National Aeronautics and

Space Administration

2023 Moon to Mars Architecture Concept Review 1white paper 2023 Moon to Mars Architecture

Background

Once the challenges of reaching and landing 

safely on Mars have been met, the first human 

explorers will be faced with the challenge of 

finding sufficient energy to power the systems 

they will need for a healthy and productive 

stay on the surface and for their ascent back to 

orbit. Surface power needs may vary from one 

human Mars mission to another depending on 

how long each crew plans to stay on Mars, their 

surface mission objectives, and the support 

services their surface and ascent vehicles will 

require. 

Studies show that a very modest mission of 

two crew members, conducting science and 

exploring the surface for no more than 30 

days while living in a pressurized rover — plus 

propellant conditioning for a small, storablepropellant crew ascent vehicle — will require 

at least 10 kilowatts (kW) of surface power. At 

the other end of the trade space, a larger crew 

complement, exploring the surface for a longer 

duration, use of cryogenic ascent propellant 

manufacturing and storage, etc., will require 

hundreds of kW, approaching megawatt (MW)-

class power systems for some architectures. 

Surface power system designs for early human 

Mars missions must account for not only crew 

life support, but ascent vehicle preparation, 

propellent quantities, and equipment keep-alive 

power. This white paper outlines some of the 

unique challenges that Mars poses to ensuring 

sufficient power is generated, particularly 

during the initial human Mars segment. 

Unique Mars Environmental

Surface Power Challenges

Dust Storms

Martian dust storms have been observed in sizes 

ranging from small, local dust devils to regional 

and even global storms. Regional storms can 

cover thousands of square kilometers and last 

for days to weeks, growing in size and moving 

from their points of origin based on atmospheric 

conditions and terrain features. Global dust 

storms encircle the entire globe, can persist for 

several weeks or months, and may evolve from 

a local phenomenon to a global event in just a 

few Martian days (called sols). 

Because the atmosphere is so thin and dry, 

it takes much longer for fine dust particles to 

settle out of the atmosphere, which places solar 

array–powered systems at particular risk. Data 

collected by the Opportunity rover during its 

fatal encounter with a global Mars dust storm 

in 2018 demonstrates just how fast and furious 

Martian weather can be: from clear skies to 

as dark as Opportunity had ever previously 

recorded (4.9τ), within three Martian sols. 

Opportunity then observed a virtual blackout 

(Figure 1A) just four sols later, with its final 

message reporting more than double prior 

recorded optical measurements. The 2018 

storm shrouded the entire planet in such a 

thick blanket of dust (Figure 1B) that even 

the Curiosity rover, operating on the other 

side of the planet, reported significant optical 

degradation. However, unlike the solarpowered Opportunity, Curiosity’s nuclear 

radioisotope power system was unaffected by 

the storm, allowing it to continue transmitting 

data to Earth.

The impact of Martian dust storms on surface 

power will depend on severity and duration. 

Regional and global storms pose significant 

risk to surface power systems in two ways: first, 

dust suspended in the atmosphere will reduce 

the amount of energy reaching surface power 

systems that rely on solar energy, such as solar 

arrays, and can disrupt power systems that 

require clear line of sight for distribution, such 

as power beaming technologies. Oversized 

arrays can compensate for some reduced array 

efficiency, but at very high solar obscuration 

even oversized arrays may not be able to 

collect enough solar energy for nominal surface 

operations and energy storage systems to wait 

out the dust storm event could be enormous.

The second problem is that dust settling out 

of the atmosphere can accumulate on solar

Mars Surface Power Generation

Challenges and Considerations
2023 Moon to Mars Architecture Concept Review 2

arrays, further reducing their efficiency. For example, 

NASA’s InSight Mars lander was able to achieve all of its 

primary science objectives, but heavy dust accumulation 

prevented the solar arrays from generating sufficient 

keep-alive power and forced controllers to suspend 

operations after the vehicle was no longer able to 

communicate with Earth.

Reduced Solar Energy Availability 

Solar energy has long been the reliable choice for inspace power applications, but solar array designs on 

Mars must account for reduced solar flux, which is at 

most 45 percent of typical Earth solar flux values and 

varies significantly with geographic location and season. 

Figure 2 presents the maximum solar flux in orbit and 

at several different latitudes over a typical Martian year. 

The dashed curves in Figure 2 show the potential impact 

of dust storms on solar flux. 

Figure 2. Mars Solar Flux Variations

The Martian day/night cycle also varies with location and 

season. Typical mid-latitude missions would experience a 

25-hour cycle, with approximately 50 percent of the time 

spent under illumination. In practice, this means that a 

solar power system must be oversized to supply power 

for daylight operations while simultaneously charging 

the energy storage (batteries or regenerative fuel cells) to 

maintain night operations, all of which requires additional 

landed mass/volume and complexity.

Gravity and Wind Loads

Although Mars gravity is only about a third of that on 

Earth, Mars has about twice the gravity of the Moon, 

meaning that large array structures designed for lunar 

applications would need higher structural strength for 

deployment on Mars. 

Unlike the Moon, Martian winds pose another unique 

challenge. The Martian atmosphere is very thin, and 

even very high wind speeds would impose lower forces 

than equivalent wind speeds on Earth. For example, 

the highest wind speed ever measured on the Martian 

surface was about 30 meters per second (m/s) at the 

Viking 2 Lander site, but the lower atmospheric density 

on Mars makes a solar array in that same wind feel like it 

is only in a 4 m/s terrestrial wind. 

However, even though the pressures felt by a solar 

array are lower on Mars, they are still exerting forces 

in addition to gravity that can be quite substantial. The 

design of very large or vertical solar arrays must account 

for these forces. 

Severe dust storms beg an obvious question: why not just 

harness the power of Martian wind? While winds must 

be accounted for structurally, the Martian atmosphere 

is too thin to generate sufficient wind power for crewed 

systems. Data collected by InSight reveals that winds at 

Elysium Planitia rarely reached a capable power threshold; 

the wind was even insufficient to reliably blow dust off of 

arrays. In short, Martian winds may be troublesome, but 

are insufficient to be harnessed.

Day/Night Cyle Temperature Variations

The Martian day/night cycle is comparable to Earth’s; 

a Martian sol is about 39 minutes longer than an Earth 

day. This means that solar-based power systems must 

be augmented with overnight energy storage solutions. 

Mars surface temperatures also vary from as warm as 30 

C to as cold as -140 C, depending on location and season.

Figure 1b. Global view of Mars during the 2018 

dust storm

Figure 1a. Simulated view of the Sun from 

Mars during a dust storm
2023 Moon to Mars Architecture Concept Review 3

Unique Mars Operational Challenges

Autonomous/Remote Power System Operation

Round-trip human Mars surface systems are dominated 

by the ascent vehicle needed to launch crew back to Mars 

orbit and return to Earth. In most mission architectures, 

the ascent vehicle is the largest and heaviest surface 

payload, making it difficult to land a fully fueled ascent 

vehicle. 

To mitigate landing risks, many architectures rely on 

landing the ascent vehicle with empty or partially full 

propellant tanks and either transferring Earth-origin 

propellant that was delivered on a separate lander or 

manufacturing propellant from Mars resources. All 

approaches require abundant surface power. 

At a minimum, a few kW will be needed to environmentally 

condition Earth-origin propellants until ascent vehicle 

use. In contrast, tens of kW will be needed to maintain 

cryogenic propellants. Additional power will be needed 

to transport propellants between landers. Manufacturing 

propellants from Mars resources will require tens to 

hundreds of additional kW. 

To reduce crew risk, the ascent vehicle will ideally be 

ready prior to crew arrival, so whether ascent propellants 

are delivered from Earth or manufactured in situ, Mars 

surface power systems must be deployed, checked out, 

activated, and maintained without human intervention 

or assistance. Depending on pre-deploy mission timing 

(which will be constrained both by vehicle availability and 

the 26-month Earth departure windows of opportunity 

for Mars), and surface concepts of operations, surface 

power systems may need to be deployed years in advance 

of crew arrival and may need to support several crew 

missions over a years-long, multi-mission campaign. 

Limited Repair Options

The sheer distance between Earth and Mars means 

that unplanned replacement units or repair parts will 

not be available. Critical crew safety capabilities, such 

as surface power, will drive reliability, redundancy, and 

possible spares provisioning mass, all of which will have 

flow-down impacts to other parts of the architecture and 

operations. 

Because loss of surface power can lead to loss of mission/

loss of crew risk on Mars, power system spares must also 

be considered in mass and volume calculations when 

comparing different power source options. This includes 

a variety of failure modes during the crewed landing 

phase concept of operations: dust storms could delay the 

crew’s connection to existing surface power sources, or 

the crew could land farther away from the pre-deployed 

power source than planned.

Plume/Surface Interactions

A particular challenge for Mars surface assets, including 

power systems, is potential impact of descent and ascent 

engines’ thrust plume debris, which is exacerbated by 

the Mars atmosphere. Power system separation from 

arriving/departing vehicles may require longer power 

distribution systems (e.g., power cabling) or power 

system handling and surface mobility. Because power 

systems must be deployed in advance of crew arrival, 

power system handling, mobility, and power distribution 

must also be performed autonomously or remotely 

without crew assistance. If sufficient separation distance 

(currently estimated at about 1 kilometer) is possible, 

surface power systems may require additional debris 

protection to mitigate potential debris impact damage.

Planetary Protection Constraints

Planetary protection refers to “the policy and practice of 

protecting current and future scientific investigations by 

limiting biological and relevant molecular contamination 

of other solar system bodies through exploration activities 

and protecting the Earth’s biosphere by avoiding harmful 

biological contamination carried on returning spacecraft, 

as described in the Outer Space Treaty.”[1]

Specific policy guidelines are being developed to establish 

quantitative and implementable planetary protection 

requirements for the safe and sustainable exploration 

and utilization of Mars. Eventual requirements may 

include sterilization goals to prevent the transmission 

of Earth-origin microorganisms to Mars, or operational 

constraints, such as limits on thermal output that could 

inadvertently create a more habitable environment for 

microorganisms.

Mars Surface Power Generation Opportunities

Surface Power Generation Technologies

Despite Mars’ many challenges, promising power 

generation technologies are available or in development. 

High energy density nuclear power, either Curiosity roverstyle radioisotope power system or fission systems, are 

unaffected by day/night cycles or weather and package 

well in volume-constrained spacecraft. Although current 

radioisotope power system designs only offer a few 

hundred watts, they may be applicable to smaller power 

load applications. For higher power crew life support or 

ascent propellant manufacturing needs, fission surface 

power is readily scalable. 

Limited solar power may be feasible if augmented by 

robotic dust wipers, pressurized gases, mechanical array 

tilting, or electrodynamic or piezoelectric dust removal to 

clear accumulated dust from the solar arrays, although 

only for applications that are not crew safety critical, 

given that surface dust removal would not mitigate the 

problem of suspended atmospheric dust during lengthy 

storms. Unique operational considerations, such as 

radiation keep-out or large array off-loading, would need 

to be evaluated for Mars. 

Lower technology readiness solutions may eventually 

offer additional options. For example, geothermal energy
2023 Moon to Mars Architecture Concept Review 4

has been proposed for use in eventual Martian 

settlements, but data on its availability is limited. Accessing 

geothermal energy requires heavy equipment and time 

to implement and may be geographically constrained to 

areas with easy access to geothermal sources, making 

it less attractive for early missions. Implementation 

of geothermal technologies would require a separate 

power source for the robotic drilling and regolith-moving 

required to access the heat sources before the crew even 

arrives. 

Fuel cells are often proposed, but they do not trade well 

for mass because they either require landed reactant 

mass or more energy and production mass to make 

reactants in-situ than the fuel cells provide. Biogeneration 

(relying on microorganisms to convert organic feedstock 

directly into heat or into another commodity, such as 

methane, that can then be used to generate power) has 

also been proposed as a power generating technology 

option. However, the introduction of microorganisms 

may be complicated by planetary protection constraints. 

Furthermore, additional safety/processing measures may 

be needed if feedstock/biomass replenishment involves 

use of Martian soil, due to the presence of perchlorates 

or other chemicals and their byproducts.

Regardless of the power source selected, it should be 

noted that multiple power systems could be integrated as 

needed to support higher power needs. This would allow 

the power system to be tailored to a specific mission, as 

more modest initial efforts evolve into more ambitious 

exploration. 

The Moon as a Testbed for Mars

The closer proximity of the Moon offers an excellent 

opportunity to demonstrate candidate Mars surface 

power generation technologies with reduced 

consequences of failure. Lunar surface systems designed 

to be extensible to Mars would need to account for the 

environmental differences, including Mars’ low-pressure 

carbon-dioxide atmosphere, increased gravity, shorter 

day/night cycle, reduced solar insolation, wind loads, dust 

storms, and increased distance from Earth that results in 

longer round-trip communication times. 

The challenge is to ensure that lunar power generation 

systems remain Mars-forward without adding 

significant cost or complexity to either the lunar or Mars 

missions. Solar and fission surface power technology 

demonstrations could serve as pathfinders for power 

system launch, landing, autonomous deployment, 

maintenance, and sustained operations in challenging 

and dynamic environments. 

Summary

Regardless of mission type, stay duration, or surface 

exploration objectives, human missions to Mars will 

require abundant, reliable surface power. Stationary 

power systems that produce at least ten kilowatts day and 

night, in varying weather conditions, will be needed for 

human ascent vehicles, habitats, propellant conditioning 

or manufacturing plants, and surface exploration 

activities. 

NASA is working to advance the technology readiness 

of a range of surface power generation technologies 

and mitigate performance challenges that some of 

these options would have in the Mars environment. An 

overarching objective is to demonstrate the technologies 

in relevant mission environments to verify performance 

and functionality. 

Power needs for humans operating on the Moon will have 

some commonality with Mars operations, opening up the 

possibility of common power technologies if strategic 

engineering choices are made and proper consideration 

is given to the different environments. Where practical, 

demonstrations can be performed directly on the Moon 

to gain operating experience on systems that will later be 

used on Mars. 
Reference

1. NASA Procedural Requirement 8715.24, Chapter 1,

https://nodis3.gsfc.nasa.gov/displayDir.cfm?Internal_ID=N_PR_8715_0024_&page_name=Chapter1

2023 Moon to Mars Architecture Concept Review 5

Key Take-Aways

Safety-critical human needs on the surface of Mars pose additional challenges, such as higher 

availability over longer periods of time, versus robotic Mars or human lunar surface missions.

The minimum practical power level required for even a short-duration, two-crew, human Mars 

surface mission is about ten kW.

Maximum required power levels could approach MW class for very in-situ resource utilizationintensive architectures.

The Mars surface power generation technology selected for the initial human Mars segment 

must accommodate both anticipated operational needs and the unique challenges of the Mars 

environment, with limited repair or replacement options.

The Artemis missions offer an opportunity to test safety-critical Mars surface power generation 

technologies and operations on the Moon to reduce risk for later Mars crews.