Having previously eschewed using the Lunar Gateway space station as a half-way stop for use with a human carrying landing system – even if it will still be built –  NASA  has announced the selection of three teams to build human landers/ascent craft which will land astronauts on the Moon as part of the Artemis programme. The target date for the initial landing is 2024.  Initial landings will be stand alone missions.  Later flights will make full use of the Gateway-enabled capabilities, including refueling and reuse of all or parts of the lander.

The awardees for NASA’s Human Landing System contracts are the teams led by Blue Origin, Dynetics (a Leidos company) and SpaceX.  Each has a different concept for their vehicles, offering a diversity of archetture and hence increasing the chance that at least one will succeed.  It is not known yet how many of these “finalists” will be proceeded with.

Update on 21 May 2020: Under pressure to do so, Doug Loverro, NASA’s Associate Administrator of Human Exploration and Operations Mission Directorate has resigned after less than six months in the position. Loverro took over from the long serving Bill Gerstenmaier when he was unceremoniously demoted in July 2019.  While the exact cause of his decision has yet to be fully revealed, it is understood to be as a result of the choice of lunar landing system finalists and how the normal procurement procedure was circumvented.

Blue Origin 

Blue Origin is the prime contractor for the National Team that includes Lockheed Martin, Northrop Grumman, and Draper. Their Integrated Lander Vehicle (ILV) is a three-stage lander that harnesses the proven spaceflight heritage of each team.

The Blue Origin-led National Team’s concept for a three-stage lunar lander/ascent/transfer craft. Courtesy: Blue Origin

Blue Origin will build the National Team’s concept’s descent element which is powered by BE-7 cryogenic engines with the firm currently working on cryogenic storage systems. Team member Lockheed Martin will build the ascent element that includes the crew cabin, which will have significant commonality with Orion. Northrop Grumman will build the transfer element based largely on its Cygnus cargo module that services the International Space Station. Northrop Grumman is also leading development of a future refueling element for a sustainable lander demonstration. Draper will provide the guidance, navigation and control, avionics, and software systems that draw largely on similar systems the company has developed for NASA.

In their proposal, the National Team outlines a plan in which the ILV can dock with either Orion or the Gateway to await crew arrival. The Blue Origin National Team’s elements for the Human Landing System can be launched individually on commercial rockets or combined to launch on NASA’s Space Launch System.

Dynetics

Dynetics proposed a robust team with more than 25 subcontractors specializing in both the larger elements and the smaller system-level components of the Dynetics Human Landing System. The large team capitalizes on Dynetics’ experience as an integrator on military and defense contracts with large subcontractor teams.

Dynetics Human Landing System. Courtesy: Dynetics

The Dynetics Human Landing System concept includes a single element providing the ascent and descent capabilities, with multiple modular propellant vehicles prepositioned to fuel the engines at different points in the mission. The crew cabin sits low to the surface, enabling a short climb for astronauts entering, exiting, or transporting tools and samples. The DHLS systems supports both docking with Orion and with Gateway, and will get a fuel top-off before descending to the surface. After the surface expedition, the entire vehicle will return for crew transfer back to Orion.  The Dynetics Human Landing System is described as being “rocket-agnostic”, capable of launching on a number of commercial rockets.

SpaceX

Starship is a fully reusable launch and landing system designed for travel to the Moon, Mars, and other destinations. The system leans on the company’s tested Raptor engines and flight heritage of the Falcon and Dragon vehicles. Starship includes a spacious cabin and two airlocks for astronaut moonwalks.

Starship on lunar surface. Courtesy: SpaceX

Several Starships serve distinct purposes in enabling human landing missions, each based on the common Starship design. A propellant storage Starship will park in low-Earth orbit to be supplied by tanker Starships. The human-rated Starship will launch to the storage unit in Earth orbit, fuel up, and continue to lunar orbit.

SpaceX’s Super Heavy rocket booster, which is also powered by Raptor and fully reusable, will launch Starship from Earth. Starship is capable of transporting crew between Orion or Gateway and the lunar surface.

Comment by David Todd:  Because the Orion spacecraft the main method of getting astronauts into the Cis-Lunar environment has an undersized service module and propulsion system, it can only get to high lunar orbit (or its equivalent) then each landing/ascent system detailed above, either has to have either a dedicated transfer system to move itself to and from low lunar orbit, or enough Delta V on board to do so on its own. And that is even after any descent and ascent from the lunar surface.  In other words propellants remain the big issue.

Refueling in orbit and on the Moon is one way around this conundrum but there are problems as the technology readiness is very much not there yet.

Likewise, cryogenic propellants (Liquid Oxygen/Liquid Hydrogen or Liquid Methane) which are to be used by most of the entrants above have very good energy and propulsive efficiency, but they are difficult to store and suffer significant boil off.

Storable hypergolic propellant combinations such as were used by the original Apollo Lunar Excursion Module (LEM) are much simpler to handle and more reliable – if offering much lower performance. That said, one suspects here that if NASA wanted to get back to the Moon quickly it should really have chosen a simpler Apollo style lunar module as its initial landing/ascent craft type, albeit with its payload/crew limitations, and leave more complicated crogenic reusable designs for later.  Such a simplified design would in effect be an Apollo LEM Mark 2, albeit with the addition of a storable propellant transfer stage. In a way, this is pretty much the Blue Origin design albeit that it eschews these simpler low energy propellants.

One other factor.  SpaceX may not be able to get its Starship back to Earth. This writer leans on his own Masters’ studies decades ago in which he came to the conclusion that high lift-to-drag bodies (such as the Starship) re-entering  Earth’s atmosphere at super-orbital speeds would have too much convective heating for thermal protection systems to handle, and that a blunt body vehicle was – and still is – the only way to do it if a direct entry is desired (an alternative is to use time consuming aero-braking manoeuvres).

There is a little hint about which concept NASA has most faith in. Of the US$1 billion awarded as the initial contract total, Blue Origin is receiving US$579 million, Dynetics is getting US$253 million, while SpaceX gets just US$135 million. NASA has also expressed public doubts via a technical review about the technology readiness state of all three competing designs’ propulsion systems. In addition, NASA noted the operational risks of SpaceX in-space refueling operation, and made an implied criticism of SpaceX’s record of missing deadlines for service delivery.

Final Conclusion

NASA needs pick a low tech quick-build lunar lander using storable propellants for initial exploration flights, and build a slower-to-develop but more technically advanced reusable design for longer-term sustainable use.

Space News has a fuller discussion about NASA’s technical review of the lunar landers here