Lockheed Martin's "Jupiter" reusable space tug, CRS-2 bid

[Norm38]

The LM presentation doesn't have much detail.  How is the swap of cargo containers accomplished?  They show the Jupiter grabbing hold of an upper stage with a new cargo container, but then what?  Where does it put the old container before it docks to the new one?  The old has to attach to the US for disposal, yes?  So it can't just be cut loose, and there's only one arm.  I can't picture it.

[QuantumG]

The old has to attach to the US for disposal, yes?

No. The tug would decelerate the container to a reentry and fly back to a stable orbit.

[Norm38]

Ahh.  So their animation is in error?  When the tug docks to the US, it'll be just the tug, having already dumped the old container?

[ChrisWilson68]

I don't think a tug system like this will noticeably decrease the probability of a successful mission--sure it will decrease it somewhat, but is it enough to ever matter?

It might descrease the probability of a successful mission, but it might also increase it.  Say for each unit built there's a 1% chance of a manufacturing defect that slips through testing and doesn't get noticed until it's in orbit.  If you build 20 of them for 20 missions you have roughly a 20% chance of one of the missions getting hit by this problem.  But if you build only 1 and use it for all 20 missions, you only have a 1% chance of that.

It all depends of the specific failure modes and how likely infant mortality is versus failure modes that go away with a throw-away system.

[WindnWar]

The old has to attach to the US for disposal, yes?

No. The tug would decelerate the container to a reentry and fly back to a stable orbit.

That would need a lot of delta-v to pull that off since part of the requirement was 2500 kilos of cargo disposal. I wonder how much fuel will be needed in each cargo pod in order to leave the Jupiter tug with enough to get back to a stable orbit and then have fuel remaining to dock with the next cargo pod. Or do you place a pod with nothing but fuel in orbit for it to dock to between missions?

[Robotbeat]

Yeah, good point. Once the mission launches successfully, odds are lower that you'll run into more infant fatalities.

[ChrisWilson68]

Like I said, the concept is interesting but given the complexities without on orbit testing of it in a complete package, I don't see how they can convince NASA that the risks would be worth it for this mission.

The beauty of CRS is that the risk lies almost entirely with the companies, not with NASA.  Most of the cargo to the station is pretty cheap and easy to replace, and NASA has multiple providers.  As we've seen with Cygnus, even if something goes wrong, it doesn't cause any serious problems for NASA.  They just shift around some missions and use other providers more until the provider with the problem works it out.

If you're thinking of risk to the station, that can be retired before the vehicle is allowed close to the station, as was done with Cygnus and Dragon 1 and will be done with CST-100 and Dragon 2 -- NASA just makes the companies demonstrate precision operations far from the ISS first.  Once it's been tested on orbit, they let them come to the station.  It can be on the same mission, so they don't even need a dedicated flight just for testing.

[nadreck]

For reliability concerns, I wonder if it would be worth it to have a second copy of the Jupiter tug module on standby in case of problems with the first?

I definitely see redundancy for ISS support. As well if you were using the Jupiter-Electric (or similar) as a tender for a seriously multi planar LEO/MEO satellite constellation you might have a tender on ever other plane but know that for a little penalty of added time it could deliver service/replacement one more plane over, and of course collect duds for deorbitiing.

I'd be curious how they can prove the reliability of the Jupiter tug, if there are rendezvous issues or equipment failures on the tug, you'll need to replace it, as if it fails its not like you can dock it at the ISS for repairs by itself, it might not even be allowed near the ISS if redundancy in equipment is lost, if they guess wrong on how often it'll have to be replaced the cost will go up quite a bit. We have seen various failures of equipment on the ATV during it's time on orbit, and most of that time was docked, this will be far more complex.

I like the concept, I'm just not sure how you prove the risk is worth it for this mission. 

The reliability is based on the experience with the individual component hardware systems: the MAVEN bus, the arm, etc. all those systems have already been tested with plenty of on orbit time. The combination may require some engineering analysis, but we are not talking anything more rigorous than mating a different comms system to the Boeing 702 bus.

Except it'll be used in a very different manner. It'll need to perform long burns many more times than the bus it's based on normally would if it is used multiple times, it'll need to refuel, something not proven on orbit at all, it'll need to do precision on orbit rendezvous, also not tested with this bus to both the station and to the cargo pods, and it introduces and additional docking that if failed prevents the mission from succeeding. Like I said, the concept is interesting but given the complexities without on orbit testing of it in a complete package, I don't see how they can convince NASA that the risks would be worth it for this mission.

I grant you the that the connectors for the fuel containers (both the SEP fuel and the hypergolic) will be new and special case technologies that require serious testing unless the whole plumbing and engines swap out with the hyper-golic fuel, the rest I believe have been proven out as subsystems or represents a much lower risk.  Certainly MAVEN engines burned more impulse than rendezvous and docking will take, SEP portion probably won't be part of the ISS servicing Jupiter, avionics and control systems for the arm and such will be new. However software engineered for spacecraft is testable and gets subjected to rigorous test long before it puts any equipment at risk.  I don't see the number of docking and rendezvous events as troublesome, just the fact that it needs to be a reliable process and given that we have reliable processes for that already I think it is no stretch of the imagination to develop, test in simulation, then fly an acceptance test and be assured that docking and rendezvous will continue to work.

[QuantumG]

Ahh.  So their animation is in error?  When the tug docks to the US, it'll be just the tug, having already dumped the old container?

Well, if the upper stage is going to be left in that orbit, it seems just as reasonable to leave an old container in that orbit too. If it's a LEO orbit it'll deorbit soon enough.

[TrevorMonty]

See post 585 on CRS2 thread on how Exoliner swap with Centuar may happen.

[TrevorMonty]

If reusable upper stages ever happen, they can swap containers stored in the upper stage. This would also give them down mass.

See Kistler upper stage concept here. PS surprised website still exists.

http://www.kistler.co/fpmain.html

[redliox]

Would be interesting if Lockheed could pull this off.  It looks like a slightly-suped-up version of a Cygnus, mainly with the robotic arm and a reusable tug being the improvements.  For something primarily geared for low orbit, doesn't look like a bad choice.  I'd favor the Dragon more so only because it can reenter, whereas this I like for potential long-term utility.

The Exoliner module has my attention because the Orion needs something just like it to enable a proper long-term mission, at least to the Moon and asteroids.  After an Orion is in orbit, a Jupiter with Exoliner could rendezvous, and deliver it to Orion.  I wouldn't go so far as to say Mars or even its moons; that would be a big stretch.  Still, it feels like a step in the right direction.

Again, it would be interesting to see if Lockheed could pull this off.

[redliox]

ISS aside, I will say the robotic arm option makes it the candidate to serve Hubble.  I wish it could give the Hubble a new tune up, but I presume they would only assign this vehicle to deorbit the renowned observatory.

[IRobot]

Would it make sense to have a dual engine, Chemical + electric? The electric thruster could be used for slow maneuvers, like spiraling down from the ISS or for spiraling up, when there is no time-sensitive cargo?

[marsman2020]

Like I said, the concept is interesting but given the complexities without on orbit testing of it in a complete package, I don't see how they can convince NASA that the risks would be worth it for this mission.

The beauty of CRS is that the risk lies almost entirely with the companies, not with NASA.  Most of the cargo to the station is pretty cheap and easy to replace, and NASA has multiple providers.  As we've seen with Cygnus, even if something goes wrong, it doesn't cause any serious problems for NASA.  They just shift around some missions and use other providers more until the provider with the problem works it out.

If you're thinking of risk to the station, that can be retired before the vehicle is allowed close to the station, as was done with Cygnus and Dragon 1 and will be done with CST-100 and Dragon 2 -- NASA just makes the companies demonstrate precision operations far from the ISS first.  Once it's been tested on orbit, they let them come to the station.  It can be on the same mission, so they don't even need a dedicated flight just for testing.

NASA also "just" paid Orbital 80% of the cost of a flight that ended with the payload burnt to a crisp on the beach 100 feet from the pad.  And the federal government is paying for the $20 million in pad repairs, even though they had no requirement to do so - because "somehow" Orbital wasn't contractually liable to fix what they broke, and the VA state space people didn't want to pay it either. 

The idea that the risk in CRS somehow lies with the vendors is only perpetuated by the fact that the % payment on the individual milestones for each flight in the publicly available versions of the as-signed CRS contracts is redacted out.  Based on the public disclosure Orbital made to their investors about the financial consequences of their failure, it seems like the actual "delivery of cargo" milestones are only about 20% of the contract value. 

[TrevorMonty]

LV failure shouldn't be an issue with Atlas.

[Star One]

ISS aside, I will say the robotic arm option makes it the candidate to serve Hubble.  I wish it could give the Hubble a new tune up, but I presume they would only assign this vehicle to deorbit the renowned observatory.

It could be adapted to remove various stuff out of orbit I would have thought. Might be a viable solution for reducing space junk.

[Galactic Penguin SST]

I wonder how much more workload would the ISS astronauts and ground controllers need for one Jupiter logistics mission compared with, say, one Cygnus?

[TrevorMonty]

I would expect LM ground crew would be in charge for Jupiter/ Exoliner/Centuar operations. So no more work for NASA staff than a Cygnus mission.

[Robotbeat]

Jupiter looks like it can carry much more cargo than Cygnus, so proportionally less involvement per ton.