Tag Archives: space debris

Space Junk Collision Could Set Off Catastrophic Chain Reaction, Disable Earth Communications

Pentagon: A Space Junk Collision Could Set Off Catastrophic Chain Reaction, Disable Earth Communications | Popular Science.

 

Orbital Debris The dots on this NASA-generated chart represent known pieces of large orbital debris. NASA

Every now and again someone raises a stern warning about the amount of space junk orbiting Earth. Those warnings are usually met with general indifference, as very few of us own satellites or travel regularly to low Earth orbit. But the DoD’s assessment of the space junk problem finds that perhaps we should be paying attention: space junk has reached a critical tipping point that could result in a cataclysmic chain reaction that brings everyday life on Earth to a grinding halt.

Our reliance on satellites goes beyond the obvious. We depend on them for television signals, the evening weather report, and to find our houses on Google Earth when we’re bored at work. But behind the scenes, they also inform our warfighting capabilities, keep track of the global shipping networks that keep our economies humming, and help us get to the places we need to get to via GPS.

According to the DoD’s interim Space Posture Review, that could all come crashing down. Literally. Our satellites are sorely outnumbered by space debris, to the tune of 370,000 pieces of junk up there versus 1,100 satellites. That junk ranges from nuts and bolts lost during spacewalks to pieces of older satellites to whole satellites that no longer function, and it’s all whipping around the Earth at a rate of about 4.8 miles per second.

The fear is that with so much junk already up there, a collision is numerically probable at some point. Two large pieces of junk colliding could theoretically send thousands more potential satellite killers into orbit, and those could in turn collide with other pieces of junk or with satellites, unleashing another swarm of debris. You get the idea.

To give an idea of how quickly a chain reaction could get out hand consider this: in February of last year a defunct Russian satellite collided with a communications satellite, turning 2 orbiting craft into 1,500 pieces of junk. The Chinese missile test that obliterated a satellite in 2007 spawned 100 times more than that, scattering 150,000 pieces of debris.

If a chain reaction got out of control up there, it could very quickly sever our communications, our GPS system (upon which the U.S. military heavily relies), and cripple the global economy (not to mention destroy the $250 billion space services industry), and whole orbits could be rendered unusable, potentially making some places on Earth technological dead zones.

NASA satellite fiery demise

Heads up! NASA satellite descends toward fiery doom | The Space Shot – CNET News.

A chart showing the latest predicted entry point for the Upper Atmosphere Research Satellite, based on data from U.S. Strategic Command. Because of uncertainty about the satellite’s behavior as it approaches the discernible atmosphere, the timing of the re-entry could change by several hours either way.

(Credit: William Harwood/MacDoppler Pro)

“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),” NASA said in a brief update. “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.

Related story
Track NASA’s crashing satellite to avoid getting hit by space junk

“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.”

A subsequent update from U.S. Strategic Command, which operates a global radar network used to monitor more than 20,000 objects in low-Earth orbit, predicted the satellite would re-enter sometime around 11:34 p.m. EDT Friday as the spacecraft flies over the southern Indian Ocean. But the prediction was uncertain by several hours and at orbital velocities of 5 miles per second, just 10-minutes of uncertainty translates into 3,000 miles of uncertainty in position.

For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.

Tracking data is expected to improve as the day wears on, and subsequent updates should be more precise.

The centerpiece of a $750 million mission, the Upper Atmosphere Research satellite was launched from the shuttle Discovery in September 1991. The solar-powered satellite studied a wide variety of atmospheric phenomena, including the depletion of Earth’s ozone layer 15 to 30 miles up.

The long-lived satellite was decommissioned in 2005 and one side of its orbit was lowered using the last of its fuel to hasten re-entry and minimize the chances of orbital collisions that could produce even more orbital debris. No more fuel is available for maneuvering and the satellite’s re-entry will be “uncontrolled.”

Nick Johnson, chief scientist with NASA’s Orbital Debris Program at the Johnson Space Center in Houston, told reporters last week he expects most of the satellite to burn up as it slams into the dense lower atmosphere at more than 17,000 mph. But computer software used to analyze possible re-entry outcomes predicts 26 pieces of debris will survive to impact the surface in a 500-mile-long down-range footprint.

“We looked at those 26 pieces and how big they are and we’ve looked at the fact they can hit anywhere in the world between 57 north and 57 south and we looked at what the population density of the world is,” he said. “Numerically, it comes out to a chance of 1-in-3,200 that one person anywhere in the world might be struck by a piece of debris. Those are obviously very, very low odds that anybody’s going to be impacted by this debris.”

For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.

Huge NASA Satellite Falling to Earth Is Largest in 30 Years

Huge NASA Satellite Falling to Earth Within Days Is Largest in 30 Years | NASA UARS & Upper Atmosphere Research Satellite | Space Junk & Orbital Debris | Space.com.

 

This happened a while ago but I’m still catching up!

The Upper Atmosphere Research Satellite hangs in the grasp of the Remote Manipulator System during deployment from Space Shuttle Discovery, September 1991.
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

For the latest news about NASA’s UARS spacecraft fall, visit: Falling NASA Satellite: Complete Coverage of UARS Spacecraft’s Fiery Demise.

A dead climate satellite that has been gradually falling toward Earth is expected to plummet down within days, making it the most massive NASA satellite to make an uncontrolled re-entry into Earth’s atmosphere in over three decades, agency officals say.

NASA’s Upper Atmosphere Research Satellite, or UARS, is expected to plunge toward Earth sometime around Friday (Sept. 23), based on the latest estimates by the agency’s orbital debris experts.

 

The bus-size UARS satellite is one of the largest NASA satellites to plunge back to Earth uncontrolled in more than 30 years.

“The most massive NASA satellite to re-enter uncontrolled since Skylab was the Pegasus 2 satellite in November 1979,” Nick Johnson, chief scientist of NASA’s Orbital Debris Program Office at the Johnson Space Center in Houston, told SPACE.com in an email. “It had a mass of 10.5 metric tons, almost twice that of UARS.” [Worst Space Debris Events of All Time ]

Skylab was the first American space station and fell to Earth in 1979, with debris falling into the Indian Ocean and onto parts of Australia. In 2003, debris from NASA’s 100-ton space shuttle Columbia fell over Texas during re-entry in a tragic accident that killed seven astronauts. However, Columbia was a crewed spacecraft —not an unmanned satellite — and broke apart due to heat shield damage during what was supposed to be a controlled descent and landing.

 

Yet, despite the uncontrolled nature of the UARS spacecraft’s return, the chance of any debris landing in a populated area remains extremely remote, agency officials said.

According to NASA, there is a 1-in-3,200 chance that debris from the UARS satellite could hit anyone anywhere in the world. But, calculating the chance that you will get hit is a different figure entirely, and the odds of that happening are somewhere on the order of 1-in-several trillion, Matney said.

“There’s always a concern,” Mark Matney, a scientist with NASA’s Orbital Debris Program Office, said in an interview. “But, populated areas are a small fraction of the Earth’s surface. Much of the Earth’s surface has either no people or very few people. We believe that the risk is very modest.”

 

Tracking a falling satellite

While NASA and the Air Force are tracking the UARS satellite as its orbit decays, officials are unable to pinpoint exactly when and where the debris will fall. [Complete Coverage: NASA’s Falling UARS Satellite]

Current predictions of the debris drop zone cover most of the planet — anywhere between the latitudes of northern Canada and southern South America. Scientists will not be able to narrow down the impact zone until about two hours before pieces of the defunct satellite hit the ground.

“It is still too early to predict the time and location of re-entry,” NASA officials said in their latest update. “Predictions will become more refined over the next two days.”

Scientists in the agency’s Orbital Debris Program Office estimate that at least 26 large pieces of the satellite will survive the fiery trip through Earth’s atmosphere.

“It’s partly a matter of not knowing enough,” said Ray Williamson, executive director of the Secure World Foundation, an organization dedicated to the peaceful use of outer space. “The shape of the structure is not perfectly spherical, so when it heats up and starts to break up, it will break into odd pieces. Once it begins to break up, then they can get a better sense of where this is roughly going to hit.”

Falling to Earth

UARS is expected to re-enter over a 500-mile (804-kilometer) path, but since majority of the Earth is covered with ocean, debris from the satellite will likely fall over water or remote, desolate regions of the planet, NASA officials have said.

“We’re pretty small compared to the total land surface area of the Earth,” Williamson told SPACE.com. “There is so much open space and ocean that generally we don’t have to worry very much about debris hitting a structure or a human.”

The massive climate satellite measures 35 feet (10.7 meters) long and 15 feet (4.5 m) wide. Originally, agency officials thought the UARS satellite would fall to Earth sometime between late September and early October, but due to heightened solar activity last week, the spacecraft has been falling faster than expected.

“As sunspots increase on the sun, the type of extreme ultraviolet radiation that affects the upper atmosphere increases also,” Matney explained. “The more the atmosphere heats, the more it expands, and the spacecraft sees more drag.”

 

UARS and beyond

NASA and the U.S. Strategic Command at Vandenberg Air Force Base in California are closely monitoring the falling UARS satellite and have been providing updates about the spacecraft’s orbit. For now, Friday remains the best estimate for when debris from UARS will reach ground. [Infographic: NASA’s Falling UARS Satellite Explained]

The $750 million UARS satellite was launched in 1991 aboard the space shuttle Discovery to study the ozone layer and Earth’s upper atmosphere. The spacecraft far outlived its original three-year mission, but was finally decommissioned by NASA in December 2005.

Even though the falling UARS satellite is not expected to pose a significant danger to humans, Williamson hopes the event highlights the critical nature of space debris, and the need to promote space situational awareness.

“It’s a serious issue,” he said. “I directed this project that did the first space debris study for US Congress. At that point, hardly anybody knew about space debris, and I thought it was very frustrating because I could see the way things were going. It turns out a decade or two later, the issue has become so concerning to people that they have begun to pay real attention to it. I think this re-entry will certainly cause a lot of interest in people.”

NASA satellite to Crash to Earth Today

Heads up! NASA satellite descends toward fiery doom | The Space Shot – CNET News.

NASA’s decommissioned Upper Atmosphere Research Satellite, out of gas and out of control, is not descending toward re-entry as rapidly as expected, officials say, likely delaying the satellite’s kamikaze plunge to Earth by a few hours, to late Friday or early Saturday.

Experts expect more than two dozen chunks of debris to survive re-entry and hit the ground in a 500-mile-long footprint somewhere along the satellite’s orbital track. But given the bus-size 6.3-ton’s satellite’s trajectory and the vast areas of ocean and sparsely populated areas UARS passes over, experts say it is unlikely any falling debris will result in injuries or significant property damage.

Additional radar tracking is required to pinpoint when–and where–the satellite will make its final descent.

 

A chart showing the latest predicted entry point for the Upper Atmosphere Research Satellite, based on data from U.S. Strategic Command. Because of uncertainty about the satellite’s behavior as it approaches the discernible atmosphere, the timing of the re-entry could change by several hours either way.

(Credit: William Harwood/MacDoppler Pro)

“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),” NASA said in a brief update. “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.

Related story
Track NASA’s crashing satellite to avoid getting hit by space junk

“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.”

A subsequent update from U.S. Strategic Command, which operates a global radar network used to monitor more than 20,000 objects in low-Earth orbit, predicted the satellite would re-enter sometime around 11:34 p.m. EDT Friday as the spacecraft flies over the southern Indian Ocean. But the prediction was uncertain by several hours and at orbital velocities of 5 miles per second, just 10-minutes of uncertainty translates into 3,000 miles of uncertainty in position.

For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.

Tracking data is expected to improve as the day wears on, and subsequent updates should be more precise.

The centerpiece of a $750 million mission, the Upper Atmosphere Research satellite was launched from the shuttle Discovery in September 1991. The solar-powered satellite studied a wide variety of atmospheric phenomena, including the depletion of Earth’s ozone layer 15 to 30 miles up.

The long-lived satellite was decommissioned in 2005 and one side of its orbit was lowered using the last of its fuel to hasten re-entry and minimize the chances of orbital collisions that could produce even more orbital debris. No more fuel is available for maneuvering and the satellite’s re-entry will be “uncontrolled.”

Nick Johnson, chief scientist with NASA’s Orbital Debris Program at the Johnson Space Center in Houston, told reporters last week he expects most of the satellite to burn up as it slams into the dense lower atmosphere at more than 17,000 mph. But computer software used to analyze possible re-entry outcomes predicts 26 pieces of debris will survive to impact the surface in a 500-mile-long down-range footprint.

“We looked at those 26 pieces and how big they are and we’ve looked at the fact they can hit anywhere in the world between 57 north and 57 south and we looked at what the population density of the world is,” he said. “Numerically, it comes out to a chance of 1-in-3,200 that one person anywhere in the world might be struck by a piece of debris. Those are obviously very, very low odds that anybody’s going to be impacted by this debris.”

For comparison, some 42.5 tons of wreckage from the shuttle Columbia hit the ground in a footprint stretching from central Texas to Louisiana when the orbiter broke apart during re-entry in 2003. No one on the ground was injured and no significant property damage was reported.