Possibilities for a single launch architecture of the Artemis missions, Page 3: Saving the lander mission for Artemis III.

 Copyright 2023 Robert Clark

  I discussed a possible single-launch lunar lander architecture here:

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage.

http://exoscientist.blogspot.com/2023/08/possibilities-for-single-launch.html

 The SpaceX delay in the Starship HLS development has led to NASA considering that Artemis might not even be a lander mission. This leaves open the possibility to save the lander mission for the Artemis III mission alternative methods for landers should be considered.

 Plus, there is the fact many knowledgeable space aficionados from the old days really do not like the SpaceX plan of using 8 to 16 refueling flights just for one lunar lander mission.

 This plan for a replacement lander could be done rather quickly and at low cost because it would use already existing space assets. Also, it would be done by our European partners so would not require NASA expenditures using all European space components. That would save $3 billion that NASA would have had to pay to SpaceX for their lander.

 This would involve even greater European involvement in successfully accomplishing the Artemis missions than just Orion’s service module so would undoubtedly get enthusiastic support from the ESA.

 It is notable that the ESA has expressed even greater support for lunar colonization plans than even NASA. This ESA produced lunar lander would allow them to further their own plans for a sustained human presence on the Moon.

 About ESA’s ATV-derived service module for Orion, that again would require low cost modifications in this plan. It would need just an addition 10 tons of propellant, which would fit easily within a service module diameter expanded to match the Orion’s diameter. Again this cost would be covered by our European partners, with no expenditure by NASA.

 Those two factors would be the easiest aspects of the plan. It might be difficult to believe a lunar lander would be among the “easiest” parts of the plan. But keep it mind it would be derived from already existing space assets.

 The trickiest aspects of the plan would be the fact the SLS would require higher payload capability to allow for the higher propellant load of the service module of 10 tons and a ca. 15 ton mass lunar lander.

 One possibility, keeping the Boeing EUS, is to put atop it a third stage consisting of the 50-ton Centaur V, as discussed in, "Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage."

 However,  I’m still not convinced the Boeing EUS is the best way to go because of its expense and its small size. If a cryogenic upper stage at a propellant load of ca. 200 ton size instead of the Boeing EUS ca. 125 tons were used, then this larger upper stage itself could do TLI burn carrying the Orion, larger SM, and ca. 15 tons lunar lander.

 I discuss here how such a larger cryogenic stage could be done in a much cheaper fashion than the Boeing EUS approach:  

Why does the Boeing Exploration Upper Stage(EUS) cost so much?  

http://exoscientist.blogspot.com/2022/11/why-does-boeing-exploration-upper.html

 I call this the trickiest aspect of the plan because Boeing has shown repeated delays in getting the core stage ready so the same might happen with their EUS stage, especially when it would have to be moved up to be ready by the 2025 Artemis III launch date, instead of on Artemis IV in 2028. As for the extra Centaur V third stage, since it is expected to first launch this year, likely it will have several launches under its belt by a 2025 Artemis III launch date.

 Note though a MAJOR reason why the development of the different versions of the SLS was arranged as it was was because of cost reasons. The development of the Boeing EUS was pushed back to delay paying for its wildly overpriced development costs. Note too not having to pay for the SpaceX Starship lander would save NASA $3 billion.

 Boeing’s charge to NASA for the EUS is a key reason why I prefer the simpler approach for an upper stage of just basing it on the core with fewer barrel rings. 

This would also give us the stage more cheaply and more quickly since it involves just using fewer rings on the tanks. If you have ever watched the video of construction taking place at the SpaceX development site, barrel rings of the tanks on the Starship and SuperHeavy are swapped out, replaced, taken-off and put back routinely.

 You’ve heard the mantra of former NASA administrator Dan Goldin, “faster, better, cheaper”? This would be "faster, better, cheaper, and simpler".

 Since this is of different design though that also brings into question its availability by a 2025 launch date. Note that this plan involves several new components. For that reason, we might want to use Artemis III as an unmanned test lander mission. We might even have it be “manned” by human-like robots, with their operation controlled from the ground on Earth.

 In this regard it is notable that several lines of evidence suggest that there might be valuable metals at the lunar South Pole, the planned location for the Artemis III landing. Indeed, the untold trillions of dollars of valuable metals speculated to exist in the main-asteroid belt on 16 Psyche might already exist just next door at the Moon's south pole! I discuss this here:

U.S. will lag behind in utilization of resources on the Moon.

http://exoscientist.blogspot.com/2023/08/us-will-lag-behind-in-utilization-of.html

 By the way, the title there stems from my dismay that the U.S. rovers to the South Polar location won’t have instruments for detecting heavy metals but the rovers from other countries will. This is such an obvious thing to include, especially when other countries will include them, that it’s mystifying why the U.S. chose not to include them.

 In any case, it would be pretty cool seeing human-like robotic astronauts prospecting for valuable metals at their landing site.

The ESA produced lunar lander I suggest using is of Apollo-like size at ca. 15 tons. But its crew module volume would be much larger as it is based on the Cygnus capsule, given life support. The Apollo lunar lander had a 6.7 cubic meter internal volume. But the Cygnus has an 18.9 internal volume, nearly 3 times that of the Apollo LEM and the expanded version of the Cygnus has a 27 cubic meter internal volume.

 But as for sending cargo or habitats to the Moon, the SLS is far too expensive, $2 billion+ per launch, and at too low flight cadence, at best 1 once per year, for that purpose. 

 Better to use lower cost launchers such as the Falcon Heavy for the purpose. I estimate using all hydrolox in-space stages, given low-boiloff tech, the FH could get 15 tons one-way to the lunar surface. 

 Using hydrolox only for the TLI burn but a storable propellant lander stage (so no low-boiloff tech needed), the FH could get 10 tons to the lunar surface.

Robert Clark

Possibilities for a single launch architecture of the Artemis missions, Page 2: using the Boeing Exploration Upper Stage.

 Copyright 2023 Robert Clark

  A comparison between the Apollo and Orion capsules:

 Rarely has a design mistake been so clearly illuminated by a single picture. Note the Orion capsule is nearly double the size of the Apollo capsule in mass. But rather than making Orion’s Service Module twice as big as the Apollo Service Module, as it should be to get similar performance, instead it is smaller by 1/3rd.

 Orion’s service module is based on ESA’s ATV cargo tug to the ISS, which had a 4.5 meter diameter and a 10 ton propellant load.

BUT THERE WAS NO REASON TO KEEP IT AT THAT SAME DIAMETER FOR THE ORION USE, NOR TO KEEP THE SAME SIZE PROPELLANT LOAD.

 If instead the diameter was made to match the capsule’s diameter, as was the case with Apollo, there would be an additional 20 cubic meters of volume inside the Service Module, well more than enough to hold an additional 10 tons of the storable propellant used.

And that is all that is needed to solve THE major problem of the SLS/Orion approach: the fact it can’t send the Orion and a lunar lander to low lunar orbit, and bring the Orion back to Earth again.

 It is because of that the idea of the lunar Gateway was proposed, where the SLS would only have to take the Orion to a further out orbit.

 But if instead the Service Module was given that additional 10 tons of propellant then it could send both the Orion and a ca. 15 ton lunar lander to low lunar orbit, and have enough propellant left over to bring the Orion back to Earth, a la the Apollo architecture.

 Rarely, has a mistake been so clearly exposed, especially when its solution is so clearly made apparent as well.

 In the blog posts, "ESA Needs to Save NASA's Moon Plans", and "Possibilities for a single launch architecture of the Artemis missions", I wrote about getting a single launch format for the Artemis lunar lander missions by using the Ariane 5 as an upper stage or by using two Centaur V stages as the upper stage for the SLS, respectively.

 This stemmed from dislike of the plan NASA was endorsing of using multiple flights and refuelings of the SpaceX Starship as the lander. I also objected to the high cost projected for the planned Boeing Exploration Upper Stage(EUS), being nearly half the cost of the entire SLS per flight, nearly $1 billion.

 However, NASA has negotiated a better price structure for the EUS. And it appears NASA is wedded to the Boeing EUS. Then I'll discuss a single launch architecture using the Boeing EUS upper stage.

 The payload to LEO of this version of the SLS with the Boeing EUS, which is version Block 1B, will be 105 tons to LEO. The current fueled mass of the Orion+Service Module is 26.5 tons. An additional 10 tons of propellant will bring it to 36.5 tons. 

 In the blog post, "A low cost, lightweight lunar lander", I discussed a lunar lander at a 13-ton total fueled mass based on the Cygnus capsule given life support as the crew module, and the Ariane 5 EPS storable propellant stage as the propulsive stage for the lander.

Calculations for the delta-v to the Moon and back.

 The Orion with its fully fueled service module has a mass of 26.5 tons. The propellant load of the service module is ~10 tons, with 16.5 total tons dry mass of the Orion and service module. We'll add an additional 10 tons propellant to the service module to bring the total mass to 36.5 tons, including 20 tons of propellant.

 The AJ-10 engine used has a vacuum ISP of 319s. We'll assume a fueled lunar lander of size ~13 tons, as described in the blog post, "A low cost, lightweight lunar lander", comparable in size to the Apollo missions lunar lander. So, a 16.5 + 13 = 29.5 ton mass for the vehicles that need to be put in low lunar orbit. But remember also we need to have some propellant left over in the service module to bring the Orion back home to Earth.

 For the delta-v calculation, after the SLS places the Orion/Service Module/lunar lander stack in trans-lunar injection(TLI) towards the Moon, we need 0.9 km/s to put the stack into low lunar orbit. This requires 13 tons of propellant, leaving 7 tons remaining:

319*9.81Ln(1 + 13/(29.5 +7)) = 0.950 km/s. The lunar lander will then be launched to land on the Moon while the Orion and service module remain in lunar orbit.

 After the lander mission is completed, the lander returns the astronauts to the Orion in lunar orbit, and the lander is then jettisoned. The Orion's service module is then fired to bring the Orion back to Earth. After lander jettison, the dry mass of the Orion and service module will be 16.5 tons. Then the 7 tons of remaining propellant is sufficient to perform the trans-Earth injection(TEI) burn of 900 m/s to escape lunar orbit and place the spacecraft back onto the free return trajectory back to Earth:

319*9.81Ln(1 + 7/16.5) = 1,100 m/s. 

 So the total mass that needs to be sent to trans lunar injection(TLI) on a path to encounter the Moon is 36.5 + 13 = 49.5 tons. Now use the rule-of-thumb that a Centaur-like hydrolox stage can send to TLI at a 3,000 m/s required delta-v a payload mass equal to its propellant load.

 So use for a third stage atop the Boeing EUS the Centaur V at an 50 ton propellant load and 5 ton dry mass. This then results in a total mass to LEO of 104.5 tons consisting of the 55 tons of the Centaur V plus the 49.5 tons of the Orion capsule/Service Module/lunar lander, within the lift capacity of the SLS Block 1B to LEO.

  Robert Clark

ESA Needs to Save NASA's Moon Plans.

Copyright 2022 Robert Clark

 The SLS was planned to have a large upper stage called the Exploration Upper Stage(EUS). This would take the SLS Block 1 to the SLS Block 1B, needed for a single flight lunar architecture. However, the multi-billion dollar cost for development of a large upper stage from scratch means it’s unlikely to be funded.

 NASA is proposing a solution using the Starship making separate flights. But this plan takes 6 flights total or likely more of the Superheavy/Starship for the Starship to fly to the Moon to act as a lander. One look at this plan makes it apparent it’s unworkable:

 Actually, it’s likely to be more complex than portrayed in the figure, needing 8 to 16 refueling flights. This is what SpaceX submitted to NASA in proposing the plan, requiring 6 months to complete the Starship refueling:

SpaceX CEO Elon Musk details orbital refueling plans for Starship Moon lander. By Eric Ralph Posted on August 12, 2021
First, SpaceX will launch a custom variant of Starship that was redacted in the GAO decision document but confirmed by NASA to be a propellant storage (or depot) ship last year. Second, after the depot Starship is in a stable orbit, SpaceX’s NASA HLS proposal reportedly states that the company would begin a series of 14 tanker launches spread over almost six months – each of which would dock with the depot and gradually fill its tanks.
…
In response to GAO revealing that SpaceX proposed as many as 16 launches – including 14 refuelings – spaced ~12 days apart for every Starship Moon lander mission, Musk says that a need for “16 flights is extremely unlikely.” Instead, assuming each Starship tanker is able to deliver a full 150 tons of payload (propellant) into orbit after a few years of design maturation, Musk believes that it’s unlikely to take more than eight tanker launches to refuel the depot ship – or a total of ten launches including the depot and lander.
https://www.teslarati.com/spacex-elon-musk-starship-orbital-refueling-details/

 Everyone, remember the Apollo missions where we could get to the Moon in a single flight? In fact, this would be doable with the SLS given a large upper stage. Then the suggestion is for the ESA to provide a Ariane 5 or 6 as the upper stage for the SLS. It would save on costs to NASA by ESA paying for the modifications needed for the Ariane core.  

 As it is now ESA is involved in a small role in the Artemis lunar program by providing the service module to the Orion capsule. But it would now be playing a major  role by providing the key upper stage for the SLS.  

 The argument might be made that the height of the Ariane 5/6 is beyond the limitations set forth by NASA for the EUS. However, if you look at the ca. 30 m height of Ariane 5 core compared to the 14 m height of the interim cryogenic upper stage now on the SLS, this would put the total vehicle height only a couple of meters beyond the height that had already been planned for the SLS Block 1B anyway:

 

 See discussion here:  

Budget Moon Flights: Ariane 5 as SLS upper stage, page 2.   

https://exoscientist.blogspot.com/2013/09/budget-moon-flights-ariane-5-as-sls.html

 Coming up: ESA also could provide a low cost lander for the Artemis program.

Payload Estimates

 Here’s the Silverbird Astronautics estimates for the payload capacity using the Ariane 5 as the upper stage. The vacuum Isp used for the Ariane 5 is taken as 462 s since it it known by the example of the RL10 engine that a hydrogen engine can have its vacuum Isp raised to this level by a nozzle extension. Specifications shown below, with the 5-segment SRB data estimated by 25% scale up of the Space Shuttle SRB’s data.

 And the results for the LEO payload:

 The estimated payload for TLI is found by putting -1.0 in for the hyperbolic C3 value for “Escape trajectory” field. This is a number that indicates it’s just below escape velocity for a free return trajectory around the Moon in case the mission has to be aborted.

 So both the LEO payload of 150 tons and the TLI payload of 60 tons are above even the Block 2 payload capacity that would use advanced carbon fiber casing for the SRB’s.

 Input data taken from: 

 

 

   Robert Clark