Posted on by Nancy Atkinson

New Satellite for Monitoring Space Debris To Launch

The Air Force Space Based Space Surveillance (SBSS) system. Credit: Boeing

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The U.S. Air Force will launch the first-ever satellite dedicated solely to tracking the positions of other satellites and the thousands of pieces of space debris in Earth orbit. The $500 million Space-Based Space Surveillance satellite, scheduled for a July 8 launch from Vandenberg Air Force Base, in California, will continuously monitor the “traffic” around the Earth, providing an unobstructed view day or night. Currently, the ground-based radar and optical telescopes used to track satellites and space junk can only be used on clear nights, and not all the observatories are powerful enough to detect objects in high or geosynchronous orbits.

This is the first satellite in the SBSS System that will eventually lead to a constellation of satellites to detect and track orbiting space objects, according to Boeing, the prime contractor for this first “Pathfinder” satellite. While the Air Force is the primary user of the SBSS satellites, the US Department of Defense will also use data from the eventual satellite system to support military operations, and NASA can use the information to calculate orbital debris collision-avoidance measures for the International Space Station and Space Shuttle missions.

The Air Force estimates there are about 1,000 functioning satellites and about 20,000 pieces of debris orbiting Earth.

The new satellite will be in orbit 627 kilometers (390 miles) above the Earth, and has an optical camera on a swivel mount, so the camera’s view can be changed without burning fuel to move the satellite, and will concentrate on satellites and debris in deep space. The information from the satellite will be sent to a command center at Schriever Air Force Base in Colorado.

The Air Force space surveillance network previously had partial use of a satellite called the Midcourse Space Experiment, which was designed to track missiles but could also monitor objects in orbit. It’s no longer functioning.

Right now, the Air Force can detect objects as small as 10 centimeters across, or about 4 inches, and they have not released information on the the capabilities of the new satellite.

The Secure World Foundation says there could be millions of pieces of debris in total around the Earth. Debris at altitudes above several hundred kilometers can stay in orbit for decades or even centuries, and those about 1,500 kilometers will remain in orbit for thousands of years. Even very small particles of space debris can have a devastating effect on anything they hit because of their high relative impact velocities.

Chart of orbital debris. Source: NASA Orbital Debris Quarterly News, April 2009,

This chart displays a summary of all objects in Earth orbit officially cataloged by the U.S. Space Surveillance Network. “Fragmentation Debris” includes satellite breakup debris and anomalous event debris, while “Mission?related Debris” includes all objects dispensed, separated, or released as part of the planned mission. Note the dramatic increase in fragmentation debris caused by the Chinese ASAT test conducted in January 2007. Another smaller increase is noted following the 2009 collision between an Iridum communications satellite and a non-functioning Russian satellite.

It is hoped the new SBSS satellite will increase the capabilities to help avoid future collisions.

Sources: Boeing, Secure World Foundation, AP

Posted on by Nancy Atkinson

Climate Change Contributes to Space Junk Problem

An upper stage of a spacecraft exploding. Image Credit: ESA

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The effects of climate change can be seen across the majority of the planet, but a new study reveals it is also affecting the space environment. New Scientist reports that increased carbon dioxide levels are cooling the upper atmosphere, which decreases the atmospheric density. This in turn affects how long defunct satellites, spent rocket boosters and other space debris stay in orbit, contributing to the space junk problem.

Atmospheric drag creates a braking effect on space debris, and eventually causes the various bits and pieces to drop out of orbit and burn up. Two researchers at the University of Southampton in the UK, Arrun Saunders and Hugh Lewis, studied the orbits of 30 satellites over the past 40 years, and recorded a gradual increase in the time they remain in orbit.

They calculated that at an altitude of 300 kilometers, the atmosphere is reducing in density by 5 per cent every decade. “The lower molecular braking means debris can remain in orbit up to 25 per cent longer,” said Lewis.

This raises the risk of collisions with satellites and makes it more hazardous to launch spacecraft. Space agencies and commercial launch companies may need to step up the current space debris mitigation procedures now in place, which include employing on-board passive measures to eliminate the potential for explosions from batteries, fuel tanks, propulsion systems and pyrotechnics, which helps reduce the number of objects in orbit. Or we may need to find a way to remove debris from orbit sooner rather than later.

Saunders and Lewis presented their work at a conference in Boulder, Colorado, last week.

Source: New Scientist

Posted on by Nancy Atkinson

Plasma Rocket Could Help Pick Up Space Trash

Artist concept of a VASIMR. Credit: Ad Astra

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Franklin Chang Diaz’s proposed VASIMR rocket engine could create very versatile spacecraft. Not only does the plasma-fueled rocket have the potential to make a trip to Mars in just over a month, it could also help clean up space trash in Earth orbit. “Our goal is to be able to have a garbage truck that will be picking up all of these objects at various orbits,” astronaut Chang Diaz said in an article in the Global Post. The debris could put into an “orbital graveyard,” he added, “or we could actually launch them to the sun and drive them to the sun, which is kind of the ultimate, cosmic dump.”

Image plot of space junk. Image credit: NASA
Image plot of space junk. Image credit: NASA

Space debris is becoming a growing problem. The number of non-operating satellites in orbit has increased, as well as debris from spacecraft explosions and, as happened earlier this year, collisions between satellites.

“The Earth has become virtually a beehive,” Chang Diaz said. “The number of satellites orbiting the Earth, we’re talking hundreds of thousands of these objects. Some of them are just junk that’s floating there simply because these satellites have run out of fuel and they just remain in orbit dead.”

The rocket, called the VASIMR for “variable specific impulse magnetoplasma rocket,” uses a high-power technology initially studied by NASA that turns argon into plasma. Propelled by an exhaust gas at temperatures close to that of the sun, the VASIMR VX-200 engine would have the ability to change orbits and accelerate and decelerate in order to pick up space debris.

In September, Chang Diaz’s company, Ad Astra, tested the rocket and achieved a milestone. During the a test on in a vacuum chamber on Earth, the engine cranked at just over 200 kilowatts, becoming the world’s most powerful electric rocket.

Possible uses for the VASIMR rocket. Credit: Ad Astra
Possible uses for the VASIMR rocket. Credit: Ad Astra

VASIMR is not suitable to launch payloads from the surface of the Earth due to its low thrust to weight ratio and its need of a vacuum to operate. It would, however be ideal to function as an upper stage for cargo, drastically reducing the fuel requirements for in-space transportation.

Ad Astra has also signed an agreement with NASA to test a 200-kilowatt VASIMR engine on the International Space Station in 2013 to help keep it in orbit. ISS boosts are currently provided by conventional thrusters, which consume about 7.5 tons of propellant per year. By cutting this amount down to 0.3 tons, Chang-Diaz estimates that VASIMR could save NASA millions of dollars per year.

Other uses of the plasma rocket engine would be lunar cargo transport, human missions to Mars or other destinations, and in-space refueling.

Sources: Global Post, Ad Astra