The new NASA video NASA 2021: Let's Go to the Moon shows artwork for three very different spacecraft sitting on the lunar surface with the overlain caption

Selecting A Human Landing System

"Selecting" suggest to me that these are official candidates submitted to NASA, is that right? If so, is it possible to outline the NASA criteria that each one was supposed to meet in order to have the possibility of selection? I'm assuming there's a "landing several folks on the Moon and returning them safely to the Earth" clause and a tonnage of cargo clause, but is there a way to express the main criteria in a form short enough to be suitable for a Stack Exchange answer?

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1 Answer 1


A short summary:

  1. The HLS needs to be able to support human life. The overarching goal is to land humans on the Moon and safely return them to the Earth.

  2. The HLS needs to be able to land on and later launch from the surface of the Moon. This is the second half of that overarching goal.

  3. The HLS needs to be able to dock with the Gateway / Orion. The base plan is for the Orion vehicle to deliver crew to the HLS, and later for the Orion return crew to the Earth.

  4. The HLS needs to be able to loiter in a Near-Rectilinear Halo Orbit for at least 60 days, and preferably over 90 days. NASA will not launch the crew until it has deemed the HLS to be in the desired HRHO orbit, and launches are oftentimes delayed.

  5. Except for emergencies that might otherwise result in loss of mission / loss of crew, the HLS needs to be able to stay on the surface of the Moon for a minimum 6.5 days.

  6. The HLS needs to be able support at least two (and preferably at least five) EVAs on the surface of the Moon that are at least four hours long, and preferably at least eight hours long.

  7. The HLS needs to be able to return at least ten kilograms of lunar material (and preferably over 100 kg) of material gathered by the crew during their EVAs to Orion.

  8. The operations of the HLS must be fully automated, but also must allow for crew override.

  9. The HLS has to follow a huge number of NASA requirements ranging from tiny things such as how to (and how not to) solder electrical connections to big things such as how to avoid having the crew bonking their heads when they move around.

What I perhaps sarcastically denoted as anti-head bonking requirements also include requirements that preclude sharp edges that might tear a crew member's suit. These human factor requirements are extremely important in supporting the first overarching requirement.

Source: Attachment F (HLS Requirements) to the HLS Broad Agency Announcement (BAA).

  • $\begingroup$ This is perfect, thanks! I'm starting to get the idea now, and I think this answer can serve as a "launch point" for many more new questions. Do you think that a minimum and maximum crew size should be asked about separately or included here? $\endgroup$
    – uhoh
    Jan 3, 2021 at 21:53
  • 1
    $\begingroup$ @uhoh Two crew, initially. $\endgroup$ Jan 4, 2021 at 1:15

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