Reusable Lunar Lander [idea]

[mordroberon]

Forgive me if this isn’t the right forum for the topic, also tried to do a search and didn’t see any threads on this.

Basically, a huge sticking point in the Artemis program seems to be criticism of HLS needing to refuel in LEO, both spacex and BO have proposals to this effect. But what if this was only a one time cost. A reusable lander, that moves between the lunar surface and lunar gateway would only need to be flown out once. And if the logistics of mining lunar ice, separating out the Os from the Hs and using that as rocket fuel, can be worked out, all the better.

It seems like a no-brainer to me if there’s going to be any sort of sustained presence on the moon. But it doesn’t look like NASA is actively making such a lander a priority. Is this because they think it’s too hard? Does the politics of getting some boots on the moon ASAP make this a low priority?

[yg1968]

Forgive me if this isn’t the right forum for the topic, also tried to do a search and didn’t see any threads on this.

Basically, a huge sticking point in the Artemis program seems to be criticism of HLS needing to refuel in LEO, both spacex and BO have proposals to this effect. But what if this was only a one time cost. A reusable lander, that moves between the lunar surface and lunar gateway would only need to be flown out once. And if the logistics of mining lunar ice, separating out the Os from the Hs and using that as rocket fuel, can be worked out, all the better.

It seems like a no-brainer to me if there’s going to be any sort of sustained presence on the moon. But it doesn’t look like NASA is actively making such a lander a priority. Is this because they think it’s too hard? Does the politics of getting some boots on the moon ASAP make this a low priority?

That's essentially what Blue will be doing, their refilling is in NRHO. NASA encourages reusability but it isn't a requirement. The lander needs to be sustainable and reusability helps in that respect. NASA wanted the providers to make their own decisions as to how to build a sustainable lander.

[catdlr]

Forgive me if this isn’t the right forum for the topic, also tried to do a search and didn’t see any threads on this.

..........

mordroberon
You haven't been formally welcomed yet.  You have posted some well-thought-out posts and we welcome good posters.  Welcome to the forum.
Best
Tony

[deltaV]

Reuse usually only beats expendable if you have a relatively high flight rate. Artemis lunar landers will only be used less than once per year so expendable may actually be cheaper.

[yg1968]

Reuse usually only beats expendable if you have a relatively high flight rate. Artemis lunar landers will only be used less than once per year so expendable may actually be cheaper.

It depends if they are used for private lunar surface missions. Both companies have been kind of quiet on what their plans are for private missions. There is also HDL missions (essentially the cargo version of HLS) but there is not that many of those. Elon Musk did say yesterday that Starship could enable a permanently occupied lunar base (he compared it to Moonbase Alpha).

[Coastal Ron]

...
Basically, a huge sticking point in the Artemis program seems to be criticism of HLS needing to refuel in LEO, both spacex and BO have proposals to this effect.

I don't think this is a "sticking point", since NASA has willingly embraced in-space refueling as the only way to achieve the goals of the Artemis program. It is a matter of physics, not policy, that mandates in-space refueling because the SLS is too small (i.e. not powerful enough), and the goals of the Artemis program have expanded beyond what the Apollo program could do with a single gigantic launcher.

It seems like a no-brainer to me if there’s going to be any sort of sustained presence on the moon. But it doesn’t look like NASA is actively making such a lander a priority. Is this because they think it’s too hard? Does the politics of getting some boots on the moon ASAP make this a low priority?

Actually NASA has no choice but to embrace a lander design that requires some degree of in-space refueling. Again, it is the physics of the equation that mandate this, not politics.

However if you ascribe to the philosophy that the Artemis program was created, at least in part, in order to give the disposable SLS and Orion hardware systems something to do, then it becomes clearer to see that the Artemis goals don't really lean into the possibilities of how in-space refueling can lower the overall cost of moving mass & people in space, and actually allow for more than one mission per year.

NASA gives lip service to making space exploration more affordable, yet their latest Mars architecture completely ignores reusable space transportation systems, and focuses only on disposable ones.

[yg1968]

However if you ascribe to the philosophy that the Artemis program was created, at least in part, in order to give the disposable SLS and Orion hardware systems something to do, then it becomes clearer to see that the Artemis goals don't really lean into the possibilities of how in-space refueling can lower the overall cost of moving mass & people in space, and actually allow for more than one mission per year.

NASA gives lip service to making space exploration more affordable, yet their latest Mars architecture completely ignores reusable space transportation systems, and focuses only on disposable ones.

Artemis wasn't created to give SLS and Orion something to do. Artemis was created in order to return to the Moon on a long term and sustained basis and in that process, it inherited SLS and Orion. The asteroid redirect mission was created in order to give SLS and Orion something to do (that mission doesn't really need humans). You can argue that Gateway was also created because of Orion. But the Moon has always been a destination in and of itself.

[Coastal Ron]

However if you ascribe to the philosophy that the Artemis program was created, at least in part, in order to give the disposable SLS and Orion hardware systems something to do, then it becomes clearer to see that the Artemis goals don't really lean into the possibilities of how in-space refueling can lower the overall cost of moving mass & people in space, and actually allow for more than one mission per year.

NASA gives lip service to making space exploration more affordable, yet their latest Mars architecture completely ignores reusable space transportation systems, and focuses only on disposable ones.

Artemis wasn't created to give SLS and Orion something to do.

So apparently you don't ascribe the philosophy I outlined above? You could have just said that... 

Artemis was created in order to return to the Moon on a long term and sustained basis and in that process, it inherited SLS and Orion.

Well the "long term" part is certainly true, given the latest Artemis II & III schedule slips. 

But the SLS+Orion are not, in any way, part of some "sustainable" mission architecture. The SLS is the most expensive disposable rocket in human history, and now NASA is proposing to EXCLUSIVELY use the SLS to support a mission to Mars. Ignoring the vast and growing fleet of far less costly transportation systems proves that politics is what governs NASA's exploration programs, not some desire to figure out how to create "sustainable" exploration methods.

And all of this just reinforces the reason why NASA needs to transition to a space exploration architecture that is reusable and relies on in-space refueling. NASA's current Moon goals can't be achieved without reusable & refuelable transportation systems, and the SLS+Orion at the most expensive part of NASA's exploration budgets - meaning that any normal program would look to the highest cost center to figure out how to redesign their system to reduce costs, but Congress (i.e. politics) won't allow that.

Which means that NASA PR is telling a lie when it says that it wants to create a "sustainable" exploration program, because cost is not part of what NASA is allowed to control.

[VSECOTSPE]

Artemis wasn't created to give SLS and Orion something to do. Artemis was created in order to return to the Moon on a long term and sustained basis and in that process, it inherited SLS and Orion.

If Artemis was intended to be long-term and sustained, then it wouldn’t be stuck with Orion/SLS.

[sdsds]

An informal survey of views expressed by spaceflight analysts and enthusiasts confirms the vast majority believe reusable hardware will become the norm for the boost phase of launch ascent. Similarly for the crew return phase of crewed flight, the consensus is that reusable vehicles will provide superior results.

There seems to be less consensus regarding hardware for upper stages of launch ascent — and for in-space propulsion and crew habitation — particularly for lunar destinations. In particular it's plausible two launches of a vehicle as small as Falcon Heavy could support a lunar surface flag-and-footprints mission using an LOR-LOR architecture.

[yg1968]

Artemis wasn't created to give SLS and Orion something to do. Artemis was created in order to return to the Moon on a long term and sustained basis and in that process, it inherited SLS and Orion.

If Artemis was intended to be long-term and sustained, then it wouldn’t be stuck with Orion/SLS.

Like I said Artemis inherited SLS and Orion, not using them wasn't an option as Bridenstine found out with his exchanges with Senator Shelby.

[yg1968]

Which means that NASA PR is telling a lie when it says that it wants to create a "sustainable" exploration program, because cost is not part of what NASA is allowed to control.

NASA is essentially forced by Congress to use SLS and Orion. NASA can control costs for certain Artemis programs by creating services-fixed price contracts but SLS and Orion costs are harder to control because that model isn't followed. In any event, almost all Artemis programs (HLS, Spacesuits, CLPS, the upcoming LTV) that were created followed the services-fixed price model, so that is huge progress. Artemis is a lot more than just SLS and Orion. Presumably, the fact that NASA is using public private partnerships for HLS means that there will eventually be commercial HLV and spacecraft alternatives (such as crewed Starship) to SLS and Orion which will be used for private lunar surface missions.

[VSECOTSPE]

Like I said Artemis inherited SLS and Orion, not using them wasn't option as Bridenstine found out with his exchanges with Senator Shelby.

Sure, but that’s doesn’t change the multiple negative impacts of Orion/SLS on Artemis.  Either decision makers and leadership are serious enough about Artemis to enable and procure the crew transport necessary for it to succeed.  Or it’s just a sub-Apollo flags and footprints adjunct to a jobs program that should be terminated as soon as politically feasible.  Shelby is gone, so that excuse doesn’t work anymore.  At some point, someone should try again to fix the program.  Probably not under Nelson/Free, but at some point.

NASA can control costs for certain Artemis programs by creating services-fixed price contracts but SLS and Orion costs are harder to control because that model isn't followed.

Even if their costs were reasonable and under control, Orion/SLS are still albatrosses for Artemis in terms of their capability (flight rate) and safety (LOC figures, workforce skills retention, complex/changing configurations).  Lack of affordability and budget is actually about third down the list of reasons why Artemis needs an exit ramp off Orion/SLS.

FWIW...

[Coastal Ron]

Which means that NASA PR is telling a lie when it says that it wants to create a "sustainable" exploration program, because cost is not part of what NASA is allowed to control.

NASA is essentially forced by Congress to use SLS and Orion.

Which everyone knows (or should know).

NASA can control costs for certain Artemis programs by creating services-fixed price contracts but SLS and Orion costs are harder to control because that model isn't followed.

Which is why NASA's PR is lying about NASA creating a "sustainable" exploration program, since they know that the SLS+Orion make it impossible for Artemis missions to be "sustainable".

Obviously the U.S. Government can afford to spend the ~$50B on developing the SLS+Orion, and the U.S. Government can afford to spend the $Billions that it takes to launch them on each mission. But that doesn't make them "sustainable".

The SLS+Orion are not driving down the cost to expand humanity into space.

The other elements of the Artemis program are attempting to lower the cost to expand humanity into space. But because the SLS+Orion limit the pace of activity the Artemis program can achieve, they eliminate the ability for NASA to lower the cost to expand humanity out into space. Which is why the Artemis program is not "sustainable".

[yg1968]

Which means that NASA PR is telling a lie when it says that it wants to create a "sustainable" exploration program, because cost is not part of what NASA is allowed to control.

NASA is essentially forced by Congress to use SLS and Orion.

Which everyone knows (or should know).

NASA can control costs for certain Artemis programs by creating services-fixed price contracts but SLS and Orion costs are harder to control because that model isn't followed.

Which is why NASA's PR is lying about NASA creating a "sustainable" exploration program, since they know that the SLS+Orion make it impossible for Artemis missions to be "sustainable".

Sustainable just means that it continues over a long period of time, it doesn't necessarily mean cheap. In any event, if SLS and Orion with HLS transports 4 astronauts per year to the surface of the Moon and crewed Starship carries private lunar missions with private citizens and other governments as customers, you might be able to have a permanently occupied lunar base as Elon Musk suggested in his SpaceX press conference of last week. Getting NASA to use the cargo versions of HLS-Starship and of the Blue Moon lander to stock pile enough cargo to the Moon would be helpful in that respect. 

[thespacecow]

Basically, a huge sticking point in the Artemis program seems to be criticism of HLS needing to refuel in LEO, both spacex and BO have proposals to this effect.

There is no such sticking point. What you're referring to as "criticism" is just haters trying to spread FUD about SpaceX and Musk, the "criticism" will go away as soon as SpaceX demonstrated orbital refueling and high launch cadence, and the tone will be changed to "this is nothing special, SpaceX didn't figure out how to do something that has never been done before, it's all old tech that has been done many times before".

Basically according these people, anything SpaceX has not accomplished is impossible, and everything SpaceX has accomplished has already been done before by someone else. There's nothing worth serious discussion here.

But what if this was only a one time cost. A reusable lander, that moves between the lunar surface and lunar gateway would only need to be flown out once. And if the logistics of mining lunar ice, separating out the Os from the Hs and using that as rocket fuel, can be worked out, all the better.

I don't see how mining propellant on the Moon can be cheaper than launching them from Earth in the short term, but optimization like these should be left to the companies. If a company thinks mining is cheaper they are free to do that and bid a lower price for lunar transportation, that's how market is supposed to work. This is also why NASA buying service instead of dictating design is a good idea, it gives companies the freedom to implement whatever design they think is the best.

[Coastal Ron]

NASA can control costs for certain Artemis programs by creating services-fixed price contracts but SLS and Orion costs are harder to control because that model isn't followed.

Which is why NASA's PR is lying about NASA creating a "sustainable" exploration program, since they know that the SLS+Orion make it impossible for Artemis missions to be "sustainable".

Sustainable just means that it continues over a long period of time, it doesn't necessarily mean cheap.

We haven't set foot on the Moon in over 50 years. Know why?

It wasn't because we didn't have the technical ability, it was because the cost was too high, and the reward was too low.

What changed is that back in 2010 Congress authorized the building of the SLS & Orion, and then in 2017 President Trump wanted some grand event to happen by the end of his potential 2nd term in office, so the return to Moon program was created. Congress and the Trump Administration did not care about the cost to return to the Moon, and the actual cost is being ignored by Congress.

Why does this matter? Because it means that the Artemis program, as currently constituted, relies on the largess of Congress, and it requires Congress to not ask hard questions about the cost of the Artemis effort.

That is NOT sustainable, that is just lucky so far. But luck can change, as we saw with the Constellation program.

In any event, if SLS and Orion with HLS transports 4 astronauts per year to the surface of the Moon and crewed Starship carries private lunar missions with private citizens and other governments as customers, you might be able to have a permanently occupied lunar base as Elon Musk suggested in his SpaceX press conference of last week.

I saw the speech that Musk gave, and it was clear he was talking about the Artemis program goals of a permanent space outpost. He wasn't talking about SpaceX spending their own money, and in fact he was very clear about their Mars goals of creating a sustainable human presence on Mars.

Getting NASA to use the cargo versions of HLS-Starship and of the Blue Moon lander to stock pile enough cargo to the Moon would be helpful in that respect.

No, it wouldn't. Not if NASA is limited to using the SLS+Orion, because that transportation architecture can't support more than four people in space for more than a month - and NO BACKUP in case there is an accident, because the SLS is only planned to launch once per year.

The SLS+Orion throttle NASA's ability to do any human space exploration.

As to the thread topic, the current Starship HLS and eventual Blue Moon landers will provide NASA with far more capabilities than NASA will be able to use if they have to use the SLS+Orion to send humans into space.

[DanClemmensen]

As to the thread topic, the current Starship HLS and eventual Blue Moon landers will provide NASA with far more capabilities than NASA will be able to use if they have to use the SLS+Orion to send humans into space.

Not quite true. Only true if they are also prohibited from using a "backup" alternative to SLS+Orion. They can keep using SLS+Orion at the lowest cadence Congress will tolerate, and use the "backup" to actually perform real missions.

[mordroberon]

Reuse usually only beats expendable if you have a relatively high flight rate. Artemis lunar landers will only be used less than once per year so expendable may actually be cheaper.

Sadly, I think you're right. I just don't like the idea of littering the surface of the moon with billion-dollar hardware. With current Artemis plans, A2 in 2025 (doable), A3 in 2026 (probably not), the other Artemis missions focused on constructing the lunar gateway until Artemis 7. It seems likely to me that there will be more delays, a launch cadence of SLS of once per year is optimistic. If there's going to be a continuous presence on the moon it will be after the mid-2030s. At which point there may be an attempt at keeping a continuous presence on the moon, and rotations every 6 months or so. Until then, having a spacecraft out of reach of servicing for years at a time doesn't sound worthwhile

[Coastal Ron]

As to the thread topic, the current Starship HLS and eventual Blue Moon landers will provide NASA with far more capabilities than NASA will be able to use if they have to use the SLS+Orion to send humans into space.

Not quite true. Only true if they are also prohibited from using a "backup" alternative to SLS+Orion. They can keep using SLS+Orion at the lowest cadence Congress will tolerate, and use the "backup" to actually perform real missions.

There is no evidence that Congress would fund NASA to create a second crew transportation system.

There is plenty of evidence that Congress is perfectly happy with the once a year mission cadence the SLS+Orion support.

So sure, while it may make sense to us to add more ways to move humans to the Moon, NASA is not funded to do that today, or the foreseeable future. Which is why I stated what I did above, that the current Starship HLS and Blue Moon landers provide far more capabilities than what NASA will need for the Artemis program.

[DanClemmensen]

As to the thread topic, the current Starship HLS and eventual Blue Moon landers will provide NASA with far more capabilities than NASA will be able to use if they have to use the SLS+Orion to send humans into space.

Not quite true. Only true if they are also prohibited from using a "backup" alternative to SLS+Orion. They can keep using SLS+Orion at the lowest cadence Congress will tolerate, and use the "backup" to actually perform real missions.

There is no evidence that Congress would fund NASA to create a second crew transportation system.

There is plenty of evidence that Congress is perfectly happy with the once a year mission cadence the SLS+Orion support.

So sure, while it may make sense to us to add more ways to move humans to the Moon, NASA is not funded to do that today, or the foreseeable future. Which is why I stated what I did above, that the current Starship HLS and Blue Moon landers provide far more capabilities than what NASA will need for the Artemis program.

SLS+Orion does not appear to have a once-a-year cadence. NASA would not need to pay to develop a second system: it would be a service. SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

[Coastal Ron]

There is no evidence that Congress would fund NASA to create a second crew transportation system.

There is plenty of evidence that Congress is perfectly happy with the once a year mission cadence the SLS+Orion support.

So sure, while it may make sense to us to add more ways to move humans to the Moon, NASA is not funded to do that today, or the foreseeable future. Which is why I stated what I did above, that the current Starship HLS and Blue Moon landers provide far more capabilities than what NASA will need for the Artemis program.

SLS+Orion does not appear to have a once-a-year cadence.

Not yet, but that is what NASA is planning for once they get everything operational.

NASA would not need to pay to develop a second system: it would be a service.

You mean like Commercial Crew? NASA paid SpaceX $3.1B to develop the Dragon Crew, but you think SpaceX will develop an Earth-to-Moon-and-Back transportation system for free? Can you show me where SpaceX has ever done something like that for the U.S. Government, because I don't think you are being realist?

SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

We can all do LEGO engineering, and imagine that the richest person in the world will spend their money on our pet projects.

The reality is that unless Congress authorizes NASA to allow competition with the SLS+Orion, it won't happen. And Congress has shown no indications they care about the cost of the SLS+Orion, or the slow mission cadence of the Artemis program, so it ain't happening.

[Negan]

SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

The only missing piece not developed or in development is a way to dock two Starship together to transport crew although it's possible the final docking design of the depot and HLS will help with this.

Edit: Dragon 2 has certainly shown us SpaceX can develop capabilities beyond NASA requirements regardless of whether people consider it "LEGO engineering".

[DanClemmensen]

SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

The only missing piece not developed or in development is a way to dock two Starship together to transport crew although it's possible the final docking design of the depot and HLS will help with this.

Edit: Dragon 2 has certainly shown us SpaceX can develop capabilities beyond NASA requirements regardless of whether people consider it "LEGO engineering".

Starship HLS will almost certainly have an active/passive IDSS docking port on its nose. Two active/passive ports can dock to each other. The reason Starship HLS needs to be active/passive is that it (probably) needs the ability to dock to the active-only IDSS port on Orion, and it also needs the ability to dock to the passive-only IDSS port on Gateway.

[Negan]

SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

The only missing piece not developed or in development is a way to dock two Starship together to transport crew although it's possible the final docking design of the depot and HLS will help with this.

Edit: Dragon 2 has certainly shown us SpaceX can develop capabilities beyond NASA requirements regardless of whether people consider it "LEGO engineering".

Starship HLS will almost certainly have an active/passive IDSS docking port on its nose. Two active/passive ports can dock to each other. The reason Starship HLS needs to be active/passive is that it (probably) needs the ability to dock to the active-only IDSS port on Orion, and it also needs the ability to dock to the passive-only IDSS port on Gateway.

From my limited understanding, the mass properties of having two Starships dock might make the current HLS IDSS docking development to Orion and the Gateway inadequate, but I hope that ends up not being the case.

[DanClemmensen]

SpaceX can provide that service using hardware that has already been designed and is already needed prior to Artemis III. Use another instance of Starship HLS as an LEO-NHRO-LEO crew transport, and use Crew Dragon for Earth to LEO and back to Earth. The actual lander meets the transport in NRHO, just as it does for SLS+Orion.

The only missing piece not developed or in development is a way to dock two Starship together to transport crew although it's possible the final docking design of the depot and HLS will help with this.

Edit: Dragon 2 has certainly shown us SpaceX can develop capabilities beyond NASA requirements regardless of whether people consider it "LEGO engineering".

Starship HLS will almost certainly have an active/passive IDSS docking port on its nose. Two active/passive ports can dock to each other. The reason Starship HLS needs to be active/passive is that it (probably) needs the ability to dock to the active-only IDSS port on Orion, and it also needs the ability to dock to the passive-only IDSS port on Gateway.

From my limited understanding, the mass properties of having two Starships dock might make the current HLS IDSS docking development to Orion and the Gateway inadequate, but I hope that ends up not being the case.

How to elephants mate? Veeery carefully.   Yes, they need to ensure that the torques can be handled. But the eventual full-up Gateway is also a substantial chunk of mass, and HLS must dock to it, so presumably docking to another HLS would not induce an order of magnitude more torque. We are getting off-topic here. There is an entire thread dedicated to this particular SLS/Orion replacement at:
    https://forum.nasaspaceflight.com/index.php?topic=59662.0

[yg1968]

What changed is that back in 2010 Congress authorized the building of the SLS & Orion, and then in 2017 President Trump wanted some grand event to happen by the end of his potential 2nd term in office, so the return to Moon program was created. Congress and the Trump Administration did not care about the cost to return to the Moon, and the actual cost is being ignored by Congress.

Why does this matter? Because it means that the Artemis program, as currently constituted, relies on the largess of Congress, and it requires Congress to not ask hard questions about the cost of the Artemis effort.

That is NOT sustainable, that is just lucky so far. But luck can change, as we saw with the Constellation program.

Just about every Artemis program that was created under the Trump Administration was a service fixed-cost/public private partnership showing that the Trump Administration did indeed care about costs. The decision to use SLS and Orion wasn't made under the Trump Administration. If the Trump Administration had started from a clean slate, I suspect that the HLV and BLEO spacecraft would have been another public-private partnership/fixed price service program.

In terms of setting an ambitious goal for the second term of a presidency (the goal of landing on the Moon in 2024), I think that is a good idea. Ideally, all Presidents (or the Vice President in the case of the Trump Administration) should try to set such an ambitious goal. Even if they don't achieve it, a lot of progress can be made in 8 years. To their credit, the Biden Administration kept Artemis intact and have continued the use of public-private partnership/fixed price service programs under Artemis (for example, the spacesuits and LTV). It wasn't obvious that this would be the case in early 2020 given Senator Nelson's prior record of creating or defending large space government programs such as SLS and Orion.   

[VSECOTSPE]

Just about every Artemis program that was created under the Trump Administration was a service fixed-cost/public private partnership showing that the Trump Administration did indeed care about costs. The decision to use SLS and Orion wasn't made under the Trump Administration. If the Trump Administration had started from a clean slate, I suspect that the HLV and BLEO spacecraft would have been another public-private partnership/fixed price service program.

I think Bridenstine cared, but I’m not sure anyone else of significance in the Trump Administration did.  Pence publicly voiced frustration with SLS schedule and contractors, but when push came to shove with Shelby, Pence didn’t expend any political capital in favor of reform.  And there was no policy dictate from the Trump White House for NASA to change its ways that I recall, and Pace has never been in favor of doing so, anyway.   To the extent NASA adopted new ways of doing business, that either originated with Bridenstine (HLS et al.) or civil servants like Zurbuchen (CLPS).

You can take the view that Bridenstine was a Trump appointee so the Trump Administration gets the credit.  But I like to give credit where credit is most due.  I think that’s with Bridenstine in this case.

To flip it around, we could blame the Bush II Administration for Constellation, and they probably should have been watching over Griffin’s shoulder more carefully.  But the debacle with Ares I and Orion and the rest that NASA is still suffering from lies at Griffin’s feet more than anyone else’s.

In terms of setting an ambitious goal for the second term of a presidency (the goal of landing on the Moon in 2024), I think that is a good idea.

It is a good idea when accompanied by the budget increases and/or policy/program changes necessary to make it happen.  See Apollo and the budget Webb laid in.  See the VSE and the sand chart budget and the program reforms we laid in (before Griffin reversed them).

I don’t recall any budget changes accompanying the Trump White House 2028 to 2024 acceleration.  Logically, there should have been.  Pursuing the same goal with less time means you have to spend more earlier.  The alternative is to change how the goal is being pursued.  Bridenstine did the best he could with what he had, but again, there was no top cover from the Trump White House when Bridenstine ran into Shelby or any direction from the Trump White House in favor of reform.

In its inability to fully plan for or see a change through in NASA HSF, the Trump White House is little different from those before it.  The Obama Administration didn’t put due diligence into its asteroid goal.  Bush II appointed Griffin and didn’t care when he went off the rails.  Etc.  But that doesn’t change the impact of the neglect.  Orion’s technical issues are still driving schedule slips.  Nelson had to finish the fundraising job on HLS because there was no budget acceleration and because Orion/SLS were still allowed to suck up the budgetary oxygen.  Suits have gotten off to a very late start.  Etc.

FWIW...

[Coastal Ron]

What changed is that back in 2010 Congress authorized the building of the SLS & Orion, and then in 2017 President Trump wanted some grand event to happen by the end of his potential 2nd term in office, so the return to Moon program was created. Congress and the Trump Administration did not care about the cost to return to the Moon, and the actual cost is being ignored by Congress.

Why does this matter? Because it means that the Artemis program, as currently constituted, relies on the largess of Congress, and it requires Congress to not ask hard questions about the cost of the Artemis effort.

That is NOT sustainable, that is just lucky so far. But luck can change, as we saw with the Constellation program.

Just about every Artemis program that was created under the Trump Administration was a service fixed-cost/public private partnership showing that the Trump Administration did indeed care about costs.

Recognizing that the Congress you have to deal with is not enthused about a program you just dropped on them is NOT the same as being "cost conscious". The Trump NASA had no alternative but to seek out commercial providers, for two reasons:

1. The then Congress was unlikely to fund NASA to develop their own lander.

2. NASA building their own lander would not have come close to meeting the aggressive schedule dates the Trump Administration announced. And when I say "aggressive", everyone should really read that as "delusional", since those of us that understand how to build hardware knew that the 2024 date was delusional.

The decision to use SLS and Orion wasn't made under the Trump Administration. If the Trump Administration had started from a clean slate, I suspect that the HLV and BLEO spacecraft would have been another public-private partnership/fixed price service program.

The Trump Administration created what is now the Artemis program, so they could have defined it so that the SLS and Orion did not meet the program goals. They certainly could have announced that the SLS and Orion were too expensive to use, since they knew the program costs at that time.

But they didn't do that. Other than the brief flirtation with using something other than the SLS in order to try and meet the 2024 landing date, they have bound the program to the SLS+Orion.

In terms of setting an ambitious goal for the second term of a presidency (the goal of landing on the Moon in 2024), I think that is a good idea.

Delusional dates waste money, and they don't make anything go faster. As someone that has been a professional factory scheduling manager, I can tell you that being realistic is far better than being delusional. And that's not to say you can't have "stretch goals", where you challenge everyone to do better, but having everyone out of sync with reality just adds to the chaos of an unrealistic program.

And look at the state of the Artemis program today. All of the issues today were known back in 2017, so all the Trump Administration did was look like they didn't know what they were doing.

Ideally, all Presidents (or the Vice President in the case of the Trump Administration) should try to set such an ambitious goal.

There is a difference between informed ambition, and uninformed ambition. The Trump Administration never did a bottoms-up assessment of the return-to-Moon effort before they announced the 2024 date, and didn't bother to do one after they announced the date either. That is just gross mismanagement - unless you like being lied to...

[Todd Martin]

As yg1968 mentioned, Blue Origin has a contract to provide a lunar lander and it will be reusable.  Lockheed's cislunar transporter will ferry liquid hydrogen and oxygen to the lunar lander (Blue Moon Mk. 2).  I like the advantages of cislunar operations using high ISP, low weight hydrolox.  I like separation of spacecraft functions to gain the benefits of optimization and utilization of Gateway.  In short, a lot less dry mass (roughly 1/3 the dry mass of the competition) means less fuel is needed.  I like the reusability and development of cryogenic propellant storage.  In short, I think NASA is getting exactly what the OP is hoping for.   

[yg1968]

You can take the view that Bridenstine was a Trump appointee so the Trump Administration gets the credit.  But I like to give credit where credit is most due.  I think that’s with Bridenstine in this case.

I am OK with giving most of the credit to Bridenstine. But I do think that Pence's 2024 goal gave a sense of urgency to the Artemis program. I am not sure that the HLS program would have been created in 2019 if it wasn't the accelerated goal. As you said yourself before, the 2024 goal gave Artemis a needed kick in the pants.

It is a good idea when accompanied by the budget increases and/or policy/program changes necessary to make it happen.  See Apollo and the budget Webb laid in.  See the VSE and the sand chart budget and the program reforms we laid in (before Griffin reversed them).

I don’t recall any budget changes accompanying the Trump White House 2028 to 2024 acceleration.  Logically, there should have been.  Pursuing the same goal with less time means you have to spend more earlier.  The alternative is to change how the goal is being pursued.  Bridenstine did the best he could with what he had, but again, there was no top cover from the Trump White House when Bridenstine ran into Shelby or any direction from the Trump White House in favor of reform.

There was an addendum to the FY20 Budget a few months after Pence announced Artemis in 2019. However, most of the plus up came in the FY21 Budget which had a fairly large HLS budget ($3.3B). 

https://www.nasa.gov/nasa-fiscal-year-2021-budget-request/

[yg1968]

Delusional dates waste money, and they don't make anything go faster.

A number of Artemis programs are fixed prices, so setting up unrealistic dates doesn't actually cost anything. Having said that, had they kept the more realistic 2028 date for the first lunar landing, Congress would have taken even more time to fund HLS and the first lunar landing probably wouldn't have been until 2032.

There is a difference between informed ambition, and uninformed ambition. The Trump Administration never did a bottoms-up assessment of the return-to-Moon effort before they announced the 2024 date, and didn't bother to do one after they announced the date either. That is just gross mismanagement - unless you like being lied to...

The big piece for the 2024 landing was the funding of the lander. NASA found out what the price for HLS would be when it received the HLS proposals in 2019. In the FY21 Budget, NASA had anticipated spending almost $21.3B on HLS. Fortunately, SpaceX lowered the price for HLS by asking for a much more reasonable $3B for the development of its lander and Blue ended up asking for a similar price for its lander.

https://www.nasa.gov/nasa-fiscal-year-2021-budget-request/

[VSECOTSPE]

I am OK with giving most of the credit to Bridenstine. But I do think that Pence's 2024 goal gave a sense of urgency to the Artemis program. I am not sure that the HLS program would have been created in 2019 if it wasn't the accelerated goal. As you said yourself before, the 2024 goal gave Artemis a needed kick in the pants.

There was an addendum to the FY20 Budget a few months after Pence announced Artemis in 2019. However, most of the plus up came in the FY21 Budget which had a fairly large HLS budget ($3.3B).

No doubt, the 2024 goal focused Bridenstine.  But there were probably ways to focus Bridenstine without setting a goal that the program was going to be judged against down the line, especially when the Trump White House would request the necessary budget increases late and kick the can to the Biden Administration to lobby for them. 

Again, par for the course for the last several Administrations.  NASA HSF is a visible but low priority.  Each White House basically takes one shot at fixing it then abandons the agency to its own devices.  But maybe Bridenstine just needed a come-to-Jesus meeting with Pence instead of Pace setting a poorly coordinated and funded goal in policy.

FWIW...

[Eric Hedman]

I am OK with giving most of the credit to Bridenstine. But I do think that Pence's 2024 goal gave a sense of urgency to the Artemis program. I am not sure that the HLS program would have been created in 2019 if it wasn't the accelerated goal. As you said yourself before, the 2024 goal gave Artemis a needed kick in the pants.

There was an addendum to the FY20 Budget a few months after Pence announced Artemis in 2019. However, most of the plus up came in the FY21 Budget which had a fairly large HLS budget ($3.3B).

No doubt, the 2024 goal focused Bridenstine.  But there were probably ways to focus Bridenstine without setting a goal that the program was going to be judged against down the line, especially when the Trump White House would request the necessary budget increases late and kick the can to the Biden Administration to lobby for them. 

Again, par for the course for the last several Administrations.  NASA HSF is a visible but low priority.  Each White House basically takes one shot at fixing it then abandons the agency to its own devices.  But maybe Bridenstine just needed a come-to-Jesus meeting with Pence instead of Pace setting a poorly coordinated and funded goal in policy.

FWIW...

I liked the idea of the 2024 goal because in my opinion no matter what date was set, it would be missed by 3 to 4 years.  If the goal was set to 2028, there would have been even less urgency by Congress to fully fund it and they would be lucky to get Artemis III flying by 2032.  I also think that the farther out the goal, the less likely Congress is to fund it at all.  Members of Congress want to still be in office when it succeeds and take credit for it.

[Coastal Ron]

Delusional dates waste money, and they don't make anything go faster.

A number of Artemis programs are fixed prices, so setting up unrealistic dates doesn't actually cost anything.

What an "interesting" statement.

Didn't you just point out on a different thread that NASA has the ability to punish contractors that don't make contract dates? So you seem to be OK with punishing contractors for not making contract dates that were fake to begin with, right? 

Having said that, had they kept the more realistic 2028 date for the first lunar landing, Congress would have taken even more time to fund HLS and the first lunar landing probably wouldn't have been until 2032.

So now you are admitting that the Trump Administration was lying to Congress about the 2024 date?

At any point does honesty and reality come into play with NASA?

There is a difference between informed ambition, and uninformed ambition. The Trump Administration never did a bottoms-up assessment of the return-to-Moon effort before they announced the 2024 date, and didn't bother to do one after they announced the date either. That is just gross mismanagement - unless you like being lied to...

The big piece for the 2024 landing was the funding of the lander.

What do you mean? NASA has spent $50B on the SLS and Orion programs so far.

NASA found out what the price for HLS would be when it received the HLS proposals in 2019.

In 2019 NASA asked for proposals, and in 2020 NASA awarded $967M in "study contracts" to Blue Origin, SpaceX and Dynetics to begin the design process for lunar landers, but how much each company would bid would not be known until the Human Landing System, Option A contract was bid and accepted in 2021. So NASA didn't know how much each of the proposals would cost until 2021.

In the FY21 Budget, NASA had anticipated spending almost $21.3B on HLS. Fortunately, SpaceX lowered the price for HLS by asking for a much more reasonable $3B for the development of its lander and Blue ended up asking for a similar price for its lander.

Assuming NASA didn't allow any of the contract bidding information to lead out, the part of NASA that was doing the federal budget process really had no idea what it would take, since all they had was old NASA studies to go by.

More importantly though, SpaceX did not "lowered the price". NASA had no clue how much it would cost to develop a lander, so stop assuming NASA requested a reasonable amount from Congress. As it happens, SpaceX was able to leverage years of self-funded work on the Starship program to bid what they did.

If anything the lack of accuracy in NASA's budget forecasts should be questioned...

And let's keep in mind that while V.P. Pence announced the return-to-Moon program in 2017, and set a date of by the end of 2024, NASA didn't award a contract for an actual Moon lander until 2021, or more than 50% of the way through the amount of time NASA had to meet the original 2024 date.

Does that seem like the fake 2024 need date for landing on the Moon was doing a good job in motivating NASA to meet that date?

[yg1968]

What an "interesting" statement.

Didn't you just point out on a different thread that NASA has the ability to punish contractors that don't make contract dates? So you seem to be OK with punishing contractors for not making contract dates that were fake to begin with, right? 

So now you are admitting that the Trump Administration was lying to Congress about the 2024 date?

At any point does honesty and reality come into play with NASA?

No one was lying. NASA asked the HLS providers if they could make the 2024 date and the providers said that they could. The Blue protest created a delay and so did the delay of Starship's IFT-1 IFT-2 test flights. These things were hard to predict at the time.

What do you mean? NASA has spent $50B on the SLS and Orion programs so far.

Yes but they were already going to spend these amounts for SLS and Orion for the Journey to Mars. What was new under Artemis was HLS (and CLPS).

In 2019 NASA asked for proposals, and in 2020 NASA awarded $967M in "study contracts" to Blue Origin, SpaceX and Dynetics to begin the design process for lunar landers, but how much each company would bid would not be known until the Human Landing System, Option A contract was bid and accepted in 2021. So NASA didn't know how much each of the proposals would cost until 2021.

That is not correct. The base period milestones weren't studies, they were the beginning of the HLS program. NASA asked the HLS providers to provide their prices for both the base period and Option A milestones in their November 2019 base period proposals (these prices were actually made public, see the link below). However, NASA allowed the providers to revise their milestone prices for Option A when they made their revised proposals under Option A (Option A was a down select of the base period HLS providers).

https://forum.nasaspaceflight.com/index.php?topic=46645.msg2103598#msg2103598

Assuming NASA didn't allow any of the contract bidding information to lead out, the part of NASA that was doing the federal budget process really had no idea what it would take, since all they had was old NASA studies to go by.

More importantly though, SpaceX did not "lowered the price". NASA had no clue how much it would cost to develop a lander, so stop assuming NASA requested a reasonable amount from Congress. As it happens, SpaceX was able to leverage years of self-funded work on the Starship program to bid what they did.

If anything the lack of accuracy in NASA's budget forecasts should be questioned...

And let's keep in mind that while V.P. Pence announced the return-to-Moon program in 2017, and set a date of by the end of 2024, NASA didn't award a contract for an actual Moon lander until 2021, or more than 50% of the way through the amount of time NASA had to meet the original 2024 date.

Does that seem like the fake 2024 need date for landing on the Moon was doing a good job in motivating NASA to meet that date?

I am not assuming anything, your facts are incorrect and as a result your conclusions are also wrong. NASA had the numbers that I quoted above (also linked below) when it prepared the FY2021 HLS Budget (more precisely, NASA had these numbers as of November 5, 2019, the date that the HLS base period proposals were due).

https://forum.nasaspaceflight.com/index.php?topic=46645.msg2103628#msg2103628

[yg1968]

I am OK with giving most of the credit to Bridenstine. But I do think that Pence's 2024 goal gave a sense of urgency to the Artemis program. I am not sure that the HLS program would have been created in 2019 if it wasn't the accelerated goal. As you said yourself before, the 2024 goal gave Artemis a needed kick in the pants.

There was an addendum to the FY20 Budget a few months after Pence announced Artemis in 2019. However, most of the plus up came in the FY21 Budget which had a fairly large HLS budget ($3.3B).

No doubt, the 2024 goal focused Bridenstine.  But there were probably ways to focus Bridenstine without setting a goal that the program was going to be judged against down the line, especially when the Trump White House would request the necessary budget increases late and kick the can to the Biden Administration to lobby for them. 

Again, par for the course for the last several Administrations.  NASA HSF is a visible but low priority.  Each White House basically takes one shot at fixing it then abandons the agency to its own devices.  But maybe Bridenstine just needed a come-to-Jesus meeting with Pence instead of Pace setting a poorly coordinated and funded goal in policy.

FWIW...

When the Trump Administration issued the FY21 NASA Budget (and the FY20 Supplemental Budget Request) which took into account the additional funding for HLS and Artemis, the Trump Administration expected to be back for a second term, so their plan wasn't to kick the can down the road to the Biden Administration since they didn't expect there to be a Biden Administration.

In any event, the FY21 budget was approved on December 28, 2020 which was still under the Trump Administration. There was enough funding for HLS-Starship in the FY21 Budget ($928M in FY21 which was an increase over the $654M that had been appropriated for HLS in FY20) but not enough for a second HLS provider.

https://www.nasa.gov/nasa-fiscal-year-2022-budget-request/

[JHošek]

NASA asked the HLS providers if they could make the 2024 date and the providers said that they could. The Blue protest created a delay and so did the delay of Starship's IFT-1 IFT-2 test flights. These things were hard to predict at the time. 

yg1968, would you agree that the IFT delay is the main factor and the impact of the Blue protest is already negligible?

[MickQ]

I suppose this thread is as good as any to pose a question.

Why are landers almost always designed/depicted with the cargo sitting atop the propulsion and tankage ??  Is there any technical or engineering reason for this ??

IMO this configuration will always necessitate the inclusion of a crane or davit of some kind and therefore introducing some level of instability when lifting weighty cargo down the side of the craft, especially in the case of Starship.

Would it not be better to have the cargo, whatever it be, attached underneath a framework that holds the engines, tanks, avionics and everything else ??  This way the cargo is placed directly on the ground.

Think Thunderbird 2 touching down, releasing a pod and flying off.

[deltaV]

Why are landers almost always designed/depicted with the cargo sitting atop the propulsion and tankage ??

Here's a guess. If rocket exhaust hits the payload the lander will probably lose net thrust and risk damaging the payload. So if the engines are on top they probably need to be angled a bit outwards like the "sky crane" Mars landing system's engines are. This isn't a big deal on Mars where you aren't using the engines for very long but on the moon the cosine losses will hurt. Putting the payload on top also protects it from debris thrown up by rocket exhaust hitting the ground.

[deadman1204]

I suppose this thread is as good as any to pose a question.

Why are landers almost always designed/depicted with the cargo sitting atop the propulsion and tankage ??  Is there any technical or engineering reason for this ??

IMO this configuration will always necessitate the inclusion of a crane or davit of some kind and therefore introducing some level of instability when lifting weighty cargo down the side of the craft, especially in the case of Starship.

Would it not be better to have the cargo, whatever it be, attached underneath a framework that holds the engines, tanks, avionics and everything else ??  This way the cargo is placed directly on the ground.

Think Thunderbird 2 touching down, releasing a pod and flying off.

This doesn't really work. Putting aside top heavy concerns (engines and fuel are very heavy), the engines need to fire down, which means they cannot be firing into the cargo. Its not different than why are wheels on the bottom of cars? The wheels need to push off the ground. Engines need to push prop out the bottom of the rocket.

[AS-503]

I suppose this thread is as good as any to pose a question.

Why are landers almost always designed/depicted with the cargo sitting atop the propulsion and tankage ??  Is there any technical or engineering reason for this ??

IMO this configuration will always necessitate the inclusion of a crane or davit of some kind and therefore introducing some level of instability when lifting weighty cargo down the side of the craft, especially in the case of Starship.

Would it not be better to have the cargo, whatever it be, attached underneath a framework that holds the engines, tanks, avionics and everything else ??  This way the cargo is placed directly on the ground.

Think Thunderbird 2 touching down, releasing a pod and flying off.

This doesn't really work. Putting aside top heavy concerns (engines and fuel are very heavy), the engines need to fire down, which means they cannot be firing into the cargo. Its not different than why are wheels on the bottom of cars? The wheels need to push off the ground. Engines need to push prop out the bottom of the rocket.

Seems the JPL Sky Crane did a good job with having the propulsion above the cargo.

[MickQ]

Yes.  Skycrane is part way to what I’m thinking of.

Obviously you would not have the engines firing down on to the top of the cargo but have the cargo positioned in between the engines.  In the final 50 or so meters of the descent the engines start to gimbal outwards to blow most debris away from the lander.

At touchdown either the engines shut down or the cargo pod is released and the lander returns directly to orbit for re use.  Another advantage of this configuration would be that if a problem occurs during descent, such as an engine out, the cargo can be dropped and the lander aborts to orbit.

[tbellman]

Yes.  Skycrane is part way to what I’m thinking of.

Obviously you would not have the engines firing down on to the top of the cargo but have the cargo positioned in between the engines.  In the final 50 or so meters of the descent the engines start to gimbal outwards to blow most debris away from the lander.

At touchdown either the engines shut down or the cargo pod is released and the lander returns directly to orbit for re use.  Another advantage of this configuration would be that if a problem occurs during descent, such as an engine out, the cargo can be dropped and the lander aborts to orbit.

Dynetics' ALPACA lander seems to be fairly close to what you are thinking of.  A frame with the cargo (cabin) in the center, and propellant tanks and engines on each side.

As for why so few have been designing landers that way, I can only speculate, but here are some possible reasons:

• Needs to be launched on its side, to fit inside launch vehicle fairings.  That gives different load paths than when it is landing and/or launching on its own on the Moon.

• You need 2, 4, 6 or 8 engines, not just a single engine.  Often, having multiple smaller engines is less mass efficient than having a single engine.

• Likewise, you need two sets of propellant tanks, one set on each side, which increases mass.

• Some payloads don't care much if they are directly on the surface, or if the are a meter or two up.  An instrument that investigates the lunar "atmosphere" may be perfectly OK with sitting on top of the lander.  Even something that drills or digs into the regolith for analysing, might need an arm anyway, and it might not matter that much if it needs to be a bit longer.  (This point of course only applies to the case where the payload is fixed to the lander and uses it as a platform.)

• (For the case where you disconnect the cargo from the lander and put it on its own on the surface.)  You probably need some mechanism for carefully lowering the cargo to the surface anyway.  You will most likely have landing legs, so after landing the cargo might be half a meter or more from the surface, and you might not want to just drop it and let it fall.  That mechanism may be easier and more lightweight than one that has to take the payload down from the top of the lander, but the difference might not make up for other complications.

• A payload that is a rover, can sometimes drive itself down from the top of the lander.  The only mechanism needed on the lander is a ramp that the rover can drive down.

• "It's not how Apollo did it."  Once you have seen one working solution, it is very easy for your brain to "lock on" to that, and it can be difficult to imagine other solutions.

[Coastal Ron]

I suppose this thread is as good as any to pose a question.
...
Would it not be better to have the cargo, whatever it be, attached underneath a framework that holds the engines, tanks, avionics and everything else ??  This way the cargo is placed directly on the ground.

Think Thunderbird 2 touching down, releasing a pod and flying off.

ULA, many years ago, proposed their Dual Thrust Axis Lander (DTAL), which is based on their Advanced Common Evolved Stage (ACES) platform. You can find the study here:

Robust Lunar Exploration Using an Efficient Lunar Lander Derived from Existing Upper Stages - United Launch Alliance

Their proposed lander looks like current "rockets with cargo on top", but lands horizontally. A pretty neat concept, that I always thought had possibilities, but no one else had proposed similar concepts for the Artemis program.

BTW, ULA used to have a dedicated section on their website called Papers and Presentations, but now it has been moved to their "Explore" section, and the link no longer works (hopefully this is temporary). Which means ULA is no longer promoting their ideas for space exploration, including those that were going to use ACES. Sad to see, and I wonder if that will change when/if someone buys them...

[MickQ]

ALPACA is basically the closest configuration to what I’m thinking of.  The difference being that the payload section ( payload meaning hab module, rover, cargo pod etc )  is quickly and easily detachable from the rest of the lander.  At touchdown the lander’s legs adjust to place the payload on the ground.  The attachment mechanism unlocks and the lander then returns to orbit for refueling and another load.

[chopsticks]

I'm surprised no one has mentioned Blue Origin's HLS. Tanks are on the top and the people are underneath.

[Asteroza]

ALPACA is basically the closest configuration to what I’m thinking of.  The difference being that the payload section ( payload meaning hab module, rover, cargo pod etc )  is quickly and easily detachable from the rest of the lander.  At touchdown the lander’s legs adjust to place the payload on the ground.  The attachment mechanism unlocks and the lander then returns to orbit for refueling and another load.

A straddle frame style lander with at least a pair of rockets, at first glance at least, seemed like a decent choice in the past, but with increasing worries about plume impingement digging a hole, is the current consensus moving towards landers with high mount rockets (effectively a puller rather than pusher configuration?)

Starship HLS is that weird one where it might be a classed as a pusher config due to waist mount rockets simply by convenience of size of lower tankage, whereas some other bottom loaders really are a puller/tractor config. Tractor style bottom loader rigs do face the long leg issue though (true long legs, or a lower structure that extends leg reach)

[DanClemmensen]

Starship HLS has landing thrusters in addition to its main Raptor engines. The landing thrusters have enough thrust to perform the last 100 meters or so of the landing (i.e., they can hover the HLS in a 0.16 g field) and they point down at an angle, ("cosine thrusters") instead of pointing straight down.

Consider an HLS that lands with the raptors pointing up, using landing thrusters near the raptors but pointing down. This would put the crew or payload section near the surface. landing legs would be at the "lunar down" end. The ogive would be discarded after the HLS was launched, so the "lunar down" end would be flat.

The lunar landing trajectory would be nearly horizontal as the raptors brought HLS near the surface. When HLS was about 100 meters above the landing point at zero velocity, raptors would flip it to lunar vertical and the landing thruster would take it down. Ascent wouhd be the reverse: landing thruster take it up to 100 meters and flip it, and raptors take over.

Presumably the crew couches would be gimballed.

[deadman1204]

I suppose this thread is as good as any to pose a question.

Why are landers almost always designed/depicted with the cargo sitting atop the propulsion and tankage ??  Is there any technical or engineering reason for this ??

IMO this configuration will always necessitate the inclusion of a crane or davit of some kind and therefore introducing some level of instability when lifting weighty cargo down the side of the craft, especially in the case of Starship.

Would it not be better to have the cargo, whatever it be, attached underneath a framework that holds the engines, tanks, avionics and everything else ??  This way the cargo is placed directly on the ground.

Think Thunderbird 2 touching down, releasing a pod and flying off.

This doesn't really work. Putting aside top heavy concerns (engines and fuel are very heavy), the engines need to fire down, which means they cannot be firing into the cargo. Its not different than why are wheels on the bottom of cars? The wheels need to push off the ground. Engines need to push prop out the bottom of the rocket.

Seems the JPL Sky Crane did a good job with having the propulsion above the cargo.

This is quite missleading. 99% of the slowing down was done before the skycrane happened. As well, it can only work for lighter payloads because its incredibly inefficient. The engines all point away instead of directly down. Add to that the damage the rovers have taken from this. For example curiosity's weather package got ruined from this.
There are alot of thnigs that are "possible", but we were talking about rockets, not 1 off landing systems that exclude 99% of the deceleration