German Satellite is Due to Hit October 22/23

Falling German Satellite Poses 1-in-2,000 Risk of Striking Someone This Month

by Leonard David,’s Space Insider Columnist
Date: 12 October 2011 Time: 07:41 AM ET
Artist's impression of the ROSAT satellite in space
Artist’s impression of the ROSAT satellite in space
CREDIT: German Aerospace Center

A big German satellite near the end of life is expected to plunge back to Earth this month, just weeks after a NASA satellite fell from orbit, and where this latest piece of space junk will hit is a mystery.

The 2.4-ton spacecraft, Germany’s Roentgen Satellite (ROSAT), is expected to fall Oct.  22 or 23.

The satellite will break up into fragments, some of which will disintegrate due to intense re-entry heat. But studies predict that about 1.6 tons of satellite leftovers could reach the Earth’s surface. That’s nearly half ROSAT’s entire mass.

There is a 1-in-2,000 chance that debris from the satellite could hit someone on Earth, though the likelihood of an injury is extremely remote, German space officials say. For German citizens, the risk of being struck is much lower, about 1 in 700,000.

All areas under the orbit of ROSAT, which extends to 53 degrees northern and southern latitude, could be in the strike zone of the satellite’s re-entry.

The bulk of the debris is likely to hit near the ground/ocean track of the satellite. However, isolated fragments could descend to Earth in a 50-mile (80-kilometer) swath along that track. [Photos: Germany’s ROSAT Satellite Falling to Earth]

The satellite will be the second large spacecraft to make a pre-announced fall from space in as many months. On Sept. 24, NASA’s 20-year-old Upper Atmosphere Research Satellite (UARS) crashed into the Pacific Ocean in a widely publicized death plunge.

The ROSAT project was a collaborative venture among Germany, the United States, and the United Kingdom. It was developed, built and launched on behalf of and under the leadership of the Deutsches Zentrum für Luft- und Raumfahrt (DLR), Germany’s space agency.

ROSAT undergoing tests in the space simulation chamber
The ROSAT satellite undergoing tests in the space simulation chamber at Dornier.
CREDIT: Dornier (now Astrium Friedrichshafen).

The uncontrollable ROSAT

ROSAT was placed into Earth orbit on June 1, 1990. The highly successful astronomy mission ended after nearly nine years, with commands sent on Feb. 12, 1999, to shut the spacecraft down.

The spacecraft does not have its own propulsion system, so it could not  be maneuvered into a controlled re-entry at the end of its mission.

Moreover, the satellite is zipping through space in deaf and silent mode. That is, ROSAT is no longer able to communicate with DLR’s control center in Oberpfaffenhofen, nor is it possible to establish contact with the spacecraft.

Still, the DLR says the probability of ROSAT coming down over an inhabited area is extremely low.

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UARS Satellite Falling Faster Than Expected

Fireball picture: Hayabusa reenters the atmosphere.

The sample capsule from Japan’s Hayabusa spacecraft became a fireball as it fell to Earth last June.

Photograph by Takashi Ozaki, Yomiuri Simbun/AP

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 Earthisn’t going out quietly. 

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.

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

A Thousand Pounds to Survive Reentry?

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

But more than 1,100 pounds (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.

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.

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So WHERE will NASA UARS Satellite Land?

Where will NASA’s UARS satellite land?

UARS animation from BBC

UARS animation from BBC
NASA says the UARS satellite will re-enter the atmosphere on September 23, 2011, give or take a day. Parts may strike Earth – but no one knows exactly where.

Between now and next weekend, a 20-year-old satellite – the Upper Atmosphere Research Satellite (UARS) – will make an uncontrolled re-entry through the Earth’s atmosphere. Pieces of the 6.5-ton satellite are expected to survive the fiery plunge and hit our planet. Trouble is, no one knows exactly where.

The chances of being hit by a falling satellite are small. Nick Johnson, chief scientist with NASA’s Orbital Debris Program, told Universe Today:

Numerically, it comes out to a chance of one in 3,200 that one person anywhere in the world might be struck by a piece of debris.

When you think about the seven billion people on Earth today, you see how vanishingly small the probability of being struck really is. After all, most of Earth is ocean, so chances are UARS will go from the fires of re-entry directly to a watery grave in the ocean depths. It’s also important to note that no injury has ever been caused by orbital debris during the half-century that we humans have been placing objects in Earth orbit.

Tongue-in-cheek debris map for UARS re-entry developed by The

NASA says the satellite is likely to begin re-entry on September 23, 2011, give or take a day. Hurtling at five miles (eight kilometers) per second, they say it could land anywhere between 57 degrees N. latitude and 57 degrees S. latitude – basically, most of the populated world.

The satellite was launched in 1991 by the space shuttle Discovery. Designed to operate for three years, six of its ten instruments are still functioning, according to NASA’s UARS page. However, the satellite was officially decommissioned in 2005, at the same time that other satellites took over its work.

This isn’t the first time a massive satellite left orbit and made an uncontrolled re-entry back to Earth. In 1979, Skylab re-entered the atmosphere, causing some nail-biting before it finally struck safely in Australia.

Bottom line: Around September 23, 2011, NASA’s Upper Atmosphere Research Satellite (UARS) will make an uncontrolled re-entry through the Earth’s atmosphere. Pieces of the 6.5-ton satellite are expected to survive the fiery plunge through the atmosphere and hit our planet, but the precise location it will strike is unknown. NASA says there is a one in 3,200 chance that a person anywhere in the world might be struck by a piece of debris.


NASA UARS Satellite Reentry Spot Unknown

NASA’s UARS satellite weighing over six tons will come down this month uncontrolled

Published on September 8, 2011 8:20 am PT
– By Jim Duran – Writer
– Article Editor and Approved – Warren Miller

No larger image

( — NASA’s Upper Atmosphere Research Satellite (UARS) is going to re-enter Earth’s atmosphere late this month or early next.

NASA announced on Wednesday that this will be uncontrolled, which means they do not know yet where it will go.

Furthermore, NASA states most of the satellite will burn up in the atmosphere, but there will be pieces that make it to the ground. Being this is an uncontrollable re-entry, it could threaten interests on the ground and in the air.

Some predictions paint September 26th as the day the satellite comes down. NASA will update weekly until the final four days of the expected re-entry and then push the updates to daily.