Mars Solar Power

This project aims to investigate the feasibility of solar power on the surface of Mars for either as the sole primary power source or in conjunction with other power source (e.g., nuclear reactors). We intend to include reference data, system analysis, and investigation of design options. Over time, this could lead towards prototyping and test of relevant systems.

All are welcome to contribute to this project. If you have comments or questions, please use the discussion tab at the top of this page.

See also the surface power evaluation conducted in the context of the MinMars project.

Introduction

A variety of potential power sources exist to support human activities on the surface of Mars. At this point in time the most likely primary power sources for human Mars missions or near-term settlement are nuclear power (in the form of a fission reactor or through the thermal output of radioactive decay as in an RTG) and solar power (as photovoltaic or solar thermal power), including combinations thereof. While other sources such as geothermal and wind power have been proposed, these are more likely to come into use after humans have been present on Mars for a longer period of time in order to both characterize the available resources (particularly for geothermal) and setup the infrastructure required by each of these options.

In the analysis and design of a Mars surface power system the total required power is of great importance. The power requirements will be for some level of electrical power and some level of high-quality thermal power (i.e., heat available at sufficiently high temperature to drive various physical-chemical processes, which could be provided as waste heat from the power generation system or through electrical power). The magnitude of the power will depend upon the intensity of activities on the lunar surface. A human mission with a small crew, limited surface mobility activity, and little or no in-situ resource utilization (ISRU) will tend to have relatively low power requirements, perhaps on the order of 10 - 20 kW. Larger crews, more extensive surface exploration, and higher levels of ISRU (including for life support consumables, surface mobility propellants, ascent and trans-Earth injection propellants, and settlement construction materials) will all tend increase power required, quite easily to 100 kW and possibly over 1000 kW (1 MW).

The required time phasing of power usage will also be important, in particular for power systems with solar power as the major or only primary power source. On the time scale of a Mars day, the largest distinguisher will be between power during lit periods and power during dark periods (for which an energy storage system, such as regenerative fuel cells or batteries, would be required). In addition, and depending in part upon the design of the solar power system, there may also be significant variation in the power generated over the course of the lit period, as the Sun moves towards and then away from its zenith. Over longer time scales, dust storms and changes in atmospheric opacity more generally, as well as changes in incident sunlight due to seasonal variations and changes in the distance between Mars and the Sun, will all impact the amount of power that can be generated at any given time using a solar power system. The variations in available solar power levels will tend to influence the system design to include an ability to vary power demand with time. As an example related to the diurnal variation, while a life support system will require certain functions to occur both day and night, it may be useful to limit certain functions to the day period, so as to limit the amount of energy that must be stored for night-time usage. On longer time-scales, it may be possible to tailor the output of ISRU processes such that they make maximal usage of the power available, with variable resource output at any given time but with a net output over the time scale of interest to meet overall need.

Motivation for Solar Power as an Alternative to Nuclear Power on Mars

• Mars missions studies frequently select nuclear fission reactors for providing surface power based upon technical considerations
  • e.g., mass, complexity, volume, etc.
• However, requiring nuclear power places a policy constraint on the critical path for human Mars missions
  • Need sustained funding to develop and test reactor
  • Need political approval for every Mars mission including a reactor
• Such a constraint compounds already existing policy challenges
  • Increased dependence on the stance of political parties/politicians
  • Sensitivity to changes in public view-point with respect to nuclear power in general
• Other options such as dynamic isotope power systems also suffer from approval and funding constraints

• If solar power can be used as primary power source on Mars it could increase the political feasibility and sustainability of human Mars missions

Selected References

• Atmospheric Effects on the Utility of Solar Power on Mars (Univ. of Arizona Press)
• NASA/TM-1999-209288 Solar Electric Power System Analyses for Mars Surface Missions (NTRS, Local Copy)
• NASA/TM-2004-213367 Mars Solar Power (NTRS, Local Copy)
• Solar Electric Power System for the Exploration of Mars (LPI)
• Telescopic Martian Dust Storms (British Astronomical Association)
• Photovoltaics for Mars (NASA Glenn)