orbit, and its altitude has been slowly decaying ever since. Now the descent is picking up speed: NASA said its altitude at 1:30 p.m. ET today ranged from roughly 120 to 130 miles (190 to 205 kilometers).
Nowadays, satellite operators lay out a well-defined procedure for the safe disposal of Earth-orbiting satellites at the end of their lifetimes. In fact, NASA and its international partners are already devoting attention to what needs to be done when it comes time to get rid of the International Space Station, sometime after 2020. But back in the 1990s, when the UARS mission was launched, such issues were "really not given a lot of thought," Johnson said.
Update for 9 p.m. ET: If North America is out of the picture, what about the rest of the world? Take a look at the graphic on this webpage from The Aerospace Corp. to see why NASA has ruled out North America based on its time estimate.
The circled icon on the map indicates the position of the UARS satellite at 4 p.m. ET Friday. The blue curves show its orbital track before 4 p.m., and the yellow curves show the track after 4. If UARS re-enters the atmosphere before 4, the potential fall zones include the Atlantic, Africa, Middle East, north Asia and the Pacific. If it happens after 4, South and Central America, south Asia and Australia come into the mix. But it'd be well into Friday evening by the time the orbital track goes over the U.S. and Canadian East Coast
Sat Sep 17, 2011 8:48 pm
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this is their story...lets see if they're right
I bet something happened to that satellite that their not saying.
