SpaceX Crewed Dragon Circumlunar Mission

[Danderman]

Btw, what is the actual limitation on the second stage that it cannot survive a three day trip. Batteries? Couldn't it go into some deep sleep for the duration and conserve power or one could make a feedback connector that Dragon could feed S2 some of its solar power that it's gathering assuming the V2 panel covers can be jettisoned before Dragon is released.

Its avionics are not designed for deep space nor is any of the systems designed to last more than 10 hours or so.  The avionics are autonomous and no capability for updates.  And it is not that simple just to add a connector with power

Apparently, keeping upper stages alive more than their nominal lifetimes is a bit of a problem. It might be possible to power a webcam and radio or some other auxiliary system, but to keep the principal systemd alive for more than 24 hours is a bit of a nightmare, unless the stage were designed for that purpose. Yeah, I was spoiled by Agena, too.

[Danderman]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

If such an upper stage were available, the Dragon would have a lot more capability, and perhaps be able to enter and leave high lunar orbit. That would make it very useful.

[Lee Jay]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

I'll take your bet! What are you offering? Steak dinner? Beverage of choice $10 or less?

(By the way, y'all are taking the wrong approach, here. Instead of trying to disprove him, you should be trying to score a free steak dinner!)

The Raptor upper stage is going to have a large PLF in which you'll find an Atlas Centaur below Dragon.  This will make TLI happen and preserve all of Dragon's fuel.

And, yes, I'm only saying that to get Jim to cover his keyboard with coffee from his nose.

[envy887]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

I'll take your bet! What are you offering? Steak dinner? Beverage of choice $10 or less?

(By the way, y'all are taking the wrong approach, here. Instead of trying to disprove him, you should be trying to score a free steak dinner!)

The Raptor upper stage is going to have a large PLF in which you'll find an Atlas Centaur below Dragon.  This will make TLI happen and preserve all of Dragon's fuel.

And, yes, I'm only saying that to Jim to cover his keyboard with coffee from his nose.

Now you did it. I'm going to go calculate the fuel remainder after TLI of Falcon Heavy with Centaur as a third stage. It's probably pretty good...

[DAZ]

The real beauty of this mission is that it is basically using the same things that SpaceX is planning to do in the near future so SpaceX is designing and building them right now. About the only exception to this would be the deep space communications system on the Dragon 2 capsule. Even this is along the same line, as it will need to build something like this for the Red Dragon mission.

But thinking along the lines of what SpaceX still needs to do for its stated objectives has given me a head scratching moment. SpaceX has announced and shown that it is working on the new Raptor engine. There is also information available that they are working on how to build the new composite propellant tanks for the ITS. It was also announced that the ITS would use gaseous methane/oxygen engines for attitude control. These attitude control thrusters would probably need to be bigger than the present Draco engines but probably smaller (but not necessarily) than the Super Draco engines. So the part that has my head itching has anybody heard anything related to the development of these new engines?

Now for the speculation part related to this thread. If just about everything that SpaceX works on is related on how to get to Mars this would lean against SpaceX using any resources toward developing a Raptor S2 for the Falcon 9. It would also lean against SpaceX developing a breakaway kit using a super Draco engine to fit in the trunk of the Dragon system to be used as a service module. All of which would be within the ability of SpaceX to produce but as they have no missions/customers that need it would be most likely a waste of resources. Now developing the above mentioned new gaseous methane/oxygen engines for attitude control is definitely on their list of things to do but is probably on their due later as opposed to do earlier list. If on the other hand, they were to move this to the do earlier list could they also possibly be willing to expend the extra resources for a breakaway service module kit?

This would allow them to accomplish something else on there to do list earlier and at the same time possibly get more experience with it. For a relatively low cost this would put another tool in their toolkit that others could conceivably use (and obviously be willing to pay SpaceX) for possible BLEO missions.

No, this could be the furtherest away from what they are doing.

the ITS uses gaseous methane/oxygen because it is readily available.  a spacecraft using it would need high pressure bottles of it.  It is not a simple mod.
It would not be Spacex low cost.

Having to use high-pressure bottles would seem to be more of constraint for the total Delta-V (which admittedly might make the concept not worth pursuing) rather than a cost issue.

Too bad it's not feasible to have a pressure fed liquid methane/oxygen engine that could also run as a gaseous methane/oxygen engine.

[philw1776]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

I'll take the NO side.  What's the terms?

[MATTBLAK]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

I'll take the NO side.  What's the terms?

I was one of the first people, I think , to even tout this idea - but I'm also one of the ones who is telling people now that it simply is very unlikely to happen! It's like the whack-a-mole idea that just refuses to go away. No matter how many times we tell people it's not going to happen; others keep raising it from the dead anew - as if they were the first to think of it!! It doesn't matter that it happens to actually be a fairly good idea - Space X will be 'freezing' the designs of Falcon 9 and Heavy soon, and moving on to other things...   

[meekGee]

While I'm firmly on the "not gonna happen" side for any methane-powered F9, here's a very partial list of things that were widely ridiculed or thought to be unlikely (some of them by me too)

- SpaceX operating barges/ships for stage recovery
- Rockets that remain vertical throughout their life cycle
- Cradle landing
- "Son of Teledesic" - large LEO constellation fielded by SpaceX (or others!)
- VLEO constellation in a "self-deorbiting" altitude fielded by SpaceX (or others!)
- Round-the-moon tourist tickets sold by SpaceX
- Mars being a "real goal" and not a trick played by Musk to encourage young engineers to work overtime
- Raptor being in real development (at the time)
- Mars Megarocket being in real development (at the time)

And there's a similar list of things that didn't happen...

But the above list is a hint that just the fact that a bunch of people are crying "it'll never happen" does not mean it won't.

The last couple of months are plenty evidence of that.

[Jim]

- Rockets that remain vertical throughout their life cycle

That was specific to Falcon 9 discussions

[Jim]

- Cradle landing

That is much like parachute recovery.

[envy887]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

I'll take your bet! What are you offering? Steak dinner? Beverage of choice $10 or less?

(By the way, y'all are taking the wrong approach, here. Instead of trying to disprove him, you should be trying to score a free steak dinner!)

The Raptor upper stage is going to have a large PLF in which you'll find an Atlas Centaur below Dragon.  This will make TLI happen and preserve all of Dragon's fuel.

And, yes, I'm only saying that to Jim to cover his keyboard with coffee from his nose.

Now you did it. I'm going to go calculate the fuel remainder after TLI of Falcon Heavy with Centaur as a third stage. It's probably pretty good...

Almost 17 tonnes translunar after recovering all three boosters!!! That's more than double the current reusable payload... Elon should look into this

[mme]

Seems to me the lack of focus on space tourism has more to do with the lack of a destination than the whole "going to Mars" thing. Would people really pay $20M+ to be cramped with 4 others in a Dragon and orbit the Earth a few times?

Will people pay $5bn to emigrate to Mars? LEO or lunar tourism will happen a long time before Mars colonization, simply because it's going to be much much cheaper. If you fly tourists to LEO every week or so the cost of an in-space module isn't that big of a factor anymore by the way.

Of course LEO or lunar tourism will happen earlier, it's self evident given this recent SpaceX announcement. But Mars is not just another business opportunity for SpaceX, they're not going to Mars to make a profit, they're making a profit so that they can go to Mars.

LEO tourism already happened 16 years ago. What I mean is LEO or lunar tourism in large numbers, i.e. hundreds or thousands of tourists per year.

And no, you cannot expect any company to shift its profits into an unprofitable project for a long period of time. If it does that it will lose out to competitors.

As long as they stay competitive they can do anything they want.

[Zed_Noir]

So who wants to bet the moon mission will use a second stage with a methane fed raptor engine?

....

The Raptor upper stage is going to have a large PLF in which you'll find an Atlas Centaur below Dragon.  This will make TLI happen and preserve all of Dragon's fuel.
....

Now you did it. I'm going to go calculate the fuel remainder after TLI of Falcon Heavy with Centaur as a third stage. It's probably pretty good...

Almost 17 tonnes translunar after recovering all three boosters!!! That's more than double the current reusable payload... Elon should look into this

What's the payload to TLI if you expended the center core?

[CuddlyRocket]

The real beauty of this mission is that it is basically using the same things that SpaceX is planning to do in the near future so SpaceX is designing and building them right now. About the only exception to this would be the deep space communications system on the Dragon 2 capsule. Even this is along the same line, as it will need to build something like this for the Red Dragon mission.

NASA will be providing that facility for Red Dragon in exchange for Martian entry, descent, and landing data.

As for lunar missions, they might just pay NASA (or ESA or the Russians - unless it's ITAR prohibited?) for the service. There are also plenty of radio telescopes whose operators might welcome a cash infusion (the construction costs of Jodrell Bank were paid off in exactly this kind of arrangement).

[rakaydos]

the usefullness of a high Loiter, high energy propellant satelite-deployment 3rd stage is not to be underestimated for GEO missions.

There is no need for such a stage, there is no additional benefit.  The second stage is all that is necessary for GEO deployments.

Including the actual GEO insertion? If there's still problems with using a second stage for lunar missions because of loiter time, how much longer does LTO take than GTO?

[TomH]

Oh God. Down the rabbit hole we fall. Ignoring reality for a moment and pretending various stages could come from varying manufacturers as they did for Saturn V, let's say you could replace the Falcon US on FH (Block V components) with an ACES 73, what kind of performance (fully disposable, add cross-feed if you want) could you get to LEO? To TLI, TMI? If ACES 73 is too much mass, how about Aces 41?

[dcporter]

I heard someone mention upthread that they thought Space Adventures was very likely involved in this. Why? What do they bring to the table when there's no Soyuz to procure or ISS paperwork to manage?

[hkultala]

[offtopic]

Oh God. Down the rabbit hole we fall. Ignoring reality for a moment and pretending various stages could come from varying manufacturers as they did for Saturn V, let's say you could replace the Falcon US on FH (Block V components) with an ACES 73, what kind of performance (fully disposable, add cross-feed if you want) could you get to LEO? To TLI, TMI? If ACES 73 is too much mass, how about Aces 41?

ACES 41 would probably decrease they payload, as it would be too small, giving much less total impulse.

ACES 73 would probably improve payloads to high-energy orbits considerably, but not much for LEO due worse T/W ratio(worse gravity losses).

[/offtopic]

[TomH]

[offtopic]

Oh God. Down the rabbit hole we fall. Ignoring reality for a moment and pretending various stages could come from varying manufacturers as they did for Saturn V, let's say you could replace the Falcon US on FH (Block V components) with an ACES 73, what kind of performance (fully disposable, add cross-feed if you want) could you get to LEO? To TLI, TMI? If ACES 73 is too much mass, how about Aces 41?

ACES 41 would probably decrease they payload, as it would be too small, giving much less total impulse.

ACES 73 would probably improve payloads to high-energy orbits considerably, but not much for LEO due worse T/W ratio(worse gravity losses).

[/offtopic]

Agreed off topic, but worthy of discussion. New thread started here:
https://forum.nasaspaceflight.com/index.php?topic=42475.0

[Jim]

About the only exception to this would be the deep space communications system on the Dragon 2 capsule.

NASA will be providing that facility for Red Dragon in exchange for Martian entry, descent, and landing data.

No, he is talking about the hardware on the Dragon.  NASA is providing the ground portion and not the hardware on the Dragon