FH to the moon?

[ArbitraryConstant]

1)  Lunar Direct.  Land Dragon on it's superdracos, with a disposable propellant stage under it.  As the superdracos are angled, if the prop stage isn't wider than Dragon, there shouldn't be a plume impingement problem.  you -might- get such a mission in a single launch.  it would be pretty limited though.  Probably about as capable as the Russian LK missions would have been.  And the dragon capsule isn't the best for staging EVA's out of obviously.
The angled Superdracos also mean you loose efficiency.  But, they are powerful enough, you might get away with it if you can carry enough extra prop in the prop stage.

I don't think this would work, not even with Saturn V. Apollo couldn't do this for the same reason SpaceX can't: delta-v from the lunar surface to Earth is too much. Apollo did LOR because they didn't have to eat the delta-v penalty of landing the return fuel and then having to return from the wrong side of that delta-v deficit.

The direct return idea would have required an even larger rocket than Saturn V. The cosine losses and under expanded exhaust from the superdracos just make it worse, they make delta-v worse when you're already incurring a large delta-v penalty.

Apollo was incredibly well optimized for the problem at hand. A simpler mission would have required a far larger launcher.

2)  Apollo-light.  Two FH launches.  one launches Dragon to LLO (would need additional prop in a service module.).

Yeah, would probably be workable. The thing to do would be to use one superdraco and give it a huge expansion nozzle. It would be pretty close to the Apollo SM main propulsion.

[macpacheco]

I think this has his statement:



It been at least 6 months since I watched the video.
But I recall Elon stating on a NPC (National Press Club) answering this question from the audience (a manned mission to the moon), that it would take two FHs to do it.
I think it was a pretty short answer, I think he said it would take two Dragons, dunno if modified or not.

[MATTBLAK]

2x Falcon Heavy launches:

Launch 1: Dragon Command Module/Service Module combo (big delta-vee capability) with a LM: Dragon-based (no heatshield at the bottom) crew module, mounted on a Descent/Ascent Stage with clustered, throttling Dracos and O2/H2O consumables. LM wet mass - 16-to-18 metric tons. Crew of two Astronauts if Dragon is to loiter for extended periods in lunar orbit. 4x crew if the LM is transporting an Outpost Crew.

Launch 2: FH with Earth Departure Stage, with either LOX/CH4 or LOX/LH2 propellants. Dragon & Dragon-LM rendezvous and dock with EDS for TLI.

On later mission architectures; propellant depots and reusable landers could be phased in. The Descent/Ascent Stage would make a good Cargo Lander if the Dragon is replaced with a cargo pallet or module on a one way trip - lots of downmass if an Ascent later is not required. Other mission efficiencies can be obtained if the Falcon Heavies in question are partly or fully reusable. Though for EDS duties; perhaps an FH could be an expendable version for maximum propellant load in the EDS.

[sdsds]

2x Falcon Heavy launches: [...]

I think you're essentially describing the mission mode dubbed "EOR+LOR" in the variation DIRECT proposed for J246 + J130. (Note the DIRECT approach was designed to provide the same level of mission capability as CxP Ares I + Ares V.) I believe the delta-v budget for a mission like that can work. But I don't believe the dollar budget for that will work. You propose an EDS and a lander, neither of which would be used in non-lunar missions and so the entire cost of developing them would be borne by the lunar effort.

The problem is that a dragon doesn't have nearly enough delta-V to land on the moon and then get back to LLO. Delta-v from LLO to the surface is 1.87km/s, so even if you had a fully fueled vehicle in LLO [...]

Yes, you are totally correct to put the initial focus on the vehicle that makes the lunar ascent. In Apollo (or as proposed for CxP) that vehicle was the ascent stage of the LM (or LSAM), and as you say it was delivered fully fueled to the lunar surface. To believe the dream of a SpaceX lunar surface sortie mission, we have to somehow imagine a Dragon-derived vehicle sitting on the Moon with sufficient propellant to get up to a lunar orbit rendezvous.

I believe there might be a way to do that at a development cost that isn't totally outlandish. In short it involves a big propulsion module in place of the trunk, AND an outboard propellant drop tank for the capsule.

[MP99]

Anyone have a number as to what delta-v crew dragon is going to be capable of

Likely a few hundred m/s. IIRC Soyuz has around 400m/s.

By contrast the Apollo CSM can do 2800m/s but more than 60% of its mass is propellant. So you need a massively boosted Dragon.

That figure for Dragon isn't even half of what's required for TEI, never mind LOI or descent / ascent.

cheers, Martin

[MATTBLAK]

Well-spotted, sdsds - those similarities to Direct's architecture!! And in the above post, I was essentially proposing a Dragon crew cabin mounted atop a 'Common Ascent/Descent Stage' with sufficient propellants and delta-vee ability to get back up to the orbiting Dragon CM. With the craft being a 'one piece' Ascent/Descent vehicle; that's why I proposed a separate propulsion module for it to be attached to. This concept might lend itself to future reusability, whether the propulsion was storable hypergolics or LOX/methane - fill up that stage over and over again from an L-1 based propellant depot.

Or if it were deemed desirable to keep the Dragon expendable and in one piece as an existing moldline, landing with its own Dracos; a crasher stage could do most of the descent delta-vee duties. The Dragon would then do the 'terminal descent burn', using perhaps only 15 or 20% percent of it's total propellants and saving the rest for ascent. Though, it still seems to me that a slight redesign, cramming as much propellants as possible into the Dragon spacecraft hull, is going to be necessary. No aero-entry braking and parachutes available like for Mars!

In fact, why not design a bare-bones, surface habitat Dragon for long sortie mission?! Use a crasher stage or Common Descent Stage to get it to the surface. But instead of Ascent propellants; devote the downmass to oxygen, water, food, a solar array and extra radiation shielding. Such a craft might make a good 'hut' for 2x crew stays lasting as long as a two week Lunar day. Rather like the old Apollo Applications for Lunar concepts that had a 'LM Shelter' with no ascent propellants - just a lot of consumables, with the crew coming along in a separate LM shuttle.

[MP99]

Hey guys,

Question about possibility here:

Assuming that FH gets the performance that spaceX has been claiming, and that spaceX develops a crewed dragon with propulsive landing capabilities to 2016, could they theoretically do a moon mission with FH/dragon?

I have no idea if we have the information to do the math here, but I assume that some of you guys are a lot better informed 

http://images.spaceref.com/news/2011/21.jul2011.vxs.pdf

Nice.

Just a reminder that this is using hydrolox for TLI & LOI, and the MPCV with maybe 4x the dV of Dragon.

Don't forget, also, that Dragon (while hypergolic, like MPCV) further reduces its Isp through cosine losses on the SuperDracos, and atmosphere-optimised nozzles.

I suspect that we will first see Raptor/methalox as an upper stage for FH, and that this would be required to make a decent-sized lander mission close.

cheers, Martin

[MP99]

Well-spotted, sdsds - those similarities to Direct's architecture!! And in the above post, I was essentially proposing a Dragon crew cabin mounted atop a 'Common Ascent/Descent Stage' with sufficient propellants and delta-vee ability to get back up to the orbiting Dragon CM. With the craft being a 'one piece' Ascent/Descent vehicle; that's why I proposed a separate propulsion module for it to be attached to. This concept might lend itself to future reusability, whether the propulsion was storable hypergolics or LOX/methane - fill up that stage over and over again from an L-1 based propellant depot.

Unfortunately, going via EML further increases the dV's over those listed in that PDF. (But in that environment, methalox is easily a "storable" propellant, which makes life much easier for a pre-positioned methalox stage.)

Or if it were deemed desirable to keep the Dragon expendable and in one piece as an existing moldline, landing with its own Dracos; a crasher stage could do most of the descent delta-vee duties. The Dragon would then do the 'terminal descent burn', using perhaps only 10 or 15% percent of it's total propellants and saving the rest for ascent.

Please note from the PDF:-

Descent by Lander: dV = 2.074 km/s
Ascent by Lander: dV = 1.974 km/s

Likely a few hundred m/s.

If this is correct, Dragon has perhaps a 1/5th of the dV to achieve what you describe (ascent + a bit of the descent).

Though, it still seems to me that a slight redesign, cramming as much propellants as possible into the Dragon spacecraft hull, is going to be necessary.

Dragon's SuperDracos are optimised for use in atmosphere (poor Isp in vacuum) and lose further Isp by cosine losses from their canted orientation.

Both seem to be fixable, but that would turn a Lunar Dragon ("Grey Dragon"?) into a whole 'nother beast from the one we're familiar with. Given the massively different thermal environment, and the likelihood of needing separate orbital and surface craft (as per Apollo, CxP, the PDF above, etc, etc), you have to question whether Dragon's chassis (which, EG includes a heatshield) is even the right starting point.

Please note that Altair's Ascent Module was about 3.2t, which included tanks for a further 3.1t of hypergolic propellant just to perform the ascent phase.

cheers, Martin

[M129K]

A dual launch with Falcon Heavy with lunar landing is possible if you assume a specially developed EDS using hydrogen and oxygen. However, I doubt SpaceX would be willing to develop something like that unless it's a longer term project.

An alternative could be to let the Falcon Heavy upper stage refuel itself in LEO with a kerolox drop tank. Assuming an empty mass of 5 tons and 50 tons of propellant, such a refueled improvised EDS could throw 26 tons on TLI and 16 tons into LLO with a seperately launched payload. A lunar lander with a mass of 16 tons and a 317 second Isp could carry a ~2 ton habitat down to the surface and back up again, sufficient for an Apollo reboot with a single stage lander. This lander could be light enough to be brought into orbit with Falcon 9, as many sources claim it can lift about 16 tons to LEO rather than 13 tons. I'm not sure about this though, so I'll leave it at that.

A second Falcon Heavy could be launched with a Dragon with an 1800 m/s delta V propulsion module (~18 tons) and a short-fueled drop tank. The tank is thrown away, Dragon undocks, turns around, waits for the tank to be moved away and redocks with the EDS. It should have barely enough delta V for TLI. If necessery, Dragon can be launched seperately like in CxP to allow for a higher TLI payload. Or, Falcon Heavy launched Dragon to GTO, where Dragon with extra propulsion module (21.2 ton total) has sufficient delta V to enter LLO and return.

Once both Dragon and the LM are in orbit, the crew descends to the surface and explores the surface/plants the SpaceX flag and returns to orbit, where Dragon is waiting for them to return. Sounds complicated, but aside from the drop tank, no development would be necessary that wouldn't be necessary with a hydrolox EDS. It might be worth the extra one or two launches, as it saves the development of hydrolox propulsion that SpaceX apparently doesn't feel like developing.

[imspacy]

I'm sure that three Falcon Heavies could do an Apollo-scale mission.  Just because the launch vehicles would be relatively inexpensive, though, doesn't mean the mission hardware would be.

Actually it does...
Most costs, problems, and delays of the Saturn/Apollo moon project derived directly from the decision to use a single massive rocket, rather than Von Braun's EOR multiple small/cheap rockets.

The great majority of Apollo costs, delays, problems were in Saturn V development, and getting a CM/SM/LM stack light enough to launch on a single Sat V...especially the LEM..
Von Braun's multi launcher Apollo approach would have gotten America to the moon 2 years sooner for less than half the cost....enabled much longer stays, more science... And left us with an affordable, sustainable space infrastructure built on economical multi-use mid-size boosters for economical lunar colonies, Mars missions, etc.

[CuddlyRocket]

Assuming that FH gets the performance that spaceX has been claiming, and that spaceX develops a crewed dragon with propulsive landing capabilities to 2016, could they theoretically do a moon mission with FH/dragon?

I'm sure the first question SpaceX would ask is: Who's paying for it?

Because until that theoretical question is asked, I don't think they'll bother with any others!

[MP99]

A dual launch with Falcon Heavy with lunar landing is possible if you assume a specially developed EDS using hydrogen and oxygen. However, I doubt SpaceX would be willing to develop something like that unless it's a longer term project.

According to DIRECT baseball cards, the "DIVHUS" has 26.8t of "Usable Post-Ascent Propellant", which for a ~50t IMLEO would give ~19.5t through TLI (exc their payload adapter & DIVHUS burnout).

Given this is basically the ICPS from SLS block 1, that would be a pretty perfect fit, mass- & prop-wise, to max out the LEO capability of an FH. And NASA will pay for mods to make this passive through the ascent / perform TLI only. This is not to say there wouldn't be significant costs to integrate with FH instead of SLS.

cheers, Martin

[Jim]

The massive costs and delays of the Saturn/Apollo moon project all derived directly from the decision to use a single massive rocket, rather than Von Braun's EOR multiple small/cheap rockets.

The great majority af Apollo costs, delays, problems were in Saturn V development, and getting a CM/SM/LM stack light enough to launch on a single Sat V...
Von Braun's multi launcher Apollo approach would have gotten America to the moon 2 years sooner for less than half the cost.... And left us with an affordable, sustainable space infrastructure built on economical multi-use mid-size boosters.

Wrong, more unsupported  statements.  You have no relevant document to back up that claim.  Lets see how many there are:
1.  Two years earlier.
2.  1/2 Costs
3.  Sustainable infrastructure
4.  delays in Saturn V development, CSM

[mmeijeri]

Wrong, more unsupported  statements.

What's your personal opinion? Would it have taken longer to use EELV class launchers in a LEO rendez-vous + LLO rendez-vous scenario, with the lander being put through TLI separately from the capsule and mostly dry and only fueled once it arrived in LLO?

[guckyfan]

Steve Jurvetson has declared he wants a flight to LLO for a foto session. They may make him a good price. FH can do  TLI. They need to increase the delta-v of Dragon for LOI and TEI. Put some extra fuel in the trunk.

[M129K]

Steve Jurvetson has declared he wants a flight to LLO for a foto session. They may make him a good price. FH can do  TLI. They need to increase the delta-v of Dragon for LOI and TEI. Put some extra fuel in the trunk.

And an engine, and you know, some fuel to begin with. Dragon has no real propulsive capabilities in its current form.

[M129K]

According to DIRECT baseball cards, the "DIVHUS" has 26.8t of "Usable Post-Ascent Propellant", which for a ~50t IMLEO would give ~19.5t through TLI (exc their payload adapter & DIVHUS burnout).

Given this is basically the ICPS from SLS block 1, that would be a pretty perfect fit, mass- & prop-wise, to max out the LEO capability of an FH. And NASA will pay for mods to make this passive through the ascent / perform TLI only. This is not to say there wouldn't be significant costs to integrate with FH instead of SLS.

cheers, Martin

Sure you can use the iCPS, but I personally doubt that would ever happen. If we're talking about a SpaceX lunar mission, I think it's more likely they would develop either a dedicated EDS themselves or do something like a drop tank for FH like I described earlier. And SpaceX isn't very keen on hydrolox propulsion, last time I heard. Apparently it's very expensive.

[guckyfan]

Steve Jurvetson has declared he wants a flight to LLO for a foto session. They may make him a good price. FH can do  TLI. They need to increase the delta-v of Dragon for LOI and TEI. Put some extra fuel in the trunk.

And an engine, and you know, some fuel to begin with. Dragon has no real propulsive capabilities in its current form.

?

The manned Dragon will have the SuperDraco as repeatedly stated in this thread.

And that may not even be necessary. The Dracos are used for orbital maneuvering in LEO. They probably can do these maneuvers too and without the cosine losses.

[M129K]

?

The manned Dragon will have the SuperDraco as repeatedly stated in this thread.

And that may not even be necessary. The Dracos are used for orbital maneuvering in LEO. They probably can do these maneuvers too and without the cosine losses.

Which are extremely inefficient sea level optimized engines firing with a significant angle. The Dracos don't have the thrust for maneuvers like TEI. The Orion main engine, for example, has 67 times the thrust of a single Draco engine. Sure, they're clustered, but they're also angled. There's also the fact that Dragon is most likely not designed to use propellant stored in the trunk, and that it might be simpler to put a real propulsion stage in the trunk than putting feed lines for the the inefficient SuperDraco engines.

Put a small prop stage with vacuum optimized SuperDraco or maybe even a Kestrel engine and you'll get much better performance and it might even be simpler to do.

[go4mars]

It would be a one way trip.  Dragon doesn't have the DV for lunar launch and TEI.   Nor does the FH have the capability to lift the necessary propellant to enable it to.

Looks like it's time for a "Grey Dragon" thread.