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Satellite re-entry poses no danger

UARS graphic

The Upper Atmospheric Research Satellite is due to re-enter Earth's atmosphere in the next 24 hours.

SPACE JUNK COMES IN different shapes and sizes, and can pose two main kinds of threats—a threat to other spacecraft (unmanned and manned) through collisions, and threats to us down here on Earth.

The satellite making news at the moment—the former Upper Atmospheric Research Satellite, better characterised as a decommissioned or defunct satellite rather than space junk—falls into the second category.

In 2005, NASA decommissioned UARS and intentionally placed it into an orbit a couple of hundred kilometres lower than its operational orbit. This was done to accelerate is eventual demise, and means it is re-entering the atmosphere 20 years earlier than it otherwise would have done.

This was a very responsible thing to do. The longer a spacecraft stays in orbit, the more chance it has of being hit by other orbital debris, leading to a destructive breakup and therefore many more bits of debris.

UARS poses a negligible threat to life and property on Earth. Most of the satellite will burn up during re-entry, with perhaps as many as 26 of the stronger or harder small pieces surviving to reach the surface.

But with the majority of Earth comprising oceans or uninhabited (or very sparsely inhabited) remote regions, the chances are overwhelming that any pieces of UARSthat survive re-entry will fall harmlessly and never be seen again.

UARS re-entry map

This map shows the orbital path of the Upper Atmospheric Research Satellite, and it's predicted impact located (yellow symbol within the orange circle at left) in the southern Pacific Ocean.

Because the spacecraft is no longer powered, NASA has no control over where it comes down.

It is thought to be tumbling gently as it makes its final orbits. Friction with the thin upper atmosphere is slowly lowering its orbit, bit by bit. Sometime in the next 24 hours it will reach a low enough point and sufficient air friction such that it will no longer be able to maintain orbital velocity.

At this point it will begin to burn up and streak across the sky like a huge fireball. It would be quite something to see, but chances are that no one will witness it.

The other kind of space junk—bits of orbital debris that range from less than a millimetre wide up to entire spacecraft—is more of a worry. Space junk can damage or destroy an operational spacecraft, leading to loss of the asset and the service it provides.

More information:

NASA UARS re-entry page

Re-entry prediction map

UARS mission

Text by Jonathan Nally, SpaceInfo.com.au. Images courtesy NASA and aerospace.org

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Space junk reaches ‘tipping point’

Diagram showing space junk in Earth orbit

Earth is circled by millions of pieces of space junk, or orbital debris, many of which pose a serious risk to satellites and astronauts. Is it time to do something about it?

ALTHOUGH NASA’S PROGRAMMES to track meteoroids and orbital debris have responsibly used their resources, the agency’s has not kept pace with increasing hazards posed by abandoned equipment, spent rocket bodies, and other debris orbiting the Earth, says a new report by the US National Research Council.

NASA should develop a formal strategic plan to better allocate resources devoted to the management of orbital debris. In addition, removal of debris from the space environment or other actions to mitigate risks may be necessary.

Some scenarios generated by NASA’s meteoroid and orbital debris models show that debris has reached a “tipping point,” with enough currently in orbit to continually collide and create even more debris, raising the risk of spacecraft failures, the report notes.

In addition, collisions with debris have disabled and even destroyed satellites in the past; a recent near-miss of the International Space Station underscores the value in monitoring and tracking orbital debris as precisely as possible.

Challenges for NASA

“The current space environment is growing increasingly hazardous to spacecraft and astronauts,” said Donald Kessler, chair of the committee that wrote the report and retired head of NASA’s Orbital Debris Programme Office.

“NASA needs to determine the best path forward for tackling the multifaceted problems caused by meteoroids and orbital debris that put human and robotic space operations at risk.

Space junk impact on space shuttle Endeavour

A small piece of space junk punched a hole through the inside of one of space shuttle Endeavour's payload bay doors, where heat radiators were situated.

The strategic plan NASA develops should provide a basis for prioritising efforts and allocating funds to the agency’s numerous meteoroid and orbital debris programmes, the report says.

Currently, the programmes do not have a single management and budget structure that can efficiently coordinate all of these activities. The programmes are also vulnerable to changes in personnel, as nearly all of them are staffed by just one person.

A global problem

The strategic plan, which should consider short- and long-term objectives, a schedule of benchmark achievements, and priorities among them, also should include potential research needs and management issues.

Removal of orbital debris introduces another set of complexities, the report adds, because only about 30 percent of the objects can be attributed to the United States.

“The Cold War is over, but the acute sensitivity regarding satellite technology remains,” explained committee vice chair George Gleghorn, former vice president and chief engineer for the TRW Space and Technology Group.

Although NASA has identified the need for removing debris, the agency and U.S. government as a whole have not fully examined the economic, technological, political, and legal considerations, the report says.

For example, according to international legal principle, no nation may salvage or otherwise collect other nations’ space objects.

Therefore, the report recommends, NASA should engage the U.S. Department of State in the legal requirements and diplomatic aspects of active debris removal.

The study was sponsored by NASA.

Adapted from information issued by the US National Academy of Sciences. Images courtesy NASA.

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Aussie scope to be upgraded

Artist's impression of an exoplanet

The University of Western Australia's 1-metre robotic Zadko Telescope will search for new planets, exploding stars and space junk.

THE UNIVERSITY OF WESTERN AUSTRALIA’S (UWA) Gingin-based Zadko Telescope will get a clearer view thanks to an agreement signed between UWA and the WA Department of Environment and Conservation (DEC) that enhances the partnership between these two organisations.

The 1-metre robotic Zadko Telescope is currently housed in an inadequate dome that is not up to the rigours of robotic operation.

Zadko Telescope

Zadko Telescope

Under the collaboration between DEC and UWA, DEC will contribute $100,000 towards the construction of a new building where the telescope will reach its full potential.

DEC astronomer Ralph Martin of Perth Observatory said: “Part of the collaboration with UWA includes searching for undiscovered planets orbiting distant stars.”

Zadko Telescope Director, UWA Associate Professor David Coward, said the new Zadko Observatory building would significantly enhance the research capabilities of DEC and UWA.

“The upgrade will also strengthen our collaboration with TAROT (Fast Action Telescopes for Transient Objects), the French international network of robotic telescopes,” Professor Coward said. “Our international team will be on the hunt for new planets and exploding stars.”

“The new Zadko Observatory building will also allow our collaboration to scan the sky for space junk that threatens the satellites on which we depend for almost every aspect of daily life from telecommunications, weather reports, security and navigation, to information about mineral deposits.”

Adapted from information issued by UWA.

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Dealing with space hazards

PEOPLE AND GOVERNMENTS rely on satellites for a growing number of crucial tasks. Any shutdown of these systems would seriously affect an enormous range of commercial and civil activities, including travel, transportation, telecommunications, information technology and broadcasting.

Europe, in particular, has no autonomous capability to watch for and warn of hazards to its vital satellites and ground infrastructure.

But in 2009, European Space Agency member states asked the Agency to embark on a new programme, known as Space Situational Awareness, or SSA. Now in its initial phase, SSA aims to develop Europe’s own scanning, detection and warning capabilities against space weather, space debris and natural near-earth objects.

Adapted from information issued by ESA.

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Space junk trackers

A map showing where large pieces of space junk are in Earth orbit.

A map showing where large pieces of space junk are in Earth orbit.

  • Space junk becoming a major problem
  • Australian observatory in tracking network
  • Provides warnings to satellite operators

Space junk is becoming such a major problem that if it continues to accumulate at present rates, it will be impossible to launch anything into space in 100 years’ time, according to researchers at The University of Western Australia.

Ranging from tiny chips of paint to big parts of spent booster rockets, thousands of pieces of space debris threaten the satellites on which we depend for almost every aspect of daily life from telecommunications, weather reports, security and navigation, to information about mineral deposits.

The University of Western Australia's Zadko Telescope

The University of Western Australia's Zadko Telescope is part of a network that tracks space junk.

A UWA team led by Associate Professor David Coward is part of a global effort to track space junk, using robotic astronomical telescopes, and warn the owners of satellites to alter their orbit until the threat has passed.

In particular, UWA is collaborating with French astronomers at the CNRS-Observatoire de Haute Provence in France in a project that links UWA’s impressive Zadko Telescope to robotic telescopes in France and Chile, called TAROT, to form a global array that scans the sky for debris.

Zadko Telescope Systems Manager, 27 year-old Dr Myrtille Laas-Bourez, is part of UWA’s School of Physics and the $100 million UWA-based International Centre for Radio Astronomy Research.

Dr Laas-Bourez, an engineer who describes herself as a ‘celestial mechanic’, worked on the TAROT robotic telescope space debris program in France, daily cataloguing the junk in real-time and informing the French Space Agency of hazards in the same orbits as its satellites.

Detecting space debris is also a priority of the Australian Federal Government, with a recent Senate report stating that Australia needs to urgently engage in space research to protect its space-based assets.

Adapted from information issued by The University of Western Australia / NASA.