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