Fwd: Space agency studying ways to capture derelict satellites, space junk

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From: "Gary Johnson" <gjohnson144@comcast.net>
Date: February 23, 2014 10:06:33 AM CST
To: "Gary Johnson" <gjohnson144@comcast.net>
Subject: FW: Space agency studying ways to capture derelict satellites, space junk

 

 

 

How to catch a satellite

 

                                      

Netting a derelict satellite

21 February 2014

Standard space dockings are difficult enough, but a future ESA mission plans to capture derelict satellites adrift in orbit. Part of an effort to control space debris, the shopping list of new technologies this ambitious mission requires is set for discussion with industry experts.

ESA's Clean Space initiative is studying the e.DeOrbit mission for removing debris, aiming to reduce the environmental impact of the space industry on Earth and space alike. 

Earth's debris halo

Decades of launches have left Earth surrounded by a halo of space junk: more than 17 000 trackable objects larger than a coffee cup, which threaten working missions with catastrophic collision. Even a 1 cm nut could hit with the force of a hand grenade.

The only way to control the debris population across key low orbits is to remove large items such as derelict satellites and launcher upper stages.

Such uncontrolled multi-tonne items are not only collision risks but also time bombs: they risk exploding due to leftover fuel or partially charged batteries heated up by orbital sunlight. 

The resulting debris clouds would make these vital orbits much more hazardous and expensive to use, and follow-on collisions may eventually trigger a chain reaction of break-ups.

                                                                           

Distribution of space debris

Targeting key orbits

e.DeOrbit is designed to target debris items in well-trafficked polar orbits, between 800 km to 1000 km altitude. At around 1600 kg, e.DeOrbit will be launched on ESA's Vega rocket.

The first technical challenge the mission will face is to capture a massive, drifting object left in an uncertain state, which may well be tumbling rapidly. Sophisticated imaging sensors and advanced autonomous control will be essential, first to assess its condition and then approach it.

Making rendezvous and then steady stationkeeping with the target is hard enough but then comes the really difficult part: how to secure it safely ahead of steering the combined satellite and salvage craft down for a controlled burn-up in the atmosphere?

Several capture mechanisms are being studied in parallel to minimise mission risk. Throw-nets have the advantage of scalability – a large enough net can capture anything, no matter its size and attitude. Tentacles, a clamping mechanism that builds on current berthing and docking mechanisms, could allow the capture of launch adapter rings of various different satellites.

Harpoons work no matter the target's attitude and shape, and do not require close operations. Robotic arms are another option: results from the DLR German space agency's forthcoming DEOS orbital servicing mission will be studied with interest.

                                                                           

Grabbing a target

Strong drivers for the platform design are not only the large amount of propellant required, but also the possible rapid tumbling of the target – only so much spin can be absorbed without the catcher craft itself going out of control.

Apart from deorbit options based on flexible and rigid connections, techniques are being considered for raising targets to higher orbits, including tethers and  electric propulsion.

A symposium on 6 May in the Netherlands will cover studies and technology developments related to e.DeOrbit, with ESA and space industry representatives presenting their research and outlining their plans. For further information, or to register, go here. 

 

Copyright 2000 - 2014 © European Space Agency. All rights reserved.

 

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Space agency studying ways to capture derelict satellites, space junk

PARIS, Feb. 21 (UPI) -- The European Space Agency says it is studying the possibility of a future mission to capture derelict satellites adrift in orbit around the Earth.

The e.DeOrbit mission under study the ESA's Clean Space Initiative, would aim to snag and collect orbiting junk to reduce the environmental impact of the space industry on Earth and space alike, the agency said in a release issued from its Paris headquarters Friday.

Decades of launches have left Earth surrounded by a halo of space junk, with more than 17,000 trackable objects larger than a coffee cup that could threaten working missions with catastrophic collision, ESA scientists said.

The only way to control the debris field across key low orbits is to remove large items such as derelict satellites and launcher upper stages, they said.

The first technical challenge such a mission would face is to safely approach a drifting object left in an uncertain state; then capture it and guide the combined satellite and salvage craft down for a controlled burn-up in the atmosphere.

Several capture mechanisms are being studied, the ESA said, including throw-nets, clamping mechanisms and harpoons.

A symposium in the Netherlands in May will cover studies and technology developments related to e.DeOrbit, the ESA said.

 

© 2014 United Press International, Inc. All Rights Reserved. 

 

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How We Will Retrieve Dead Satellites In The Future? Hint: It Likely Won't Be Using Astronauts

by Elizabeth Howell on February 21, 2014

NASA astronaut Dale Gardner captures the malfunctioning WESTAR-VI satellite in 1984. Gardner was using the Manned Maneuvering Unit, a sort of space backpack that was discontinued for astronaut use after the Challenger explosion of 1986. Credit: NASA

I'll admit it: I'm too young to remember 1984. I wish I did, however, because it was a banner year for the Manned Maneuvering Unit. NASA astronaut Dale Gardner, for example, used this jet backpack to retrieve malfunctioning satellites, as you can see above. (FYI, Gardner died Wednesday (Feb. 19) of a brain aneurysm at the age of 65.)

After three shuttle flights, however, NASA discontinued use of the backpack in space for several reasons — most famously, safety considerations following the shuttle Challenger explosion of 1986. But thirty years on, the problem of dead satellites is growing. There are now thousands of pieces whipping around our planet, occasionally causing collisions and generally causing headaches for people wanting to launch stuff into orbit safely.

Space agencies such as NASA and the European Space Agency have been working hard on reducing debris during launches, but there's still stuff from decades before. And when a satellite goes dead, if it's in the wrong orbit it could be circling up there for decades before burning up. How do you fix that?

Robotics has come a long way in 30 years, so space agencies are looking to use those instead to pick up derelict satellites since that would pose far less danger to astronauts. One example is the e.DeOrbit mission recently talked about by ESA, which would pick up debris in polar orbits of altitudes between 800 and 1,000 kilometers (about 500 to 620 miles).

One design idea for the e.DeOrbit mission, which would retrieve dead satellites from orbit. Credit: European Space Agency

The mission would use autonomous control and image sensors to get up close to the drifting satellite, and then capture it in some way. Several ideas are being considered, ESA added. A big enough net could easily nab the satellite, or perhaps one could clamp on using tentacles or grab it with a harpoon or robotic arm. Here's a 2013 proposal with more information on e.DeOrbit. ESA noted there is a symposium coming up May 6 to discuss this in more detail.

e.DeOrbit is one of just several proposals to pick satellites up. A Swiss idea called CleanSpace One appears to use a sort of pincer claw to grab satellites for retrieval. The Phoenix program (proposed by Defense Advanced Research Projects Agency) would take useable parts off of broken satellites for use in new satellites, and in past years DARPA had some ideas to remove satellites from orbit as well. Another option is satellite refueling to make these machines useable again, a possibility that NASA, Canada and many others are taking seriously.

 

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