Space debris is a constant threat to astronauts, satellites, space stations, and billionaire tourists. Gonzalo Sánchez and his colleagues of the E.T. PACK Project have come up with an approach that can be used to deorbit satellites in the future.
The ESA's Space Debris Office estimates that there are over 34,000 pieces of large debris in Low Earth Orbit consisting of dead satellites, boosters, dropped wrenches, paint flecks and all manner of other assorted junk. At some difficult to predict point in the future it is possible, as the amount of this debris increases, for a cascading effect known as the Kessler syndrome to occur making Low Earth Orbit extremely dangerous and effectively closing it off for use.
The new satellite deorbiting technology is intended to help avoid this outcome and is called the Electrodynamic Tether technology for Passive Consumable-less deorbit Kit (E.T.PACK) system.
The key to this system is a low work-function tether that consists of a strip of aluminum tape coated with a special material that allows it to emit electrons when illuminated by the Sun. This causes the tether to become attracted to Earth's magnetic field via the Lorentz Force, effectively lowering its altitude until it burns up in Earth's atmosphere.
The tether itself would measure 2 cm (0.8 in) in width, 50 microns in thickness, and several kilometers in length. During the launch of the satellite, the tether would be rolled up in a reel and only deployed once the satellite was in orbit. In this way, future satellites would be able to self-destruct and not become part of the space debris problem.
The project, which is funded by the European Commissions is expected to conclude in three years culminating in a prototype for a demonstration flight. The technology has captured the interest of the ESA and various space industries.
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In recent years, the odds of orbital collisions has doubled due to all the debris, large particles, and just plain scrap flying around in orbit. These are fragments left from launches as well as from collisions between other objects already in orbit. The Economist is reporting that several methods for de-oribiting space junk are being tested, with the goal to get a handle on the problem while there is still time to do so. So far, nets, harpoons, and magnets are among the options which have been considered.
In the first test, the servicer will use springs to push the pod out and then, once it is ten metres away, will approach it again, lock onto the docking plate using an arm fitted with a magnetic head, retract the arm and pull it back to the servicer. For the second test, it will push the pod at least 100 metres away before its starts approaching it. A reaction wheel and a set of magnetic torque-generators will then put the pod into a tumble involving all three axes of motion, at a speed of half a degree a second.
This is, as it were, an important twist—for chunks of orbiting debris typically spin in this fashion. A real deorbiting mission will therefore have to deal with such spinning objects. Markings on the pod will help the servicer work out its prey’s motion. Using eight thrusters, it will manoeuvre itself until those markings appear, to its sensors, to be stationary. This will mean its motion exactly matches that of the tumbling pod, and that the magnetic head can therefore be extended to do its job.
For the third capture test, the servicer will first use its thrusters to back off several kilometres from the pod, putting the pod beyond sensor range. Then it will search for it, as would need to be the case if it were hunting for a real derelict spacecraft.
(Score: 0) by Anonymous Coward on Sunday June 16 2019, @01:37PM (7 children)
I get how it works once the tether is stretched out -- but how does it get from a roll (of aluminum / aluminized tape) into a linear configuration? If I unrolled some ribbon in orbit I think it would quickly be one big tangle. Unless the material has almost no bending stiffness (very limp), it will have some curvature when it comes off the roll.
(Score: 2, Informative) by realDonaldTrump on Sunday June 16 2019, @02:26PM (4 children)
It's made of Aluminum, right? Aluminum, as everyone knows, is attracted (not sexually) to a Magnet. And, it's also attracted to Gravity. Look at story. They say Gravity will make it very "taut." Polite way to say, stiff. So don't worry about the stiffness!!!
(Score: 0) by Anonymous Coward on Sunday June 16 2019, @03:47PM
Curses ... Foiled Again!
(Score: 1) by fustakrakich on Sunday June 16 2019, @05:59PM (2 children)
Aluminum, as everyone knows, is attracted... to a Magnet.
It is, eh? I think that's just another one of *your*, er... fibs, yeah, that's it...
Or to put it another way, Aluminum is about as magnetic as *you* are. Of course I mean that in the nicest possible way, right?
La politica e i criminali sono la stessa cosa..
(Score: 1, Troll) by realDonaldTrump on Monday June 17 2019, @01:01AM (1 child)
Obviously I was being sarcastic. Although, not as sarcastic as you might think.
Look at Summary. Did you even look at Summary? They say, tether is "attracted to Earth's magnetic field." Another way of saying, Earth is a HUGE MAGNET. And, it attracts Tether (Aluminum). Sounds like a lie, right? Youre on a Fake News Sight. They lie about Magnet. They lie about Vaccine. They lie about Microsoft. And, they lie about me!!!!
(Score: 0) by Anonymous Coward on Monday June 17 2019, @01:23AM
Where is the Woosh mod?
(Score: 5, Informative) by ElizabethGreene on Sunday June 16 2019, @03:33PM
You are right to question this. Many electrodynamic tether experiments have ended up in a tangled failure. e.g. JAXA's Kounotori Integrated Tether Experiments (KITE) I assume that solving this issue is one of the technical goals of this project.
If they can figure it out we'll be able to move around LEO for the price of sunlight and time. That has applications far beyond just space junk removal. E.g. if you were patient you could use it to stretch an elliptical orbit to throw a cubesat out to a lagrange point and into the IPN [wikipedia.org] Getting out there takes a bunch of delta-v, but once you are there it only takes relatively tiny amounts of thrust to move very far from Earth.
(Score: 2) by Muad'Dave on Monday June 17 2019, @01:04PM
I'm just guessing here, but since they're claiming that it'll generate a negative charge on it's surface form sunlight, those electrons will repel each other and push the tape into a linear shape (as you said, only if it's very limp).
(Score: 2) by leftover on Sunday June 16 2019, @04:05PM (2 children)
Put a slight crosswise bow in the tether and it will try to stay straight coming off the powered roll.
OR put a small rocket motor on the end and pull the tether out
OR ...
Bent, folded, spindled, and mutilated.
(Score: 1) by RandomFactor on Sunday June 16 2019, @04:34PM (1 child)
Maybe it could spin during unrolling like a weight on a string?
it's an interesting question. Several Kilometers length does present challenges.
В «Правде» нет известий, в «Известиях» нет правды
(Score: 1, Interesting) by Anonymous Coward on Sunday June 16 2019, @05:18PM
Ah, this might be the trick -- keep the outer end of the coil attached to the satellite and use the roll as the weight on the end. With almost no air drag, perhaps it could be slung out like a yo-yo?
The only way this is going to get added to any launches is if the weight is the bare minimum.