Andy44
owner: Oil Creek Astronautix
A question was asked about the anomalous Progress mission: how would you go about docking with such a vehicle if you had to? What if it were manned vs. unmanned?
A while back when NASA's last Hubble repair mission happened they installed a docking adaptor on the HST in order to grab it and deorbit it with some other vehicle in the future. That got me to thinking: if HST's failure mode at end of life involves loss of attitude control, then there might not be a way to do a controlled deorbit. Or is there?
In an alternate version of Arthur C. Clarke's novel 2001: A Space Odyssey, there is a chapter in which Discovery's skipper Dave Bowman has to race out and grapple a tumbling AE-35 antenna array which has been sheared off of Discovery in an accident. His strategy is to approach the object in the work pod, visually identify the axis of rotation, rotate the pod along that axis, and grab the antenna with the pod's manipulator arms. Then he would use the pod's jets to despin both objects, and finally to return to Discovery. (The alternate versions of various chapters are well worth the read)
In the case of HST, where you aren't too concerned with damaging the object since you are trying to deorbit it anyway, you have things you can grab onto firmly, solar panels and other external appendages.
The problem would be doing this with a robotic vehicle. These sorts of things are much easier with a human pilot on the spot looking out a window and making rapid decisions in realtime.
Then of course, you need the proper grappling equipment. As far as I know, no such thing currently exists. The RMS used on STS was pretty flimsy IIRC. You'd want a very sturdy grappling arm or arms, and enough RCS fuel to maneuver and despin all that mass along with your own.
I can think of a few other less conventional ideas for this. A few:
- find a way to fasten a yo-yo despin device to the rotating vehicle, using a magnet or some sort of glob of glue, like using chewing gum. You'd "throw" the device at the vehicle, and after it sticks to the vehicle, activate the depsin. It would have to be stuck to the right part of the vehicle, and the despin yo-yo cables would have to be able to unspool clear of solar panels and other appendages of the target vehicle.
- Use some sort of bumper to rub up against the target vehicle and slow it down with friction. Also fraught with difficulties and constraints. You need a part of the vehicle that is fairly round and smooth, with no swinging solar panels to wack you as you apply the bumper. You also would need jets to apply constant pressure, which means changing your orbit as well as wasting propellant.
- Similar to the sticky yo-yo device, substitude a jet pack for the yo-yo. Stick the jet pack to the object, then use the jets to despin. Problems here include mass of propellant needed in the jet pack for this to work, as well as thruster scorching of target vehicle surfaces due to attachment at wierd angles.
What if it were a manned Soyuz (or any other) capsule?
In this case we want to make sure the crew are not harmed, so we have to be careful what sort of damage we are willing to do to the target vehicle. If the plan is to abandon the vehicle rather than use it to deorbit the crew, you have more freedom to grapple it. You may also get assistance from the crew themselves, depending on their ability to act and how much control they still have over the spacecraft.
I guess they can always try the Sandra Bullock fire extinguisher method if all else fails...
...which is not entirely silly" they can abandon the vehicle in space suits, one at a time, and the rescue vehicle can now track them down and pick them up. This was the plan to rescue shuttle astronauts if they got lost during spacewalks, just fly the orbiter over and scoop them up in the payload bay. Would require more delta-V, of course, but might in fact be the safest way to do it.
What do you guys think?
---------- Post added at 08:56 PM ---------- Previous post was at 08:44 PM ----------
I just thought of another crazy idea: use a sticky momentum wheel device, similar to the sticky yo-yo, but a self-contained unit with a large gyroscopic wheel, motor, and battery inside. Once it attaches itself to the target vehicle, orient the wheel appropriately and spin it up, absrobing the angular momentum of the target vehicle. This should stop or at least slow it down long enough for the rescue vehicle to grapple or dock with it. At that time you can turn off the wheel and dump the angular momentum using the rescue vehicle's jets. This might be the best idea, since the wheel has none of the problems of cable entanglements or jet plume impingement. Would have to do the math on how big a wheel and battery you'd need, of course.
A while back when NASA's last Hubble repair mission happened they installed a docking adaptor on the HST in order to grab it and deorbit it with some other vehicle in the future. That got me to thinking: if HST's failure mode at end of life involves loss of attitude control, then there might not be a way to do a controlled deorbit. Or is there?
In an alternate version of Arthur C. Clarke's novel 2001: A Space Odyssey, there is a chapter in which Discovery's skipper Dave Bowman has to race out and grapple a tumbling AE-35 antenna array which has been sheared off of Discovery in an accident. His strategy is to approach the object in the work pod, visually identify the axis of rotation, rotate the pod along that axis, and grab the antenna with the pod's manipulator arms. Then he would use the pod's jets to despin both objects, and finally to return to Discovery. (The alternate versions of various chapters are well worth the read)
In the case of HST, where you aren't too concerned with damaging the object since you are trying to deorbit it anyway, you have things you can grab onto firmly, solar panels and other external appendages.
The problem would be doing this with a robotic vehicle. These sorts of things are much easier with a human pilot on the spot looking out a window and making rapid decisions in realtime.
Then of course, you need the proper grappling equipment. As far as I know, no such thing currently exists. The RMS used on STS was pretty flimsy IIRC. You'd want a very sturdy grappling arm or arms, and enough RCS fuel to maneuver and despin all that mass along with your own.
I can think of a few other less conventional ideas for this. A few:
- find a way to fasten a yo-yo despin device to the rotating vehicle, using a magnet or some sort of glob of glue, like using chewing gum. You'd "throw" the device at the vehicle, and after it sticks to the vehicle, activate the depsin. It would have to be stuck to the right part of the vehicle, and the despin yo-yo cables would have to be able to unspool clear of solar panels and other appendages of the target vehicle.
- Use some sort of bumper to rub up against the target vehicle and slow it down with friction. Also fraught with difficulties and constraints. You need a part of the vehicle that is fairly round and smooth, with no swinging solar panels to wack you as you apply the bumper. You also would need jets to apply constant pressure, which means changing your orbit as well as wasting propellant.
- Similar to the sticky yo-yo device, substitude a jet pack for the yo-yo. Stick the jet pack to the object, then use the jets to despin. Problems here include mass of propellant needed in the jet pack for this to work, as well as thruster scorching of target vehicle surfaces due to attachment at wierd angles.
What if it were a manned Soyuz (or any other) capsule?
In this case we want to make sure the crew are not harmed, so we have to be careful what sort of damage we are willing to do to the target vehicle. If the plan is to abandon the vehicle rather than use it to deorbit the crew, you have more freedom to grapple it. You may also get assistance from the crew themselves, depending on their ability to act and how much control they still have over the spacecraft.
I guess they can always try the Sandra Bullock fire extinguisher method if all else fails...
...which is not entirely silly" they can abandon the vehicle in space suits, one at a time, and the rescue vehicle can now track them down and pick them up. This was the plan to rescue shuttle astronauts if they got lost during spacewalks, just fly the orbiter over and scoop them up in the payload bay. Would require more delta-V, of course, but might in fact be the safest way to do it.
What do you guys think?
---------- Post added at 08:56 PM ---------- Previous post was at 08:44 PM ----------
I just thought of another crazy idea: use a sticky momentum wheel device, similar to the sticky yo-yo, but a self-contained unit with a large gyroscopic wheel, motor, and battery inside. Once it attaches itself to the target vehicle, orient the wheel appropriately and spin it up, absrobing the angular momentum of the target vehicle. This should stop or at least slow it down long enough for the rescue vehicle to grapple or dock with it. At that time you can turn off the wheel and dump the angular momentum using the rescue vehicle's jets. This might be the best idea, since the wheel has none of the problems of cable entanglements or jet plume impingement. Would have to do the math on how big a wheel and battery you'd need, of course.
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