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ESDMD #1105: Mars Ascent Propulsion for Human Exploration

Propulsion to lift crew and cargo from the Mars surface back to orbit (bin 2, rating 12 of 57). Ascent is a high "gear ratio" operation: lifting just two crew is estimated to need more than 30 t of propellant with current technology, and ascent from Mars "has never been attempted". Candidates are storable, cryogenic, solid and hybrid rocket engines. A Mars-only gap (Tech gaps spreadsheet, ESDMD #1105).

Quotations below are from row ESDMD #1105 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. 256).

Description

"Mars atmosphere and gravity make ascent a high "gear ratio" operation, meaning several kilograms of ascent propulsion mass are required for every kilogram lofted back to orbit. At a minimum, ascending just two crew members—even without any return cargo—is estimated to require more than 30 tons of propellant to a 5-sol Earth transportation vehicle parking orbit with current technology. New technologies are required to return crew and cargo to Mars orbit."

Impacts and benefits: "Ascent stage performance has significant impact throughout the architecture. Without gap closure, architecture may require large amounts of ascent propellant to be delivered from Earth or produced in-situ and stored for long durations, which may threaten architecture viability."

Current state of the art

"Ascent from Mars surface has never been attempted. Current solutions are conventional storable propellant liquid rocket engines."

Performance target

Mars: "Enable crew and cargo to ascend to Mars orbit. Desired performance will be informed by ongoing and future definition tasks."

Child gaps

  • 1105-01: High-efficiency, high-thrust liquid rocket engine with storable propellant for Mars ascent propulsion
  • 1105-02: Robust liquid rocket engine with cryogenic propellant for Mars ascent propulsion
  • 1105-03: Reliable and human-rated solid propellant rocket engine for Mars ascent propulsion
  • 1105-04: High-efficiency, high-thrust rocket engine with hybrid propellant system for Mars ascent propulsion

Traceability

  • Use cases and functions: UC-T-101 M -- FN-T-102 M; UC-T-208 M -- All FN
  • Definition tasks: Mars: Crew Mars Parking Orbit; Crew Mars Ascent Availability; Crew Mars Ascent Propulsion Type; Crew Mars Ascent Propellant Strategy; EDLA Systems Reuse Strategy

Segments and sub-architectures

Priority

Priority bin 2, overall prioritization rating 12 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 gap is Mars-only in the spreadsheet, and the Users Guide does not name it among its near-term Moon Base challenges (Technology and knowledge challenges).

Sources

Tech gaps spreadsheet, ESDMD #1105 · ADD Rev C, pp. 78, 199, 256 · Mars Ascent Propellant Considerations (2024), p. 4