NASA HLS (Human Landing System) Lunar Landers

[jongoff]

That was 1 ton of payload in addition to a crew cabin. A cargo-only version would have a lot more payload. And if you based your depot in a high polar LLO like you ought to for surface ops, you could probably get north of 15tons of delivered payload out of a lander that size. Possibly closer to 20-30mT. I'd have to run some numbers.

~Jon

The 1 ton payload is also in addition to sufficient propellant to fly back to EML2. If we turn Lockheed's lander into a cargo lander with 39 tons of payload, we just turned it into a bigger version of NASA's notional expendable descent stage; a ~90 ton behemoth of an expendable descent stage you'd have to get into LLO, somehow. Not a reasonable scenario without some very big propellant plants already on the moon.

The 39 tons of payload is what I got starting in LLO with a full tank of propellant, dropping down to the lunar surface, dropping that payload off, and then flying the now payloadless cargo lander back to LLO--this isn't an expendable descent stage I'm talking about. But yeah, getting a 39 ton payload to LLO would probably require in-space refueling in LEO and LLO. But you know what, if you're going to be doing a reusable lander, you pretty much already have to have in-space refueling solved, so I don't see what this is a show-stopper.

By comparison, this "behemoth" is in the same size class as a max-payload Xeus lander. And it's *way* tinier than a BFR.

~Jon

[jongoff]

Lockheed Martin's 62 ton lunar lander can only land 1 ton of payload to the lunar surface, versus the ~15 tons of this notional design. If you don't have a separate descent stage actually building the kind of base you need to enable large scale ISRU is very difficult.

That was 1 ton of payload in addition to a crew cabin. A cargo-only version would have a lot more payload. And if you based your depot in a high polar LLO like you ought to for surface ops, you could probably get north of 15tons of delivered payload out of a lander that size. Possibly closer to 20-30mT. I'd have to run some numbers.

~Jon

Yeah, if you assume the crew cabin is ~10mT of the 22mT dry mass for the LM lander (ie that the lander propulsion section is ~12mT), I get a payload drop-off capability of ~39mT using base your system in LLO. I still get 12mT of drop-off capability if you base your system out of NRHO. This is part of why I think NRHO sucks as a staging point for lunar lander missions--adding another 40% to the round-trip dV is silly.

~Jon

I think there are other factors to consider. The table below is from here.

Yes I've seen this table, and written about it before. One of the things that makes me really suspicious of their conclusions is that Orion was originally designed to survive just fine in LLO, and now all of the sudden radiators are insufficient. I haven't  had the time to go through the paper in detail, but it definitely smacks of someone having a preordained solution that they then setup strawmen to defend. As for Orion not being able to get to LLO, NASA could've solved that problem just fine with a earth departure stage that had longergevity than EUS, and having that stage do the lunar orbit insertion burn. LLO may not be sufficiently handicapped accessible for Orion/SLS, but it definitely makes a huge (factor of 3x) difference in how much cargo you can land with a reusable lander, which in my opinion ought to swamp those considerations.

~Jon

[tea monster]

Although the article states that the lander is 'reusable', only the ascent stage is reusable. Every time you want to do a surface sortie, or even send down some cargo, you have to expend an SLS launch to haul an Orion and your new descent stage out to the Gateway. So that is about 1 billion bucks a shot for your 'reusable' lander, not even taking into account how much a new descent stage will cost for each mission.

A fully reusable lander, even with a much lower payload mass, will quickly start being phenomenally cheaper when you consider how often you can fly and the how much each mission will really cost. A standard Space-X, BO or ULA launcher can deliver a tank of propellant to the Gateway Station and you can launch to the surface of the Moon again.

The only problem with this idea is that the lander has to be serviced at the Gateway. This is going to involve creating the ability to give the lander an overhaul at the Gateway. This applies to the original plan as well though, as the ascent stage would also need to be refueled and it's engines checked on a regular basis.

Maybe it would be better to have the lander returned to the ISS for a check-up? It might be easier to set up a service depot in Earth orbit rather than shipping all the kit to do this out to the Gateway.

[A_M_Swallow]

{snip}
Maybe it would be better to have the lander returned to the ISS for a check-up? It might be easier to set up a service depot in Earth orbit rather than shipping all the kit to do this out to the Gateway.

The repair kit would have to be taken to the Gateway once, where as the lander would have to be taken to the ISS and returned to the Gateway multiple times. So servicing the lander at the Gateway is probably better.

A second PPE can be used as a space tug to take heavy items from LLO to the Gateway.

[TrevorMonty]

Maybe it would be better to have the lander returned to the ISS for a check-up? It might be easier to set up a service depot in Earth orbit rather than shipping all the kit to do this out to the Gateway.

With refuelling on surface from ISRU a 6kms lander could operate from LEO. This is most likely commercial transport system  for servicing large base. 

[Proponent]

One of the things that makes me really suspicious of their conclusions is that Orion was originally designed to survive just fine in LLO, and now all of the sudden radiators are insufficient. I haven't  had the time to go through the paper in detail, but it definitely smacks of someone having a preordained solution that they then setup strawmen to defend.

The paper that woods170 attached to his post indicates that Orion ought to be able to handle the thermal loads imposed in LLO.  Since it is about Orion's thermal control system whereas the paper above touches on it only peripherally, I have more confidence in the former.

[M129K]

Currently a three stage lunar lander seems to be the preferred option. A single stage lander would apparently be too big for SLS, but that's probably too big when including Orion. Even LM's large lander would probably fit on a cargo version of Block 1 SLS with only minimal propellant on board for reaching EML2, at least in terms of mass.

Interesting to see that the abilities of commercial launch providers are being taken into account for lunar lander components. I guess NASA doesn't want to put all their eggs in the SLS basket.

https://twitter.com/jeff_foust/status/1062711376907526144

[Zed_Noir]

Currently a three stage lunar lander seems to be the preferred option. A single stage lander would apparently be too big for SLS, but that's probably too big when including Orion. Even LM's large lander would probably fit on a cargo version of Block 1 SLS with only minimal propellant on board for reaching EML2, at least in terms of mass.

Interesting to see that the abilities of commercial launch providers are being taken into account for lunar lander components. I guess NASA doesn't want to put all their eggs in the SLS basket.

https://twitter.com/jeff_foust/status/1062711376907526144

So there is single stage, two stage & 3 stage Moon lander concepts.

Just who is working on what? And is NASA is still baseling staging the lander from LOP-G in the NRHO orbit?

[Tulse]

Does a separate descent stage mean that that part is expendable?

[speedevil]

Does a separate descent stage mean that that part is expendable?

Unless you go and pick it up later, yes.
(and probably quite soon, as it may not be rated for lunar night temps)

[MATTBLAK]

If they mounted a deployable/retractable set of solar arrays on the descent stages; they could become useful surface infrastructure 'power stations' and not just junk left on the surface. I say retractable solar arrays because they could be stowed temporarily to avoid damage from the Ascent stage engine blast.

[Oli]

I think there are other factors to consider. The table below is from here.

Yes I've seen this table, and written about it before. One of the things that makes me really suspicious of their conclusions is that Orion was originally designed to survive just fine in LLO, and now all of the sudden radiators are insufficient. I haven't  had the time to go through the paper in detail, but it definitely smacks of someone having a preordained solution that they then setup strawmen to defend. As for Orion not being able to get to LLO, NASA could've solved that problem just fine with a earth departure stage that had longergevity than EUS, and having that stage do the lunar orbit insertion burn. LLO may not be sufficiently handicapped accessible for Orion/SLS, but it definitely makes a huge (factor of 3x) difference in how much cargo you can land with a reusable lander, which in my opinion ought to swamp those considerations.

~Jon

Regardless of Orion's capabilities, isn't the total delta-v from TLI to the surface and back the relevant figure? LLO saves you roughly 500m/s compared to NRO, which isn't much. I don't see where the 3x factor should come from. That said, the paper I linked to isn't only about lander missions. It's about where to position a cis-lunar gateway.

[GWH]

Not super impressed with this 3 stage plan and the timeline proposed.

This would be a perfect fit for commercial launch capabilities in the early 2020s, but doesn't hold relevance beyond those dates as new capabilities emerge.

3x15 tonne modules is pretty inline with upcoming commercial launch system capabilities, Falcon Heavy, Vulcan Heavy and New Glenn are all within this range of performance or quite close to it. Lunar landings could be achievable in the early to mid 2020s, and this would be an apt plan for lunar access given those resources.

But one just needs to look a little further, at upcoming commercial capabilities using concepts like distributed lift and propellant depots. With ULA's ACES, SpaceX's BFR, and Blue Origin's (hints of) long duration stages I can't see a good fit for this more complicated 3 stage system.  The path seems much less clear to developing ISRU and reducing costs of a lander like this. NASA is already supporting ULA's and others capabilities that would pave the way for a simpler single or two stage system, yet they aren't laying the ground work to move forward on architectures that can be enabled by that technology. Proposals like this demonstrate the cognitive dissonance that seems to be holding NASA back.

[Proponent]

Regardless of Orion's capabilities, isn't the total delta-v from TLI to the surface and back the relevant figure? LLO saves you roughly 500m/s compared to NRO, which isn't much.

It's 730-900 m/s from NRHO to LLO.  Call it 800 m/s.

If it's, say 2000 m/s between LLO and the surface.  Then a fully reusable LLO-based lander needs a delta-V or 4000 m/s, whereas an NRHO-based one needs 5600 m/s.  If Isp is 350 s, then the respective mass fractions are 0.31 and 0.20.  That's a pretty significant difference.

[RonM]

If the current LOP-G proposal is anything like the Boeing proposal from several years ago then the station can easily change orbit. NRHO at first and move to LLO for reusable lander missions.

[Zed_Noir]

If the current LOP-G proposal is anything like the Boeing proposal from several years ago then the station can easily change orbit. NRHO at first and move to LLO for reusable lander missions.

So how do you get to LLO with Orion?

AFAIK the LOP-G is more or less stuck in the deployed orbit.

Unless you are thinking of the LOP-G is going to be a transfer vehicle between NRHO and LLO. Which brings up more safety issues.

[RonM]

If the current LOP-G proposal is anything like the Boeing proposal from several years ago then the station can easily change orbit. NRHO at first and move to LLO for reusable lander missions.

So how do you get to LLO with Orion?

AFAIK the LOP-G is more or less stuck in the deployed orbit.

Unless you are thinking of the LOP-G is going to be a transfer vehicle between NRHO and LLO. Which brings up more safety issues.

If Congress would spend money to build a lunar lander, then they would spend money to upgrade LOP-G and Orion. It's more money for their favorite contractors (campaign contributors). Any of these issues can be solved by throwing money at it.

Anyway, it's all BS. LOP-G, SLS, Orion won't survive once commercial space starts landing spacecraft on the Moon and Mars.

[Steven Pietrobon]

So how do you get to LLO with Orion?

Make EUS last the three days to the Moon and have EUS put Orion into LLO. Orion then has enough delta-V to perform TEI.

[Joseph Peterson]

Yes I've seen this table, and written about it before. One of the things that makes me really suspicious of their conclusions is that Orion was originally designed to survive just fine in LLO, and now all of the sudden radiators are insufficient. I haven't  had the time to go through the paper in detail, but it definitely smacks of someone having a preordained solution that they then setup strawmen to defend. As for Orion not being able to get to LLO, NASA could've solved that problem just fine with a earth departure stage that had longergevity than EUS, and having that stage do the lunar orbit insertion burn. LLO may not be sufficiently handicapped accessible for Orion/SLS, but it definitely makes a huge (factor of 3x) difference in how much cargo you can land with a reusable lander, which in my opinion ought to swamp those considerations.

~Jon

The critical assumption can be found on page 7.

To measure the relative difference of each orbit option, an assumption is made that the spacecraft has body-fixed radiators covering the surface of the element.

I don't want to get too far of topic, so if anyone has a link to the paper's thread handy, I will post my full opinion there.  For now, I'll leave it at:

Using LLO appropriate radiators is easy enough for rocket engineering.  This looks like an assumption that was made so that LLO would get more red.

Edit: Corrected paper('s) grammar error.

[Joseph Peterson]

If the current LOP-G proposal is anything like the Boeing proposal from several years ago then the station can easily change orbit. NRHO at first and move to LLO for reusable lander missions.

So how do you get to LLO with Orion?

AFAIK the LOP-G is more or less stuck in the deployed orbit.

Unless you are thinking of the LOP-G is going to be a transfer vehicle between NRHO and LLO. Which brings up more safety issues.

One option that would continue Orion development funding until flight data can inform changes is an investigation into refueling Orion's service module(SM).  Orion becomes and effective cis-Lunar shuttle with abort to Earth capability with refueling.

Another option would be to do away with co-manifested cargo in favor of a larger SM.

I could go on, but extending Orion's range to LLO is something I believe should be done if we plan on actually using Orion to support Lunar exploration.  While I am partial to refueling, any option that works, works for me.  Whether we should build Orion go to the Moon have their own topics.

Edit: Two grammar errors in two coomments.  Bad me.