NASA asks industry for 'space tug' ideas to deorbit International Space Station

[Admin]

NASA is looking for spacecraft ideas to remove the U.S. segment of the International Space Station after its expected retirement in 2030.

NASA asks industry for 'space tug' ideas to deorbit International Space Station : Read more

 

[fj.torres]

Instead of deorbiting it, why not fill it with noble gas, *raise* the orbit, and leave it at high altitude as a monument/future museum, like the WWII ship museums?
Attach a bunch of ion thrusters and let its own solar cells boost it? Might even be cheaper than building a vehicle just to destroy it.

 

[steve_foston]

If the ISS is going to be deorbited then place it on the surface of the moon - I agree with FJ it should be turned into a museum as it is the largest man made object ever created and as such it is an important historical artefact. Imagine the pyramids being destroyed! As the space tourism industry grows it would then become an important destination. Much better than the vandalism involved in polluting the oceans.

 

[fj.torres]

If the ISS is going to be deorbited then place it on the surface of the moon - I agree with FJ it should be turned into a museum as it is the largest man made object ever created and as such it is an important historical artefact. Imagine the pyramids being destroyed! As the space tourism industry grows it would then become an important destination. Much better than the vandalism involved in polluting the oceans.

Maybe time to start a petition?
Remind the idiotpoliticians who they work for (when not lining their pocket with bribes). Preserve the station!

 

[benglover2015]

Instead of deorbiting it, why not fill it with noble gas, *raise* the orbit, and leave it at high altitude as a monument/future museum, like the WWII ship museums?
Attach a bunch of ion thrusters and let its own solar cells boost it? Might even be cheaper than building a vehicle just to destroy it.

Hmm, good question. Someone asked that here, too. <https://www.quora.com/Why-cant-we-s...ce-instead-of-burning-it-up-in-the-atmosphere>

In short, "The cost to develop the technology to accomplish the move and the cost of executing the move would be great. It is not realistic to expect Congress to pay for such a thing. And if they did, it would likely be in lieu of going to Mars or returning to the Moon or whatever the next great adventure will be. Preserving the past would prevent the future." - Robert Frost

 

[fj.torres]

Hmm, good question. Someone asked that here, too. <https://www.quora.com/Why-cant-we-s...ce-instead-of-burning-it-up-in-the-atmosphere>

In short, "The cost to develop the technology to accomplish the move and the cost of executing the move would be great. It is not realistic to expect Congress to pay for such a thing. And if they did, it would likely be in lieu of going to Mars or returning to the Moon or whatever the next great adventure will be. Preserving the past would prevent the future." - Robert Frost

Riiightt...

That's the same excuse they used to let SKYLSB burn inhstead of adding the other two, including the one fully finished and sitting in the SMITHSONIAN. And thrn spent 20 years to assemble the potluck station at ten times the cost.

Have they actually priced it?
What's the price for an RFQ?
Ion thrusters are not new tech and the station cused an be moved as is.
And there's several New Space companies developing new ones on their own.

Obviously the price will be outrageous if they sign with the old space friends of the party but there are plenty of cheaper options.

The whole point of ion thrusters is they work for long periods of time so the could be mounted on a CYGNUS full of fuel and draw power from the station solar wings.
Not talking a moon landing or GEO but elevating the orbit regularly to keep it up above the junk belt.

Wanna bet if they give it away to a New Space consortium they find a way to refurbish anf maintain it and use it as a commercial station *and* make a profit?

Eventually the price of moving it to GEO will drop.

 

[billslugg]

ISS is nearing the end of its certified lifetime. The metal beams and metal skin may develop tiny cracks and fail suddenly. When the thousands of suppliers provided NASA with the parts, they all gave projected lifetimes NASA agreed to. Those times are going to run out some day. No one wants to be the scapegoat if an astronaut dies on an uncertified vehicle. Once the craft is retired, no one will go near it. No amount of refurbishment in orbit would be sufficient.
ISS cannot exist unless someone is living in it. There are ongoing maintenance tasks needed simply to maintain its orientation.
The ISS cannot exist without being able to look up at other satellites in order to fix its position, thus cannot exist at GEO, it would wander.
People cannot go outside the Van Allen belts but for very short times or with heavy shielding. No one could occupy it in GEO.
There is no scientific value in saving it. NASA has zero interest in saving it.

It is unlikely to be saved.

 

[Unclear Engineer]

Getting back to discussing the job of deorbiting it, that doesn't sound very difficult. They have been using Progress rockets to boost its orbit all along, and are (were , did ?) working on having SpaceX provide a boost capability, too. Deorbiting is mainly boosting in the opposite direction. I guess they need to be careful that the thrust is not too great for the structural integrity, but strong enough that the orbit can be changed sufficiently to make the reentry point predictable to the necessary precision to put the stuff that survives reentry into the South Pacific "graveyard". Is there really anything more to it? I would think we already have engines and fuel tanks and guidance infrastructure available.

 

[billslugg]

This paper says the Russian cargo ships leaving ISS use a 100 m/s delta V in order to land at a predictable spot.
ISS mass is 419,000 kg
It is moving at 7,900 m/s
Kinetic energy on orbit is 1/2 x m x v^2 = 1.308e13 joules.
Velocity after retro burn = 7,900-100 = 7,800 m/s
Kinetic energyafter retro burn = 1.274e13 joules
Delta energy required = 6e11 joules = 6e8 BTU = 27,000 pounds of rocket fuel

That is a fairly large tug.

https://conference.sdo.esoc.esa.int/proceedings/sdc7/paper/1008/SDC7-paper1008.pdf#:~:text=In%20a%20targeted%20decay%2C%20the%20energy%20change%20to,less%20than%201%25%20of%20the%20total%20orbital%20energy.

 

[Classical Motion]

No one likes my ionizing laser for net charge on debris idea. Before that thing comes down, why not install coils and generate a M field and try some magnetic steering? I have read just a length of wire can generate large voltages and currents out there. Let's test Ampere principles on a large scale.

 

[billslugg]

If you generate a current with solar cells and then run a current through a loop you can accelerate ISS. It would take a lot of power.

 

[Classical Motion]

Wouldn't a weak M field cause a net drag? I would have thought just a naked un-powered loop would cause some drag. And wouldn't that cause a rate of fall and an increase in V?

Would the increase in the weak M field V, cause more drag? Would more particles going thru loops, cause more drag? Maybe even increasing the loop field? I'll bet space is a strange place for a loop.

None the less, if we had a method of cheaply increasing drag on debris, won't that clear the orbits. Or do we need acceleration to clear in a reasonable time?

 

[billslugg]

If a wire has a current that you put into it, it will see force from any external magnetic field. Earth's field is very weak but can do some work, especially since the wire is going so fast. Such a wire could be used to steer, slow and speed up a craft.

The problem is current requires a loop. If you put a loop out there, the bottom half will cancel out what the top half is doing. Instead of slowing down or speeding up the loop with try and rotate.

Rather they run the return wire up the center of coaxial cable thus it is shielded. The current flow in the shield does the work.

Now the problem is when you stick out that wire, you need an equal mass at each end or it will simply rotate around the craft.

 

[StarFrontiers]

Aerobraking with a small drag plane on a heat-tolerant cable?

Hmm. My initial thought was SiC fiber cable (very high temp, long enough breaking length) with a small controllable pitch planing drogue, much like a plane or "otter" used for trawling, naval minesweeping and the like. Pay the cable/drogue out retrograde, it should drop (lower orbit) and "speed up" below the station until you can insert it into a wee bit of atmosphere. Some drag/attitude control should be possible by several means, even if the reel mechanism lacks a retrieval system. A single plane, or multiple drogue/planes in a string...plenty of options to consider. Basically it would be an aerobrake generating a small but constant force.
Yes, kinda risky compared to tried-and-true retro engine burn at periapsis for bringing down such a large object, but in my years of eyebrow raising and chuckling at various space-tether applications, the application of those models to do the opposite job had not been something I considered.
-Please folks, shoot holes in this idea...for science!

 

[StarFrontiers]

This paper says the Russian cargo ships leaving ISS use a 100 m/s delta V in order to land at a predictable spot.
ISS mass is 419,000 kg
It is moving at 7,900 m/s
Kinetic energy on orbit is 1/2 x m x v^2 = 1.308e13 joules.
Velocity after retro burn = 7,900-100 = 7,800 m/s
Kinetic energyafter retro burn = 1.274e13 joules
Delta energy required = 6e11 joules = 6e8 BTU = 27,000 pounds of rocket fuel

That is a fairly large tug.

https://conference.sdo.esoc.esa.int/proceedings/sdc7/paper/1008/SDC7-paper1008.pdf#:~:text=In%20a%20targeted%20decay%2C%20the%20energy%20change%20to,less%20than%201%25%20of%20the%20total%20orbital%20energy.

At what ISP? How many burns? Any inclination adjustment? Those are factors. Still, a <20T payload heavy lift vehicle could probably deliver the system. That vehicle exists. It would cost a lot less than the decommissioning of an aircraft carrier

 

[Unclear Engineer]

Regarding tailing conductive wires from spacecraft that we intend to deorbit:

If that became a common thing, wouldn't that seriously increase the probability of collisions between deorbiting things? It would take substantial periods of time for each satellite to decay its orbit sufficiently to reenter the atmosphere to burn-up. While in the process, what was initially a very small volume (that we hope did not intersect orbits with any other small volume) gets turned into a substantially longer line that would have substantially more probability of intersecting another long line on another satellite with a slightly (or greatly) different obit inclination.

 

[billslugg]

StarFrontiers
Yes, we could deliver 27,000 pounds of fuel to ISS and push it to a higher orbit, but to what end? If we put ISS into GEO we must still have people on it to maintain it. ISS cannot maintain orientation or position without constant human intervention. ISS cannot host humans at GEO, too much radiation.

Unclear Engineer
A space tether could deorbit a satellite using only the energy from its solar cells. However, it would take a very long time, a landing site could not be predicted, the tether adds complexity and mass to the vehicle and could be a hazard to other craft.

I don't see much advantage to the concept.

 

[StarFrontiers]

StarFrontiers
Yes, we could deliver 27,000 pounds of fuel to ISS and push it to a higher orbit, but to what end? If we put ISS into GEO we must still have people on it to maintain it. ISS cannot maintain orientation or position without constant human intervention. ISS cannot host humans at GEO, too much radiation.

Unclear Engineer
A space tether could deorbit a satellite using only the energy from its solar cells. However, it would take a very long time, a landing site could not be predicted, the tether adds complexity and mass to the vehicle and could be a hazard to other craft.

I don't see much advantage to the concept.

Agree completely. Never said anything about raising orbit. Perhaps you conflated my post with another one. I thought the 14 tons of fuel was for *deorbiting*, and that was what you were indicating by "land/reenter in a predictable spot". Was that calculation for 100m/s velocity change for deorbit or for something else? Space station isn't really set up for HEO operations at all. We are on the same page there, just inquiring about the precision of what I thought was a performance requirement for a de-orbit burn tractor system.
Another factor there is that the RFP (I believe, as mentioned in the article) was for deorbiting the USA and maybe EU and or Japanese sections, not the Russian bits. That may or may not be accurate.

 

[billslugg]

Yes, you are correct, I am quoting the number for deorbiting not raising the orbit.
I assumed a 100 m/s delta to put ISS in a predictable landing zone. This is the current Progress standard.