Author Topic: NASA reviews progress of habitat development for deep-space exploration  (Read 89207 times)

Offline Chalmer

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Is there any reason that the lander isn't completely reusable? Otherwise, this moon program is going to be slow going with only one SLS launch a year. I'm assuming that the recent requirement to put the Orion on a new launch vehicle is to free up SLS launches for delivering DSG parts?

Can the lunar lander be lofted by anything else?

What lunar lander? There is none.

DSG phase one plans so far is a Bus+A Hab+An Airlock. All co-launched with Orion on SLS on EM-2, EM-3 and EM-5 respectively.

Online brickmack

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What lunar lander? There is none.

Referring to the Boeing DSG concept, which includes a lander.

Is there any reason that the lander isn't completely reusable? Otherwise, this moon program is going to be slow going with only one SLS launch a year

Mass, most likely. Single stage to lunar surface and back is rather harder. I would question how much harder though. Looking at the Apollo LM for example (since its the only such thing flown...), if you combine the total dry and gross masses into a single stage, it has a pretty decent delta v capacity already, and it can match the round-trip delta v of the Apollo LM (4720 m/s) if it can shed "only" 940 kg of dry mass. I'd take a guess that eliminating the extra weight required in a 2 stage system (separate ascent engine, tanks, and plumbing, separation systems, etc) would have very nearly gotten them to the point of it being viable, requiring only a smallish increase in mass, but Apollo was so mass limited they needed to shave off every milligram so it made sense. With modern materials and higher performance engines, it should be even easier. I'd agree with your statement, a few kilograms mass reduction aren't worth tossing any prospect of economic viability or useful flightrate.

I'm assuming that the recent requirement to put the Orion on a new launch vehicle is to free up SLS launches for delivering DSG parts?

There is no such requirement, just a congressionally mandated study into alternatives, to which NASA basically replied "lol, not happening"

Can the lunar lander be lofted by anything else?

Boeings concept should barely fit into Vulcan-ACES, and quite easily into FH's and New Glenn's payload mass capacity. Fairing volume is harder, its a pretty wide payload. New Glenn can support it, FH cannot, Vulcan ACES probably could aerodynamically but it would require a new fairing (a 7 meter fairing was determined feasible for Atlas V, so on a 5.4 meter core it should be fine)

Offline TrevorMonty

A DSG based reusable single stage lander needs 5-5.5km/s for round trip. For methane its 3.5t fuel per 1t dry mass, LH its 2.3t.


Online KelvinZero

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A DSG based reusable single stage lander needs 5-5.5km/s for round trip. For methane its 3.5t fuel per 1t dry mass, LH its 2.3t.
Gripe: I wish I could respond with "ISRU!"

It's frustrating that 45 years after Apollo, 8 years after LCROSS, water ISRU and even basic oxygen ISRU can't be a serious part of the conversation. We just haven't done the necessary homework. We absolutely could have, but we didn't.

One of the reasons Im am enthusiastic about this DSH is that even if done for the wrong reasons, politicians will be embarrassed by astronauts twiddling their thumbs, so will squeeze out some money for in space projects so they have something to do. Finally, some budget may be allowed to dribble to the ISRU tech development HSF really needs to make sense.

Online brickmack

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ISRU on the moon would be pretty easy. The only issue is infrastructure, we need a way to completely robotically deploy and test this without humans on-site, otherwise if you choose the wrong location or theres a mechanical failure before redundancy is established, a few astronauts die. Which means either a completely separate design (expensive), or a vehicle large enough to do useful missions without ISRU and still be reusable but could be enhanced by it later (like 2016ITS, ~40 tons to lunar surface and back without prop transfer)

Offline Nibb31

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Mass, most likely. Single stage to lunar surface and back is rather harder. I would question how much harder though. Looking at the Apollo LM for example (since its the only such thing flown...), if you combine the total dry and gross masses into a single stage, it has a pretty decent delta v capacity already, and it can match the round-trip delta v of the Apollo LM (4720 m/s) if it can shed "only" 940 kg of dry mass. I'd take a guess that eliminating the extra weight required in a 2 stage system (separate ascent engine, tanks, and plumbing, separation systems, etc) would have very nearly gotten them to the point of it being viable, requiring only a smallish increase in mass, but Apollo was so mass limited they needed to shave off every milligram so it made sense. With modern materials and higher performance engines, it should be even easier. I'd agree with your statement, a few kilograms mass reduction aren't worth tossing any prospect of economic viability or useful flightrate. (a 7 meter fairing was determined feasible for Atlas V, so on a 5.4 meter core it should be fine)

There were other reasons for staging the LM, notably redundancy for abort modes, restartability, and protecting the ascent engine from landing damage.

Offline redliox

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Is there any reason that the lander isn't completely reusable? Otherwise, this moon program is going to be slow going with only one SLS launch a year. I'm assuming that the recent requirement to put the Orion on a new launch vehicle is to free up SLS launches for delivering DSG parts?

Can the lunar lander be lofted by anything else?

Hard to say, but maybe.  The thought that comes to mind would be Falcon Heavy or perhaps Vulcan; in both cases a lander could be cobbled together via 3 launches:
1) Core Lander (maybe resuable?)
2) Crasher Descent Stage
3) Booster to get prior 2 items to DSG locale

Fuel and replacement Descent Stages could be later ferries via Orion (or something better later).
"Let the trails lead where they may, I will follow."
-Tigatron

Online brickmack

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If Vulcan is used as the launch vehicle, suddenly the whole thing just got a lot easier. Refuel ACES in LEO, payload capacity to TLI is well beyond SLS performance and it can directly insert to cislunar orbit. Lander design can be augmented with ACES tech to increase performance, and later ACES (tanker config) launches deliver propellant for additional landing missions until surface ISRU is established. FH is nice, but nowhere near as capable

Online envy887

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If Vulcan is used as the launch vehicle, suddenly the whole thing just got a lot easier. Refuel ACES in LEO, payload capacity to TLI is well beyond SLS performance and it can directly insert to cislunar orbit. Lander design can be augmented with ACES tech to increase performance, and later ACES (tanker config) launches deliver propellant for additional landing missions until surface ISRU is established. FH is nice, but nowhere near as capable

The problem is that ACES is no closer to flying than any other reuseable transfer stage and/or lander concept.

Offline wannamoonbase

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Is there any reason that the lander isn't completely reusable? Otherwise, this moon program is going to be slow going with only one SLS launch a year. I'm assuming that the recent requirement to put the Orion on a new launch vehicle is to free up SLS launches for delivering DSG parts?

Can the lunar lander be lofted by anything else?

Hard to say, but maybe.  The thought that comes to mind would be Falcon Heavy or perhaps Vulcan; in both cases a lander could be cobbled together via 3 launches:
1) Core Lander (maybe resuable?)
2) Crasher Descent Stage
3) Booster to get prior 2 items to DSG locale

Fuel and replacement Descent Stages could be later ferries via Orion (or something better later).

I disagree with crasher stages.   I think landers need to be designed for disassembly and reuse on the surface.   Tanks will be reused for strong ISRU products.

Eventually there would be a tank farm with loads of LOx.
« Last Edit: 09/12/2017 04:41 AM by wannamoonbase »
Excited to be finally into the first Falcon Heavy flow, we are getting so close!

Offline tea monster

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The only reason that I'm asking is that if you only send a team to the surface when you launch an SLS, then you are only sending one team a year (assuming that no other launches are used for other projects). If the lander is reusable you get a lot more lunar visits in that year than one. I'm not an engineer, but I'm going to assume that the increase in science and usability will far outweigh saving a few pounds per trip.

The Apollo program got 4 flights off in one year (1969). If we are aiming for lunar 'operations' then 1 flight/1 landing per year is probably not going to fulfill that. Even if they manage to increase the flight rate to 2 per year, it's still a slog.

Also, what happens if there is an accident and a crew is stuck on the lunar surface or at the DSG?

Offline Zed_Noir

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....
Also, what happens if there is an accident and a crew is stuck on the lunar surface or at the DSG?

Call up the folks at Hawthorne for help. The best and probably the only near term option for retrieving crew stranded at the DSG or getting a lander to the DSG in time. Maybe our Amazon pal can also do these missions at a later date.

Offline tea monster

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Yes, hopefully either Bezos or Musk could make a quick rescue run.

I imagine that when making plans, that NASA won't write that into the manuals. It may be that they have a second Orion docked to the station as a lifeboat (one SLS mission down). Option two is to have an SLS booster mothballed in Florida, ready to fuel and go in case of emergencies (again, one year out of the program).

I don't know if it is possible to detach The Power and Propulsion module from the rest of the DSG if the Orion suffers a major failure. I don't know enough rocket science to calculate how much delta V you would need to change orbit to return it to LEO and dock with the ISS. It might be possible to fit it with one of those inflatable heat shields that they tested recently to shed enough velocity to dock with the ISS.

Online A_M_Swallow

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Yes, hopefully either Bezos or Musk could make a quick rescue run.

I imagine that when making plans, that NASA won't write that into the manuals. It may be that they have a second Orion docked to the station as a lifeboat (one SLS mission down). Option two is to have an SLS booster mothballed in Florida, ready to fuel and go in case of emergencies (again, one year out of the program).

I don't know if it is possible to detach The Power and Propulsion module from the rest of the DSG if the Orion suffers a major failure. I don't know enough rocket science to calculate how much delta V you would need to change orbit to return it to LEO and dock with the ISS. It might be possible to fit it with one of those inflatable heat shields that they tested recently to shed enough velocity to dock with the ISS.

SEP tugs are slow so it would take months to fly the DSG back to the ISS.

If it is unmanned an Orion can be lifted to LEO as cargo on a smaller launch vehicle. The spacecraft can then be pushed to the DSG by a second Power and Propulsion module.

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