Right On Commander!
This is why the docking computer is worth the credits
Astroboffins are gearing up to test a method to remove future space junk from Earth's orbit with the launch of ELSA-d, an experimental spacecraft that uses magnetism to snare debris. ELSA-d, which stands for End-of-Life Services demonstration, hitched a ride to space on a Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan …
My first thought on this was - shame about all that titanium and aluminium alloy up there - how many satellites are fitted (or will be fitted) with the necessary chunks of ferrous metals - aka largely pointless mass?
Can't help thinking that if you can navigate closely enough to do a magnetic capture - per the rather fine video - you might do better with a grapple or a sticky net or something. This kinda looks like a solution that doesn't have a problem; that is, the problem is real but it's not in a state that this solution solves... and it's not clear that without legislation everything else launched will have the necessary ferrous chunks attached.
Is this thing intended only to catch complete satellites? In which case, I think Cubby Broccoli's fine documentary 'Moonraker' demonstrates prior art.
The reason for the magnetic docking is so that it can be released in a 'burn-up' orbit, and the clean-up satellite can move on to the next target.
If you use a net or sticky capture then you can't release it cleanly and your clean-up mission becomes a one time deal.
I'm hoping (not expecting, but hoping) that this is more of a demonstration of manoeuvrability and approach etc, rather than the actual attachment mechanism.
A camera-shutter type mechanism to attach to an exhaust nozzle would be my choice, but for a proof-of-concept an electromagnet is fine.
Cubby Broccoli? Gerry Anderson!
Gerry Anderson also 'documented' this in an episode of UFO called "Conflict". SHADO was concerned about space junk in orbit providing cover for UFOs, and by the end of the episode, had a program to clear the larger items. Synopsis from fandom says:
"ED Straker is convinced that space debris, discarded rocket boosters and other junk, is both a danger and a cover for alien activity. But even after the deaths of two SHADO astronauts, he is unable to convince General Henderson of the International Astrophysical Commission to resolve the problem. By the time Straker takes Henderson to SHADO HQ to prove his point, it may be too late, they will only be able to clear away the debris if they can survive the attack of the UFO that is homing in on them from behind it!"
ferrous mass is more than just pointless, it can cause very real problems in orbit thanks to interaction with the earth's magnetic field at high speeds (think "braking effects")
For small/brokenup stuff a ground-based laser broom is likely to be far more effective than this and for larger stuff an ion tug likely fills the same niche
In any case the REAL impediment to de-orbiting garbage is political, not technical:
If you demonstrate the ability to bring down a dead/uncooperating package of your own, you also just demonstrated the ablity to bring down other people's active spy/comms sats - and whilst kinetic shootdowns come with a built-in dissuader against actually using them, being able to down a bird WITHOUT creating a debris hazard trail may encourage indiscriminate activities (aka, space warfare)
First demonstrated over 50 years ago. IIRC, there was some Anglo-Japanese collaboration then.
https://youtu.be/_qixtjMoMUA?t=67
In terms of actual technology, the landing is very much like what SpaceX do routinely these days
It was in Moonraker that 'Q' remarked Bond was "attempting re-entry"
While NOAA said the satellite is not a threat to the space station or “other critical space assets,” it is in a sun-synchronous orbit used by other weather and Earth observation spacecraft.
Some of those satellites are not only threatened by such debris, but also pose a threat of creating more debris. Weeden noted a report by NASA’s inspector general in January that found two NASA missions in polar orbits, QuikSCAT and Terra, not only fail to meet the 25-year threshold for deorbiting spacecraft after the end of their missions, they also pose a risk of explosion because of batteries that cannot be disconnected or propellant tanks that cannot be depressurized."
The best thing to do - in the future - is to make a satellites last act a dive towards Earth.
Sufficiently elliptical - that then means that the orbit *crosses* virtually every orbit in use at extreme velocity. Transfer stages usually decay within a few months because they keep perigee as low as they can.
It also still requires really quite significant energy:
For a typical GTO with a semi-major axis of 24,582 km, perigee velocity is 9.88 km/s and apogee velocity is 1.64 km/s,
For a GS orbit around earth we get about 3km/s orbital velocity, so you'd need to take 1.5km/s worth of fuel - and of course the additional fuel to get *that* fuel into LEO, GTO, and then GSO.
Alternatively you can boost the satellite ~300km up for a genuinely small dV expenditure, getting it out of the way of one of the busiest orbits.
I don't really care if this actually works (of course I'll be happy if it does), I'm just happy that there are people who are finally actively tackling the problem.
We've been hearing about this issue for over a decade, now someone is actually trying to do something about it.
Here's hoping it works !
The problem is that the deltaV necessary to match orbits is quite expensive, and then the additional effort of moving from one orbit to another means that the cost of de-orbiting some of this junk is likely to be higher than the cost of originally putting it up there in the first place!
While space was mainly the remit of governments, it was quite obvious who should bear the cost of this. But when it comes to commercial satellites and the debris associated with them, the cost of doing the cleanup may bankrupt the original companies (if they still exist), because you can bet your bottom dollar that they only put a small amount of thought into what happened at the end of their life.
The real problem is not the larger objects that we can track, but the smaller ones. Unfortunately, the laws of motion mean that even small objects traveling at orbital speeds can inflict a lot of damage.
Just do the same thing as oil and mining companies do to pay for cleanup costs.
Everybody pays into a fund during operation from their profits and then when the rig/mine closes the company sells the operation to a subsidiary which declares bankruptcy and the government pays for the cleanup.
Meanwhile the contents of the fund having been distributed as stimulus to the companies everytime the market price drops.
… a bigger vacuum cleaner. A Spaceballs sized vacuum cleaner in fact.
This uses exactly as much fuel to deorbit the payload as it would take for the payload to carry to deorbit itself (which is a significant part of the fuel needed to orbit it in the first place)
Plus you need the fuel to orbit the capture gadget, and have it manouver and have it move itself to the deorbit level. Newton is a bitch!
There are more energy-realistic options like attaching sails which increase drag and cause things to deorbit themselves - which the Japanese have also demonstrated.
However if you have a space agency that needs some funding between major missions this is a good thing (tm) it is quick and cheap to build and nobody can object - not military, not-environmental, not wasteful 'science' etc
"exactly as much fuel"
A good ion thruster will use much less fuel than the hydrazine (etc) used in many station keeping systems.
Not only that, you only need to give the debris enough of a nudge to intersect the atmosphere... then let nature take its course (while our intrepid hero jets away). The shuttle did not need to carry a massive fuel tank to de-orbit.
"Not only that, you only need to give the debris enough of a nudge to intersect the atmosphere..."
Yeah - that's still quite alot of a nudge.
The shuttle was already in a very low orbit, the ISS requires regular reboosting.
Any higher than LEO and the energies get really significant really fast.....
It suddenly became very popular to take care of the safety of the orbit. I love that things like this are popular. But it also looks like we do have a problem called Kessler's Syndrome. For some reason, some deny it.
But space tugs, which are increasingly featured in the UK aerospace news, tell us the problem is real.