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ESDMD #0503: In-Space & Surface Transfer of Earth-Storable Propellants

Safe, reliable transfer of hypergolic and electric-propulsion propellants, and of high-pressure gases, between assets in space and on the Moon and Mars surfaces (bin 6, rating 50 of 57). Hypergolic transfer has been demonstrated in space and is routine on the ground, but "subsystems at scale are TRL 2-3" (Tech gaps spreadsheet, ESDMD #0503).

Quotations below are from row ESDMD #0503 of the tech gaps spreadsheet. ADD Rev C's Appendix D prints the same table for this gap, and it matches the row field for field (ADD Rev C, p. 226).

Description

"Planned Moon and Mars exploration missions benefit from propellant transfer of hypergolic and electric propulsion propellants, including both in-space and Moon and Mars surface operations. This gap captures the required activities to enable efficient propellant transfer with acceptable risk posture."

Impacts and benefits: "Without gap closure, the architecture will be unable to transfer storable propellant between elements."

Current state of the art

"Hypergolic propellant transfer has been demonstrated in space and is common for ground operations. Subsystems at scale are TRL 2-3."

Performance target

Moon/Mars: "Enable the thermal conditioning and reliable and safe transfer of storable propellant and high pressure gases between exploration assets in space and on the surface of the Moon and Mars."

Child gaps

  • 0503-01: Cold- and dust-tolerant seals to enable surface transfer of high-pressure fluids
  • 0503-02: Compressors and pumps for filling or venting of high-pressure fluids in reduced gravity and microgravity
  • 0503-03: Autonomous commodity transfer and recovery
  • 1104-06*: In-space transfer of electric propulsion (EP) propellant

The starred child gap also appears under #1104, Mars transportation propulsion. The asterisk marks "a child gap with multiple parents" (ADD Rev C, p. 199).

Traceability

  • Use cases and functions: UC-U-501 L -- FN-U-507 L; UC-U-502 L -- FN-U-508 L; UC-T-108 M -- FN-T-210 M; UC-T-108 M -- FN-T-211 M; UC-T-108 M -- FN-T-212 M; UC-U-501 M -- All FN
  • Definition tasks: Mars: Crew In-Space Propulsion Type; Cargo In-Space Propulsion Type; Crew In-Space Return Propellant Strategy

The two lunar pairs (UC-U-501 L -- FN-U-507 L and UC-U-502 L -- FN-U-508 L) also appear under cryogenic fluid transfer, #1107.

Segments and sub-architectures

Priority

Priority bin 6, overall prioritization rating 50 of 57. The rating is "the gap's location in the prioritized list of gaps", so 1 is the highest priority, and bins group gaps of similar priority, bin 1 highest. Criticality, urgency, breadth and depth set the order; cost is not considered (ADD Rev C, pp. 78, 199; method on the gaps index).

Moon Base relevance

Not established by the sources so far. The Users Guide does not name #0503 among its near-term Moon Base challenges (Technology and knowledge challenges).

Sources

Tech gaps spreadsheet, ESDMD #0503 · ADD Rev C, pp. 78, 199, 226