Thread: 5 TON NASA Satellite to crash to earth FRI. or SAT.

16 September 2011 Last updated at 11:52 ET

Nasa satellite UARS nearing Earth 'could land anywhere'

The 'productive scientific life' of the UARS ended in 2005 when it ran out of fuel

A five tonne, 20-year-old satellite has fallen out of orbit and is expected to crash somewhere on Earth on or around 24 September, according to Nasa.

Nasa says the risk to life from the UARS - Upper Atmosphere Research Satellite - is just 1 in 3,200.

Hurtling at 5m (8km) per second, it could land anywhere between 57 degrees north and 57 degrees south of the equator - most of the populated world.

However, most of the satellite will break or burn up before reaching Earth.

Scientists have identified 26 separate pieces that could survive the fall through the earth's atmosphere, and debris could rain across an area 400-500km (250-310 miles) wide.

Nasa said scientists would only be able to make more accurate predictions about where the satellite might land two hours before it enters the Earth's atmosphere.

Re-entry

The 1 in 3,200 risk to public safety is higher than the 1 in 10,000 limit that Nasa aims for.

However, Nasa told reporters that nobody had ever been hurt by objects re-entering from space.

Members of the public are not allowed to keep pieces of the satellite that may fall to Earth, or sell them on eBay, as they remain the property of the US government.

The UARS was launched in 1991 by the Discovery space shuttle, and was decommissioned in 2005.

The latest satellite re-entry is much smaller than Skylab, a satellite that re-entered the earth's atmosphere in 1979.

It was some 15 times heavier than the UARS, and when it crashed in Western Australia the US government was fined a $400 clean-up fee by the Australian government.

Sputnik 2 crashed on Earth in 1958, travelling from over New York to the Amazon in 10 minutes. It was viewed by many people and left a trail of brightly coloured sparks behind it.

http://www.bbc.co.uk/news/world-us-canada-14952001

Good luck with the satellite crash.

Don't forget to wear your hardhat.

NASA Satellite Falling Faster Due to Solar Activity

UARS to crash-land Friday, but no one yet knows where.

Traci Watson
for National Geographic News
Published September 21, 2011

It may be doomed, but the NASA satellite that's about to crash-land on Earth isn't going out quietly. (Also see "Space Debris: Five Unexpected Objects That Fell to Earth.")

To scientists' surprise, the six-ton Upper Atmosphere Research Satellite, or UARS, has picked up speed and is now expected to plummet through the atmosphere Friday.

Only two weeks ago government scientists projected that the satellite could return to Earth as late as the first days of October.

"The spacecraft is coming in a little faster than we'd originally anticipated," said NASA orbital debris scientist Mark Matney. As a result, "it's coming in sooner rather than on the later side."

The satellite's speed is due to a recent spike in the amount of ultraviolet rays being emitted by the sun, Matney said. (See "As Sun Storms Ramp Up, Electric Grid Braces for Impact.")

The radiation increase caused Earth's atmosphere to expand, which increased drag on the satellite, causing it to fall faster.

(See "Solar Megastorm Could Cripple Satellites for a Decade.")

A Thousand Tons to Survive Reentry?

Experts predict that most of the UARS spacecraft will burn up in Earth's atmosphere.

(Related: "Hayabusa Spacecraft Returns With Fiery Show.")

But more than 1,100 tons (500 kilograms) of debris will probably survive the fiery plunge and slam down to Earth.

The biggest piece to reach the surface intact will most likely be a 300-pound (150-kilogram) piece of the spacecraft's frame.

However, it's still too early to know where the satellite's components will land, Matney said.

The only tip scientists can give for now about the location of the "debris footprint" is that it will be somewhere between 57 degrees north latitude and 57 degrees south latitude—an area encompassing most of Earth's populated land.

(Also see "Space Station to Fall to Earth—Find Out How and Where.")

Odds of Debris Hitting You: 1 in 3,200

UARS, which collected data on Earth's atmosphere from 1991 to 2005, was designed well before scientists started to worry about space debris.

(See "Space Junk Cleanup Needed, NASA Experts Warn.")

During the satellite's development, its creators focused on how to deploy it safely, not how it would end its days, said the University of Michigan's Wilbert Skinner, one of the lead scientists for UARS.

"I don't think we took any time at all wondering what its ultimate fate would be," Skinner said, adding that, at the time, such concerns were "background noise."

Though the satellite's death plunge will be dramatic—and will create a visible light show for nearby observers—it is unlikely to endanger anyone on the ground.

The odds that debris from UARS will strike a human are 1 in 3,200, NASA says.

"There's no need to panic—no need to put on a hard hat," Matney said. "The probability [of harm] is quite low, certainly compared to other daily risks that we're quite comfortable with."

http://news.nationalgeographic.com/news ... th-nation/

Falling satellite slows down, Earth strike delayed

By MARCIA DUNN - AP Aerospace Writer | AP – 18 mins ago...

CAPE CANAVERAL, Fla. (AP) — A dead 6-ton satellite baffled NASA experts Friday by slowing its descent toward Earth and delaying its ultimate crash until the early part of the weekend.

The space agency is now predicting the satellite will crash down to Earth late Friday or early Saturday, Eastern Time. Increased solar activity had been causing the atmosphere to expand and the satellite to fall more quickly, but that's no longer such a major factor, experts said. What's more, the orientation of the satellite apparently has changed in orbit, and that's slowing its fatal plunge.

Friday morning, NASA cautioned there is now a slim chance any surviving debris will land in the United States. Earlier this week, NASA said North America would be in the clear and that the satellite would strike somewhere Friday afternoon.

"It is still too early to predict the time and location of re-entry with any certainty," NASA said in a statement.

The Aerospace Corp., based in California, is estimating the strike sometime between about 6 p.m. and 4 a.m. EDT, which would make a huge difference in where the debris might wind up. Those late-night, early-morning passes show the satellite flying over parts of the United States.

Any surviving wreckage is expected to be limited to a 500-mile swath.

The Upper Atmosphere Research Satellite, or UARS, will be the biggest NASA spacecraft to crash back to Earth, uncontrolled, since the post-Apollo 75-ton Skylab space station and the more than 10-ton Pegasus 2 satellite, both in 1979.

Russia's 135-ton Mir space station slammed through the atmosphere in 2001, but it was a controlled dive into the Pacific.

Most of the UARS satellite will disintegrate, but 26 pieces — representing 1,200 pounds of heavy metal — are expected to rain down somewhere. The biggest surviving chunk should be no more than 300 pounds.

Chances are the wreckage will slam into the ocean; nearly three-quarter of the Earth is covered in water.

In any event, no one has ever been hurt by falling space junk to anyone's knowledge, and there has been no serious property damage. NASA put the chances that somebody somewhere on Earth will get hurt at 1-in-3,200. But any one person's odds of being struck have been estimated at 1-in-22 trillion, given there are 7 billion people on the planet.

UARS was launched in 1991 from space shuttle Discovery to study the atmosphere and the ozone layer. NASA shut it down in 2005 after lowering its orbit to hurry its demise. With a satellite-retrieval mission ruled out following the 2003 Columbia disaster, NASA did not want the satellite hanging around orbit posing a debris hazard.

Space junk is a growing problem in low-Earth orbit. More than 20,000 pieces of debris, at least 4 inches in diameter, are being tracked on a daily basis. These objects pose a serious threat to the International Space Station.
___

Online:

Satellite updates: www.nasa.gov/uars

Aerospace Corp: http://reentrynews.aero.org/1991063b.html

http://news.yahoo.com/falling-satellite ... 59374.html

RELATED

FAA Issues Warning for Pilots to Watch Out for NASA's Falling Dead Satellite

http://www.alipac.us/ftopict-250746.html