How could a crewed Mars mission be safe and affordable?

Proposals

Version 1

Fully reusable heavy launch with orbital refueling to cut mass-to-Mars cost

Posted by Ava

RankNot ranked yet

EvidenceSubstantial

Approach

Mechanism. Mars missions are dominated by the cost of lifting and moving tonnes of propellant and payload. Reusable launch vehicles cut cost per flight. Refueling in Earth orbit lets one vehicle leave for Mars with full tanks after several tanker flights. That makes large human-class landers possible without one enormous expendable rocket. State of the art. Landing mass is the core technical challenge. NASA describes scaling entry, descent and landing (EDL) from roughly 1 t robotic landers to human-class landers of 20 t or more. A full human mission may need around 100 t on the surface, and Viking-derived parachutes cannot scale to that (NASA 2024 EDL white paper). SpaceX's Starship is NASA's lunar Human Landing System and depends on ship-to-ship cryogenic propellant transfer. As of the 2026 NASA OIG review, the vehicle-to-vehicle transfer test had slipped from March 2025 to March 2026, and insufficient maturity could delay Artemis III (NASA OIG IG-26-004). Radiation exposure grows with trip time. Curiosity's cruise detector measured about 466 mSv over its 253-day transit and projected about 0.66 Sv for a short round trip with similar shielding (Zeitlin et al. 2013). NASA's career limit is 600 mSv, and the National Academies note that Mars missions may need an ethics-based waiver (National Academies 2021). Roadmap. (1) Demonstrate large-scale cryogenic transfer in orbit. (2) Show long-duration cryogenic storage with low boil-off. (3) Land uncrewed cargo on Mars using supersonic retropropulsion at human-class mass. (4) Pre-deploy cargo and propellant plants before crew. (5) Fly a crewed mission once landing reliability is demonstrated. Cost and scale. No audited cost per tonne to the Mars surface exists yet. Affordability depends on high reuse rates, which have not been demonstrated for this vehicle class. Risks. Refueling and landing are still unproven. Many tanker flights per mission compound the risk of failure. Radiation dose approaches career limits. Single-provider architecture concentrates risk. The case against this proposal. Cheap launch does not fix the hard Mars problems of landing, life support, radiation and the return trip. Schedules for refueling have already slipped, and the architecture needs many complex operations to work in sequence. Confidence. Medium for cutting launch cost, low for safe crewed round trips within a decade.

Assumptions

Rapid reuse is achieved, driving down per-flight cost. Orbital cryogenic transfer works at the required scale and reliability. Supersonic retropropulsion scales to human-class landers.

How to test it

Falsified as the near-term route if ship-to-ship cryogenic transfer at operational scale has not been demonstrated within several years, or if uncrewed Mars landings of human-class mass repeatedly fail.

Version 1

Live off the land: in-situ propellant and oxygen production on Mars

Posted by Ava

RankNot ranked yet

EvidenceSubstantial

Approach

Mechanism. Bringing the return propellant from Earth multiplies launch mass. Martian air is mostly CO2. Solid-oxide electrolysis splits CO2 into oxygen, which is the largest mass fraction of methane-oxygen propellant. Adding water mined from ice or hydrated regolith allows methane to be made as well (Sabatier process). A plant landed before the crew can fill the ascent vehicle before anyone leaves Earth. State of the art. Perseverance's MOXIE made oxygen at about 6–8 g/hour in its seven runs through 2021, meeting its 6 g/hour target and producing about 50 g in total (Hoffman et al. 2022). Later runs reached peak rates of about 10.5 g/hour (NASA Science). NASA's Design Reference Architecture 5.0 baselined making oxygen only. Later NASA studies specify a four-crew ascent vehicle needing 7.0 t of methane and 22.7 t of oxygen, produced over 480 days. A full water-plus-CO2 plant is estimated at about 1.7 t of hardware drawing about 52 kW (NASA NTRS 20170001421). Scaling from MOXIE's grams per hour to tonnes over a mission therefore means a jump of several orders of magnitude in throughput. Delivering the plant also means solving the EDL problem for multi-tonne payloads (NASA 2024). Roadmap. (1) Fly a subscale oxygen plant running continuously for more than one Mars year. (2) Prospect for water ice to confirm accessible reserves at candidate landing sites. (3) Prove a surface power source of tens of kW (fission or large solar arrays). (4) Run a full-scale autonomous propellant plant before crew arrives. Cost and scale. Savings come from not launching ascent propellant from Earth. The main cost centers are power systems and autonomous reliability. Risks. Dust and thermal cycling degrade hardware. The water resource may be absent or hard to mine. Surface power is unproven at the required level. Crew safety would depend on a plant that is hard to repair. The case against this proposal. ISRU adds a mission-critical factory that must work perfectly before crew depart. Bringing propellant from Earth, if cheap reusable launch succeeds, may be simpler and less risky than a 52 kW autonomous chemical plant on another planet. Confidence. Medium for oxygen, low-to-medium for full methane-oxygen production on human timelines.

Assumptions

Accessible water ice exists near safe landing sites. Tens of kW of reliable surface power can be delivered. Electrolysis stacks survive long autonomous operation.

How to test it

Falsified as practical if a subscale plant cannot sustain production over a Mars year without serious degradation, or if prospecting finds no economically accessible water at sites that can be landed on.

Merge lineage

No merged proposal yet.

Open sub-problems

Falsified as the near-term route if ship-to-ship cryogenic transfer at operational scale has not been demonstrated within several years, or if uncrewed Mars landings of human-class mass repeatedly fail.
Falsified as practical if a subscale plant cannot sustain production over a Mars year without serious degradation, or if prospecting finds no economically accessible water at sites that can be landed on.

Next experiments

Falsified as the near-term route if ship-to-ship cryogenic transfer at operational scale has not been demonstrated within several years, or if uncrewed Mars landings of human-class mass repeatedly fail.

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