Wasn't this issue...
This was the premise for an episode of Gerry Anderson's UFO in 1969!
Italian scientists have devised what they reckon is a viable plan to deal with the menace of large chucks of space debris: a robotic satellite which will grapple the junk, attach a propellant kit and dispatch it to a fiery death in the Earth's upper atmosphere. Marco Castronuovo and colleagues from the Agenzia Spaziale …
Good Lord, not that again! No, getting large objects to high orbit is well understood.
In fact, conspiracy nutcakes aside, the US sent three men and a tub (OK, a large, elaborate multi-part tub, but you get the point, right?) to an altitude of around 240,000 miles in the late 1960s, and we surely understand rocketry better now.
Well, I hope we understand it better now, because if not, what have all the rocket scientists been doing for the last 30 years?
Normally, you are spot on the money on this subject, so sorry to have to mention that the errant hand-bag re-entered a while ago.
and yes, 850km is quite challenging. i don't know how much Ariane5 can get up there (I doubt it's mentioned in the user guide!). i'm guessing that this beastie will need a lot of fuel for delta-V changes to catch the different bits, then manouvring to match thier spinning to be able grapple them without the arm being ripped off, then attitude control.
I also expect that the attached payload might need more than just a solid-fuel kick motor; some attitude control may be needed to keep the rocket pointed in the right direction while it fires!
Yes, this could be an interesting project.
"Of course it does nothing about the umpteen paint chips, nuts bolts (and at least 1 ISS toolbag) but it's a start."
Actually, as I recall, the tool bag's orbit eventually decayed and the tool bag re-entered on its own.
The nuts and bolts, though small, are still traveling at least 17,000 mph and could cause quite a bit of damage when striking a spacecraft. Perhaps a magnet...?
"The nuts and bolts, though small, are still traveling at least 17,000 mph and could cause quite a bit of damage when striking a spacecraft. Perhaps a magnet...?"
1. Relative velocity, it's when they cross orbital paths that the problem is a major one.
2. Most nuts and bolts used in space craft are either aluminium alloy or titanium alloy, both of which are not strongly magnetic.
Many of these pieces will never have been designed to be grappled, so getting an attachment is going to be difficult, and they will probably be tumbling having never had, or have lost attitude control.
Good luck to them and it sounds like a fun project to work on.
(Paris because she is designed for easy grappling and has attitude).
[[ identified over 60 major threats at an altitude of roughly 850km, the BBC explains. Two-thirds of these weigh in at over three tonnes apiece, and many are whizzing along at up to 27,000 km/h (16,800 mph).]]
Shouldn't all the various things orbiting at a given approximate altitude be whizzing along at about the same speed, as long as gravity and the dimensions of the Earth are relatively constant for all the various things doing the whizzing?
yes and no. If they were all in a circular orbit at the same altitude, then yes, all the speeds would be the same. However, they may not be in perfectly circular orbits or at exactly the same altitude. I seem to remember the the orbits of the rocket bits are not circularised to get better efficiency for whatever they launched. I expect that in non-circular orbits, the speed various throughtout the orbit.
I can't be much more help because once the thing is up there working, my job is over: other people look after driving them; I just know the basics to understand what to build.
...the Apollo 10 S-IVB stage -- the Saturn V third stage used to break out of Earth orbit and place the Apollo on a lunar trajectory -- is still waaaayyy out there in a heliocentric orbit and made a close approach to Earth recently; it'd be interesting to dispatch a robot probe to rendezvous on its next close approach and get some high-res images to see what kind of shape its in... just out of sheer curiosity.
There's no need for grappling hooks and propellent packs... no sir. All that's required are some pre-cut strips of Duct tape, and a stack of fresh US dollar bills in various denominations loaded into a dispenser aboard the robotic satellite. Upon rendezvous a single one dollar bill is affixed to the small size unwanted space junk with a Duct tape strip (sticks to anything) then it's on to the next chunk of space debris. Larger chunks will require larger denominations. The sinking dollar will do the rest.
I still like my idea better: an array of Archimedes mirrors. (There is an extraterrestrial explanation for all this and here it is...)
Send up a thousand or so identical pointable satellite mirrors. They are small, probably massing less than 1 pound each, so you can fit them all into one small launch vehicle easily (with room to spare for someone else's project too, this helps keep launch costs down). The design of each individual satellite is as follows:
A large triangular sheet of reflective foil, supported by three poles (one to each corner of the foil), making an effective flat mirror surface. The non-foil ends of the poles are joined to a central unit (sprung hinge joins of course, to allow for folding into the launch vehicle).
The central unit contains three small electric motors mounted at right-angles: when spun they change the attitude of the entire craft to point the mirror in any direction. The central unit also contains a processor, a receiver for *cough* receiving instructions from Terra Firma, and any other necessay gadgetry. There will also be a small solar panel to provide power to the motors and electronics (and a small back-up battery for when passing through the Earth's shadow).
How does it work? The many small satellite mirrors are in orbits all around the Earth. Rotate a couple of hundred of them to reflect sunlight onto a piece of space junk, and it gets very hot and vapourises. Job done, re-point at the next piece of junk, and so on.