Author Topic: A Dragon derived general purpose Mars lander?  (Read 54506 times)

Offline charliem

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A Dragon derived general purpose Mars lander?
« on: 04/17/2012 07:46 PM »
Until now all the landers sent to Mars have been designed with only one very specific mission in mind. Few have been used more than once. That means the landing platform research, development and building costs kept high, impacting heavily on Mars mission budgets.

If we want to see human footprints on Mars one day, costs for every phase of the enterprise has to go down. Reductions in [earth] launch prices seem to be already under way. Achieving the same with [mars] landing would take us one more step towards that goal.

I think that a [first generation] general purpose, expendable, cheap mars lander, is doable in a relatively short time if developed from what already exists. It'd make Mars exploration much more affordable, and could also help to deliver hardware and/or consumables for the first human expeditions.

I was intrigued by what I read about a possible Red Mars mission once Falcon Heavy and the Dragon escape system become operational, although the declarations about it only be able to deliver 1 mt of payload sounded oddly small compared with its capabilities on Earth.

That took me to wonder if the Dragon could be used as base for a new vehicle that could fulfill the role I talked about before, with as little change as possible.

After some BOE found why the 1 mt figure: for the same ship dimensions (mass included) the terminal velocity on Mars is roughly five times that on Earth. Add that up with the low delta-v capability of the Dragon (only 1.290 kg of N2O4/MMH propellants) and that's it.

Well, 1 mt is not bad (1 mt is 10% more than the Curiosity rover), specially at the price, but there's also the small problem of how to extract the payload from the interior (and, of course, in this case the heavier the better).

So two questions: (1) Payload Extraction, and (2) Mass Enhancement, and the answers cannot be too radical, because if they imply a complete redesign then we'd loose right what we want to keep, low price and time.

The second problem looks the easier to solve: Interior supplementary tanks (if a F/A-18 can do it why not a spacecraft?). One from the aprox. 10 m3 of interior space of a Dragon gives you another tonne of propellants, elevating, if I'm not mistaken, the payload mass from 1 to 3 mt. Not bad. And with two tonnes of added propellants the payload mass gets near 5 mt.

About the first problem. Red Dragon solves it by simply not getting the payload out at all, drilling directly through the hull. Ingenious but not a general solution.

Someone suggested in other thread an extendable crane that could elevate the payload to let it out through the 1.3 m wide forward hatch, and also gently down outside.

Seems like a possibility, although it'd have the hatch size limitation (the Opportunity rover would not had fit, even folded, much less something bigger).

I wonder if there is a simple method for widening the aperture without having to completely re-engineer the hull. Sounds far fetched but if the payload is protected or though enough, what about a thermite cordon around the half level of the vessel and some hydraulic pushers? I know zit about explosives but I'd like someone with more knowledge on the matter confirm its impossibility.

And I know, Falcon Heavy doesn't exist yet, neither the Dragon escape system. I'm building on air, sure, but, hey, without a lot of previous dreams no rocket would had ever been built.
« Last Edit: 04/17/2012 09:57 PM by Chris Bergin »

Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #1 on: 04/18/2012 09:22 AM »
There have been eight landing attempts over 36 years at Mars. Six different designs, or five if you count MPL/Phoenix as being more-or-less the same.

Over that sort of time technology moves on, and in each case payload requirements were quite different. E.g. do you want a rover, that can land on its wheels or egress a platform? Do you want a lander with legs to maximise surface payload? What size does this paylaod need to be?

There have been attempts to standardise Mars landers. In fact, they have all been born of the same development program already, leading to a standardised but scalable basic entry vehicle shape and parachute. That is already much more standardisation than you will find in most spacecraft designs given the spread of time and different purposes and payloads.

For MER, it was initially proposed to reuse the MPF lander design, but in the end they had to scale it all up to fit the payload.


Anyway, as to Dragon- I think some of the technologies behind it are sound, and applicable to a Mars lander. But it would be ridicuolous to handicap the design by basing it on the Dragon capsule itself. Firstly, why restrict the diameter to 3.6m? Why not take it out to the maximum that the LV can cope with? Landed mass scales closely with vehicle diameter. Secondly, why put everything inside a sealed capsule? The basic design should be more flexible than that, allowing a multitude of different payloads to be flown.

When it comes to a human mission to Mars, I do think a standardised lander design is the way to go. We will need to build up flight experience with it landing unmanned payloads before we entrust humans to the system. However, to able to do this, the design must have the flexibility to land *all* of the mission elements, be they habitats, rovers, ascent vehicles, or indeed the crew.
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Offline kevin-rf

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Re: A Dragon derived general purpose Mars lander?
« Reply #2 on: 04/18/2012 01:17 PM »
There have been eight landing attempts over 36 years at Mars. Six different designs, or five if you count MPL/Phoenix as being more-or-less the same.

Small nit, Eight US, actually by my fingers Seven with one more on the way. That number does not include Russian and European attempts.
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #3 on: 04/18/2012 02:06 PM »
Correct, I was counting MSL as being 'in progress'. Also I didn't want to complicate things by adding in the various Soviet and one ESA attempts, the context being standardising landers- doing this internationally would be even more difficult.
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Offline Sparky

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Re: A Dragon derived general purpose Mars lander?
« Reply #4 on: 04/18/2012 02:18 PM »
Just a thought:

In terms of extraction, Dragon (and likely any Mars derivative) has a CBM sized opening on top. Could some of the landing legs be designed to be extendable/retractable, to tip the capsule onto its side after landing?

Offline A_M_Swallow

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Re: A Dragon derived general purpose Mars lander?
« Reply #5 on: 04/18/2012 04:00 PM »
Just a thought:

In terms of extraction, Dragon (and likely any Mars derivative) has a CBM sized opening on top. Could some of the landing legs be designed to be extendable/retractable, to tip the capsule onto its side after landing?

The manned Dragon and Dragonlab have a side hatch.  It may be simpler for surface equipment to exit through that.
http://www.spacex.com/downloads/dragonlab-datasheet.pdf

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #6 on: 04/18/2012 05:02 PM »
There have been attempts to standardise Mars landers. In fact, they have all been born of the same development program already, leading to a standardised but scalable basic entry vehicle shape and parachute. That is already much more standardisation than you will find in most spacecraft designs given the spread of time and different purposes and payloads.

For MER, it was initially proposed to reuse the MPF lander design, but in the end they had to scale it all up to fit the payload.


Anyway, as to Dragon- I think some of the technologies behind it are sound, and applicable to a Mars lander. But it would be ridicuolous to handicap the design by basing it on the Dragon capsule itself. Firstly, why restrict the diameter to 3.6m? Why not take it out to the maximum that the LV can cope with? Landed mass scales closely with vehicle diameter. Secondly, why put everything inside a sealed capsule? The basic design should be more flexible than that, allowing a multitude of different payloads to be flown.

Well Kaputnik, all you said is reasonable, not much different from what I've been thinking for years, but lately, as I realized that at the present slowing down pace most likely we are not going to see a human foot set on Mars before 2040 (or even longer, if ever), much less have a settlement, I've started to look for different approaches.

The traditional way of doing space exploration has been, to date, by specific mission oriented designs, most of them one of a kind (and yes, I'm aware of the many similarities between Viking, Pathfinder, MPL, MER, Phoenix and MSL, and even russian's Mars and ESA's Beagle).

That way is, no doubt, the ideal one if your resources are large enough to sustain it. The problem, as I see it, is that it looks like the R&D, and building, and operating costs of those awesome machines, are growing at a much higher rate than our financial capacity (or will if you prefer) allows.

And then I heard about Red Dragon.

At first was quite surprised. Never thought that a vehicle like that (a capsule! O_O) could be re-purposed to land and do science on Mars, but then wondered: If it can do that, what other things could it do? And then, following the same train of thought: What are the minimum changes necessary to turn it into a more general platform/lander?

A fresh design for a general purpose lander would be much more elegant, no doubt, but who is going to do it? And who is going to finance it? And how much time is going to take? After all, "they" had at least since 1975, 37 years, and I see no indication of any will to build anything remotely similar.

At least Dragon has one clear quality, it's [almost] already here.

So the question in my mind right now is: Do we keep waiting for the best, or do we try to go ahead with what we have, plus all the ingenuity we can muster?

And who said to restrict ourselves to 3.6 m? That's just a starting point. The fairing for a Falcon Heavy is 5.2 m in diameter. I see no reason to, at the very least, try to use that. But that is phase 2. Start humble, prove yourself, and then, maybe, you'll get farther.

P.E. I'm not advocating the use of Dragon for humans, but just as a starting point to speed up the previous steps.

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #7 on: 04/18/2012 05:08 PM »
The manned Dragon and Dragonlab have a side hatch.  It may be simpler for surface equipment to exit through that.
http://www.spacex.com/downloads/dragonlab-datasheet.pdf

Problem is size. The top hatch is more or less squared, and 1.3 m wide. The side hatch is much smaller (aprox. 0,66 x 0.7 m).

Offline docmordrid

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Re: A Dragon derived general purpose Mars lander?
« Reply #8 on: 04/18/2012 06:59 PM »
Does "detived" in include he possibility of modifying the side hatch to be much larger, or perhaps to also include a folding/extensible ramp? I'd think that would be a good derivation jumping off point. Might also want to reduce the height to lower the c/g. The pressure vessel is made up of welded panels so ISTM mods like this would be a CNC w/plasma cutter away for a decent fabricator
« Last Edit: 04/18/2012 07:00 PM by docmordrid »
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #9 on: 04/18/2012 07:00 PM »
A fresh design for a general purpose lander would be much more elegant, no doubt, but who is going to do it? And who is going to finance it? And how much time is going to take? After all, "they" had at least since 1975, 37 years, and I see no indication of any will to build anything remotely similar.

Why not get SpaceX to do it? They are not averse to altering their designs. Of their seven launches, how many have been the exact same configuration?
The benefits of creating a dedicated lander rather than a modified LEO taxi would be huge, and the increased payload would probably pay for itself fairly quickly in terms of $/kg landed.

Quote
And who said to restrict ourselves to 3.6 m? That's just a starting point. The fairing for a Falcon Heavy is 5.2 m in diameter. I see no reason to, at the very least, try to use that. But that is phase 2. Start humble, prove yourself, and then, maybe, you'll get farther.
Well, I was sort of assuming you said it. If it's not 3.6m, it's not a Dragon.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #10 on: 04/18/2012 07:34 PM »
 I think the basic premise is wrong.

I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.

So first we should decide what the mission is. Is it a manned lander? Is it for cargo? Is it for science? I believe it will be far better and cheaper in the long run to start with a blank sheet of paper and design the vehicle for its particular purpose. Rather than taking something like Dragon and go through all sorts of permutations to modify it for another purpose we should start from the bottom up.

Now if SpaceX wish to design a Mars lander for a specific purpose, there is no reason why they cannot use Dragon technology and systems for it. But that is very different from starting with an already mature design and trying to morph it into something else.

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Offline starsilk

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Re: A Dragon derived general purpose Mars lander?
« Reply #11 on: 04/18/2012 07:35 PM »
Does "detived" in include he possibility of modifying the side hatch to be much larger, or perhaps to also include a folding/extensible ramp? I'd think that would be a good derivation jumping off point. Might also want to reduce the height to lower the c/g. The pressure vessel is made up of welded panels so ISTM mods like this would be a CNC w/plasma cutter away for a decent fabricator

depending on how the panels are arranged, you could presumably just hinge and open the whole top two thirds like flower petals... would be difficult to keep that as a 'pressure vessel' though.

Offline oiorionsbelt

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Re: A Dragon derived general purpose Mars lander?
« Reply #12 on: 04/18/2012 07:39 PM »
I think the basic premise is wrong.
 I believe it will be far better and cheaper in the long run to start with a blank sheet of paper and design the vehicle for its particular purpose.

SpaceX's Red Dragon proposal would sugest they disagree with you.
« Last Edit: 04/18/2012 07:39 PM by oiorionsbelt »

Offline starsilk

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Re: A Dragon derived general purpose Mars lander?
« Reply #13 on: 04/18/2012 07:45 PM »
I think the basic premise is wrong.

I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.

So first we should decide what the mission is. Is it a manned lander? Is it for cargo? Is it for science? I believe it will be far better and cheaper in the long run to start with a blank sheet of paper and design the vehicle for its particular purpose. Rather than taking something like Dragon and go through all sorts of permutations to modify it for another purpose we should start from the bottom up.

Now if SpaceX wish to design a Mars lander for a specific purpose, there is no reason why they cannot use Dragon technology and systems for it. But that is very different from starting with an already mature design and trying to morph it into something else.

well, SpaceX are quite clear that they want to put people on Mars. so there is a pretty reasonable chance that some thought has been applied to using Dragon for that purpose - they've already repeatedly said the heat shield was designed to be capable of Earth reentry from Mars, for example.

I'm sure they'd very much like to have NASA sponsor testing that out by using it for unmanned landing(s). if Dragon can be hacked to land robots on Mars, then why design a whole new cargo lander? now you have to test BOTH of them. they've also made a conscious decision to use a "manned" (capable) vehicle for cargo transport to the ISS (cf Orbital's solution). I see a pattern here.

that's not to say a cargo lander wouldn't be necessary for Mars colonization.. but why not test out the vehicle you already have, first, before designing the next one?

Offline DaveH62

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Re: A Dragon derived general purpose Mars lander?
« Reply #14 on: 04/18/2012 07:59 PM »
Combining a few ideas into some questions.

Could they build a 5 meter dragon for Mars to increase payload? It would be a redesign, but could they keep the existing basic design and just expand the size?

Could the attach an upper stage rocket, where the trunk goes, to enter from orbit, and then fire Draco's once in the atmosphere? Seems like a safer method, and would increase payload capacity.

Could they increase the side hatch size and make it a ramp for offloading payload?

Do they have a articulating payload arm for moving payload that is won't roll out the ramp?

Lastly a comment: I do think standardizing delivery systems might constrain some payloads, but the payoff would be reduced development cycles, lower costs and reduced risks for each program. Maybe that is wrong, but it seems very reasonable to assume standardizing components and processes would reduce costs for space exploration as it has for all other industry.

Offline SpacexULA

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Re: A Dragon derived general purpose Mars lander?
« Reply #15 on: 04/18/2012 08:27 PM »
Why not get SpaceX to do it? They are not averse to altering their designs. Of their seven launches, how many have been the exact same configuration?
The benefits of creating a dedicated lander rather than a modified LEO taxi would be huge, and the increased payload would probably pay for itself fairly quickly in terms of $/kg landed.

Agreed, the cost per kg to Mars no matter what is going to way out pace any savings using refurbished/re purposed hardware.

Imagine how much payload SpaceX might be able to land with a PICAX heat shield scaled up to 4.5 Meters (Scaled up to fill their fairing), Draco thrusters hinged to allow for no cosine losses, and an airframe optimized for Mars entry. 

SpaceX has always said the long term goal is Mars, I can see 1-2 one off reuse of Dragon Capsules for Mars Landing, but if they ever get contracts to seriously go to Mars, it's really likely going to be a bird designed just for Mars Entry...

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Offline Bob Shaw

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Re: A Dragon derived general purpose Mars lander?
« Reply #16 on: 04/18/2012 09:14 PM »
Perhaps Red Dragon could deliver an anthropomorphic robot to Mars, and serve as a fuel store or battery pack. Just put a couch in, and some Apollo-style EVA handles on the exterior. My back of the envelope calculation suggests this would work on Luna, too...

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #17 on: 04/18/2012 09:57 PM »

well, SpaceX are quite clear that they want to put people on Mars. so there is a pretty reasonable chance that some thought has been applied to using Dragon for that purpose - they've already repeatedly said the heat shield was designed to be capable of Earth reentry from Mars, for example.

That's exactly the point: Dragon designed as an Earth lander, not a Mars lander. It's quite feasible to imagine it being used to bring members of a Mars expedition back to Earth on the last stage of their journey. But it isn't a Mars lander (despite what Musk says).

From Kaputnik
Quote
Imagine how much payload SpaceX might be able to land with a PICAX heat shield scaled up to 4.5 Meters (Scaled up to fill their fairing), Draco thrusters hinged to allow for no cosine losses, and an airframe optimized for Mars entry.

Just what I was arguing: a Mars lander designed from the ground up, but using Dragon technology, makes much more sense. I believe it could actually be cheaper than "hacking" the current vehicle's configuration.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #18 on: 04/18/2012 11:58 PM »
That's exactly the point: Dragon designed as an Earth lander, not a Mars lander. It's quite feasible to imagine it being used to bring members of a Mars expedition back to Earth on the last stage of their journey. But it isn't a Mars lander (despite what Musk says).

Just what I was arguing: a Mars lander designed from the ground up, but using Dragon technology, makes much more sense. I believe it could actually be cheaper than "hacking" the current vehicle's configuration.

Well, SpaceX is not the only one who says a Dragon could land on Mars. When the NASA engineers studied the proposal they didn't see any evident reason why a Dragon could not do it either.

What's the definition of a mars lander? Because from my point of view it is anything that can land on Mars without crashing, while carrying some significant payload.

Dragon is not the most beautiful solution but, what's the problem if it gets the job done?

As they say, the perfect is enemy of the good enough.

I'd very much like to see SpaceX designing a mars lander from the ground up, and am convinced their engineers'd like it as much as we, probably even Elon would, but SpaceX is not a non-profit, and this work can be as expensive, if not more, that designing the Falcon 9, which took about $300 million to develop IIRC.

So the question is not if there are better solutions, because of course there are, the only question is whether there is one that we can afford, at least for now (are you not a bit tired of waiting, cause I am).

I'd like to repeat this: In its present state a Dragon capsule can deliver 1 mt of payload to the surface or Mars (each MER rover weighted 185 kg, and the MSL rover 925). If my BOE calcs are not wrong just adding 1 mt of propellant would add 2 mt to the payload capacity (leaving ~9m3 of free volume), and without having to touch the heat shield.

Offline savuporo

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Re: A Dragon derived general purpose Mars lander?
« Reply #19 on: 04/19/2012 12:09 AM »
I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.
Planetary environment, yes, but mission - why?

Wouldn't it make scientific community happy if there was a predictable schedule of small mars landers with fixed capacity every 2 years - say, two or four of them every time ? And the missions would be designed for the lander, not vice versa.
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #20 on: 04/19/2012 07:23 AM »
I'd like to repeat this: In its present state a Dragon capsule can deliver 1 mt of payload to the surface or Mars

[citation needed]
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #21 on: 04/19/2012 07:57 AM »
I don't think that planetary landers are general purpose. I think they are specialized vehicles and should be custom designed for the mission and the planetary environment they are going to land in.
Planetary environment, yes, but mission - why?

Wouldn't it make scientific community happy if there was a predictable schedule of small mars landers with fixed capacity every 2 years - say, two or four of them every time ? And the missions would be designed for the lander, not vice versa.


I'm sure it would make them very happy. But the basis of small landers already exists: the MER/Phoenix system with either airbags or thrusters for the final touchdown. Dragon, as designed, is not required for that.

What's missing is not the technical means but the budget.

As far as designing for the mission is concerned, consider the two missions: landing a small weather station and landing a human habitat on Mars. I think it's obvious that different designs of landers would be needed for those.

The claim has been that a Dragon derived vehicle would be cheaper. I am doubtful of this. SpaceX have a long way to go before they will have an operational Mars EDL system. That experience will cost. And they have enough on their plate at the present time, anyway.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #22 on: 04/19/2012 08:16 AM »

Well, SpaceX is not the only one who says a Dragon could land on Mars. When the NASA engineers studied the proposal they didn't see any evident reason why a Dragon could not do it either.

If you read the first two pages of the Red Dragon thread you'll see this has already been discussed. Some engineers at Ames looked at it. It wasn't an official NASA study.

Quote
What's the definition of a mars lander? Because from my point of view it is anything that can land on Mars without crashing, while carrying some significant payload.

Agreed.

Quote
As they say, the perfect is enemy of the good enough.

I agree with that too. I'm not claiming that Dragon won't work or that the other approach is "perfect." I'm claiming that Dragon will not necessarily be cheaper and that the other approach is better.
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Offline docmordrid

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Re: A Dragon derived general purpose Mars lander?
« Reply #23 on: 04/19/2012 09:05 AM »
I'd like to repeat this: In its present state a Dragon capsule can deliver 1 mt of payload to the surface or Mars

[citation needed]

This do?

Quote
>
Falcon Heavy can throw Dragon to Mars
– Throw mass > 10 t to Mars (C3 ~ 10 km2/s2)

– Red Dragon injected mass ~ 6.5 t plus payload
>
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Online dcporter

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Re: A Dragon derived general purpose Mars lander?
« Reply #24 on: 04/19/2012 11:58 AM »
"Present state" is a bit of a stretch, as there's no pacific ocean on mars to splash down into. Assuming announced & funded developments go as planned, Dragon ought to be able to do so in the future.

Offline savuporo

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Re: A Dragon derived general purpose Mars lander?
« Reply #25 on: 04/19/2012 12:47 PM »
As far as designing for the mission is concerned, consider the two missions: landing a small weather station and landing a human habitat on Mars. I think it's obvious that different designs of landers would be needed for those.
Thats not obvious to me at all. I think it would be perfectly possible to design the entire mission architecture and hardware to be landed by the same lander.
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Offline Nathan

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Re: A Dragon derived general purpose Mars lander?
« Reply #26 on: 04/19/2012 01:22 PM »
Remove the pressure vessel and Design a back shell that is either jettisoned on descent or simply opened on the ground. We would then have a dragon 'truck' that could land more than one tonne on mars ( pressure vessel weight being replaced by payload mass).

A landing system can be a common element but the bulk of the expense will then be the unique cargo landed.

I'd prefer a five meter verion though as that would allow even greater mass to be landed.
It could perhaps form the basis of a multi lander settlement project. One way? Just thoughts and only basic math in the above.
Given finite cash, if we want to go to Mars then we should go to Mars.

Offline ChefPat

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Re: A Dragon derived general purpose Mars lander?
« Reply #27 on: 04/19/2012 02:14 PM »
Remove the pressure vessel and Design a back shell
I believe the pressure vessel is also the "frame" that everything attaches to.
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #28 on: 04/19/2012 02:38 PM »
"Present state" is a bit of a stretch, as there's no pacific ocean on mars to splash down into. Assuming announced & funded developments go as planned, Dragon ought to be able to do so in the future.

'Present state' is indeed a stretch.

At the moment, Dragon has proved that it can do a couple of orbits in LEO and then make a splashdown on Earth.

The super-dracos need to be finished, operational, and then qualified for Mars operation.
Some sort of landing gear needs to be designed and operational.
The Dragon would need significant mods to take account of the different aspects of the mission:
- longer total duration
- very different communications requirements
- very different thermal environment
- surface operations are again different, only moreso

How the vehicle operates on the surface is a huge question as well. Any sort of solar array deployment is going to need a Heath-Robinson deployment mechanism. Internal power supplies are more likely, but again would need to be qualified and tested. Thermal management on the surface is again something to tackle.
To some extent the surface operation mods depend on the vehicle's configuration and payload once operational on the surface. This is likely different for different types of mission... leading us back to bespoke landers.

Also it should be no small issue that the proposed descent/landing profile for a Red Dragon is very different from anything that has been attempted before. It is a much bigger difference than, e.g, Viking to MSL, or Viking to MER.
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #29 on: 04/19/2012 02:39 PM »
Remove the pressure vessel and Design a back shell that is either jettisoned on descent or simply opened on the ground. We would then have a dragon 'truck' that could land more than one tonne on mars ( pressure vessel weight being replaced by payload mass).

A landing system can be a common element but the bulk of the expense will then be the unique cargo landed.

I'd prefer a five meter verion though as that would allow even greater mass to be landed.
It could perhaps form the basis of a multi lander settlement project. One way? Just thoughts and only basic math in the above.

OK, so we take a Dragon capsule, make it a different size, and make it not a capsule any more.

How is that different to making a 5m heatshield plus backshell plus retros?  Which is the 'dedicated Mars lander' that I suggested could be made using SpaceX technology.
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Offline SpacexULA

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Re: A Dragon derived general purpose Mars lander?
« Reply #30 on: 04/19/2012 03:42 PM »
OK, so we take a Dragon capsule, make it a different size, and make it not a capsule any more.

How is that different to making a 5m heatshield plus backshell plus retros?  Which is the 'dedicated Mars lander' that I suggested could be made using SpaceX technology.

From what I have read SpaceX likes to keep their design teams busy with 1 project at a time, example:

Propulsion team:
Kestrel
Merlin 1A
Merlin 1B
Merclin 1C
Draco
Merlin Vac
Merlin 1D
Super Draco

or

Superstructures:
Falcon 1
Falcon 9
Falcon 9 Mk2
Falcon 9 Heavy

These items got developed pretty much 1 at a time, and dimes to donuts it was ruffly the same crew that did all of their designs.

At some point around 2015-2017 (hopefully) SpaceX is going to finalize the LEO, propulsive landing Dragon, and very likely about that time SpaceX will move the team working on Dragon to their next project.  IMHO will see a dedicated Mars or Moon Lander then, but no sooner.


« Last Edit: 04/19/2012 03:43 PM by SpacexULA »
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #31 on: 04/19/2012 07:19 PM »
As far as designing for the mission is concerned, consider the two missions: landing a small weather station and landing a human habitat on Mars. I think it's obvious that different designs of landers would be needed for those.
Thats not obvious to me at all. I think it would be perfectly possible to design the entire mission architecture and hardware to be landed by the same lander.

It's possible but it's not the best solution. A general purpose lander would have to be able to deliver payloads of greatly varying sizes and masses, depending on the mission.

It would be a bit like having a general purpose launch vehicle. Imagine that it was Delta IVH. You could use this vehicle to launch anything up to 20 tons into LEO. That covers a large range of possible payloads. But imagine using it to launch only a small science satellite. You could do it, but it makes no sense. So instead we have different classes of vehicles to handle different classes of payloads.

In a similar way, I suggest there will be different designs of Mars landers to handle different classes of landed payloads. A general lander, Dragon derived or otherwise, cannot handle all the possibilities.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #32 on: 04/20/2012 01:24 AM »
Well, SpaceX is not the only one who says a Dragon could land on Mars. When the NASA engineers studied the proposal they didn't see any evident reason why a Dragon could not do it either.
If you read the first two pages of the Red Dragon thread you'll see this has already been discussed. Some engineers at Ames looked at it. It wasn't an official NASA study.

Maybe it was not an official study, but I think it was more than the result of a superficial look by "some engineers" (thanks docmordrid):

ARC (Ames): John Karcz, Gary Allen, Alfonso Davila, Brian Glass, Jennifer Heldmann, Lawrence Lemke, Margarita Marinova, Christopher McKay, Carol Stoker, and Kerry Trumble
KSC (Kennedy): Phil Metzger and Tony Muscatello
LRC (Langley): Artem Dyakonov and Karl Edquist
JSC (Johnson): Jerry Sanders

... I suggest there will be different designs of Mars landers to handle different classes of landed payloads. A general lander, Dragon derived or otherwise, cannot handle all the possibilities.

I never suggested that this had to be the ONLY general purpose mars lander, only thing I said is that Dragon could serve as base for the first one.

As you said, today we have a whole family of general purpose launchers, and depending on the case they choose one or the other, but what no one does anymore is to design a new one for each mission.

I think the time is coming to do it also with the [mars] landers.

We already design the payloads having in mind the available launchers. Why not doing it with also thinking in the available landers (once there is one, evidently)?

And about what's cheaper, if adapting Dragon or building something new based on its tech. I have no doubt that in the long run a new platform can be cheaper, but there is no long run unless there is a short run first, we have to start somewhere.

"Aim to the stars and if you don't reach them maybe you'll reach the Moon" is not always good advice, some times you just end up with spit on your face.

Offline savuporo

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Re: A Dragon derived general purpose Mars lander?
« Reply #33 on: 04/20/2012 05:14 AM »
It's possible but it's not the best solution. A general purpose lander would have to be able to deliver payloads of greatly varying sizes and masses, depending on the mission. 
And better ( best ) is the eternal vile enemy of good enough. Best solutions tend to be time consuming and expensive. Often more than several orders of magnitude more than a working solution.
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Offline Kaputnik

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Re: A Dragon derived general purpose Mars lander?
« Reply #34 on: 04/20/2012 07:30 AM »
As you said, today we have a whole family of general purpose launchers, and depending on the case they choose one or the other, but what no one does anymore is to design a new one for each mission.

I think the time is coming to do it also with the [mars] landers.

We already design the payloads having in mind the available launchers. Why not doing it with also thinking in the available landers (once there is one, evidently)?

We don't have to design a new LV for every mission because there is a choice available.
Are you suggesting we go down the same route for Mars payloads?

There are a lot of variables. What size is it to be? What is the payload? Does it have to be removed from the capsule? If not, how is it to be powered? What landing site elevation do we aim for?

If you propose a single design of Mars lander, bang goes all your flexibility.

The current system is pretty good. NASA designed an entry and landing system back in the 70s at huge cost. They have managed to scale and modify this ever since to suit every payload them have wanted to land.

Also, you should read 'Roving Mars' to see how JPL tried to shoehorn the MERs into a MPF-size lander. Sometimes these ideas just don't work out.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #35 on: 04/20/2012 09:48 AM »

And better ( best ) is the eternal vile enemy of good enough. Best solutions tend to be time consuming and expensive. Often more than several orders of magnitude more than a working solution.

I've never heard the best called "vile" before.

Your point is correct when applied to simple technology. But we are talking about advanced technology where "good enough" has to be very good indeed. That's why I view the claim that designs using adapted from Dragon technology will be cheaper with considerable skepticism. There is no prospect of building a Mars lander that is "several orders of magnitude" cheaper at the present time. A "cheap" lander was tried--Beagle 2--and it failed. The team were underfunded and didn't do all the testing that was necessary.

From Kaputnik:

Quote
There are a lot of variables. What size is it to be? What is the payload? Does it have to be removed from the capsule? If not, how is it to be powered? What landing site elevation do we aim for?

If you propose a single design of Mars lander, bang goes all your flexibility.

The current system is pretty good. NASA designed an entry and landing system back in the 70s at huge cost. They have managed to scale and modify this ever since to suit every payload them have wanted to land.

Also, you should read 'Roving Mars' to see how JPL tried to shoehorn the MERs into a MPF-size lander. Sometimes these ideas just don't work out.

+1
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Offline luksol

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Re: A Dragon derived general purpose Mars lander?
« Reply #36 on: 04/20/2012 10:16 AM »
I just want to point out that increasing payload mass is not so desirable as it sounds.

I've read a discussion somewhere else about it and landing a big mass on Mars is not so simple. Because thin marsian atmosphere does not provide enough friction, there is a limit on mass of landing craft that can be slowed down to subsonic speed (in combination with parachutes), which is required for thrusters to work properly.

I am not an expert, so I have no idea about exact numbers, but if requested I can dig out an article where I've read about it.

Apparently MSL is just below this limit, so I wouldn't be too existed about Dragon delivering even more mass, not now at least.
There are some ways to overcome this problem that are being studied at the moment, but my knowledge about that is almost non-existant so I will not say anything not to confuse anyone. Maybe engineers will solve this problem in near future.

Sorry for being a bit vague, like I said before, no expert! :)
« Last Edit: 04/20/2012 10:17 AM by luksol »

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #37 on: 04/20/2012 04:46 PM »
We don't have to design a new LV for every mission because there is a choice available.
Are you suggesting we go down the same route for Mars payloads?

Yep, that's exactly what I'm suggesting, for the long run but starting now.

Settlement or not, humans or just hardware, how many more $2.5 billion missions like MSL do you thing NASA'll be able to finance, even in international partnerships? (the lander is only a portion, but not negligible)

If you propose a single design of Mars lander, bang goes all your flexibility.

Let me quote myself: "I never suggested that this had to be the ONLY general purpose mars lander, only thing I said is that Dragon could serve as base for the first one."

Also, you should read 'Roving Mars' to see how JPL tried to shoehorn the MERs into a MPF-size lander. Sometimes these ideas just don't work out.

And sometimes they do. I think there's some indication that this could be one of those. The preliminary cost estimation for Red Dragon LV and lander sounds almost ridiculous, less that $200 million.

For God's sake, NASA even tried to develop new electrical engines for Curiosity, and had to abandon the idea because the mounting costs. How many times are they going to try reinvent the wheel? (not that I'm against reinventing a better wheel, but not if that means going broke).

I've read a discussion somewhere else about it and landing a big mass on Mars is not so simple. Because thin marsian atmosphere does not provide enough friction, there is a limit on mass of landing craft that can be slowed down to subsonic speed (in combination with parachutes), which is required for thrusters to work properly.

That's one on the beauties of Dragon (if works as planned), it won't need to slow down to subsonic speeds, nor use parachutes. It's, indeed, a quite different machine than its precursors.

Offline luksol

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Re: A Dragon derived general purpose Mars lander?
« Reply #38 on: 04/20/2012 08:18 PM »

That's one on the beauties of Dragon (if works as planned), it won't need to slow down to subsonic speeds, nor use parachutes. It's, indeed, a quite different machine than its precursors.


Nope. The same rule applies. You are referring to Dragon landing on thruster, right? The problem with that is that if you try to land on thrusters with supersonic speeds they are difficult to control. So difficult that apparently noone wants to try. You need to slow down first. Then fire thrusters.

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #39 on: 04/20/2012 08:29 PM »

That's one on the beauties of Dragon (if works as planned), it won't need to slow down to subsonic speeds, nor use parachutes. It's, indeed, a quite different machine than its precursors.


Nope. The same rule applies. You are referring to Dragon landing on thruster, right? The problem with that is that if you try to land on thrusters with supersonic speeds they are difficult to control....
Not true. Gosh darnit, why does EVERYONE on the internet think this? It's been refuted several times. Off-axis thrusters are not so difficult to control. A big thruster right in the middle of the heatshield would lower the drag, but even that is possible. Dragon's (currently abort) thrusters are mounted around the perimeter, so they don't have to reduce drag.

Red Dragon has technical difficulties. But this oft-repeated supersonic retropropulsion thing isn't the kind of show-stopper everyone on the Internet thinks, not even close.

Current Mars lander designs slow to subsonic speeds because that's generally a lot more mass-efficient than propulsive landing, and current payloads have generally been small enough that supersonic retropropulsion isn't needed.
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Offline StephenB

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Re: A Dragon derived general purpose Mars lander?
« Reply #40 on: 04/20/2012 09:21 PM »
Would a dragon still be supersonic on Mars if they follow the entry profile where they gain altitude before starting to drop again?

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #41 on: 04/20/2012 10:11 PM »
Would a dragon still be supersonic on Mars if they follow the entry profile where they gain altitude before starting to drop again?
Yes. Terminal velocity at Mars is very high for that size/mass of an object because of the very thin atmosphere.

BESIDES, SUPERSONIC IS OKAY!!!

It's a performance penalty is all.
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Offline ChefPat

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Re: A Dragon derived general purpose Mars lander?
« Reply #42 on: 04/20/2012 10:31 PM »
From the "Red Dragon" thread.
What speed will Dragon be going at the top of the "rise"?
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #43 on: 04/20/2012 11:54 PM »
From the "Red Dragon" thread.
What speed will Dragon be going at the top of the "rise"?

Not enough data but if that graphic is more or less accurate you could calculate a very rough first approximation by measuring the altitude and range from the top point to landing.

About the terminal velocity don't have that data either, but can always try to estimate from what little we know. Mine is 380-450 m/s.

Offline luksol

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Re: A Dragon derived general purpose Mars lander?
« Reply #44 on: 04/21/2012 07:12 AM »

That's one on the beauties of Dragon (if works as planned), it won't need to slow down to subsonic speeds, nor use parachutes. It's, indeed, a quite different machine than its precursors.


Nope. The same rule applies. You are referring to Dragon landing on thruster, right? The problem with that is that if you try to land on thrusters with supersonic speeds they are difficult to control....
Not true. Gosh darnit, why does EVERYONE on the internet think this? It's been refuted several times. Off-axis thrusters are not so difficult to control.
Oh, don't get me wrong, I'd be delighted if supersonic wasn't a problem. I was just referring to something I've read, I am not an expert, just enthusiast. One question though. Has this been tried ? I mean landing on thrusters while supersonic?

Offline Nathan

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Re: A Dragon derived general purpose Mars lander?
« Reply #45 on: 04/21/2012 08:05 AM »
Remove the pressure vessel and Design a back shell that is either jettisoned on descent or simply opened on the ground. We would then have a dragon 'truck' that could land more than one tonne on mars ( pressure vessel weight being replaced by payload mass).

A landing system can be a common element but the bulk of the expense will then be the unique cargo landed.

I'd prefer a five meter verion though as that would allow even greater mass to be landed.
It could perhaps form the basis of a multi lander settlement project. One way? Just thoughts and only basic math in the above.

OK, so we take a Dragon capsule, make it a different size, and make it not a capsule any more.

How is that different to making a 5m heatshield plus backshell plus retros?  Which is the 'dedicated Mars lander' that I suggested could be made using SpaceX technology.
I wasn't disagreeing with you I just prefer the sound of my own voice! A dedicated large dragon with backshell and retros sounds fine to me. I think the existing dragon could be modified to have a backshell (strong enough for entry) to increase payload to surface in the near term before the dedicated large lander is built though.
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Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #46 on: 04/22/2012 04:18 PM »
Good eye.  I added a few in bold.  No one will be bored.
Propulsion team:
Kestrel
Merlin 1A
Merlin 1B
Merclin 1C
Draco
Merlin Vac
Merlin 1D
Super Draco
Highly reusable version of 1D
Methane version of 1D
Staged combustion version of 1D-sized
Raptor cryogenic stage
Merlin 2
Subsequent merlin 2 upgrades
Niche engines for parts of the reusable Mars architecture


or

Superstructures:
Falcon 1
Falcon 9
Falcon 9 Mk2
Falcon 9 Heavy
reusability upgrades
raptor stage
methane versions
15 meter diameter per core BFR
reusable ISRU mars architecture components
22 meter diameter BFR cryogenic upper stage


IMHO will see a dedicated Mars or Moon Lander then (2015-2017), but no sooner.
I think dragon would more likely continue to be essentially an all-purpose vehicle in that timeframe but with those added capabilities.


That's exactly the point: Dragon designed as an Earth lander, not a Mars lander...it isn't a Mars lander (despite what Musk says).
I suspect Elon has a bit more insight into his design requirements than you do.  He might very well have said, "we will design a capsule which to the best of our early knowledge is step-wise evolvable for landing both on Earth and on Mars with pre-determined upgrades using certain general assumptions".   That would have been after Gary's capsule work, so I don't know if anyone here could confirm or deny this. 
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #47 on: 04/22/2012 10:20 PM »

I suspect Elon has a bit more insight into his design requirements than you do. 

And I suspect that you are too eager to accepting Musk's predictions at face value. Around 2006 or so he predicted (I paraphrase) "when the Space Shuttle retires in 2010, there will be only one partially reuseable launch vehicle in the world--Falcon 1."

He is not always right, and it is not a given that using the current Dragon design is the best way to do a Mars lander.
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Offline oiorionsbelt

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Re: A Dragon derived general purpose Mars lander?
« Reply #48 on: 04/22/2012 10:24 PM »

I suspect Elon has a bit more insight into his design requirements than you do. 


He is not always right, and it is not a given that using the current Dragon design is the best way to do a Mars lander.
If not 'the best', do you think it is a 'likely' Mars Lander?

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #49 on: 04/22/2012 10:39 PM »
At the moment, no. Now of course, that can change. But currently there are no Mars landers planned by NASA after MSL and ExoMars is in flux. The budget climate is poor.

Now imagine a bunch of billionaires come along and say "Elon, will you do a Mars landing for us?" (I don't think SpaceX could fund it themselves). Then I think the better (and cheaper) way to do it would be to design the spacecraft from the ground up, using Dragon derived technology to achieve the mission goal.
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Offline oiorionsbelt

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Re: A Dragon derived general purpose Mars lander?
« Reply #50 on: 04/22/2012 10:47 PM »
Do you think Red Dragon is an after thought, or do you think Mars was contemplated earlier on in the design?

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #51 on: 04/23/2012 03:47 AM »
... imagine a bunch of billionaires come along and say "Elon, will you do a Mars landing for us?" (I don't think SpaceX could fund it themselves). Then I think the better (and cheaper) way to do it would be to design the spacecraft from the ground up, using Dragon derived technology to achieve the mission goal.

Now, I'd like to see that  ;D

Could SpaceX develop and build it for a fraction of the cost we are used to, as they did with Falcon 9?

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #52 on: 04/23/2012 08:57 AM »
Could SpaceX develop and build it for a fraction of the cost we are used to, as they did with Falcon 9?

What do you mean by a "fraction?" 10%? 50%/ 98%? I assume you mean "a lot" cheaper. It appears that Falcon 9 is "a bit" cheaper than other launch vehicles, but not "a fraction" of their cost. There has been considerable skepticism of SpaceX's prices on other threads.

So, to answer your question on that basis: no.

SpaceX has no experience of landing on Mars, experience which JPL and its contractors have gained only at great expense over many years. Of course SpaceX can learn from and build on that experience. Maybe they could do a lander "a bit" cheaper, but not much. Mars landers are like launch vehicles, you only have one chance to get it right. So you have to test meticulously, which is expensive.

If you go for cheaper (remember "faster, better, cheaper?") then you risk being Beagle 2 or MPL.
« Last Edit: 04/23/2012 09:00 AM by douglas100 »
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #53 on: 04/23/2012 09:07 AM »
Do you think Red Dragon is an after thought, or do you think Mars was contemplated earlier on in the design?

I don't know. I think Musk is sincere in his Mars ambitions, but I have no idea if Red Dragon was an afterthought.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #54 on: 04/23/2012 06:22 PM »
Could SpaceX develop and build it for a fraction of the cost we are used to, as they did with Falcon 9?

What do you mean by a "fraction?" 10%? 50%/ 98%? I assume you mean "a lot" cheaper. It appears that Falcon 9 is "a bit" cheaper than other launch vehicles, but not "a fraction" of their cost. There has been considerable skepticism of SpaceX's prices on other threads.

So, to answer your question on that basis: no.

By a fraction I mean half or less.

I'm by no means certain, just wondering, but fail to see how you can be so sure of the opposite.

Comparing price tags is difficult when most are hidden. What we do know is SpaceX has repeatedly declared Falcon 9 and Dragon development costs were about $300 million each (of course they could be lying :P).

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #55 on: 04/23/2012 07:00 PM »
Mars landers are like launch vehicles, you only have one chance to get it right. So you have to test meticulously, which is expensive.
They tested the merlin vacuum by sticking it on a rocket.  Using your examples (Beagle 2 or MPL), if they made a few of them at the same time instead of just 1, then subsequently launched versions would have been better and cheaper.  It isn't like SpaceX plan to only ever land 1 thing on Mars.  Doing the mission faster better and cheaper could be a good way of gathering data for  follow-on red dragons (improving the success). 

If you go for cheaper (remember "faster, better, cheaper?") then you risk being Beagle 2 or MPL.
Conversely, if you don't aim to be faster & better & cheaper, you likely won't be. 
« Last Edit: 04/23/2012 07:04 PM by go4mars »
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Offline StephenB

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Re: A Dragon derived general purpose Mars lander?
« Reply #56 on: 04/23/2012 07:27 PM »
From the "Red Dragon" thread.
What speed will Dragon be going at the top of the "rise"?
Surely the vertical component of the speed velocity is zero at that point?
« Last Edit: 04/23/2012 07:49 PM by StephenB »

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #57 on: 04/23/2012 07:50 PM »
From the "Red Dragon" thread.
What speed will Dragon be going at the top of the "rise"?
Surely the vertical component of the speed velocity is zero at that point?
Correct.  But I think it's reasonable to assume he means tangential velocity.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #58 on: 04/23/2012 08:31 PM »

By a fraction I mean half or less.

I'm by no means certain, just wondering, but fail to see how you can be so sure of the opposite.

Comparing price tags is difficult when most are hidden. What we do know is SpaceX has repeatedly declared Falcon 9 and Dragon development costs were about $300 million each (of course they could be lying :P).

I assumed you asked me for my opinion and that's what I gave you. If I gave you the impression I was "so sure" of the opposite, I apologize. I certainly hold the opinion quite strongly, but it is just that, an opinion.

Now I think you are on the right lines with the development cost of Falcon 9, but you  said develop and build it for a fraction of what we are used to. I mistook that for the cost of a Falcon 9 flight to a customer.

But I think that comparing the development of a launch vehicle with the development of a spacecraft might not be too useful. Spacecraft (I mean main payloads) are often more expensive than their launch vehicles. Look at the delay in launching the COTS Demo C2+: the delay is in the spacecraft not the F9. I suggest that major spacecraft are harder to do than launch vehicles and that a Mars lander is harder (and more expensive) to do than a cargo vehicle to ISS. Remember there have been over 100 successful automatic cargo flights to space stations , but only 6 successful Mars landings.

I think it makes more sense to compare like with like. We should compare a hypothetical SpaceX Mars lander with real Mars landers past and present when we debate whether SpaceX can do a Mars lander radically cheaper.

And in return, my question to you is, do you think they can do a Mars lander a lot cheaper than in the past and if so, why?
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Offline oiorionsbelt

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Re: A Dragon derived general purpose Mars lander?
« Reply #59 on: 04/23/2012 08:51 PM »
 I think they will, because like you, I believe Elon is sincere in his Mars ambitions.
If he can't do it a lot cheaper those ambitions won't amount to much.
So it seems that for the first time there is someone with the 'possible' means and the sincere desire too get to Mars, IF they can to it cheaply enough.

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #60 on: 04/23/2012 08:56 PM »
They tested the merlin vacuum by sticking it on a rocket.  Using your examples (Beagle 2 or MPL), if they made a few of them at the same time instead of just 1, then subsequently launched versions would have been better and cheaper.  It isn't like SpaceX plan to only ever land 1 thing on Mars.  Doing the mission faster better and cheaper could be a good way of gathering data for  follow-on red dragons (improving the success). Conversely, if you don't aim to be faster & better & cheaper, you likely won't be. 

As they said at the time of cheaper, better, faster, "choose any two." After MPL NASA abandoned the approach.

The Soviet Union tried something like this approach. In 1971 they launched two orbiter/landers and had a partial success with the Mars 3 lander. So they tried again 1973. This time they launched four Protons during the launch window and did less well than in  71.

 You talk about Mars landers as if they were something coming off the production line and "we'll just keep launching them (along with an FH each time) until we get it right." This is completely unrealistic. That is how you make yourself bankrupt if you're a private company.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #61 on: 04/23/2012 09:02 PM »
I think they will, because like you, I believe Elon is sincere in his Mars ambitions.
If he can't do it a lot cheaper those ambitions won't amount to much.
So it seems that for the first time there is someone with the 'possible' means and the sincere desire too get to Mars, IF they can to it cheaply enough.

It all depends on the fate of SpaceX and how well they execute their customer contracts so that they remain in business. But then I think Musk will need substantial outside investments to realize his Martian ambitions.
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Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #62 on: 04/23/2012 09:42 PM »
You talk about Mars landers as if they were something coming off the production line and "we'll just keep launching them (along with an FH each time) until we get it right." This is completely unrealistic. That is how you make yourself bankrupt if you're a private company.
There's a dragon assembly line.  That's a big difference.

If the first Red Dragon mission costs $500 million, including the science instruments, and including launch, I think it's fair to assume that the cost of dragon including Mars related changes and developments are less than $300 million (Assuming $200 million for science payloads and a FH launch). 

If a "crew dragon" not including launch vehicle costs in the range of $90 million, then we are at a maximum "red dragon" cost difference of $210 million (which includes development costs of re-purposing dragon). 

If we assume that $60 million of that is in new dragon hardware (interplanetary communications, programming, control systems, etc.), and $150 million of that is for the development of that hardware and new features, then it leaves us with we end up with a cost of $350 million for all subsequent dragon missions (assuming the science payloads and launch costs don't get cheaper). 

The data from the first one should lend tighter margins to subsequent missions (more downmass on the next ones).

In a budget constrained environment, paying $250M to have a company take your tonne+ on a ride to the surface of Mars sounds like a pretty good deal to me.  If folks are worried about getting rovers out of the hatch, a "saws-all" on a track inside the pressure-hull would be worth looking at. 


I don't understand the skepticism in your statement above.  Dragons and FH cores are something that is coming off the production line. 

To be fair, falcon cores won't be into "production mode" for another 6 months or so.  But the dragon line is pretty much ready to go. 
« Last Edit: 04/24/2012 01:48 AM by go4mars »
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #63 on: 04/23/2012 10:51 PM »
There isn't a production line for Mars landers. The Dragons being produced are for COTS.

There is no current market for a production line of Mars landers.

Quote
I don't understand the skepticism in your statement above.

That's because you keep making unrealistic proposals.
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Offline oiorionsbelt

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Re: A Dragon derived general purpose Mars lander?
« Reply #64 on: 04/23/2012 11:44 PM »
There isn't a production line for Mars landers. The Dragons being produced are for COTS.

Is the COTS Dragon  production line easily modified  for Dragon Rider/ Red Dragon?

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #65 on: 04/24/2012 01:50 AM »
Is the COTS Dragon  production line easily modified  for Dragon Rider/ Red Dragon?
The cost estimate and statements made with the proposal suggest that the production line is easily modified for red dragon (a few bells and whistles added to a stock dragon). 
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Offline beancounter

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Re: A Dragon derived general purpose Mars lander?
« Reply #66 on: 04/24/2012 03:25 AM »
Is the COTS Dragon  production line easily modified  for Dragon Rider/ Red Dragon?
The cost estimate and statements made with the proposal suggest that the production line is easily modified for red dragon (a few bells and whistles added to a stock dragon). 

Well there's certainly going to be a few second-hand Dragons floating around.  Various configurations could be tried on some of these which should be possible and they've been paid for.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #67 on: 04/25/2012 03:03 AM »
... I think that comparing the development of a launch vehicle with the development of a spacecraft might not be too useful. Spacecraft (I mean main payloads) are often more expensive than their launch vehicles. ...

I think it makes more sense to compare like with like. We should compare a hypothetical SpaceX Mars lander with real Mars landers past and present when we debate whether SpaceX can do a Mars lander radically cheaper.

And in return, my question to you is, do you think they can do a Mars lander a lot cheaper than in the past and if so, why?

Ok, lets then talk development and building separately.

About development: 6 successful landings on Mars to date, one more in the coming. 5 different designs, although all of them variations of the same basic idea (including MSL). That meant savings in development for the last 4, but also that not being identical they had to expend some more (from the news I read quite more).

The case for SpaceX is not that different. They also have tech already developed they could reuse, like the pica-x heat shield, the super Dracos, power systems, some of the avionics, etc. The main reason I started this thread was to hear opinions about the feasibility of using an almost untouched Dragon for this role, because if it were feasible it would mean maximizing commonality, and in doing so, minimizing costs, starting with development.

But it's up to SpaceX to decide their path. Elon might think best aiming for something completely different, maybe cheaper to build, or more flexible, or for heavier payloads, etc.

So, answering your question: Do I think they COULD do it cheaper? Yes, I think they could. Will they do it? Who knows.

About building I have less doubt. I'm convinced that, given their business principles, if SpaceX ever design and develop a Mars lander, they are not going to plan to use it only for one mission and then design something different. If they do it, they'll try to use it as many times as possible (not as many opportunities as a launcher but more than one or two, I hope).

If you make more than one item of any design, it follows that some of the costs can be shared, and so the final product tends to be less expensive. That's one other thing I like about repurposing Dragon, that in doing it (if at all doable), even if the final product is not ideal, at least it could be cheaper, because that would give it three roles to play, three different configurations, cargo, crew transport, and Mars lander.

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #68 on: 04/25/2012 10:28 AM »
Quote
6 successful landings on Mars to date, one more in the coming.

Hope you're right!

You could argue that the MER and Phoenix are variations of the same design with a different option for the terminal braking and landing. That would put MPL in the same group. So in a sense we already have a kind of general Mars lander. The differences between them were driven by the nature of the payload to be landed.

You could imagine a system using SpaceX technology, like you say and there's no reason that they couldn't do it. Could they do it cheaper? Probably, but that depends on what the mission is.

Quote
The main reason I started this thread was to hear opinions about the feasibility of using an almost untouched Dragon for this role, because if it were feasible it would mean maximizing commonality, and in doing so, minimizing costs, starting with development.

I've already said that I think an untouched Dragon is a poor choice. My (amateur) thoughts about what a Dragon derived design could be like would be:

1. Keep the current Dragon heat shield and mold line
2. Use the current thrusters and Super Dracos for an all propulsive landing
3. Get rid of the pressure vessel and have a backshell which separates
4. Jettison the heat shield before braking to reduce landing mass and allow the super Dracos to point straight down
5. Replace the trunk with a cruise stage.

This means essentially a new spacecraft, but it means the payload is exposed to the Martian environment on landing and can  be offloaded if required.

As for will they do it, as you said, who knows? If SpaceX wish to carry out their own Mars mission I think Mr. Musk will have to dip deeper into his personal fortune. It's difficult to imagine a series of such spacecraft being built at the present time unless some HBP* comes along and pays for it.

(*HBP=Hypothetical Billionaire Philanthropist  :))





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Offline upjin

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Re: A Dragon derived general purpose Mars lander?
« Reply #69 on: 06/11/2012 01:10 PM »
I like this topic.  Since the Falcon Heavy will launch soon and based on the success of the Dragon to ISS, it is possible that additional funding could come from rich investors, various governments, and/or various companies.  Such investors may have a vested interest in Mars.  Not just NASA, but many others.  Per Musk, he is anticipating that there will be significant business for SpaceX in missions to Mars.

Falcon Heavy and Dragon would mean that there is a vehicle to get to and land on Mars, thus it would encourage investment and projects to use them.  Such investment would likely help provide SpaceX with the additional capital to modify their Dragons for various missions.
« Last Edit: 06/11/2012 01:14 PM by upjin »

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #70 on: 06/11/2012 01:45 PM »
1. Keep the current Dragon heat shield and mold line
2. Use the current thrusters and Super Dracos for an all propulsive landing
3. Get rid of the pressure vessel and have a backshell which separates
4. Jettison the heat shield before braking to reduce landing mass and allow the super Dracos to point straight down
5. Replace the trunk with a cruise stage.


'sactly right.

Still, they might send a single minimally-modified Dragon in order to validate and qualify subsystems and to be able to incorporate lessons learned into the first Martian lander.

It's not so much for the cost savings since they'll get private funding for such a mission, it's because they can do it much sooner and with less required development.
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #71 on: 06/11/2012 03:26 PM »

It's not so much for the cost savings since they'll get private funding for such a mission, it's because they can do it much sooner and with less required development.

Will they? From where?
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #72 on: 06/11/2012 04:25 PM »
May I remind you that there are at least 3 different proposals we know of to use Dragon for scientific mission to Mars? Red Dragon, Ice Dragon, and Red Dragon-MSL.

Even if Dragon is not a general purpose mars lander looks like some people think it's good enough as is/will be.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #73 on: 06/11/2012 04:43 PM »

It's not so much for the cost savings since they'll get private funding for such a mission, it's because they can do it much sooner and with less required development.

Will they? From where?

Look at how many rich folks are willing to put funds into developing their own launch technology.   Supporting a Mars mission with an existing rocket and vehicle is a) cheaper, b) less risky, c) quicker, and d) more gratifying.     Of course they'll fund it.

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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #74 on: 06/11/2012 05:25 PM »

1.  Look at how many rich folks are willing to put funds into developing their own launch technology.

2.    Supporting a Mars mission with an existing rocket and vehicle is a) cheaper, b) less risky, c) quicker, and d) more gratifying.     Of course they'll fund it.


1.  Not an applicable analogy.

2.  Meaningless. There is no return for investors.

Of course, they won't fund it.
« Last Edit: 06/11/2012 05:26 PM by Jim »

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #75 on: 06/11/2012 05:27 PM »

Still, they might send a single minimally-modified Dragon in order to validate and qualify subsystems and to be able to incorporate lessons learned into the first Martian lander.

No, because its viability is not a given

Offline wolfpack

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Re: A Dragon derived general purpose Mars lander?
« Reply #76 on: 06/11/2012 05:36 PM »
As much as I like these guys (SpaceX), let's be real. They're not sending anything to Mars. I think sometimes we forget just how hard that is to do.

Elon Musk is an inspiring individual, no doubt, but if the goal is to run a profitable company that may someday be offered for public ownership, then investors are not going to want to hear words like "Mars" or "making life interplanetary". They want to hear things like "backlog" and "book-to-bill". That means launching paying customers' spacecraft into the part of space that they paid to have it put in. And it ain't gonna be Mars.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #77 on: 06/11/2012 05:43 PM »

Still, they might send a single minimally-modified Dragon in order to validate and qualify subsystems and to be able to incorporate lessons learned into the first Martian lander.

No, because its viability is not a given

So you're saying they won't test it because it's not tested...    I can't really argue with that.  :)
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Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #78 on: 06/11/2012 05:48 PM »

1.  Look at how many rich folks are willing to put funds into developing their own launch technology.

2.    Supporting a Mars mission with an existing rocket and vehicle is a) cheaper, b) less risky, c) quicker, and d) more gratifying.     Of course they'll fund it.


1.  Not an applicable analogy.

2.  Meaningless. There is no return for investors.

Of course, they won't fund it.

It wasn't an analogy, and the two parts of the paragraphs are not stand-alone sentences.  The first is an observation, and the second compares the proposition at hand to it, which makes it both applicable and meaningful.

As for ROI, none of these people are in it for a 5-year ROI.  They do it because they've got more money than they can spend, so they LIKE to do it.

There's no ROI in buying a luxury yacht either, but obviously people do.  It's just that some people find things like funding a Mars mission more gratifying than a yacht. (or they already have one)
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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #79 on: 06/11/2012 06:27 PM »

Still, they might send a single minimally-modified Dragon in order to validate and qualify subsystems and to be able to incorporate lessons learned into the first Martian lander.

No, because its viability is not a given

So you're saying they won't test it because it's not tested...    I can't really argue with that.  :)

No, they are going to do it because it is not worth the return

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #80 on: 06/11/2012 06:28 PM »

1.  Look at how many rich folks are willing to put funds into developing their own launch technology.

2.    Supporting a Mars mission with an existing rocket and vehicle is a) cheaper, b) less risky, c) quicker, and d) more gratifying.     Of course they'll fund it.


1.  Not an applicable analogy.

2.  Meaningless. There is no return for investors.

Of course, they won't fund it.

It wasn't an analogy, and the two parts of the paragraphs are not stand-alone sentences.  The first is an observation, and the second compares the proposition at hand to it, which makes it both applicable and meaningful.

As for ROI, none of these people are in it for a 5-year ROI.  They do it because they've got more money than they can spend, so they LIKE to do it.


Going to Mars and building a launch vehicle are two different things.  Building launch vehicles has a chance on ROI.  No one has the money to fund Mars missions
« Last Edit: 06/11/2012 06:32 PM by Jim »

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #81 on: 06/11/2012 06:30 PM »

There's no ROI in buying a luxury yacht either, but obviously people do.  It's just that some people find things like funding a Mars mission more gratifying than a yacht. (or they already have one)


Unsubstantiated.  No one has unfunded a Mars mission, hence, no gratification, therefore your comparison is meaningless.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #82 on: 06/11/2012 06:34 PM »

There's no ROI in buying a luxury yacht either, but obviously people do.  It's just that some people find things like funding a Mars mission more gratifying than a yacht. (or they already have one)


Unsubstantiated.  No one has unfunded a Mars mission, hence, no gratification, therefore your comparison is meaningless.

So again, you're saying that won't fund it because they haven't funded it yet.

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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #83 on: 06/11/2012 06:52 PM »

There's no ROI in buying a luxury yacht either, but obviously people do.  It's just that some people find things like funding a Mars mission more gratifying than a yacht. (or they already have one)


Unsubstantiated.  No one has unfunded a Mars mission, hence, no gratification, therefore your comparison is meaningless.

So again, you're saying that won't fund it because they haven't funded it yet.


No, I never said that once, much less again.  Just pointing out all the flaws in your logic, such as somebody finding gratification in funding a Mars mission when no one has done it yet.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #84 on: 06/11/2012 06:56 PM »

There's no ROI in buying a luxury yacht either, but obviously people do.  It's just that some people find things like funding a Mars mission more gratifying than a yacht. (or they already have one)


Unsubstantiated.  No one has unfunded a Mars mission, hence, no gratification, therefore your comparison is meaningless.

So again, you're saying that won't fund it because they haven't funded it yet.


No, I never said that once, much less again.  Just pointing out all the flaws in your logic, such as somebody finding gratification in funding a Mars mission when no one has done it yet.


Then I'll be specific.

The question was why would anyone fund a Mars mission. "Would" used here in a conditional future-tense.

My answer was, they'd do it because of gratification.

Your response was - but there is no gratification since nobody did it yet.

Circular.

k?
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Offline mr. mark

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Re: A Dragon derived general purpose Mars lander?
« Reply #85 on: 06/11/2012 07:10 PM »
Mars is a driving company goal and a motivating factor in SpaceX employee relations. They are convinced they are working towards a Mars goal. I've talked with some of them and it's the first thing out of their mouths. It's a mantra for them. I talked with one the other day discussing the MARS 1 mission. Evidently, it was all the talk on the factory floor. SpaceX employees are driven and goal motivated.
« Last Edit: 06/11/2012 07:15 PM by mr. mark »

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #86 on: 06/11/2012 07:19 PM »
Remember the reason Elon Musk said was the main one for he ending in the launch business?

He wanted to send a mission to Mars on his own money, but it was too expensive.

You can take that as proof that no one's going to try because there's not money to make, or you can take it as proof that someone is going to do it as soon as it is affordable for billionaires.

Choose you favorite.
« Last Edit: 06/11/2012 07:20 PM by charliem »

Offline mr. mark

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Re: A Dragon derived general purpose Mars lander?
« Reply #87 on: 06/11/2012 07:24 PM »
What SpaceX is counting on is that due to budget constraints NASA is going to need them to do some work in BEO with a focus on Mars based missions. In other words SpaceX is like a race car that is drafting behind another one (NASA). If you know something about racing you'll get my meaning.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #88 on: 06/11/2012 07:31 PM »
Remember the reason Elon Musk said was the main one for he ending in the launch business?

He wanted to send a mission to Mars on his own money, but it was too expensive.

You can take that as proof that no one's going to try because there's not money to make, or you can take it as proof that someone is going to do it as soon as it is affordable for billionaires.

Choose you favorite.


As I know the story, it was too expensive to go to Mars on existing launchers, so he got into the launch business with the express purpose of going to Mars.   Everything Elon has said to date corroborates this.

Anyway, aside from the Billionaire funded option, consider SpaceX's recent history:
"Stop talking about a rocket, build one and we'll believe you" -->
"Stop talking about a big rocket, build one and we'll believe you" -->
"Stop talking about a capsule... " etc.

This will no doubt continue. But then for the same people to say "there's no point in sending a Dragon to Mars"?

No value in validating subsystems, hardware and software?
No value in validating operations?
No PR value?  motivational value?

Hell if they can just get there in one piece it's worth their own $.
If they can land, or return w/o landing - even more so.

If you're looking for ROI within that single flight, then you're just looking wrong.
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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #89 on: 06/11/2012 07:42 PM »

No value in validating subsystems, hardware and software?


It doesn't nothing of the sort.  Dragon as it exists can not perform the mission

Offline DaveH62

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Re: A Dragon derived general purpose Mars lander?
« Reply #90 on: 06/11/2012 07:42 PM »
I think the best Mars financial model is dependent on continued commercial success, and winning part of commercial crew.
At that point they will have the credibility to sell a NASA science mission. If they can stick to a ~500 million cost for a solid mission that should be fundable even in a flat funding environment.

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #91 on: 06/11/2012 07:43 PM »
As I know the story, it was too expensive to go to Mars on existing launchers,

Still is.

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #92 on: 06/11/2012 07:44 PM »
I think the best Mars financial model is dependent on continued commercial success, and winning part of commercial crew.
At that point they will have the credibility to sell a NASA science mission.

That still doesn't mean the vehicle can perform the mission.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #93 on: 06/11/2012 08:10 PM »
The question is whether you want to emphasize doing it sooner, sending off a "minimally modified" Dragon, or you whether you want to wait untill you built a purpose-built, somewhat Dragon derived, Mars vehicle.

Clearly, the purpose-built lander will be a better vehicle...   The only thing we're talking about here is whether the value of sending off the minimally modified Dragon is worth the expense, and how they'll fund it.

Since it's SpaceX's vehicle and rockets, my estimate is "yes" even if it's on their own $, but that with some creative thinking they can even get some or all of the $ from interested parties.

How minimal is "Minimal" depends on the mission they'll decide to do.
a) one-way trip
b) two-way trip
c) landing

Each of these has different amounts of value in the categories we discussed above. In case of EDL there is value even if there's only partial success.
« Last Edit: 06/11/2012 08:19 PM by meekGee »
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Offline mr. mark

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Re: A Dragon derived general purpose Mars lander?
« Reply #94 on: 06/11/2012 08:18 PM »
SpaceX will most likely go to Mars when NASA asks them to go. If Dragon is the vehicle of choice then it will meet the criteria that NASA has instructed it to do.   
« Last Edit: 06/11/2012 08:18 PM by mr. mark »

Offline Mongo62

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Re: A Dragon derived general purpose Mars lander?
« Reply #95 on: 06/11/2012 09:22 PM »
The question of whether a Red Dragon style mission should use a near-stock Dragon or a Dragon-derived Mars lander probably comes down to cost vs benefit.  What is the total mission cost of a near-stock Dragon plus launcher (presumably a Falcon Heavy) plus one-tonne payload, versus the total mission cost of a Dragon-derived Mars lander (presumably a lot more expensive than a near-stock Dragon) plus launcher plus several-tonne payload?  Is the ratio of mission costs greater or less than the ratio of payload masses?

There are other factors as well -- for example, the payload on the Dragon-derived Mars lander would presumably have much better access to the Martian environment, while the payload on the near-stock Dragon would be capable of arriving years earlier -- but I assume that the cost per tonne of payload to the Martian surface would be the largest single factor.

Of course there is nothing to prevent sending a near-stock Dragon for one or more Mars oppositions, and then a Dragon-derived Mars lander on subsequent oppositions.
« Last Edit: 06/11/2012 09:27 PM by Mongo62 »

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #96 on: 06/11/2012 09:29 PM »
The question is whether you want to emphasize doing it sooner, sending off a "minimally modified" Dragon, or you whether you want to wait untill you built a purpose-built, somewhat Dragon derived, Mars vehicle.

Clearly, the purpose-built lander will be a better vehicle...   The only thing we're talking about here is whether the value of sending off the minimally modified Dragon is worth the expense, and how they'll fund it.

Since it's SpaceX's vehicle and rockets, my estimate is "yes" even if it's on their own $, but that with some creative thinking they can even get some or all of the $ from interested parties.

How minimal is "Minimal" depends on the mission they'll decide to do.
a) one-way trip
b) two-way trip
c) landing

Each of these has different amounts of value in the categories we discussed above. In case of EDL there is value even if there's only partial success.


They don't have the money or resources to spare for such a mission.   They have other commitments to keep before there is "free time" for such a mission.

And there is no value for just EDL because there is no data returned for no or partial success.

Some objective thinking needed about Spacex, instead of assuming Spacex can and will do everything.
« Last Edit: 06/11/2012 09:52 PM by Jim »

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #97 on: 06/11/2012 11:01 PM »
The question of whether a Red Dragon style mission should use a near-stock Dragon or a Dragon-derived Mars lander probably comes down to cost vs benefit.

SpaceX has Mars as a prime driver.  And they want it within their lifetime.

So cost to them is more than just $.   It's also "how long will it take", and "how many resources (e.g. development team time) does it require".

As Jim correctly points out - they're resource limited in many ways.  So suppose a purpose-built lander is more cost effective, but can only happen in 6 years, whereas a minimally-modified one can be launched in 2.   That's 4 years of advanced knowledge, and that's tangible, even if not in "straight" dollars.

Also, remember that cost != price.   Their price incorporates amortized equipment, overhead + profit.   The incremental cost of another rocket or another capsule, especially when they are masters of their own schedule, is going to be a lot lower.

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Offline DaveH62

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Re: A Dragon derived general purpose Mars lander?
« Reply #98 on: 06/12/2012 12:17 AM »
I think the best Mars financial model is dependent on continued commercial success, and winning part of commercial crew.
At that point they will have the credibility to sell a NASA science mission.

That still doesn't mean the vehicle can perform the mission.
Correct.

Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #99 on: 06/12/2012 12:22 AM »
but can only happen in 6 years, whereas a minimally-modified one can be launched in 2. 

No, that is my point, they can't do it in 4 years much less two.

Offline DaveH62

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Re: A Dragon derived general purpose Mars lander?
« Reply #100 on: 06/12/2012 02:00 AM »
but can only happen in 6 years, whereas a minimally-modified one can be launched in 2. 

No, that is my point, they can't do it in 4 years much less two.
TBD

Offline A_M_Swallow

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Re: A Dragon derived general purpose Mars lander?
« Reply #101 on: 06/12/2012 02:42 AM »
SpaceX listed on a stock market may find that a long term mission with little profit is unpopular with its shareholders.  Fortunately there is an easy way for Elon Musk to solve this problem - set up MarsX.  MarsX can contract SpaceX to build and launch the spacecraft.

Offline rst

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Re: A Dragon derived general purpose Mars lander?
« Reply #102 on: 06/12/2012 04:22 AM »
SpaceX listed on a stock market may find that a long term mission with little profit is unpopular with its shareholders.  Fortunately there is an easy way for Elon Musk to solve this problem - set up MarsX.  MarsX can contract SpaceX to build and launch the spacecraft.

After a SpaceX IPO, Musk might still retain enough voting rights to keep control of the company, as Zuckerberg has with Facebook, or (much earlier) Henry Ford did with Ford.  This doesn't necessarily mean a majority of the shares of common stock; both Zuck and Ford did it in part by having a class of "insider-only" shares with enhanced voting rights.  (Elon's certainly aware of these situations, and I think he's at least hinted in public that he's likely to try the same with SpaceX.)

Companies with this sort of arrangement (Facebook now, possibly SpaceX in the future) are still required to regularly disclose information on their financial results and general health.  But if there are shareholders who don't like those reports, they might as well sell; they can complain, but they have no legal recourse.
« Last Edit: 06/12/2012 04:25 AM by rst »

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #103 on: 06/12/2012 05:44 AM »
whether a Red Dragon style mission should use a near-stock Dragon or a Dragon-derived Mars lander probably comes down to cost vs benefit.
So cost to them is more than just $. 

The incremental cost of another rocket or another capsule, especially when they are masters of their own schedule, is going to be a lot lower.
If they have an assembly line pushing out 20-40 cores per year (they have stated that they want to achieve this in the next few years) then there may occasionally be a time when they have some extra hardware laying around without a customer.  Questions emerge at that point:.

1) What's better value: To leave the hardware in a warehouse until a customer maybe shows up?  Or to collect impressive publicity and advertising (such as an X-prize competition on a donated Mars launch)?  Will the current excess hardware be obsolete soon anyway? 

2) Would Elon himself be the customer and finally launch "Mars Oasis"?

3)  Consider a "standing army" versus a "marching army".  Keep them moving and accomplishing things or they'll be more expensive and less keen. 
« Last Edit: 06/12/2012 10:19 PM by go4mars »
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Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #104 on: 06/12/2012 08:58 AM »
If you can tell me who the customers are for these "20 to 40 cores per year" I'll start to believe your premise. SpaceX are smart people. There is no way they would build a large number of cores without customers.
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Offline Lampyridae

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Re: A Dragon derived general purpose Mars lander?
« Reply #105 on: 06/12/2012 11:04 AM »
I've already said that I think an untouched Dragon is a poor choice. My (amateur) thoughts about what a Dragon derived design could be like would be:

1. Keep the current Dragon heat shield and mold line
2. Use the current thrusters and Super Dracos for an all propulsive landing
3. Get rid of the pressure vessel and have a backshell which separates
4. Jettison the heat shield before braking to reduce landing mass and allow the super Dracos to point straight down
5. Replace the trunk with a cruise stage.

This means essentially a new spacecraft, but it means the payload is exposed to the Martian environment on landing and can  be offloaded if required.

My (amateur) thoughts:

1. Not going to happen. CO2 atmosphere poses very different issues to an N2 one. This is why Viking and on used 70 degree cones. The Russians thought Mars had an N2 atmosphere; this is how they lost their early probes.
2. Would require some degree of modification due to supersonic starts, but possible. Fuel requirement would be large.
3. Likely in any case.
4. It would be dumb not to jettison the heat shield.
5. Better to mount the trunk up front and launch inside a fairing.

All this really gets you is a MSL-sized payload, because we still need better chutes, inflatable decelerators and other tricks to land anything bigger... and as Jim says - where is the market?

My (professional) thoughts:
Aiming for Mars is more about branding at the moment than company goals. Yes, in 20 years SpaceX may be in a position to do such things. Where there is no market, one create a market. But not too early - anybody remember a thing called an Apple Newton?
« Last Edit: 06/12/2012 11:05 AM by Lampyridae »
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Offline wolfpack

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Re: A Dragon derived general purpose Mars lander?
« Reply #106 on: 06/12/2012 01:15 PM »
If they have an assembly line pushing out 20-40 cores per year (the have stated that they want to achieve this in the next few years) then there my occasionally be a time when they have some extra hardware laying around without a customer.

No, they won't. Do Boeing or Airbus have extra airplanes laying around waiting for a customer?

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #107 on: 06/12/2012 01:28 PM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.
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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #108 on: 06/12/2012 02:49 PM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.

No, production is order based.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #109 on: 06/12/2012 04:36 PM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.

No, production is order based.

In modern facilities, correct.  But the production capacity is there.  So the incremental cost to make one more article for internal consumption is low, especially when flex-scheduled to a time when orders are low.
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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #110 on: 06/12/2012 04:42 PM »

In modern facilities, correct.  But the production capacity is there.  So the incremental cost to make one more article for internal consumption is low, especially when flex-scheduled to a time when orders are low.

 Which is applicable to any production facility, which is meaningless since it still doesn't mean it will happen.  The cost will still be too high.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #111 on: 06/12/2012 04:51 PM »
Which is applicable to any production facility, which is meaningless since it still doesn't mean it will happen.  The cost will still be too high.

Yes and no - it's applicable to any production facility, but useful only when the producer is also the consumer, and only when the producer is vertically integrated, or else most of the benefit is lost.

Whether it's too high for them is TBD.  It depends on what value *they* attribute to a "as soon as possible" Mars mission.
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Offline Jim

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Re: A Dragon derived general purpose Mars lander?
« Reply #112 on: 06/12/2012 05:07 PM »
but useful only when the producer is also the consumer,

They are no more the consumer than ULA is for Atlas or Delta

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #113 on: 06/12/2012 05:31 PM »
but useful only when the producer is also the consumer,

They are no more the consumer than ULA is for Atlas or Delta

I read this as saying that SpaceX are not interested in using its rockets for their own Mars missions - yes?
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Offline wolfpack

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Re: A Dragon derived general purpose Mars lander?
« Reply #114 on: 06/12/2012 06:09 PM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.

Maybe for the "pieces-parts" makers if they have order cancellations, but not for a systems integrator. No one starts building an airplane without signed orders for said airplane. I'm certain the same applies for spacecraft and launch vehicles.

Another thing to consider is that, if SpaceX becomes publicly owned, it will have a Board of Directors that has to approve funding for projects (in a broad sense). If there's no return on money spent flying to Mars, then why would they approve it?

SpaceX has enough on their plates right now with redesigning F9, meeting CRS obligations, and competing for CCDev on its "anything-but-even" playing field.

Offline docmordrid

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Re: A Dragon derived general purpose Mars lander?
« Reply #115 on: 06/12/2012 07:08 PM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.
>
Another thing to consider is that, if SpaceX becomes publicly owned, it will have a Board of Directors that has to approve funding for projects (in a broad sense). If there's no return on money spent flying to Mars, then why would they approve it?

As previously noted ad nauseum, even if SpaceX goes IPO there can issue both voting and non-voting stock. If Musk holds 50.1% of the voting stock, even if it's only 10% of all the stock sold, he retains total control of the company. .

Quote
SpaceX has enough on their plates right now with redesigning F9, meeting CRS obligations, and competing for CCDev on its "anything-but-even" playing field.

Sounds like v. 1.1 is about finished given they're going to fly it with flt. 6, and with 1,800+ people and still hiring I find it difficult to believe they can't walk and chew gum.
« Last Edit: 06/12/2012 07:12 PM by docmordrid »
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #116 on: 06/12/2012 10:20 PM »
Very interesting this morning presentations by John Karcz from Nasa Ames (min 32:00) and M. Rover? from JPL (min 42:24) on Dragon missions to Mars.

Looks I'm not the only one that thinks Dragon looks promising as a delivery platform to Mars, at least for medium sized scientific missions.

I'd like to highlight a few points (words taken from the video between quotation marks, the rest is mine):

- About Falcon Heavy and Dragon mods needed to launch to Mars "there are some changes we should have to be made but ... they aren't too bad, they're pretty straightforward" (min 35:40).

- As we know Dragon needs to prove a number of its [yet] theoretical capabilities, but my personal impression about the Nasa personnel doing the presentations is that they are non as skeptical as some over here ... ;D

- As currently planned Ice-Dragon would land a 1 mT payload at an altitude of -3 km (MOLA ref.), but "should be able to deliver quite more than that" (min 41:10). And it could also land that tonne as high as -1.3 km (min 49:15), and achieve a 10 km accuracy (using MSL guidance techniques).

- Supersonic retro propulsion is now just TRL 2 and is the main worry for the mission planning (min 50:40).

- Dragons heat-shield is expected to be able to endure a 6 km/s entry into the martian atmosphere.

- Red Dragon's ballistic coefficient will be 450 kg/m2 (min 48:06) (add entry mass 7.2 km/s and diameter 3.7 m, and that gives an hypersonic Cd of ~1.5).

- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing mach 2.24. Deceleration will reach 7 g.

- For payload deployment the three apertures of a Dragon capsule (instrument bay included) should suffice for many things but if that's not enough, and given that the shell of the capsule was designed for containing the pressure of a full atmosphere and for these mission that's not a worry, it should be possible to "put significant holes in that capsule with fairings over them ..."  (min 01:25:40).

- Dragon's propellant capacity "is modular and they have the capacity to put quite a bit of propellant in the vehicle ...". By now they are considering 1.9 mT and that's enough for the missions considered (01:28:10).

- The superDracos "have a very, very wide [throttling] range" (01:29:00) (according to the previous presentation at least 5%-100%).

And there were more interesting things, but that's enough for one post.

EDIT: spelling & grammar
EDIT2: mach 2.24 before landing, not 2.24 km/s
« Last Edit: 06/13/2012 12:00 AM by charliem »

Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #117 on: 06/12/2012 10:24 PM »
if SpaceX becomes publicly owned, it will have a Board of Directors that has to approve funding for projects (in a broad sense).
SpaceX already has a board of directors.  The dominant holders of voting shares select the directors.  Unsurprisingly, 2 of the directors have the last name "Musk". 
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Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #118 on: 06/12/2012 10:28 PM »
just about every type of factory occasionally has surplus inventory to deal with... It sounds like this is the production model for SpaceX.
Maybe for the "pieces-parts" makers if they have order cancellations, but not for a systems integrator.
Which would you define SpaceX as? 

I would suggest that they are essentially both.  I don't know exactly what they buy externally, but walking around their factory convinced me that it probably isn't much.
« Last Edit: 06/12/2012 10:30 PM by go4mars »
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Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #119 on: 06/12/2012 10:32 PM »
Very interesting this morning presentations by John Karcz from Nasa Ames (min 32:00) and M. Rover? from JPL (min 42:24) on Dragon missions to Mars.

Looks I'm not the only one that thinks Dragon looks promising as a delivery platform to Mars, at least for medium sized scientific missions.

I'd like to highlight a few points (words taken from the video between colons, the rest is mine):

- About Falcon Heavy and Dragon mods needed to launch to Mars "there are some changes we should have to be made but ... they aren't too bad, they're pretty straightforward" (min 35:40).

- As we know Dragon needs to prove a number of its [yet] theoretical capabilities, but my personal impression about the Nasa personnel doing the presentations is that they are non as skeptical as some over here ... ;D

- As currently planned Ice-Dragon would land a 1 mT payload at an altitude of -3 km (MOLA ref.), but "should be able to deliver quite more than that" (min 41:10). And it could also land that tonne as high as -1.3 km (min 49:15), and achieve a 10 km accuracy (using MSL guidance techniques).

- Supersonic retro propulsion is now just TRL 2 and is the main worry for the mission planning (min 50:40).

- Dragons heat-shield is expected to be able to endure a 6 km/s entry into the martian atmosphere.

- Red Dragon's ballistic coefficient will be 450 kg/m2 (min 48:06) (add entry mass 7.2 km/s and diameter 3.7 m, and that gives an hypersonic Cd of ~1.5).

- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing 2.24 km/s. Deceleration will reach 7 g.

- For payload deployment the three apertures of a Dragon capsule (instrument bay included) should suffice for many things but if that's not enough, and given that the shell of the capsule was designed for containing the pressure of a full atmosphere and for these mission that's not a worry, it should be possible to "put significant holes in that capsule with fairings over them ..."  (min 01:25:40).

- Dragon's propellant capacity "is modular and they have the capacity to put quite a bit of propellant in the vehicle ...". By now they are considering 1.9 mT and that's enough for the missions considered (01:28:10).

- The superDracos "have a very, very wide [throttling] range" (01:29:00) (according to the previous presentation at least 5%-100%).

And there wer more interesting things, but that's enough for one post.

Thank you!

The large increase in available propellant (versus the other Dragons) and the very high velocity at initial retropropulsion does answer some of the criticisms pretty strongly.

Also, the 7gee acceleration means that 1) they may have very low gravity losses) and 2) they might be planning on sticking the landing (ballsy).
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #120 on: 06/12/2012 10:39 PM »
To hear about the technical challenges still ahead for Dragon look from min 50:20 into the video.

Well Go4mars, all this talking by people with much better access to the real specs gives me hope, but let's try not to be too optimistic.

After all the main obstacle to reach Mars is not technology, but money ... :-\

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #121 on: 06/12/2012 10:43 PM »
Technology is still a pretty big one, to be honest. Mars is really, really hard. Even if you throw a trillion dollars into it.
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Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #122 on: 06/12/2012 11:32 PM »
...
- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing 2.24 km/s. Deceleration will reach 7 g.
...
Actually, that's Mach 2.24, NOT 2.24 km/s! Huge difference! Easy mistake, though. :)

Mach 2.24 is less than 1km/s.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #123 on: 06/12/2012 11:59 PM »
...
- The SuperDraco engines will start only 800 m from the surface, while the capsule is doing 2.24 km/s. Deceleration will reach 7 g.
...
Actually, that's Mach 2.24, NOT 2.24 km/s! Huge difference! Easy mistake, though. :)

Mach 2.24 is less than 1km/s.

Thanks Robotbeat, you're right. I'll edit it right away.

Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #124 on: 06/13/2012 12:09 AM »
When converting Mach 2.4 to km/s, are those local Mach numbers?

Regarding sticking the landing, while I think that's possible on Earth (saves propellant, reduces the influence of wind), it is less likely on Mars - the final terrain is not known and definitely not obstacle free, gravity losses are less, and wind influence is less.

But otherwise - Yeeeha!
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Offline jabe

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Re: A Dragon derived general purpose Mars lander?
« Reply #125 on: 06/13/2012 12:40 AM »
the final terrain is not known and definitely not obstacle free,
curious,
define "not known"...MRO has pretty good resolution..Apollo had worse resolution maps then what we have for mars..
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Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #126 on: 06/13/2012 01:20 AM »
the final terrain is not known and definitely not obstacle free,
curious,
define "not known"...MRO has pretty good resolution..Apollo had worse resolution maps then what we have for mars..
jb

If you're coming to land on a pad on Earth, it's flat concrete with a homing beacon.

With all of MRO's capabilities, it has a roughly 1 m resolution, enough to get a good understanding of 5 m ground features.  The laser altimeter is worse.


Sure, Apollo was worse, but we're not yet at the point where we can stick the landing without surveying the surface from the landing craft and reacting to the findings.

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Offline billh

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Re: A Dragon derived general purpose Mars lander?
« Reply #127 on: 06/13/2012 02:05 AM »
The SuperDraco engines will start only 800 m from the surface, while the capsule is doing mach 2.24.

D***!

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #128 on: 06/13/2012 02:18 AM »
The SuperDraco engines will start only 800 m from the surface, while the capsule is doing mach 2.24.

D***!
You should watch the presentation. It's really not TOO bad. In the proposed flight profile that the second speaker presented, the Dragon would enter a "constant descent velocity" mode at ~40m above the surface and descend at 2.4m/s until landing, kind of like MSL. That means it's okay if the altimeter (or range-finder) is off by a couple dozen meters.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #129 on: 06/13/2012 02:36 AM »
When converting Mach 2.4 to km/s, are those local Mach numbers?

I think so.

You can calculate the speed of sound from temperature and atmosphere composition. For the martian atmophere is: ss = sqr (247.42*T)   (T in ºK, ss in m/s).

At 3 km below MOLA the mean temperature is 245 ºK so the average speed of sound should be around 246 m/s (it swings quite a bit from day to night, summer to winter, and even with dust storms).

So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #130 on: 06/13/2012 02:39 AM »
When converting Mach 2.4 to km/s, are those local Mach numbers?

I think so.

You can calculate the speed of sound from temperature and atmosphere composition. For the martian atmophere is: ss = sqr (247.42*T)   (T in ºK, ss in m/s).

At 3 km below MOLA the mean temperature is 245 ºK so the average speed of sound should be around 246 m/s (it swings quite a bit from day to night, summer to winter, and even with dust storms).

So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!

To be honest, I'd bet they mean Mach 1 = 343m/s.
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #131 on: 06/13/2012 02:49 AM »
For those who think that turning Dragoncrew in a general purpose mars lander is a wacky idea, I wonder what they'll think about this group of people presentation (the most "interesting" part is from min 17:00)?

http://www.livestream.com/marsconcepts2012_hep/video?clipId=pla_cd665151-0af9-4099-a2b4-d6ceee9e084c

Offline billh

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Re: A Dragon derived general purpose Mars lander?
« Reply #132 on: 06/13/2012 02:54 AM »
Depending on which of you is right about what Mach 1 is on Mars, that means the engines start firing only 1 or 2 seconds before impact would occur! And the entire deceleration at 7gs would take place in 4 or 5 seconds. That's steely-eyed missile man stuff, for sure.

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #133 on: 06/13/2012 03:29 AM »
So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!

Those numbers can't be right. I've rechecked them against the presentation and this time it's not my mistake.

In one of the slides we can read: "* Performs a direct transition to powered flight at Mach 2.24 800 m above ground utilizing SuperDraco thrusters".

That speed can't be vertical, because then a simple v=sqr(2.h.a) says that the minimum distance to brake from 550 m/s to zero at 7 gees is 2200 meters, so the only possibility that remains is a very very shallow descent.

???

Offline Downix

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Re: A Dragon derived general purpose Mars lander?
« Reply #134 on: 06/13/2012 04:18 AM »
I don't know.  But just about every type of factory occasionally has surplus inventor to deal with.  Cars, toys, furniture...

It sounds like this is the production model for SpaceX, though I'm not saying I know for sure either way.

No, production is order based.

In modern facilities, correct.  But the production capacity is there.  So the incremental cost to make one more article for internal consumption is low, especially when flex-scheduled to a time when orders are low.
Boeing set up the Decatur factory for Delta IV to produce 48 Delta IV cores a year, so having such production capacity is nothing new.  The issue is lack of demand, which is what resulted in the ULA merger in the first place.
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Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #135 on: 06/13/2012 04:39 AM »
Boeing set up the Decatur factory for Delta IV to produce 48 Delta IV cores a year, so having such production capacity is nothing new.
I wonder how things might have been different if Boeing had produced 48 cores for a few years instead (stockpiling the extras). 

I suggest that the production cost per rocket could have been lower, that it could have had a lot of commercial use, that lead-times to launch could have decreased, and that the long-term profit could have been higher. 

Just because Boeing did it a certain way (which made some sense in the context of their main target customer and from a quality perspective), doesn't mean it is the best or only way of doing things.
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Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #136 on: 06/13/2012 04:41 AM »
So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!

Those numbers can't be right. I've rechecked them against the presentation and this time it's not my mistake.

In one of the slides we can read: "* Performs a direct transition to powered flight at Mach 2.24 800 m above ground utilizing SuperDraco thrusters".

That speed can't be vertical, because then a simple v=sqr(2.h.a) says that the minimum distance to brake from 550 m/s to zero at 7 gees is 2200 meters, so the only possibility that remains is a very very shallow descent.

???

+1, there's an inconsistency somewhere. Forgetting about gravity, that works out to be about a 70 degree angle.
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Offline meekGee

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Re: A Dragon derived general purpose Mars lander?
« Reply #137 on: 06/13/2012 05:27 AM »
Boeing set up the Decatur factory for Delta IV to produce 48 Delta IV cores a year, so having such production capacity is nothing new.  The issue is lack of demand, which is what resulted in the ULA merger in the first place.

So in this case, IF Boeing wanted to self-fund their own Mars mission, and IF Boeing was vertically integrated, then the cost to them would have been lower than the price of a launcher.

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Offline MATTBLAK

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Re: A Dragon derived general purpose Mars lander?
« Reply #138 on: 06/13/2012 06:07 AM »
They could do a Mars mission launch campaign from 'mass-produced' Delta IV-H if the funding and demand were there. Upgrading the D-4H to lift nearly 50 tons to orbit would be relatively simple (in Rocket Science terms) and 'relatively' cheap. With enough launchpads, D4-H's and Falcon Heavies could be launched in 'salvos' to assemble a mission each 26 month launch window.

Other challenges are the interplanetary Hab Modules - coming and going from Mars - and all their ancilliary needs including radiation protection, the Ascent Vehicle and surface systems including power, Crew Rover vehicles and scientific tools and equipment.

I'd love to see someone do a *New* detailed paper on a Mars mission architecture using available boosters - D4-H - and soon-to-be-available Falcon Heavy. Then, do a rational, credible design for all the other gear as mentioned above, do a sober cost analysis - which always gets laughs or starts arguments - then also build in 'Plan B' and 'Plan C' options...

So many Mars Mission designs have come before!! Some are mostly credible, others only partly so. Nothing seems to divide 'Space Cadets' (like me) more passionately than how to do a Mars mission. Start with a (relatively) clean sweep, crunch the numbers and come forward with a new, rebranded 'Man On Mars' mission design that has looked hard at the 40+plus years of studies done before and incorporates what has been learned. If it stands up well to the 'Giggle factor' and gets a two-thirds or more majority of positive opinion; then it will be a triumph.

Get people to Mars: Near Earth Asteroids are interesting but people and especially TV Hosts/comedians may confuse it with an old Bruce Willis movie and bore quickly. I'd love to see a (basic) Moonbase, but unless Mars is the ultimate goal, people will lose interest.

EDIT: Actually, this isn't a bad start - http://marssociety.org.au/sites/default/files/library/willson-et-al.pdf

http://www.marsdrive.com/Home
« Last Edit: 06/13/2012 06:18 AM by MATTBLAK »
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Offline Lampyridae

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Re: A Dragon derived general purpose Mars lander?
« Reply #139 on: 06/13/2012 07:15 AM »
- As we know Dragon needs to prove a number of its [yet] theoretical capabilities, but my personal impression about the Nasa personnel doing the presentations is that they are non as skeptical as some over here ... ;D

Interesting, so Dragon can manage a re-entry through a CO2 atmosphere? I wonder how cost effective it is compared to standard entry options such as MSL. Pity that it's limited to only 1mT, but it's a stepping stone to a large manned Mars lander.



EDIT: different image for MSL heatshield, original was way too big.
« Last Edit: 06/13/2012 07:16 AM by Lampyridae »
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Offline docmordrid

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Re: A Dragon derived general purpose Mars lander?
« Reply #140 on: 06/13/2012 07:53 AM »
- As we know Dragon needs to prove a number of its [yet] theoretical capabilities, but my personal impression about the Nasa personnel doing the presentations is that they are non as skeptical as some over here ... ;D

Interesting, so Dragon can manage a re-entry through a CO2 atmosphere? I wonder how cost effective it is compared to standard entry options such as MSL.

MSL's is PICA and SpaceX's is PICA-X, an evolved version they worked on with NASA Ames and which they make in-house.

http://www.airspacemag.com/space-exploration/Visionary-Launchers-Employees.html?c=y&page=3

Quote
According to Mueller, SpaceX’s material, called PICA-X, is 10 times less  expensive than the original, “and the stuff we made actually was better.”
DM

Offline douglas100

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Re: A Dragon derived general purpose Mars lander?
« Reply #141 on: 06/13/2012 08:33 AM »

Interesting, so Dragon can manage a re-entry through a CO2 atmosphere? I wonder how cost effective it is compared to standard entry options such as MSL. Pity that it's limited to only 1mT, but it's a stepping stone to a large manned Mars lander.

Thank you for your comments on my points about a Dragon derived lander.

Slightly OT:

Your point about N2 as opposed to CO2: I have never heard this idea before, that the Russians lost the 71 landers by believing that the Martian atmosphere was nitrogen. Do you have any references? Remember that they claim that the Mars 3 lander reached the surface and survived a short time.

It's not clear to me why the molecular makeup of the atmosphere would have much affect on entry. I would have thought that the temperature and density profiles would be much more important. Remember that CO2 is about 50 percent denser than nitrogen under the same conditions. If the Russians had designed for a nitrogen atmosphere you would think that the fact it was actually CO2 would have made landing easier.
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Offline go4mars

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Re: A Dragon derived general purpose Mars lander?
« Reply #142 on: 06/13/2012 01:33 PM »
Are we even confident that the heat shield shape would be the same for a red dragon? 

Would the superdraco plume effects increase drag by concentrating atmosphere toward the heatshield, subduing the noted historical shape effect through active compensation? 
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Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #143 on: 06/14/2012 06:34 PM »
The info disclosed these days during the Concepts and Approaches meeting is inspiring. It also gave us some more bits of data with which nourish speculations (don't know whether that's good or bad, but fun, yes that is ;D).

If Red Dragon can really land 1 mT of payload on Mars, I wonder how hard could be to expand it somewhat.

Red Dragon is said to start the propulsive deceleration 800 m from the surface, flying at an angle of, maybe, 10-15 deg, and doing about mach 2.2 (~540 m/s), burning a maximum of 1,900 kg of propellants.

From some BOE calcs seems that increasing the fuel to 3,400 kg max payload should reach 2 mT, although the speed at which the engines had to be started would also grow, to mach 3.1 (~765 m/s).

One of the presenters, from Nasa Langley I think, commented that they were not aware of any test for supersonic retro-propulsion, but that they thought it was the most promising EDL technology.

Another one from Nasa Ames talked a bit about a possible future sample recovery mission using also a Dragon.

Well, I suspect but don't know for sure, that a SuperDraco can do its job against a mach 2.2 flow (or 3.1). Anyhow it seems that we are not going to have to wait too much for experimental proof (or disproof). There's a lot of people interested.

And this time the idea to take two MER like rovers and a MAV rocket to Mars within a Dragon wasn't mine ... ;)

Offline Robotbeat

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Re: A Dragon derived general purpose Mars lander?
« Reply #144 on: 06/14/2012 06:55 PM »
BTW, for the sort of manned Mars mission concepts which come out of NASA, the payloads require at least: 1) supersonic retropropulsion or 2) a deployable heatshield. This is true even with the really big fairings. The SuperDracos are so powerful that they could be strong enough to be put on even a manned-class lander for supersonic retropropulsion (at the expense of higher gravity losses).
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Online MikeAtkinson

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Re: A Dragon derived general purpose Mars lander?
« Reply #145 on: 06/14/2012 07:11 PM »
So the Dragon capsule has to start its SuperDraco engines at ~550 m/s, 800 m before crashing, and decelerate at 7 g ... what a ride!!

Those numbers can't be right. I've rechecked them against the presentation and this time it's not my mistake.

In one of the slides we can read: "* Performs a direct transition to powered flight at Mach 2.24 800 m above ground utilizing SuperDraco thrusters".

That speed can't be vertical, because then a simple v=sqr(2.h.a) says that the minimum distance to brake from 550 m/s to zero at 7 gees is 2200 meters, so the only possibility that remains is a very very shallow descent.

???

+1, there's an inconsistency somewhere. Forgetting about gravity, that works out to be about a 70 degree angle.

Could they have meant 800m above the datum, which would mean landing 1400m below the datum.

Add in some constant velocity descent (which was mentioned) and we have a landing at about 1500m below the datum.

Offline charliem

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Re: A Dragon derived general purpose Mars lander?
« Reply #146 on: 06/14/2012 09:58 PM »
Could they have meant 800m above the datum, which would mean landing 1400m below the datum.

Add in some constant velocity descent (which was mentioned) and we have a landing at about 1500m below the datum.

The written paragraph is clear: "800 m above ground" (sic).

And it's not necessary after all.

I've done some more math. It seems that indeed the flight path of a Dragon would be really flat, under 20 degrees while crossing the 0 altitude MOLA reference.

You can see it in this graphic for the entry path: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=28668.0;attach=392917

Vertical and horizontal scales are very different. Once you compensate for that it's evident how shallow the whole trajectory is. Quite different that an earth reentry.

Following that path 2,200 meters ahead on the final approach mean only about 500 or 600 of descent.

Offline modemeagle

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Re: A Dragon derived general purpose Mars lander?
« Reply #147 on: 06/15/2012 12:28 AM »
Could they have meant 800m above the datum, which would mean landing 1400m below the datum.

Add in some constant velocity descent (which was mentioned) and we have a landing at about 1500m below the datum.

The written paragraph is clear: "800 m above ground" (sic).

And it's not necessary after all.

I've done some more math. It seems that indeed the flight path of a Dragon would be really flat, under 20 degrees while crossing the 0 altitude MOLA reference.

You can see it in this graphic for the entry path: http://forum.nasaspaceflight.com/index.php?action=dlattach;topic=28668.0;attach=392917

Vertical and horizontal scales are very different. Once you compensate for that it's evident how shallow the whole trajectory is. Quite different that an earth reentry.

Following that path 2,200 meters ahead on the final approach mean only about 500 or 600 of descent.

Finally, a chance to post on this topic!!

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