Orion BEO before SLS

[Sparky]

I suspect that this has been talked about elsewhere, but I couldn't find an in depth discussion of it, so I apologize in advance if this thread is redundant.

Since Orion will be ready before SLS, and since DIVH is unlikely to become manrated in the foreseeable future, what about a mission profile such as this to perform manned BEO flights before the second SLS flight, which seems to be planned for NET 2019

-Launch Commercial crew to ISS
-Launch Orion to ISS on DeltaIVH
-Launch Modified Centaur with NDS docking ring to near ISS
-Crew transfer to Orion
-Orion departs ISS and rendezvous with Centaur
-Centaur does eyeballs-out TLI

Aside from politics, what reasons would prevent such a mission if the powers that be wanted an early manned mission to Lunar orbit?

[SpacexULA]

Because ISS is in the wrong orbit for lunar transfer?  You could get there but it would be a lot of extra fuel.

[mmeijeri]

Because ISS is in the wrong orbit for lunar transfer?  You could get there but it would be a lot of extra fuel.

This is a myth. The problems would be political, not technical.

[apace]

You don't need the ISS to do such a stunt. Simply rendezvous and docking in low earth orbit and do it.

[FinalFrontier]

You don't need the ISS to do such a stunt. Simply rendezvous and docking in low earth orbit and do it.

Crew transfer could be potentially easier. Also, a vehicle such as the dragon (or CST) which are the front runners for commercial crew are designed for LEO or LEO-ISS orbits in mind, nothing else. To do a LEO-Transfer rendezvous would probably be harder rather than simply transferring the crew and changing vehicles at the ISS. You would, however, most likely need something larger than a centaur in order to get enough fuel. That or perhaps two centaurs stacked on one another (although what you would launch that on I have no idea). Perhaps one way would be to simply launch two centaurs individually, Then dock them to each other then dock to Orion after it undocks from ISS and fly on. Or if you don't need that much fuel, simply modify an existing b2 centaur to carry slightly more fuel (aux tank?).

[mmeijeri]

You don't need the ISS to do such a stunt. Simply rendezvous and docking in low earth orbit and do it.

You would have a lot of time pressure to launch your crew before your Centaur boils off or your Centaur before your crew boils off. Using the ISS and launching the crew first takes away the time pressure. This is similar to what was planned for Early Lunar Access, which was to use the Shuttle both as a launch vehicle and a makeshift space station and a Titan to launch a Centaur. It would be more flexible because unlike the Shuttle the ISS doesn't have an endurance of two weeks max.

[FinalFrontier]

You would have a lot of time pressure to launch your crew before your Centaur boils off or your Centaur before your crew boils off. Using the ISS and launching the crew first takes away the time pressure. This is similar to what was planned for Early Lunar Access, which was to use the Shuttle both as a launch vehicle and a makeshift space station and a Titan to launch a Centaur. It would be more flexible because unlike the Shuttle the ISS doesn't have an endurance of two weeks max.

Read my above post. Regardless of fuel reqs. the centaur would still have to be modified, at the very least, for extended stay. That means it would probably resemble something like one of the fuel depots discussed in the ULA ACES proposal when completed. In any case it would not be a standard centaur. In fact, its possible it would be too heavy to launch on an AV which would mean launching it as the primary payload on a delta 4, perhaps

[Zed_Noir]

If you want an Orion BEO mission of some sort before 2019. You could use a Falcon Heavy if available. Presuming that SpaceX will not simply do their own Moonshot with the Dragon.

Alternatively the Atlas V Heavy could be ordered for a similar mission.

[mmeijeri]

Regardless of fuel reqs. the centaur would still have to be modified, at the very least, for extended stay. That means it would probably resemble something like one of the fuel depots discussed in the ULA ACES proposal when completed.

Modifications to the Centaur would be relatively minor, a "mission kit", there are papers that describe this on the ULA website. It is far less than ACES, provided you launch the Centaur last.

In fact, its possible it would be too heavy to launch on an AV which would mean launching it as the primary payload on a delta 4, perhaps

Yes, you would need an EELV Heavy, which is not a problem.

[FinalFrontier]

If you want an Orion BEO mission of some sort before 2019. You could use a Falcon Heavy if available. Presuming that SpaceX will not simply do their own Moonshot with the Dragon.

Alternatively the Atlas V Heavy could be ordered for a similar mission.

Err, the FH upper stage will not be anywhere near as tried and tested as the centaur is, and as such getting it ready for such a mission would be a good deal more risky and more technically challenging, imo, then simply using multiple or one modified centaur for this mission.

[mmeijeri]

Err, the FH upper stage will not be anywhere near as tried and tested as the centaur is, and as such getting it ready for such a mission would be a good deal more risky and more technically challenging, imo, then simply using multiple or one modified centaur for this mission.

Not if you use a single launch so you don't need to rendez-vous in LEO. Of course in the larger context I prefer multiple launches and use of a LEO station, but FH would be simpler. More expensive perhaps, but simpler, just like SLS.

[FinalFrontier]

Err, the FH upper stage will not be anywhere near as tried and tested as the centaur is, and as such getting it ready for such a mission would be a good deal more risky and more technically challenging, imo, then simply using multiple or one modified centaur for this mission.

Not if you use a single launch so you don't need to rendez-vous in LEO. Of course in the larger context I prefer multiple launches and use of a LEO station, but FH would be simpler. More expensive perhaps, but simpler, just like SLS.

The point I am making is largely risk related. FH is not yet built, and is also not yet man-rated (nor is it intended to be manrated from the start like dragon or F9 were). On top of that, even if it you did man rate it for a mission such as this, the major issue is still risk, primarily regarding the upper stage, as you have no flight record to go on. Even if FH had already been flying for 2 years prior, you would still have alot of risk, and thus risk driven mods/costs involved due to the lack of a record comparable to Centaur.

Centaur is pretty much the most capable upper stage we have right now, its been flying for many years and has had almost no failures. If it was up to me, I would prefer to fly a mission kit centaur than an as yet untried FH upper stage for such a mission.

Of course if your mission is going to be 2019 or later than it may be a different story by then. But again, this is just my personal thinking on this. I also think NASA would be more comfortable with a Centaur because of how risk averse they are, especially for a mission like this which, if for no other reason than politics, I sort of doubt they would ever fly.


But thats just me.

[mmeijeri]

You don't need the ISS to do such a stunt.

It wouldn't be a stunt, it's an excellent way to get to L1/L2, which is a convenient stop on the way to practically anywhere else. As long as there is nothing there you wouldn't do it too often, but it would be a good test mission. It could also test endurance and radiation shielding. After that you could do a variant of the kissing Orions and do more elaborate man-tended radiation shielding tests.

[mmeijeri]

Obviously relying on a launch vehicle and components like RL-10 that have flown many times is less risky than doing the same with unflown vehicles and components. At the same time a single launch is easier than rendez-vous in LEO. As I said, my preference is to use multiple launches rather than an HLV, unless the private sector develops that HLV on its own dime, but single launch does have its advantages.

[FinalFrontier]

Obviously relying on a launch vehicle and components like RL-10 that have flown many times is less risky than doing the same with unflown vehicles and components. At the same time a single launch is easier than rendez-vous in LEO. As I said, my preference is to use multiple launches rather than an HLV, unless the private sector develops that HLV on its own dime, but single launch does have its advantages.

That is my preference too, and a centaur based mission would have multiple launches. However, if it was possible to eliminate many of the risks involved with using an FH (and if said FH was manrated), this would probably be cheaper than a mutli-launch centaur style campaign.

[clongton]

In a perfect world, Orion would launch to the ISS where the crew would oversee the final provisioning and checkout of the nuclear powered Lunar bound in-space spacecraft. When it was time they would board the lunar spacecraft, depart, execute the mission and return to ISS, where they would safe the lunar spacecraft for reuse on the next mission, transfer to Orion and return to the earth's surface.

But this is not a perfect world.

[apace]

In a perfect world, Orion would launch to the ISS where the crew would oversee the final provisioning and checkout of the nuclear powered Lunar bound in-space spacecraft. When it was time they would board the lunar spacecraft, depart, execute the mission and return to ISS, where they would safe the lunar spacecraft for reuse on the next mission, transfer to Orion and return to the earth's surface.

But this is not a perfect world.

In such a perfect world you don't need an Orion ;-)

[A_M_Swallow]

You don't need the ISS to do such a stunt.

It wouldn't be a stunt, it's an excellent way to get to L1/L2, which is a convenient stop on the way to practically anywhere else. As long as there is nothing there you wouldn't do it too often, but it would be a good test mission. It could also test endurance and radiation shielding. After that you could do a variant of the kissing Orions and do more elaborate man-tended radiation shielding tests.

If they will be doing the trip several times they will want to use a stretched Service Module.

[Zed_Noir]

Obviously relying on a launch vehicle and components like RL-10 that have flown many times is less risky than doing the same with unflown vehicles and components. At the same time a single launch is easier than rendez-vous in LEO. As I said, my preference is to use multiple launches rather than an HLV, unless the private sector develops that HLV on its own dime, but single launch does have its advantages.

Just one question. Is the Centaur or the DCUS currently man-rated?

[mmeijeri]

Just one question. Is the Centaur or the DCUS currently man-rated?

Depends on what you mean by that term. But it is being worked on for Centaur under CCDev.