Dynetics lunar lander

[Paul451]

Dynetics have solved issue by not using drop tanks any more.

It is also possible that they still have two expendable tanks, otherwise only Starship could refill them.

How do you figure that? AIUI, the original plan had the two replacement tanks and the refuelling for the ascent tanks delivered by a single shipment on Vulcan. They've just replaced the drop tanks plus refuelling with only refuelling. The masses are virtually the same.

[JasonAW3]

Gotta say I'm both highly entertained and puzzled by the name for this vehicle: ALPACA

They're probably still a bit fuzzy on the details...

[Nathan2go]

It is also possible that they still have two expendable tanks, otherwise only Starship could refill them.

How do you figure that? AIUI, the original plan had the two replacement tanks and the refuelling for the ascent tanks delivered by a single shipment on Vulcan. They've just replaced the drop tanks plus refuelling with only refuelling. The masses are virtually the same.

Refueling also implies use of an expendable tank or tanks. A single Vulcan shipment is much lighter than what NASA said was plausible in the original stuff. Did you mean single SLS?

[GWH]

NASA's source selection statement clarifies that Dynetics would be one stage, no drop tanks as per the new design:

First, Dynetics’ proposed single stage integrated Descent Ascent Element (DAE) lander design requires no in-space integration of lander elements or staging/separation events.  This pre-integrated design will also allow for terrestrial testing of the entire system, which will increase the fidelity of testing data generated. I concur with the SEP’s conclusion that this design greatly simplifies Dynetics’ proposed architecture and its ability to execute.

[GWH]

The ALPACA needed to be put on a serious weight loss regime:

Of particular concern is the significant weakness within Dynetics’ proposal under Technical Area of Focus 1, Technical Design Concept, due to the SEP’s finding that Dynetics’ current mass estimate for its DAE far exceeds its current mass allocation; plainly stated, Dynetics’ proposal evidences a substantial negative mass allocation. This negative value, as opposed to positive reserves that could protect against mass increases at this phase of Dynetics’ development cycle, is disconcerting insofar as it calls into question the feasibility of Dynetics’ mission architecture and its ability to successfully close its mission as proposed. While Dynetics recognizes and has been actively addressing this issue during its base period performance, its proposal does not provide sufficient details regarding its plan for executing on and achieving significant mass opportunities, especially when in the same breath, the proposal also identifies material additional mass threats. I concur with the SEP that collectively, Dynetics’ mass margin deficit at this juncture, coupled with  insufficient substantiation as to precisely how Dynetics will address this issue, creates a potent risk to successful contract performance. 

[GWH]

Propellant transfer was highlighted as an issue:

First, Dynetics’ proposal did not provide sufficient substantiation regarding the design maturity and performance capabilities of its tanker support spacecraft, which is a cornerstone of its mission architecture and is critical to successful completion of its demonstration mission. Similarly, critical technical details regarding the Mission Unique Logistics Element (MULE) are absent across numerous areas of Dynetics’ proposal. In both cases, this dearth of information complicates NASA’s ability to verify and validate the feasibility of Dynetics’ approach or its ability to close its mission as proposed.

Within Technical Area of Focus 2, the SEP also assigned Dynetics a weakness regarding development risk and relative maturity of its proposed complex propellant transfer capability. This weakness is of heightened interest to me because Dynetics’ ability to transfer propellant in this manner is considered to be a key attribute to enable its proposed mission approach. For one, Dynetics’ proposal envisages a much more optimistic and mature level of technical readiness for its in-space cryogenic fluid transfer. Moreover, Dynetics’ proposal lacks detail concerning operational specifics of this capability and is unclear about key component design attributes. This lack of detail raises questions about Dynetics’ ability to address these admittedly significant development challenges and to develop a viable propellant transfer capability on a schedule that aligns with its proposed demonstration mission.

[jdon759]

NASA's source selection statement clarifies that Dynetics would be one stage, no drop tanks as per the new design:

First, Dynetics’ proposed single stage integrated Descent Ascent Element (DAE) lander design requires no in-space integration of lander elements or staging/separation events.  This pre-integrated design will also allow for terrestrial testing of the entire system, which will increase the fidelity of testing data generated. I concur with the SEP’s conclusion that this design greatly simplifies Dynetics’ proposed architecture and its ability to execute.

This line seems to suggest that the old drop tanks were still there, but had morphed into something less drop tank-y:

First, Dynetics’ proposal did not provide sufficient substantiation regarding the design maturity and performance capabilities of its tanker support spacecraft, which is a cornerstone of its mission architecture and is critical to successful completion of its demonstration mission.

[textbookwarrior]

NASA's source selection statement clarifies that Dynetics would be one stage, no drop tanks as per the new design:

First, Dynetics’ proposed single stage integrated Descent Ascent Element (DAE) lander design requires no in-space integration of lander elements or staging/separation events.  This pre-integrated design will also allow for terrestrial testing of the entire system, which will increase the fidelity of testing data generated. I concur with the SEP’s conclusion that this design greatly simplifies Dynetics’ proposed architecture and its ability to execute.

This line seems to suggest that the old drop tanks were still there, but had morphed into something less drop tank-y:

First, Dynetics’ proposal did not provide sufficient substantiation regarding the design maturity and performance capabilities of its tanker support spacecraft, which is a cornerstone of its mission architecture and is critical to successful completion of its demonstration mission.

We got rid of the drop tanks in August. I am shocked that they didn't say anything about the engines....that was the largest technical risk on everyone's mind (except NASA's I guess)

[whitelancer64]

NASA's source selection statement clarifies that Dynetics would be one stage, no drop tanks as per the new design:

First, Dynetics’ proposed single stage integrated Descent Ascent Element (DAE) lander design requires no in-space integration of lander elements or staging/separation events.  This pre-integrated design will also allow for terrestrial testing of the entire system, which will increase the fidelity of testing data generated. I concur with the SEP’s conclusion that this design greatly simplifies Dynetics’ proposed architecture and its ability to execute.

This line seems to suggest that the old drop tanks were still there, but had morphed into something less drop tank-y:

First, Dynetics’ proposal did not provide sufficient substantiation regarding the design maturity and performance capabilities of its tanker support spacecraft, which is a cornerstone of its mission architecture and is critical to successful completion of its demonstration mission.

We got rid of the drop tanks in August. I am shocked that they didn't say anything about the engines....that was the largest technical risk on everyone's mind (except NASA's I guess)

Did you change engines? Or were the methane engines giving problems? I understand if you can't reply with details.

[textbookwarrior]

NASA's source selection statement clarifies that Dynetics would be one stage, no drop tanks as per the new design:

First, Dynetics’ proposed single stage integrated Descent Ascent Element (DAE) lander design requires no in-space integration of lander elements or staging/separation events.  This pre-integrated design will also allow for terrestrial testing of the entire system, which will increase the fidelity of testing data generated. I concur with the SEP’s conclusion that this design greatly simplifies Dynetics’ proposed architecture and its ability to execute.

This line seems to suggest that the old drop tanks were still there, but had morphed into something less drop tank-y:

First, Dynetics’ proposal did not provide sufficient substantiation regarding the design maturity and performance capabilities of its tanker support spacecraft, which is a cornerstone of its mission architecture and is critical to successful completion of its demonstration mission.

We got rid of the drop tanks in August. I am shocked that they didn't say anything about the engines....that was the largest technical risk on everyone's mind (except NASA's I guess)

Did you change engines? Or were the methane engines giving problems? I understand if you can't reply with details.

The engines have been the same since the beginning (lox/lng), but I have not seen any correct guesses online as to what specific design they are. I think that's  all I can say right now

[RotoSequence]

We got rid of the drop tanks in August. I am shocked that they didn't say anything about the engines....that was the largest technical risk on everyone's mind (except NASA's I guess)

The whole thing seems pretty surprising to me, I thought for sure Alpaca was a shoe-in. 

[MATTBLAK]

In some ways, I would have preferred it.

[TrevorMonty]

With ISRU LOX avaliable on surface dry mass wouldn't be such issue. May need to wait a few years for this to happen. On plus side a SpaceX lander could deliver significant size ISRU plant in single landing.



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[niwax]

We got rid of the drop tanks in August. I am shocked that they didn't say anything about the engines....that was the largest technical risk on everyone's mind (except NASA's I guess)

The whole thing seems pretty surprising to me, I thought for sure Alpaca was a shoe-in. 

I was also really excited for it, just the right combination of a traditional and safe but also reasonably advanced design at a reasonably price and operational complexity. But looking at deficiencies listed in the document, their marketing did a better job than the engineering and I don't think they stood a chance even with enough budget to fund all three. Being overweight this early in the design is a big no-no.

I was already wondering how they could go without drop tanks and not lose performance. Sad, it was such an elegant solution to mass fraction without expendable landers, loads of docking or more complicated refueling. Plug in a new tank and go again.

[Joseph Peterson]

I was already wondering how they could go without drop tanks and not lose performance. Sad, it was such an elegant solution to mass fraction without expendable landers, loads of docking or more complicated refueling. Plug in a new tank and go again.

Plumbing and support structure needed for drop tanks is going to require a non-trivial amount of mass.  I'll leave the calculations for real rocket engineers but my opinion is that stretching the permanent tanks could result in a lower dry mass penalty at ascent than adding all the extra bits needed to support drop tanks.  Even if my opinion is in error larger permanent tanks removes a staging event.  One less thing that can go wrong can easily be worth some extra dry mass.

[AstroWare]

I think that there is still the possibility Dynetics lives on as a CLPS provider.

1. It seems like the best design to deliver ISS type modular lunar base elements. Starship and Blue Moon Landers could also compete, but the logistics of offloading favor Dynetics.

2. As a lander only, the mass fraction issue is much less important than if it was an ascender as well.

3. I don't know specifically the ALPACA capabilities, but if it could be launched on a single heavy lift vehicle, then docked to it's payload in orbit, it could eliminate orbital fueling ops.

[Nathan2go]

The engines have been the same since the beginning (lox/lng), but I have not seen any correct guesses online as to what specific design they are. I think that's  all I can say right now

Ooh, let me guess: what about electric pump-fed, with variable thrust via variable pump power?

A pump-fed (instead of pressure fed) engine would produce a very large dry mass savings from lower required tank pressure (thinner tank walls and smaller pressurization system).  An electric pump would have lower development cost, shorter schedule, and greater reliability than a turbo-pump design.  Ordinarily, the batteries needed would be so heavy as to offset the savings, unless the batteries are progressively dropped in-flight as with the  Rocket Labs Electron. 

If ALPACA discarded some of the batteries at the Lunar landing site, I'm sure they would be useful as spares for something (off-site rover fast-charging stations?)

The ALPACA however, could also recharge the batteries during the mission: following the burn to descend to low lunar orbit, between landing and ascent, and between reaching low lunar orbit, and ascent to Gateway.  (Even with re-charging, the total battery mass needed for ascent would be less than half of what is used for descent, so there is still an incentive to drop some).

I'm sure the drop mechanism for a battery would be simpler and lighter than a plumbing disconnect system for a tank.

But needing to stop and wait for battery re-charge at various points in the mission would likely be considered a disadvantage by NASA.

Also as you mentioned, it is odd that NASA did not mention engines in their sourcing statement. I would have thought using a proven engine (e.g. Rutherford) would be a strength, and an unproven engine a weakness.  Since the report did not give it either, it must be in between proven and unproven?

[textbookwarrior]

The engines have been the same since the beginning (lox/lng), but I have not seen any correct guesses online as to what specific design they are. I think that's  all I can say right now

Ooh, let me guess: what about electric pump-fed, with variable thrust via variable pump power?

A pump-fed (instead of pressure fed) engine would produce a very large dry mass savings from lower required tank pressure (thinner tank walls and smaller pressurization system).  An electric pump would have lower development cost, shorter schedule, and greater reliability than a turbo-pump design.  Ordinarily, the batteries needed would be so heavy as to offset the savings, unless the batteries are progressively dropped in-flight as with the  Rocket Labs Electron. 

If ALPACA discarded some of the batteries at the Lunar landing site, I'm sure they would be useful as spares for something (off-site rover fast-charging stations?)

The ALPACA however, could also recharge the batteries during the mission: following the burn to descend to low lunar orbit, between landing and ascent, and between reaching low lunar orbit, and ascent to Gateway.  (Even with re-charging, the total battery mass needed for ascent would be less than half of what is used for descent, so there is still an incentive to drop some).

I'm sure the drop mechanism for a battery would be simpler and lighter than a plumbing disconnect system for a tank.

But needing to stop and wait for battery re-charge at various points in the mission would likely be considered a disadvantage by NASA.

Also as you mentioned, it is odd that NASA did not mention engines in their sourcing statement. I would have thought using a proven engine (e.g. Rutherford) would be a strength, and an unproven engine a weakness.  Since the report did not give it either, it must be in between proven and unproven?

Wish I could say. I absolutely can't take NASA's technical analysis of the lander seriously because it isn't mentioned. Anyways.. it was a fun and interesting program with some good lessons learned. Best of luck to SpaceX and NASA.

[tbellman]

Wish I could say. I absolutely can't take NASA's technical analysis of the lander seriously because it isn't mentioned. Anyways.. it was a fun and interesting program with some good lessons learned. Best of luck to SpaceX and NASA.

I don't know if you have read the full report from the source evaluation panel, or just Kathy Lueder's source selection statement, but just in case, the source selection statement only mentions a subset of the SEP findings.

Note that this selection statement does not identify or describe SEP findings for each offeror with which I concur but that did not represent significant considerations in my analysis or ultimate determinations.

(I don't suppose the full reports will be made available.  It would have been interresting to read them.)

Anyway, I will say that I liked the concept of ALPACA, and I hope you can find some way of continuing your work on it, and get it to work!

[Gliderflyer]

The engines have been the same since the beginning (lox/lng), but I have not seen any correct guesses online as to what specific design they are. I think that's  all I can say right now

Ooh, let me guess: what about electric pump-fed, with variable thrust via variable pump power?

A pump-fed (instead of pressure fed) engine would produce a very large dry mass savings from lower required tank pressure (thinner tank walls and smaller pressurization system).  An electric pump would have lower development cost, shorter schedule, and greater reliability than a turbo-pump design.  Ordinarily, the batteries needed would be so heavy as to offset the savings, unless the batteries are progressively dropped in-flight as with the  Rocket Labs Electron. 

If ALPACA discarded some of the batteries at the Lunar landing site, I'm sure they would be useful as spares for something (off-site rover fast-charging stations?)

The ALPACA however, could also recharge the batteries during the mission: following the burn to descend to low lunar orbit, between landing and ascent, and between reaching low lunar orbit, and ascent to Gateway.  (Even with re-charging, the total battery mass needed for ascent would be less than half of what is used for descent, so there is still an incentive to drop some).

I'm sure the drop mechanism for a battery would be simpler and lighter than a plumbing disconnect system for a tank.

But needing to stop and wait for battery re-charge at various points in the mission would likely be considered a disadvantage by NASA.

Also as you mentioned, it is odd that NASA did not mention engines in their sourcing statement. I would have thought using a proven engine (e.g. Rutherford) would be a strength, and an unproven engine a weakness.  Since the report did not give it either, it must be in between proven and unproven?

May or may not be some clues in this video:

(I do wish we had talked more about the engines....)