Physics of orbital salvaging of space debris

[rhapsodyinspace2]

Physics of orbital salvaging of space debris I why I am here. Can someone inform me how the physics work in this application.

A few questions...

1) First question is I keep hearing its not a viable plan....OK, with that said, the least I would like to know is about how much fuel you would need to carry out a salvage operation.

A space tug (lets say it weighs 4,500 lbs.) would stay in orbit at all times, never re-entering the atmosphere and the salvage destination would be close to the I.S.S.

The salvaged item would be a Space Shuttle External tank.

2) So how much fuel would you need to take your space tug from point A(I.S.S. station) to point B(External tank) grab the external tank and get back to point A and park it in orbit?

3) How big would your fuel tank need to be?

4) Same questions but insert a defunct satellite?

5)What about the hardest, or farthest grab of space debris in a difficult orbit?

any help would be appreciated!

 

[MeteorWayne]

Well the first problem is that the Shuttle external tank burns up in the atmosphere, so is not in orbit. It never enters orbit.

BTW, I don't think this belongs in Physics (despite your title ), it's more of a Space Business and Technology question, but I'll leave it here for a while.

Wayne

 

[rhapsodyinspace2]

If you were to have a salvage business NASA would put the External tank into orbit for you. It takes more fuel for them to get it to burn up into the ocean(safely disposing of it instead of letting it become debris in orbit) then it does to put it into space. They would do it because it would be a fuel saver to them and they would have more room for payloads....A win win for everyone!

I also posted It on my $700 million forum....Figured this way the place to put it? My bad! lol

Anywho.....Can anyone help me?...lol

Ummmm...Thank you Wayne!

 

[MeteorWayne]

If you were to have a salvage business NASA would put the External tank into orbit for you. It takes more fuel for them to get it to burn up into the ocean(safely disposing of it instead of letting it become debris in orbit) then it does to put it into space. They would do it because it would be a fuel saver to them and they would have more room for payloads....A win win for everyone!

I also posted It on my $700 million forum....Figured this way the place to put it? My bad! lol

Anywho.....Can anyone help me?...lol

Ummmm...Thank you Wayne!

Sorry, you are wrong. Carrying that mass to orbit would need more propellant, and there's none to spare. That's why the launch window is only 10 minutes long; any more change in plane would take too much propellant, more than they have to spare. As I've stated, changing planes is very expensive in terms of delta velocity.

It takes less propellant to drop off the tank before carrying it to orbit. So they would have LESS mass for payloads.

Physics is a cruel taskmaster.

You should probably research the problem more before making such statements. It is not our job to educate you; if you are making such proposals, it is your job to research the physics. It's not one of my areas of expertise, so I don't have th formula handy. We had a user here who was very good at it, but he has disappeared. Again, it's YOUR job to run the numbers, we are just pointing you in the right direction.

Wayne

 

[rhapsodyinspace2]

I was told that it took more fuel to change the orbit of the External tank so that it would fall into the ocean and be disgarded that way! If I was wrong I am sorry! Damn this gets harder as it goes! lol

Consider me slapped!

 

[MeteorWayne]

Who told you that? Where did you get that impression?

I could be wrong, you know. Perfectaion isn't one of my attributes

 

[rhapsodyinspace2]

I have known about it for awhile but I was reading up on some of the other threads. The one on External tank usages I think about page 35? It also said the president would make 3 or 5(?) tanks available if there was a business in place to take care of them. (I hardly see that still happening with the Space shuttle winding down though) But who knows?

Anyway thanks for leaving this here for a day or 2!

I am just trying to figure stuff out! lol

 

[MeteorWayne]

Page 35 of what?

 

[dangineer]

Just wanted to confirm MW's remark that it would cost more in fuel to bring the external fuel tank into orbit. This is because the external fuel tank is jettisoned on a sub-orbital trajectory and it does not have enough velocity to maintain orbit. To increase its velocity, you would need to carry more fuel.

Now, on to your proposal for ferrying orbital debris to the space station, or just trying to salvage it in general, this really isn't economical. Although it is technically feasible, it would be a very costly program. Since the ISS has limited or no capabilties to process debris, you would need to return the debris to Earth, which would require very expensive thermal protection systems, and a recovery system. The spacecraft would end up being very complicated and sophisticated, utilizing advanced avionics systems for rendezvous and proximity operations, and some sort of remote manipulator system to grapple the debris, not to mention orbital debris sheilding to protect againts inadvertant impacts.

Unfortunately, most of the space junk out there is not very useful, as it is usually heavily damaged by collisions with other space junk and the intense radiation environment in space. Any electronic components would likely be damaged beyond any sort of reuse and the metal would be weak and degraded. Thus the returns for this stuff would be very small compared to the price of getting it back to Earth safely.

rhapsodyinspace2, if you would still like to know how much fuel it would take to perform the mission you suggested, I could help you with the equations describing the orbital mechanics, just PM me or something. FYI, knowing the exact amount of fuel also requires knowing what kind of fuel you are using.

 

[rhapsodyinspace2]

Just wanted to confirm MW's remark that it would cost more in fuel to bring the external fuel tank into orbit. This is because the external fuel tank is jettisoned on a sub-orbital trajectory and it does not have enough velocity to maintain orbit. To increase its velocity, you would need to carry more fuel.

Now, on to your proposal for ferrying orbital debris to the space station, or just trying to salvage it in general, this really isn't economical. Although it is technically feasible, it would be a very costly program. Since the ISS has limited or no capabilties to process debris, you would need to return the debris to Earth, which would require very expensive thermal protection systems, and a recovery system. The spacecraft would end up being very complicated and sophisticated, utilizing advanced avionics systems for rendezvous and proximity operations, and some sort of remote manipulator system to grapple the debris, not to mention orbital debris sheilding to protect againts inadvertant impacts.

Unfortunately, most of the space junk out there is not very useful, as it is usually heavily damaged by collisions with other space junk and the intense radiation environment in space. Any electronic components would likely be damaged beyond any sort of reuse and the metal would be weak and degraded. Thus the returns for this stuff would be very small compared to the price of getting it back to Earth safely.

rhapsodyinspace2, if you would still like to know how much fuel it would take to perform the mission you suggested, I could help you with the equations describing the orbital mechanics, just PM me or something. FYI, knowing the exact amount of fuel also requires knowing what kind of fuel you are using.

dangineer, OK, I wonder if NASA would be interested if a salvage company would pay them to put the extra fuel in the External tank to get it into orbit where it could be docked with the tug.

OK, lets go with it not being practical but barely technically feasible. It would be processed at the I.S.S. at least until the vehicle is ready. I would send a small foundry up to the I.S.S. No debris would be coming back to earth.

I am more concerned about the metal. Would it become a viable metal after being melted and reformed into new sheets? Or would it be just a fatigued metal in a new form? I do admit, it would be nice to collect defunct satellites for reuse or just to get their solar arrays and add them to my power supply. But understand it would be a crap shoot on the quality of satellites I would be salvaging.

Yes I still would like to know how much fuel it would take to perform this type of mission. Since I was using the External tank as an example the tug would use the same fuel as the Space shuttle external tank. There by hoping on recovering the extra fuel still in the External tank.

Thanks I was about to give up on this. I really appreciate it.

 

[EarthlingX]

How much fuel would be needed depends on engine isp (Specific Impulse or effective exhaust velocity), delta V required and mass of the ship. With this view, there is a catch in time, but you can (technically) put more power in nuclear reactor than in chemical mass.
In short, VASIMR and version of Radioisotope thermoelectric generator, for starters.
Let's play with 50 t mass and 5km/s delta V.

 

[EarthlingX]

Well, as with many other things, my idea was not so new.
There are smarter, more knowledgeable people, who already done the calculating, with a bit different configuration (Projected Lunar Cargo Capabilities of High-Power VASIMR Propulsion) (edit 2009.09.03, link is not working anymore) :
http://forum.nasaspaceflight.com/index. ... ach=160672

Another paper (VASIMR Performance Measurements at Powers Exceeding 50 kW and Lunar
Robotic Mission Applications) :
http://www.adastrarocket.com/ISGLP_JPSquire2008.pdf

Lunar Tug Using Plasma Rocket:
http://www.youtube.com/watch?v=ZXofYP_VfUg

OTV can be used for clearing orbit around the ISS plane, refueling satelites and doing short excursions.
It can also be used as a construction vehicle with the proper module.

Robotic version:
http://www.spacedaily.com/reports/Space ... d_999.html