Power for a first outpost: fission against solar through a dust storm

Question

What keeps a four-person outpost powered through a global dust storm?

Assumptions

• Total load78.8 kW: crew 31.1 kW (Rucker 2016), O₂ plant 34 kW (Kleinhenz & Paz 2017), propellant cooling 6.7 kW, breathing O₂ up to 7 kW (Study 001)
• Sol24.66 hours
• Fission unitKilopower-class, 10 kWe nameplate, about 8.75 kWe delivered; 1,500 kg complete (2017 overview) to 1,800 kg (2016 overview)
• NASA reference loads92 kWe is NASA’s figure for the solar option; the nuclear option is about 30 kWe (Cataldo 2009, DRA 5.0)
• Solar point designNASA study at Jezero (18° N): 120-day storm at average optical depth 5 (Rucker 2016)
• Worst case onlyOpportunity, June 2018: array output 645 → 22 Wh per sol at optical depth 10.8; batteries 200 Wh/kg pack-level (our assumption)

The numbers

Load:  31.1 crew + 34 O₂ plant + 6.7 propellant cooling + 7 breathing O₂ ≈ 78.8 kW
Energy per sol:  78.8 kW × 24.66 h ≈ 1,943 kWh

Fission:  10 running units × 8.75 kWe ≈ 87.5 kWe delivered  (≥ 78.8 kW)
          + 1 spare = 11 units × 1,500–1,800 kg ≈ 16.5–19.8 t
          first expedition, O₂ plant running before crew lands: 5 + 1 units

NASA’s own trade (Rucker 2016), 120-day dust storm at full power:
  solar ≈ 17.8 t     fission ≈ 9.15 t

Worst case, labelled (one aged, dusty rover; not a design):
  storm / normal output  22 / 645 ≈ 3.4 %  → array ≈ 29 × clear-sky size
  60 sols on batteries:  1,943 kWh × 60 / 0.2 kWh/kg ≈ 583 t

Result

Modeled: 16.5–19.8 t of fission (10 running 10 kWe units plus 1 spare, about 87.5 kWe delivered) carries the full 78.8 kW load, including the 34 kW oxygen plant, through a dust storm. The first expedition needs 5 + 1 units if the O₂ plant runs before the crew lands. For a 120-day dust storm at full power, Rucker 2016 puts solar at about 17.8 t against about 9.15 t for fission. The battery figure is a labelled worst case, not a design.

Trade-offs

Open problems

• No 10 kWe Kilopower unit has been built.
• The Rucker 2016 numbers come from a single site and a single storm case.
• Storm attenuation for a large, cleaned array is uncertain. Battery life in Martian cold over years is not established at this scale.

What would change the answer

• Put life support and thermal control on fission; run oxygen production and excavation on daytime solar and pause them in storms.

Sources

1. NASA, Kilopower Overview (IAC 2017, NTRS 20180000691)
2. NASA, Nuclear Systems Kilopower Overview (2016), NTRS 20160012354
3. Rucker et al., “Solar Versus Fission Surface Power for Mars,” AIAA SPACE 2016, NTRS 20160010550
4. Kleinhenz & Paz, “An ISRU Propellant Production System to Fully Fuel a Mars Ascent Vehicle,” AIAA 2017-0423 (2017)
5. NASA, “NASA Announces Artemis Concept Awards for Nuclear Power on Moon” (2022): 40 kW, under 6 t
6. NASA NSSDC, Mars Fact Sheet (solar irradiance 586.2 W/m²)
7. SpaceNews, “Mars rover Opportunity weathering major dust storm” (2018): tau 10.8, 22 Wh
8. “Power Requirements for the NASA Mars Design Reference Architecture (DRA) 5.0,” NTRS 20120012929