Space

ESA endeavours to understand the unpredictable tumbling of space debris

ESA endeavours to understand t...
Earth is surrounded by a cloud of debris that is becoming increasingly hazardous to operational satellites (Image: ESA)
Earth is surrounded by a cloud of debris that is becoming increasingly hazardous to operational satellites (Image: ESA)
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Earth is surrounded by a cloud of debris that is becoming increasingly hazardous to operational satellites (Image: ESA)
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Earth is surrounded by a cloud of debris that is becoming increasingly hazardous to operational satellites (Image: ESA)
The debris that the ESA is attempting to study includes the upper stages of launch vehicles such as that which delivered the Proba-2 satellite, featured in this artists impression (Image: ESA - P. Carril, 2009)
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The debris that the ESA is attempting to study includes the upper stages of launch vehicles such as that which delivered the Proba-2 satellite, featured in this artists impression (Image: ESA - P. Carril, 2009)
The ESA's e.DeOrbit satellite will grab defunct satellites and drag them into a re-entry trajectory (Image: ESA)
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The ESA's e.DeOrbit satellite will grab defunct satellites and drag them into a re-entry trajectory (Image: ESA)
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As part of its Clean Space Initiative, the ESA is planning a satellite salvage mission called e.DeOrbit that would use a satellite to net space debris and remove it from low Earth orbit. To capture such debris using an autonomous system, it needs to be targeted effectively, which is difficult when the debris is tumbling unpredictably. To fine tune the design of the e.DeOrbit mission, the ESA will commission a study to shed light on why space debris tumbles the way it does.

In recent years, a number of de-commissioned satellites have made uncontrolled re-entries whilst under observation, as have a few operational satellites that became the victim of catastrophic system failures. It was found in every case that the satellite began to tumble uncontrollably before its orbit had decayed sufficiently to be pulled back into the Earth's atmosphere.

There are a number of theories for this tumbling behavior that the study sets out to validate. One such theory blames the behavior on the increased drag created by the Earth's atmosphere when interacting with one side of a satellite. The debris, unable to correct for the imbalance, is then slowly forced into an irreversible spin.

Other theories assert that it may be a faint but steady push of sunlight, micrometeoroid and debris impacts, internal magnetic fields, the sloshing of leftover fuel, or the release of internal pressure in the form of a gas leak or exploding battery, which is ultimately responsible for the erratic behavior.

The goal of the study is to pinpoint the drivers for the loss of equilibrium by combining detailed computer analysis with existing monitoring techniques, such as optical telescopes, ground-based radar observation. However, alongside these commonly used methods, the study will investigate the potential of rarely used techniques in an attempt to gain a more precise understanding of the movements of the space debris.

These include space-to-space optical and radar observations using satellites in nearby orbits, as well as highly accurate laser ranging. This process involves the bouncing of laser beams off the reflective surface of an object and has the ability to accurately track a piece of debris to within a few centimeters of its actual position.

It is hoped the study will provide information that will allow the design of the e.DeOrbit mission to be fine tuned to enable it to assess the condition of target debris before approaching it.

Source: ESA

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4 comments
Rt1583
While I can see the value (to the space industry and scientists) of learning the causes of the tumbling, I don't see why it would be necessary to know this for the purpose of a collection system.
For the purpose of catching something, you don't need to know why it moves in the way it does, you only need to know that it does move in the way it does.
apropos626
You will want to know where on Earth it's going to fall. Tumbling may cause the object to fall where you don't expect.
Michiel Mitchell
is it just me or does that start to look like a land-fill... of sorts... no wonder nobody wants to be seen with us anymore...
Mirmillion
It appears that, if tumbling space junk requires special handling, more than one method of collecting debris is have to be worked out and tested. I presume that a tumbling mass will be more likely to transfer lateral forces to the vehicle doing the capturing - thereby causing it to use more fuel to stabilize or, potentially, become space junk in its own right. Those nasty corners and jagged surfaces, thought not to be a factor in deployment in a vacuum, have certainly come back to haunt the NASA's of the world.
After all of the analysis is complete it may be that the best policy will be to match the velocity of the junk in question, grab it as required by its size, shape and spin and either jettison into deep space or land it in the trunk of the next space shuttle. Maybe the Canada Arm can be configured to throw a fastball, curve or slider...