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

[Danderman]

Doesn't make sense to me.

How does "Precession" apply to this? 

Objects in the same orbital plane at different altitudes have differing amounts of precession. Even a difference of 50 km altitude will result in Jupiter;s orbital plane precessing away from ISS, so that after a week, the plane change to return to ISS would be non-trivial.

If you look at the CSI video above, you will see a Progress tug performing a rendezvous and docking with a canister some 50 km below ISS; in that case, if the docking is delayed by more than a few days, the Progress cannot return to ISS without expending significant amounts of propellant.

[Jimmy Murdok]

I'd put an EVA hatch in the Exoliner and also the suit servicing equipment, and use the Exoliner as your airlock in the pictured configuration.

Looks like Bigelow is building another Beam with frontal door to be used as an airlock for their station. As it's quite small and inexpensive module, could be a good option to be carried in the unpressurized section and installed with the arm or directly plugged on the side of the container to be inflated in orbit.

[Nilof]

Objects in the same orbital plane at different altitudes have differing amounts of precession. Even a difference of 50 km altitude will result in Jupiter;s orbital plane precessing away from ISS, so that after a week, the plane change to return to ISS would be non-trivial.

If you look at the CSI video above, you will see a Progress tug performing a rendezvous and docking with a canister some 50 km below ISS; in that case, if the docking is delayed by more than a few days, the Progress cannot return to ISS without expending significant amounts of propellant.

How much would the delta-v requirement change for a 27 degrees orbit? In the degenerate case of an equatorial orbit, the delta-v is clearly zero because you can absorb the precession into the phase of the orbit. For a 90 degrees orbit, the precession rate is zero so there should be no delta-v cost here either. I'm curious as to how the cost changes inbetween these two cases.

[Danderman]

To fly from ISS to a 27 degree orbit would effectively require warp drive.

[Robotbeat]

To fly from ISS to a 27 degree orbit would effectively require warp drive.

Or a tether.

[Danderman]

To fly from ISS to a 27 degree orbit would effectively require warp drive.

Or a tether.

At this point, discussions about precession and high delta-V belong in a topic other than the LockMart Jupiter topic.

[Nilof]

To fly from ISS to a 27 degree orbit would effectively require warp drive.

Ah sorry if my post was unclear. I meant for the case of a hypothetical space station in a 27 degrees inclination orbit, such as a future Bigelow commercial station. For service vehicles like Jupiter, would the delta-v to cancel out precession due to orbital altitude differences be a bigger or a smaller problem at these inclinations?

[Danderman]

To fly from ISS to a 27 degree orbit would effectively require warp drive.

Ah sorry if my post was unclear. I meant for the case of a hypothetical space station in a 27 degrees inclination orbit, such as a future Bigelow commercial station. For service vehicles like Jupiter, would the delta-v to cancel out precession due to orbital altitude differences be a bigger or a smaller problem at these inclinations?

Precession would be a major issue at the standard 28.5 orbit.

In almost all cases, if the ISS tug were separated from the station, they would have to maintain a similar orbit at the same altitude, matching any maneuvers conducted by the station, in orbit to be able to return without using their entire prop supply.  One way to do this would be to change altitude from time to time, climbing higher, and then lower.

Here is an example of an architecture for an ISS-based tug to be used for repair of Globalstar satellites, which are at 1400 km. The time spent at 1400 km incurs  a precession "loss", so after such a mission, the tug has to descend very low, to spend time to "catch up" with ISS so the ascending nodes finally match:

https://www.google.com/patents/US20020130222?dq=ininventor:%22David+Anderman%22&ei=LTwhVfD4KoatogS7ioCYDg&cl=en

[Comga]

@Burninate:

http://en.wikipedia.org/wiki/Nodal_precession

Thanks belegor
Yes Burninate, it is about the rates at which the orbital planes rotate, the same effect that is used to find sun synchronous orbits and that causes launch windows to the ISS to shift ~7 minutes earlier every day. It has nothing to do with atmospheric drag. Phasing IS a much easier effect to cancel.  But precession is a real effect and a serious constraint on where to "park" a Jupiter/Exoliner.

[Endeavour_01]

I'm concerned about EVA's, as the stack will need to be disassembled each time. Besides that, the solution is quite practical and realistic to do something interesting with SLS+Orion in the 2020's. I really hope NASA invests in this solution for CRS-2.

I'd put an EVA hatch in the Exoliner and also the suit servicing equipment, and use the Exoliner as your airlock in the pictured configuration.

Looks like Bigelow is building another Beam with frontal door to be used as an airlock for their station. As it's quite small and inexpensive module, could be a good option to be carried in the unpressurized section and installed with the arm or directly plugged on the side of the container to be inflated in orbit.

You could definitely do that and I think it would be good to develop an EVA capable/2-docking port EAM. However, I don't think the stack would need to be disassembled for EVA's. According to the material NASA is putting out for ARM you could just use the Orion hatch for EVA egress/ingress.

[Space Ghost 1962]

For reference, here is an animation showing the CSI approach to ISS servicing, using intermodal containers, and an ISS-based tug. In the case of CSI, the tug was Progress, not Jupiter.

FYI only.

Thank you for bringing CSI up. Compared to Jupiter, it would seem that this failed COTS proposal differed in two ways - an "arm" for an additional CBM, and the ability to use an already existing, on-orbit vehicle as dual use tug.

IIRC, there was a Loral bus as a tug not unlike Jupiter, no arm, no replenished fuels from container, and no payload exchange with a US whereby the US could dispose the container. With CSI, I assume passive reentry instead.

Note also the docking to the RS as well, and the potential for such in refueling ISS propulsion.

But this brings up another way to do the Lockheed proposal as well - just do Exoliner as derivative of ATV's pressurized container. Then contract the "tug" part of the mission as one or more of Dragon/Cygnus/CST100/Progress/HTV/Soyuz ... and launch only the Exoliner, starting from first launch. Need additional docking adapter or limited berthing (needs just couple/decouple unpressurized) second "fixture".

The advantage of this approach would be low risk, high mass/volume efficiency cargo to ISS. No tug!

[Danderman]

One capability that Jupiter enables is delivery of a 4th Node to ISS.

[Danderman]

Thank you for bringing CSI up. Compared to Jupiter, it would seem that this failed COTS proposal differed in two ways - an "arm" for an additional CBM, and the ability to use an already existing, on-orbit vehicle as dual use tug.

You are correct. n 2006, the only tug around was Progress. And yes, Jupiter uses berthing, rather than docking, although berthing is actually a form of docking.

If CSI were bidding today, their approach would undoubtedly incorporate more advanced technology, such as a dedicated tug.

However, in the final analysis, Lockheed seems to be using an updated version of the CSI approach of an ISS  tug and intermodal containers stabilized in orbit by an upper stage; CSI's approach was considered innovative in 2006, and apparently was.

[woods170]

One capability that Jupiter enables is delivery of a 4th Node to ISS.

Oh no. Not Node 4 again. Can we please let the subject of Node 4 rest? Thanks.

[Robotbeat]

One capability that Jupiter enables is delivery of a 4th Node to ISS.

Oh no. Not Node 4 again. Can we please let the subject of Node 4 rest? Thanks.

4th Node, fine, but the ability to add new large modules is valuable.

[A_M_Swallow]

One capability that Jupiter enables is delivery of a 4th Node to ISS.

Oh no. Not Node 4 again. Can we please let the subject of Node 4 rest? Thanks.

4th Node, fine, but the ability to add new large modules is valuable.

A method of attaching science labs, spaceship assembly & repair yards and docking ports to Bigellow spacestations will be needed. A space tug sounds like the right tool for this job.

[Todd Martin]

Since Jupiter has an arm, why can't the tug simply latch onto an open hand restraint on the outside of the ISS (or perhaps something beefier and dedicated for the tug) instead of wasting fuel maneuvering around?

[Danderman]

Since Jupiter has an arm, why can't the tug simply latch onto an open hand restraint on the outside of the ISS (or perhaps something beefier and dedicated for the tug) instead of wasting fuel maneuvering around?

A single attachment point would likely lead to the tug swinging about every time there is a propulsive maneuver by ISS. The arm would have to be strengthened to be able to support the mass of the tug while attached to ISS, in inverse proportion to the area of the attachment point.

As an example, Soyuz and Progress have an attachment area with a diameter of about 1 meter. On top of this, hooks and clamps are used to strengthen the attachment.

The tug would have an attachment area of maybe 100 to 200 mm, which generates a sort of lever arm on the tug and increases the intensity of any velocity imparted to the tug via the arm.

What the tug really needs is a docking or berthing port.

I suspect that the reason this is not in Lockheed's current concept is because the costs of developing the port interface and the costs of the ISS partners paying for the additional prop required by the tug's additional mass is simply beyond the scope of their proposal.

[Space Ghost 1962]

Note that it can "dual attach" using arm and attachment used with Centaur.

And, this can be axially aligned in various places on ISS. Like ones along longitudinal axis of thrust ...

[Danderman]

Note that it can "dual attach" using arm and attachment used with Centaur.

And, this can be axially aligned in various places on ISS. Like ones along longitudinal axis of thrust ...

Hand waving here.

I could axially align my pickup truck in various places on SLS, along the longitudinal axis of thrust, too.