SpaceX moon landing.

[kerbiloid]

4 minutes ago, Xd the great said:

I see what you mean here, but the bfs was supposed to have the same safety as a airline jet.

Airline jets dont have emergency parachutes or ejection seats as far as i know...

Airline jets don't fall every 70th flight.

(4/300 or so. And the last 2 ones were not the prehistorical early Soyuz, but enough advanced tech)

Edited August 16, 2018 by kerbiloid

[p1t1o]

4 minutes ago, Xd the great said:

I see what you mean here, but the bfs was supposed to have the same safety as a airline jet.

Airline jets dont have emergency parachutes or ejection seats as far as i know...

FunFact: if you put ejection seats into airliners, you will significantly decrease their safety. 

[kerbiloid]

Spoiler

1 minute ago, p1t1o said:

if you put ejection seats into airliners, you will significantly decrease their safety. 

There is a solution.

 

[sevenperforce]

Dragon 2 has no good lunar surface sortie options; you really need an airlock. It also doesn't have enough dV for even a one-way trip, and its SuperDracos are A) not vacuum-optimized, and B) far too thrusty.

That being said, it would probably be easier to convert the Dragon 2 into a lunar descent/ascent module than anything else. It would just be a lot of work:

Spoiler

• Strip off aeroshell, chute pack, and heat shield
• Remove six of the eight superdracos; add vacuum-optimized engine bells to the two that remain
• Move radiators and solar panels from trunk to the open spaces on the capsule
• Install extended trunk
• Add additional propellant tanks to the exterior of the capsule
• Add additional propellant tanks inside the trunk, crossfed to the superdracos
• Cut hatch in floor, leading to an airlock in the trunk
• Add landing legs to exterior of trunk

If NASA funded it, they would do it. It wouldn't be reusable, though, and it would need another D2 in lunar orbit for a rendezvous. It also would need to be dropped off in low lunar orbit, and it would have to launch unmanned inside a fairing.

[tater]

I can imagine a SpaceX lunar surface architecture using extant launch vehicles, and purpose-built lunar landers.

Any attempt at Earth orbit rendezvous with multiple launches has problems (unless stage 2 can be useful for far longer than they have ever waited for a second engine fire). Free return might also be non-trivial, so more failure modes.

Seems like you'd need a few FH flights, and a trunk with a propulsion system for the capsule. Put a lander in LLO, as well as a return stage (1 launch each, ideally they rendezvous in LLO). Send crew with FH, and a modified trunk (as a service module). Dragon with SM does rendezvous with lander (return stage has a docking tunnel on top, with a ring at the top, and 1 on the side. LM docks to the side, Dragon to the nose). Crew transfers to lander and does excursion. Returns to Return stage, transfers, and LM is dumped. Return stage boosts dragon on TEI.

[sevenperforce]

1 hour ago, tater said:

I can imagine a SpaceX lunar surface architecture using extant launch vehicles, and purpose-built lunar landers.

Any attempt at Earth orbit rendezvous with multiple launches has problems (unless stage 2 can be useful for far longer than they have ever waited for a second engine fire). Free return might also be non-trivial, so more failure modes.

Seems like you'd need a few FH flights, and a trunk with a propulsion system for the capsule. Put a lander in LLO, as well as a return stage (1 launch each, ideally they rendezvous in LLO). Send crew with FH, and a modified trunk (as a service module). Dragon with SM does rendezvous with lander (return stage has a docking tunnel on top, with a ring at the top, and 1 on the side. LM docks to the side, Dragon to the nose). Crew transfers to lander and does excursion. Returns to Return stage, transfers, and LM is dumped. Return stage boosts dragon on TEI.

I did the math once before, using Block 4 numbers, and IIRC it could be done with two Falcon Heavy launches and one Falcon 9 launch. With Block 5 it would probably still be the same, but with better margins.

[sh1pman]

4 minutes ago, sevenperforce said:

I did the math once before, using Block 4 numbers, and IIRC it could be done with two Falcon Heavy launches and one Falcon 9 launch. With Block 5 it would probably still be the same, but with better margins.

Expendable or reusable launches?

[tater]

9 minutes ago, sevenperforce said:

I did the math once before, using Block 4 numbers, and IIRC it could be done with two Falcon Heavy launches and one Falcon 9 launch. With Block 5 it would probably still be the same, but with better margins.

I figured B5 FH, reusable.

Also, I am assuming nominal stage 2 use, so all other burns at the Moon have to be propulsion units on the payload.

The only real downside is safety. if the crew vehicle can be given enough dv via a SM to go from free-return to LOI and rendezvous, you at least get one abort OTW. Once LOI is done, it's rendezvous with the TEI stage or die, however.

[sevenperforce]

1 hour ago, sh1pman said:

Expendable or reusable launches?

With Block 4? Reusable on the single-stick; fully-reusable on one of the FHs, core-expendable on the other FH.

With B5 you could probably manage full reuse on all three launches.

53 minutes ago, tater said:

I am assuming nominal stage 2 use, so all other burns at the Moon have to be propulsion units on the payload.

One thing you can do is launch a Dragon 2, then do another launch, dock and mate the Dragon 2 to the second stage, and restart the second stage. Maximum of 4-6 hours between launch and restart, which has already been demonstrated. No use of S2 BLEO. 

53 minutes ago, tater said:

The only real downside is safety. if the crew vehicle can be given enough dv via a SM to go from free-return to LOI and rendezvous, you at least get one abort OTW. Once LOI is done, it's rendezvous with the TEI stage or die, however.

The very first step would be the production of a drop-in propulsion pallet using clustered Dracos, a single SuperDraco, or something like a Rutherford (if LOX boil-off can be managed). Basically a fuel-only service module you can lego in. Then you can figure the capabilities of such a module and calculate accordingly.

[sevenperforce]

Updated numbers give 6.57 tonnes to lunar transfer on a recoverable Falcon 9 Block 5.

If you launch nothing but a naked S2 with a docking adapter (to allow another vehicle to mate with it) to act as a transfer stage, it reaches orbit with 17.6 tonnes of residuals. That's enough to send a payload of 9.822 tonnes on lunar transfer.

[tater]

30 minutes ago, sevenperforce said:

Updated numbers give 6.57 tonnes to lunar transfer on a recoverable Falcon 9 Block 5.

If you launch nothing but a naked S2 with a docking adapter (to allow another vehicle to mate with it) to act as a transfer stage, it reaches orbit with 17.6 tonnes of residuals. That's enough to send a payload of 9.822 tonnes on lunar transfer.

Seems like the logistics of multiple launches and a rendezvous might make it easier to just use FH.

That said, the kind of automated docking we are talking about is a skill set that SpaceX will need, anyway.

 

[sevenperforce]

50 minutes ago, tater said:

Seems like the logistics of multiple launches and a rendezvous might make it easier to just use FH.

That said, the kind of automated docking we are talking about is a skill set that SpaceX will need, anyway.

Since Falcon Heavy will not be man-rated, you'd need multiple launches and docking regardless.

Was just considering whether Falcon 9 alone can do the job that FH would previously have been needed for.

Though my numbers were off; see other thread.

[tater]

Yeah, I get that. This is a fun “LEGO rocket” sort of mission planning, though, and man rating FH should be an easier task than rating a lunar lander  

Or a TEI stage that you have to meet in place or die. All this is well outside what NASA would be comfortable with.

[sevenperforce]

14 hours ago, tater said:

Yeah, I get that. This is a fun “LEGO rocket” sort of mission planning, though, and man rating FH should be an easier task than rating a lunar lander  

Man-rating a launch vehicle is kind of a different ballgame. You're looking at a completely different contingency set.

14 hours ago, tater said:

Or a TEI stage that you have to meet in place or die. All this is well outside what NASA would be comfortable with.

Well, we know what NASA was comfortable with back during Apollo, and we know what they were considering during Constellation. Who knows if they'd still be comfortable with it.

What do they want? Duplicate everything? Triplicate?

[tater]

41 minutes ago, sevenperforce said:

Man-rating a launch vehicle is kind of a different ballgame. You're looking at a completely different contingency set.

Yeah, but they still try and maximize their abort modes. Sending a single stack means that they have more options in that regard (Apollo 13 being the case in point). I honestly think this thread is a more sensible for what they could do for a rich, private client than what NASA might ever sign off on.

 

41 minutes ago, sevenperforce said:

Well, we know what NASA was comfortable with back during Apollo, and we know what they were considering during Constellation. Who knows if they'd still be comfortable with it.
 

They are far more risk averse than Apollo. They pushed Apollo 8 forward literally thinking it might be a coin flip.

 

41 minutes ago, sevenperforce said:

What do they want? Duplicate everything? Triplicate?

Honestly? These days? Probably.

[sevenperforce]

24 minutes ago, tater said:

Yeah, but they still try and maximize their abort modes. Sending a single stack means that they have more options in that regard (Apollo 13 being the case in point). I honestly think this thread is a more sensible for what they could do for a rich, private client than what NASA might ever sign off on.

Unless you have full or nearly-full reuse, no rich private client will be able to afford it. The exception is if you find a way to monetize the moon. If you monetize the moon, all bets are off.

The real issue with Apollo 13 was life support failure. The CSM had enough dV to perform the necessary course corrections, I believe. And if you do Earth-Lunar-Orbit-Rendezvous, like Constellation, then you can still have the same single-stack redundancy. Dual-Lunar-Orbit-Rendezvous, where the LM is sent to lunar orbit before the CM and you do double rendezvous-and-docking in lunar orbit, lacks the backup life support option which saved Apollo 13 but you still have the free-return abort.

24 minutes ago, tater said:

1 hour ago, sevenperforce said:

What do they want? Duplicate everything? Triplicate?

Honestly? These days? Probably.

Then you need LOP-G with multiple ascent/descent vehicles and pre-placed rovers and habs. Basically the whole Martian/Ares mission profile, but local.

[tater]

I don't think NASA is sending people to the Moon any time soon, possibly not within my lifetime (unless commercial does it first).

LOP-G is where you send a spacecraft that can't go to the Moon.

I'm deeply pessimistic about what NASA can do with human spaceflight these days.