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NASA Human Landing System


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40 minutes ago, sevenperforce said:

We've got new legs!

And they look remarkably similar in shape to the ones shown in the most recent #dearMoon renders.

But...but there's no way SpaceX would put a seam in their heat shield! Would they? Could they? And even if they did, surely the heat shield wouldn't contact the ground directly!

I'm convinced that they are just spitballing at this point. Those new legs don't have any actual actuation path.

Lunar. Spaceship.

If it stays in the vacuum, it doesn't need actuated legs - if they can fold out and stay permanently locked in this position it would be perfectly acceptable.

For the same reason, it doesn't actually need a heatshield -  though it might actually need better insulation of the hull than just a sheet of stainless steel.

If i would be designing it, i would strip bare every aerodynamic feature i could get away with, and even shave as much weight as possible from structural frames.

It's not like this ship would have to withstand stress of Earth-to-space launch more than once. Lunar landing and launch? Pfftt.

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4 minutes ago, Scotius said:

Lunar. Spaceship.

If it stays in the vacuum, it doesn't need actuated legs - if they can fold out and stay permanently locked in this position it would be perfectly acceptable.

For the same reason, it doesn't actually need a heatshield -  though it might actually need better insulation of the hull than just a sheet of stainless steel.

If i would be designing it, i would strip bare every aerodynamic feature i could get away with, and even shave as much weight as possible from structural frames.

It's not like this ship would have to withstand stress of Earth-to-space launch more than once. Lunar landing and launch? Pfftt.

I agree with all of the above.

My point is that they now have a similar OML to the regular starship, which would suggest commonality, but there is none.

I will point out, however, that they still need to actuate in the first place. They can't launch deployed like that -- the aero loads would be impossible.

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13 minutes ago, sevenperforce said:

I agree with all of the above.

My point is that they now have a similar OML to the regular starship, which would suggest commonality, but there is none.

I will point out, however, that they still need to actuate in the first place. They can't launch deployed like that -- the aero loads would be impossible.

One possible solution would be... to launch without any legs :)

Then send another (regular) Spaceship with legs in the cargo hold, do rendez-vous in LEO, plug legs into Lunar Spaceship using spacewalk or a robotic arm and be on your merry way :)

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50 minutes ago, sevenperforce said:

I wonder how many refueling missions this will take and whether they will have reserves to attempt an aerocapture return to LEO.

Or if they would refill in LLO, and use a dedicated tanker?

Tug/ferry architecture is actually pretty sensible.

Launch a tanker that can survive multiple pass aerocapture, never does EDL. Fill it, then sent to TLI. It could have larger tanks, too. If they had a 1500t wet tanker, it could deliver about 380t of props to NRHO and still get home. That's more than enough props for a Lunar SS round trip from Gateway to the surface and back (has ~1400m/s left over).

They could leave another in NRHO as a depot, actually, and only use what they need to maximize down and up mass by not taking props to the surface and back.

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Wow. That's either incredibly incompetent or extremely arrogant to assume that they could submit a proposal that doesn't comply with the rules and still expect to get an award.

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1 hour ago, sevenperforce said:

I wonder how many refueling missions this will take and whether they will have reserves to attempt an aerocapture return to LEO.

NASA only accepted the high-risk on-orbit refuel development because they're all proposed to be completed in LEO. Honestly I think this partly depends on whether they'll launch Starship by itself to LEO or would they have Superheavy to lift it... maybe it'd only need like one refuel, if they don't reuse Superheavy ? Or if it's no superheavy then yes that'd be a lot of refuel needed (they basically get the same fuel fraction per launch and I don't think we have an SSTO here).

Reading the selection documentation, honestly seems like a no-brainer to put SpX again, this is basically CCDev next-stage (and it has about as much budget as CCDev did). If they had more hands for the contestants honestly then any of the three might get it, but with how it played out only the one who was ready was chosen.

Edited by YNM
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Dynetics required refilling operations as well, and long term, "sustainable" and reuse were supposed to be part of all the submissions, so either National Team adds that later, or they skip it (either not good), and whatever the method is, it's still a requirement all 3 have to figure out.

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4 minutes ago, tater said:

long term, "sustainable" and reuse were supposed to be part of all the submissions, so either National Team adds that later, or they skip it (either not good)

Probably a bit of both. They basically wanted to sell a lander for HLS, in contrast with SpX which sees HLS as a side project (their vehicle goes up regardless how it goes on HLS) and Dynetics which wants to tap off the extra moon missions onwards.

"Sustainable" here is basically saying that you can continue make your things happen for decades to come and not have a problem anywhere (incl. if we stop buying it). If it's reusable then there's a mix of longevity and production, if it's disposable then that's on production.

3 minutes ago, JoeSchmuckatelli said:

Has there ever been in-orbit refueling of anything on the scale of what's needed? 

There's a good reason it's called "high risk". Even then SpX has the upper hand TRL-wise since it's already at hardware test phase, albeit very early.

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5 minutes ago, YNM said:

"Sustainable" here is basically saying that you can continue make your things happen for decades to come and not have a problem anywhere (incl. if we stop buying it). If it's reusable then there's a mix of longevity and production, if it's disposable then that's on production.

I've understood all the talk at least (in this case fro Bridenstine among others) that they mean not flying throw away spacecraft. The purpose is to eventually have a facility on the surface that is more akin to ISS.

A long term goal obviously ISRU of water there. BO seems to reach this just by "land there, then eventually they mine water and refill a hydrolox lander" I guess.

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From the report:

"Whilse I recognize that return of cargo and scientific payloads may be limited by Orion's current capabilities"

Burn, lol. I guess Starship will just have to tranship them for return to earth in another starship then.

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15 minutes ago, JoeSchmuckatelli said:

Has there ever been in-orbit refueling of anything on the scale of what's needed? 

Progresses semi-regularly top-up fuel tank on ISS (in Zvezda module). Station needs regular orbit-raising boosts, plus there's always the possibility of a collision risk requiring a change of orbit. Generally station needs 7 tons of fuel per year for those tasks.

Not sure if it counts as large scale refueling, but it is being done regularly.

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20 minutes ago, JoeSchmuckatelli said:

Has there ever been in-orbit refueling of anything on the scale of what's needed? 

Not remotely. We're talking over a thousand tons of propellant transfer. 

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2 minutes ago, Scotius said:

Not sure if it counts as large scale refueling, but it is being done regularly

The fact that it's done at all is cool - add 'regularly' to the equation and that gives me confidence that the knowledge is there to pull it off 

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The report has an interesting section on abort capabilities.

Basically, excess capacity in all things leads to improved survivability. Multiple redundant engines is a plus. Excess propellant gives greater ability to return to rendezvous orbits. Greater consumables storage gives much greater ability to linger waiting for a rescue.

This was a significant strength of the lunar starship proposal which stands in stark contrast to the criticisms it gets as a launch vehicle.

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12 minutes ago, RCgothic said:

Basically, excess capacity in all things leads to improved survivability. Multiple redundant engines is a plus. Excess propellant gives greater ability to return to rendezvous orbits. Greater consumables storage gives much greater ability to linger waiting for a rescue.

All the vehicles have to deal with the abysmal capabilities of Orion.

This means that abort contingency means returning to NRHO (with any relevant phasing issues). If safety was really a principle concern, it strikes me they would need a crew vehicle capable of LLO since that maximizes abort opportunities.

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8 minutes ago, RCgothic said:

This was a significant strength of the lunar starship proposal which stands in stark contrast to the criticisms it gets as a launch vehicle.

I mean the criticism is whether it can work with existing payload demands or not, or would it makes excess supply. (that does work to lower cost though so a good thing in a way.)

NASA considers the fact that the vehicle in itself is supposed to work as-is in a commercial variant as 'highly sustainable', compare and contrast with BOs which really you wouldn't have someone else pay for it, with at most what they have is take the technology developed on it and put it in a different product that's more commercialized. At least with Dynetics they were considering fully autonomous landing platforms with the nice low-slung payload position so private entities can land stuff on the Moon using their platform as easily on their own.

31 minutes ago, tater said:

I've understood all the talk at least (in this case fro Bridenstine among others) that they mean not flying throw away spacecraft. The purpose is to eventually have a facility on the surface that is more akin to ISS.

Yeah, that's the point of  'sustainable' exploration - an outpost on the Moon, not just 6 landings on the Moon. You *could* use throw-away spacecrafts as long as they're fit for the purpose, like on the ISS we have the myriad of resupply vehicles which we throw away after we're done, but reusability is a plus.

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Another interesting set of wording in the report is that "SpaceX's plans to self fund and assume financial risk for over half of the development and test activities as an investment in its architecture..."

That wording is interesting. "More than half". Not "three quarters of" or "the vast majority of".

SpaceX bid $2.94Bn. On the basis of the above I think it's likely that this indicates total starship development will be less than $10Bn in total.

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