Red Dragon Discussion Thread (1)

[Wyvern]

Has SpaceX announced any tests of a future Mars lander? Or any technical designs at all?  I'd kinda like to see a prototype of their lander or the propulsion system they intend to use before we determine the feasibility of their plans. 

Even if they intend to just use a simple Dragon vessel I would like to see their landing technique demonstrated on Earth.  If only because Earth could at least give us an idea of the feasibility of SpaceX's plan.

[go4mars]

The real issue I have with this is that I think people are taking Elon at face value when a grain of salt woudl be more applicable. He said that with the LAS, Dragon would be 'capable of landing on any solid body in the solar system'. That doesn't really stand up to scrutiny. Mercury? Venus? Io

We seem to be guessing without the full suite of assumptions.  Everyone here seems pretty much unanimous that Dragon (as we know it) lacks the ability to land several tons of science payloads.  "more than the mass of all prior Mars missions combined" or some such.  So...  We must be missing something.  Maybe with a fuller picture, Mercury and Venus are possibilities.  Maybe the pressure-hull was designed to Venusian specs.  Maybe there are drop tanks, trunk ballutes, or a descent tractor tower.  It appears that we just won't know until the 2013 competition.

[Robotbeat]

It's also possible that this Red Dragon is planning on deploying supersonic parachutes of some kind, which should make a pretty big difference in how much fuel is needed for a given payload. Supersonic parachutes could be the difference between several hundred kilograms of payload and a couple tons of payload.

Keep in mind that not even a full ton of real payload has actually landed on Mars, yet (not counting the MER's landing platforms).

[Patchouli]

It's also possible that this Red Dragon is planning on deploying supersonic parachutes of some kind, which should make a pretty big difference in how much fuel is needed for a given payload. Supersonic parachutes could be the difference between several hundred kilograms of payload and a couple tons of payload.

Keep in mind that not even a full ton of real payload has actually landed on Mars, yet (not counting the MER's landing platforms).

This shows some examples of what they could try.
http://www.planetaryprobe.org/SessionFiles/Session6A/Presentations/5_Adler_Supersonic_Decel.pdf

Testing these entry systems could be one task for the proposed Grasshopper RLV.

[Kaputnik]

The real issue I have with this is that I think people are taking Elon at face value when a grain of salt woudl be more applicable. He said that with the LAS, Dragon would be 'capable of landing on any solid body in the solar system'. That doesn't really stand up to scrutiny. Mercury? Venus? Io

We seem to be guessing without the full suite of assumptions.  Everyone here seems pretty much unanimous that Dragon (as we know it) lacks the ability to land several tons of science payloads.  "more than the mass of all prior Mars missions combined" or some such.  So...  We must be missing something.  Maybe with a fuller picture, Mercury and Venus are possibilities.  Maybe the pressure-hull was designed to Venusian specs.  Maybe there are drop tanks, trunk ballutes, or a descent tractor tower.  It appears that we just won't know until the 2013 competition.

And that's the nub of it. The involvement of NASA Ames seems to lend credibility to the idea of a Dragon landing on Mars, but until more details are made available we can only look at what is and is not possible within the laws of physics.
By the way, I seriously hope that Dragon has *not* been built to withstand a landing on Venus!

[Kaputnik]

It's also possible that this Red Dragon is planning on deploying supersonic parachutes of some kind, which should make a pretty big difference in how much fuel is needed for a given payload. Supersonic parachutes could be the difference between several hundred kilograms of payload and a couple tons of payload.

Keep in mind that not even a full ton of real payload has actually landed on Mars, yet (not counting the MER's landing platforms).

This shows some examples of what they could try.
http://www.planetaryprobe.org/SessionFiles/Session6A/Presentations/5_Adler_Supersonic_Decel.pdf

Testing these entry systems could be one task for the proposed Grasshopper RLV.

From 11,000ft?

[MikeAtkinson]

This shows some examples of what they could try.
http://www.planetaryprobe.org/SessionFiles/Session6A/Presentations/5_Adler_Supersonic_Decel.pdf

Also relevant is http://www.planetaryprobe.org/SessionFiles/Session6A/Presentations/6_Cassell_HIAD.pdf

This I think is more likely for Red Dragon, as I think it would enable lower peak deceleration, which is important if SpaceX plan to eventually use it for manned landings.

Testing these entry systems could be one task for the proposed Grasshopper RLV.

It doesn't seem likely that the first phase of Grasshopper testing will go high enough or fast enough for Mars EDL testing. Who knows about later stages.

My guess is that they are going to go for either: a Hypersonic Inflatable
Aeroshell Decelerator, inflated before decent. Then ~45m supersonic ringsail parachute at mach 3, then super Draco thrusters for final decent from about mach 0.5. This would probably be the most mass efficient approach.

An alternative is to do away with the supersonic ringsail parachute and go straight to a powered decent. Although the extra fuel is likely to mass more than the parachute, there would be fewer critical events during entry and development and testing of a large supersonic ringsail parachute would not be required.

[Jim]

And that's the nub of it. The involvement of NASA Ames seems to lend credibility to the idea of a Dragon landing on Mars,

Not really.  There are always PI's who are willing to sell their souls for a rides.  And that is just it, it is a PI from Ames and not the Ames organization.

[Kaputnik]

There are always PI's who are willing to sell their souls for a rides.  And that is just it, it is a PI from Ames and not the Ames organization.

Well that explains a lot. Not that I don't want to see such a mission happen, I just don't find it credible as currently presented.

[Patchouli]

Again, don't make statements that have no basis in fact.  You don't know what you are talking about.

Any launch large quantity of nuclear material is going to have huge cost and red tape associated with it regardless of whether it is commercial or gov't managed.

Am-241 is not "more readily available", since it hasn't been launched as an RTG.   The red tape would take just as long as obtaining Pu.

It not some statement I randomly made here's a paper on the subject.
www.niac.usra.edu/files/studies/final_report/393McNutt.pdf
The cost for an equivalent amount of Am-241 is much cheaper then Pu-238 but there is little experience with it and it's lower temp which means lower efficiency with existing technology.

From 11,000ft?

I figure eventually they'd get it to altitudes above 100K feet which should simulate Martian conditions.
Not sure how it would compare with high altitude balloon testing.
For small scale a balloon would definitely would be cheaper farm it out to someone with a lot of experience with large high altitude balloons.
 But full scale the Grasshopper may work better.

[hop]

The cost for an equivalent amount of Am-241 is much cheaper then Pu-238 but there is little experience with it and it's lower temp which means lower efficiency with existing technology.

You are missing the point. Am-241 is not available as an operational, ready to launch RTG. Getting it there would be extremely expensive, even if subsequent production was cheaper than Pu-238. The whole attraction of Red Dragon is supposed be that it's quick and cheap. Developing novel applications of radioactive materials is the last thing you want to do in that case. Citing a high level advanced concepts study doesn't help your argument, no one denies that you could make some kind of RTG with Am-241. The argument is over whether it is plausible for Red Dragon.

This illustrates a frequent problem here. Realists like Jim say "X is not plausible in the real world" and the proponent of the fantasy in question responds with a whole list of arguments about why X doesn't violate any fundamental laws of physics...

I figure eventually they'd get it to altitudes above 100K feet which should simulate Martian conditions.

Which has absolutely no basis in reality.

[Jason1701]

Again, don't make statements that have no basis in fact.  You don't know what you are talking about.

Any launch large quantity of nuclear material is going to have huge cost and red tape associated with it regardless of whether it is commercial or gov't managed.

Am-241 is not "more readily available", since it hasn't been launched as an RTG.   The red tape would take just as long as obtaining Pu.

It not some statement I randomly made here's a paper on the subject.
www.niac.usra.edu/files/studies/final_report/393McNutt.pdf
The cost for an equivalent amount of Am-241 is much cheaper then Pu-238 but there is little experience with it and it's lower temp which means lower efficiency with existing technology.

From 11,000ft?

I figure eventually they'd get it to altitudes above 100K feet which should simulate Martian conditions.
Not sure how it would compare with high altitude balloon testing.
For small scale a balloon would definitely would be cheaper farm it out to someone with a lot of experience with large high altitude balloons.
 But full scale the Grasshopper may work better.

Forget about the Am-241.

[docmordrid]

I have to agree - having dealt with them before, the DoE/NRC certs for a new Am-241 RTG system alone would push the mission way into the future.  IIRC ESA started looking at Am-241 RTG's last year, but it's doubtful they have a gadget yet.

There are far easier/cheaper ways to skin this cat.

[Jim]

Again, don't make statements that have no basis in fact.  You don't know what you are talking about.

Any launch large quantity of nuclear material is going to have huge cost and red tape associated with it regardless of whether it is commercial or gov't managed.

Am-241 is not "more readily available", since it hasn't been launched as an RTG.   The red tape would take just as long as obtaining Pu.

It not some statement I randomly made here's a paper on the subject.
www.niac.usra.edu/files/studies/final_report/393McNutt.pdf

"If Spacex does this as a private mission it might be easier simply due to the huge cost and red tape associated with Pu-238.
Am-241 would be more readily available.'

The paper you cite has nothing to do with the above statement made by you.

There is nothing there that supports your supposition that "it might be easier".

The fact that the element is more easier to obtain has nothing to do with its ability to be part of a certified source for an RTG.

That is the problem I have with your posts, you take a little information and come to an unrelated and unsupported conclusion.  This is common to many of your posts.

[Patchouli]

The point. Am-241 is not available as an operational, ready to launch RTG. Getting it there would be extremely expensive, even if subsequent production was cheaper than Pu-238. The whole attraction of Red Dragon is supposed be that it's quick and cheap. Developing novel applications of radioactive materials is the last thing you want to do in that case. Citing a high level advanced concepts study doesn't help your argument, no one denies that you could make some kind of RTG with Am-241. The argument is over whether it is plausible for Red Dragon.

True an Am-241 RTG would require it's own development program which would be expensive.
The easier part is it's more common it's found as nuclear waste and should not scare the public as much as plutonium even though Pu-238 is not the same stuff as Pu-239 and thus should not be scary.
Still it's something that should be a NASA and DOE funded project like the ASRTG as it's probably too expensive and long term for the private sector.
Well someone like Jeff Bezos probably could afford such a program but he has more near term space related problems.

This is why I figure Spacex will simply avoid any use of radio heat sources entirely on Red Dragon and make it completely solar powered.
Both solar cell and battery technology have improved since the MER rovers were designed.
As for deployment I think the surface cells could be folded inside the door if the vehicle need not remain pressurized once landed.

Change the hings and latches so it opens downward to allow it to be used as a ramp for deploying a small rover.

As for discounting high altitude testing as an analog to Mars that is exactly how NASA tested Mars entry systems.
It's probably about as good as you can get without actually going to Mars.

[go4mars]

I figure eventually they'd get it to altitudes above 100K feet which should simulate Martian conditions.

Which has absolutely no basis in reality.

But it's what we've got to work with short of going to Mars or building a cryogenic rarified CO2 hypersonic wind tunnel.  If they end up doing the orbcomm's on mostly individual flights, there may be accompanying dragonlabs the could "pretend Mars" in the rarified chilly upper atmosphere (while waiting for reusable stages).  It might be worth destroying a used dragon in the process of briefly testing a trunk ballute as a random example. 

[hop]

As for discounting high altitude testing as an analog to Mars that is exactly how NASA tested Mars entry systems.
It's probably about as good as you can get without actually going to Mars.

But it's what we've got to work with short of going to Mars or building a cryogenic rarified CO2 hypersonic wind tunnel.

Sorry, I guess I wasn't clear. I wasn't arguing against high altitude testing. That played an important role in Viking development, and could play a role in Red Dragon. No argument there.

The "no basis in reality" refers to Patchouli's unsupported speculation that "Grasshopper" would reach 100k feet. As far as I know, there is no evidence that it is anything other than a low altitude test bed. If there is documented evidence to the contrary, I'm happy to be corrected.

[Robotbeat]

They're not cleared for over 10,000 feet at this time. Doesn't mean it isn't technically capable of that altitude. We're talking about a quite high performance engine (compared to the other VTVLs of late, not counting DC-X).

[Patchouli]

But it's what we've got to work with short of going to Mars or building a cryogenic rarified CO2 hypersonic wind tunnel.  If they end up doing the orbcomm's on mostly individual flights, there may be accompanying dragonlabs the could "pretend Mars" in the rarified chilly upper atmosphere (while waiting for reusable stages).  It might be worth destroying a used dragon in the process of briefly testing a trunk ballute as a random example. 

I thought about the wind tunnel and figured it would be insanely expensive.

Though using a Dragon lab as a test mule esp if payload return is not absolutely needed would be a good option along with maybe using a COTS Dragon since NASA requires each one visiting ISS to be new.

They're not cleared for over 10,000 feet at this time. Doesn't mean it isn't technically capable of that altitude. We're talking about a quite high performance engine (compared to the other VTVLs of late, not counting DC-X).

It is pretty much a modified F9 first stage so having the performance is likely.
I figure one eventual purpose for Grasshopper might be to do little Joe type tests with the LAS.

They'll probably qualify the block one LAS the same way Orion's is but the modifications for landing with the LAS will likely require more testing.

[Jim]

They're not cleared for over 10,000 feet at this time. Doesn't mean it isn't technically capable of that altitude. We're talking about a quite high performance engine (compared to the other VTVLs of late, not counting DC-X).

And it probably won't be.  The test area is small.  It isn't the southwest where Viking chutes were tested or like Blue Origin's test area.

So doing testing at 100K not going to happen in Waco.