Future power systems for space exploration

1
Future power systems for space exploration

• Overall Goal of past S54 Study,2001 -2003
• Findings and Recommendations
• ESA Contract 14565/00/NL/WK
• April 13th, 2005, M. Lang, TEC-MPC

2
Overall Goal and Content of past S54 Study

• Study into future power systems for space
  exploration, aimed specifically at a human
  mission to the Mars surface to take place in the
  2020-2030 timeframe, comprised of 5 parts 2
  extensions
• System requirements/constraints
• Technology Inventory
• Nuclear power systems
• Architectural design of reference system
• Technology Development
• Ext. 1 Nuclear power for static mission
  element, ISRU Technologies,
  Regenerative Power Sources for Mobile
  Applications
• Ext. 2 Two-Stroke Engines for Mars Exploration,
  Stirling Cycle Engines
  for Space Power Applications

3
Study team

• QinetiQ (formerly UK Defence Evaluation Research
  Agency, DERA)
• AEA Technology (Space)
• Serco Assurance (formerly AEA Technology
  Consulting)
• Technicatome
• Technical University Graz

• Study management
• Gas cooled nuclear power systems, nuclear
  technology inventory
• Gas cooled reactor core design, safety
  assessment, nuclear technology inventory
• Liquid metal cooled reactor design, nuclear
  technology inventory
• Non-nuclear technology inventory

4
Work flow with parallel studies
Study S51 Scenarios Architectures - Phase 1
Task 1 Requirements Constraints
Task 2 Technology Inventory
Study S56 Automation Robotics
Task 3Nuclear Power Systems
ISRU design
Task 4 Architectural Design of Ref. System
MPL design
Task 5Technology Programme
Study S51 Scenarios Architectures - Phase 3
Aurora
Task 6 Final Reporting
5
Where are we now?

• S54 study completed with 2 extensions and
  recommendations
• S56 study completed with recommendations
• S51 completed with study of 2 selected mission
  elements (ISRU MPL)
• Related technology studies on-going e.g. ISRU,
• H2 storage, materials structures, thermal
  control
• Aurora programme in progress

6
System Requirements Constraints Understanding
the problems of exploring Mars

• Requirements definition - what do we want to do?
• Constraints (European)
• Constraints (Martian)
• Definition of future power systems
• Power generation
• Power/energy storage
• Power management and distribution
• Related technologies LSS, ISRU, materials
  structures, thermal control

7
Mission elements definition

• 1. Disseminated surface elements
• - Micro inspection rover - Autonomous research
  island
• - Long range exploration rover - Drilling
  platform
• 2. Mobile pressurised laboratory, MPL
• 3. Utility truck, U/T
• 4. Regenerative life support system testbed,
  Greenhouse
• 5. In Situ Resource utilisation (ISRU) chemical
  plant
• - Expendable lander
• - Aerobot

8
Static mission elements power requirements
9
Mobile mission elements power requirements
10
Mars environment (1) solar energy

• ? Oversized, heavy array to account for worst
  case, or
• ? Optimal sized array (NASA GRC) but higher risk
  if global dust storm persists.

11
Mars (2) the atmosphere

• Earth Mars
• Pressure - density 1000mBar - 1.225kg/m3 7mBar -
  0.02kg/m3
• Makeup CO2 0.03 95.3
• N2 78.1 2.7
• Ar 0.9 1.6
• O2 21 0.13
• Water several (var.) None
• ? ? wind, structural effects
• ? ? Long term corrosive effects CO2
• ? ? No water, but otherwise a valuable resource

12
Mars (3) surface effects

• Gravity 0.38x terrestrial lower traction power
• Dust 100-150ppm clay silicates, 3?m ?.
  Accumulate on exposed surfaces and reduce PV
  array power by 0.28/day (Pathfinder)
• Wind velocity high (4x Earth typical), but low
  dynamic pressure
• Potential highly oxidising environment
• Low, highly variable temperatures -80C to -130C
  night, up to 30C day. Assumed -30C mean summer
  day, -60 winter for PV arrays. Assumed insulation
  -40C min internals night.

13
Mars (4) other effects

• ?V Mars-Earth return 20.5km/s, orbit aerocapture
  only
• ? ?4kg to LEO for 1kg to Mars orbit
• ? ?7kg LEO for 1kg to Mars surface
• Radiation
• 6mth trip time, solar flare / GCR risk
  (negligible to systems)
• Distance
• signal round trip time 6-45 mins telerobotics
  difficult
• orbit conjunctions every 26 mths min surface
  stay 20mths (600 days)

ArV with LH2/LOX TMI stage - 6t capability to
Mars orbit - 4t max. to Mars surface
14
Life Support Systems (LSS)

• Not studied in detail as part of S54, however.
• Lightweight
• Active thermal control needed
• Portable power 8hr EVA, up to 300W gives 2.4kWhr
• Li-ion 6.1kg weight on Mars (now) - 2.5kg (15
  yrs) possible
• Fuel cells require 23wt H2 stg. density to
  compete due to need to store O2.
• TPV, microturbines possible but require fuel /
  oxidiser storage
• A difficult problem.

15
In-Situ Resource utilisation (1) requirements

• ISRU The use of Martian resources (
  terrestrial feedstock) to generate propellant
  life-support consumables on Mars, reducing
  required mission mass and cost.
• A 6 person mission to the Mars surface, staying
  600 days, requires

• 7t CH4 fuel for return vehicle rocket engines
• 25t O2 oxidiser to combust CH4
• 5t O2 for life-support
• 24t H2O for drinking, washing, etc.
• 4.5t buffer gases (usu. N2) to make up for
  leakage

16
In-Situ Resource utilisation (2) the problem

• No H2O, or free H2 on Mars bring H2 from Earth
• Numerous chemical reactions required for ISRU
  NASA JSC estimate 3.8t
• Requires significant energy to run reactors, e.g.
  electrolyser. NASA estimate 40-50kWe
• Autonomous deployment, reliable operation to
  produce requirements in 12-15 mths, store for
  36mths

• Bring H2 from Earth 2-4t, e.g. LH2
• Mass intensive 3.8t from Earth (30t LEO)
• 40-50kWe continuous, up to 15 mths
• Autonomous, reliable

17
In-Situ Resource utilisation chemistry (i)

• Centrifugal compressor CO2 collection,
  15-20kg/hr.
• Simple, deployable composite fans.
• Sabatier 4H2 CO2 ? CH4 2H2O
• Goes to completion at 2-300 C (pipe reactor
  catalyst), exothermic
• Electrolysis 2H2O power ? 2H2 O2
• With Sabatier, produces O2 CH4 in 2.25 1 ratio

Problems 1) Insufficient O2 produced 2) No
separation CO, N2, Ar 3) Power for storage,
cooling, separation products
18
In-Situ Resource utilisation chemistry (ii)

• Additional O2 generation
• Reverse Water Gas Shift not exothermic,
  separation a problem
• Methane pyrolysis / catalytic reduction
  temperature, scaleup
• High temperature CO2 electrolysis high power,
  robustness?
• Photocatalytic CO2 reduction v. recent
  discovery, not quantified
• Ar/N2 separation
• Amine absorption loop non-ideal as large CO2
  mass flow rate
• Adsorption zeolites undesirable chemical / polar
  effects
• Physical separation CO2 snow - best option
  (NASA)
• Power reduction
• Cooling CH4 / O2 with H2 feedstock
• Low power processes where possible

19
Promising power storage technologies

• High temperature batteries ZEBRA, Sodium
  Sulphur, combined heat and power.
• Not yet exploited for space despite extensive
  development
• Li-ion batteries. Questions to resolve
• performance at extreme low temperatures (-40 to
  -80C)
• potential for scale-up current state-of-the-art
  focussed on portable consumer electronics
• lifetime currently limited to a few hundred to
  1000 cycles.
• H2-O2 Fuel cells extremely high power densities.
  
• Need to address fuel / oxidiser storage on Mars
• Redox batteries (Regenerative fuel cells)

20
Power storage technology comparison
21
Power generation technology PV arrays (i)

• Photovoltaic conversion - cell types / efficiency

• Crystalline Si 10?cm B(S) FR / HiETA up to 17
• GaAs ATJ AM0 optimised 30 (40 possible)
• CIS, CuInSe2 thin film 12 current, gt20
  predicted
• Cleft GaAs, thin Si, ?-Si, TiOx (dye sens.) not
  considered in detail
• LILT cells to be added
• GaAs cells not tested on Mars Beagle 2 (NASA
  Athena rovers using crystalline Si)

22
Power generation technology PV arrays (ii)

• Photovoltaic conversion - array designs

ISS Si flexible
CIS rollout
ITSAT inflatable
AEC-Able Ultraflex
Pathfinder rigid panel
23
Power generation technology Wind energy

• Wind viable terrestrial power generation, up to
  several MW per turbine
• Horizontal axis 2/3 blade turbines common
• Considerable European (Danish, UK, German)
  expertise
• Studies for Mars carried out (Bremen, Houston
  Uni.s)

• Low dynamic pressure on Mars 4.6x wind speed of
  10x blade diameter for same power density
• Geographical restriction on Mars, e.g. Tharsis
  Montes
• Accurate forecasting data required
• Erection of mast may be difficult balloons?

24
Power generation technology Thermal transfer

• Diurnal temperature gap utilisation -
  thermoelectric conversion
• Large area required due to low TEC eff
• Power not available all day
• Geothermal may also be a possibility (active
  Mars)
• Accurate subsusrface mapping required

Time in Martian Hours
Surface cools during nighttime
Surface heats up due to solar insolation
Depth below surface (m)
25
Power generation technology Other

• Power beaming from Areosynchronous orbit
• Laser or microwave
• gt50 efficiency theoretically possible
• Auburn Uni. POWOW study using ?1.06?m laser
• 4t array in orbit, 360kWe ? 75kWe on surface
• No hydro / wave / tidal power on Mars
• No fossil fuel reserves known, CO2 non-oxidising
• Combustion engines non-ideal (fuel cells higher
  power density)

26
Power management distribution (PMAD)

• 28V current, ISS 120V. 600V - 5000V desirable for
  Mars (long distance power transmission). 160kWe
  over 2km _at_ 200V?20t cable!
• Paschen breakdown in Mars atmosphere / dust
  discharge may be an issue
• PMAD efficiency (NASA estimates)
• Current 80-90, 40-50W/kg
• 5 years 85-95, 125W/kg
• 15 years 95, 250W/kg, integrated bus
• Further research required.

27
Nuclear power options

• Radioactive heater units, e.g. Pathfinder
• RTGs
• Viking SNAP 19, 2x35W
• Ulysses, Galileo, Cassini up to 875W _at_ 5W/kg. 2
  only, 250W.
• ARPS, 10W/kg Cm-244 up to 20W/kg. Development
  required.
• Not available in / to Europe
• DIPS dynamic isotope power (Pu-238 Stirling)
  2-10kW proposed.
• Fission reactors SNAP-10A, ROMASHKA, Topaz,
  SP-100. Preferred to RTGs above 1kWe.

28
Why nuclear?

• Low solar flux on Mars at best, 22 AM0. More
  typically 13 AM0, and 30 of the time, 6 of
  AM0 or less.
• i.e. an array sized to deliver 50kWe on the Mars
  surface would be delivering 1MW in LEO. No
  capability!
• Pathfinder lost 16 of its power in 83 days due
  to dust. 600 day surface stay 100 power loss
• PV not considered viable gt50º lat., nor for reqs
  gt20kWe.
• NASA considers nuclear power ENABLING for Mars
  surface.
• (ref. Cataldo, IAF 2000 SAE power systems, Nov.
  2000)

29
WP1xx Summary

• Mission elements definition
• Static, mobile elements power/energy
  requirements
• Mars constraints
• solar energy (or the lack of it)
• atmosphere, environmental effects (e.g.
  temperature, dust)
• Mass limits to Mars
• Power storage options Li-ion batteries,
  flywheels, fuel cells
• Power generation options mainly solar, wind,
  nuclear
• PMAD
• Nuclear technology overview

30
Why a technology inventory?

• To establish the areas that would enhance
  Europes capabilities and the value of power
  systems within human Mars exploration scenarios.
  Innovative, enhancing.
• To support study effort by searching various
  databases including journals, patents, proposals,
  web-sites, organisations and NASA archives.
  Up-to-date information resource.
• Coordinated effort between S51, S54, S56 studies,
  and relevant to future work. Interdisciplinary
  (relevant to CDF).
• Roadmap to allow ESA to focus technology
  development resources early on for later human
  Mars exploration
• ? COST REDUCTIONS

31
Scope of inventory
Internal combustion
Nuclear (fast)
Solar dynamic
Nuclear (thermal)
Mars surface
Trans- Mars
Wind
Regen -erative
Power generation
Geothermal
Open
Cryo- coolers
PV arrays, concentrators
Coatings, structures
WWW based Technology inventory
Regen. fuel cell
Non regen. fuel cell
Passive cryo/ heat storage
Primary batteries
Cooling loops
Radiators
Secondary batteries
Heat Pipes
Phase change materials
Chemical reactions
Flywheels
Martian resources
Systems issues
EVA
32
Primary technology selection criteria

• I Cost
• II Physical constraints, broken down into
• Low mass
• Compact dimensions (low volume)
• Long operational lifetime, without maintenance
• III Satisfaction of performance requirements
  (e.g. specific power, efficiency, etc.)
• IV Product assurance, broken down into
• Survivability
• Reliability
• Safety
• Availability
• V Environment survivability, broken down into
• Thermal inputs, loads, ranges
• Radiation
• Atmospheric constituents (95 CO2)
• Low gravity
• Absence of water vapour
• Cleanliness/contamination (planetary protection)

Total technology value 4 (lowest) - 6 (highest)
33
Secondary technology selection criteria
Total technology value 1 (lowest) - 3
(highest)

• i. Introduction of new technologies. A higher
  rank will be given to new technologies that will
  be brought to maturity within the time-scale and
  cost constraints of the mission.
• ii. Breadth of expertise in Europe is the
  technology unique to one supplier who could be at
  risk?
• iii. Impact of technology on international
  mission.

34
Ranking total technology score

• Total technology score this total score is a
  numerical output for the overall performance of a
  technology, incorporating the benefits of
  Europes position as a scientific leader.
• Primary technology selection criteria are
  essential to a successful mission, and are worth
  between 4 (lowest) and 6 (highest) points.
• Secondary evaluation parameters are important,
  but not essential to the success of the mission
  worth between 1 (lowest) and 3 (highest) points.
• Qualitative analysis of technology selection
  the individual evaluation parameters for each
  technology are compared.

35
Example technologies

• Solar cells performance optimised for Mars
  surface conditions.
• Regenerative fuel cells.
• High T, CO tolerant fuel cells for combined
  heat/power
• Flywheels for power storage
• Efficient Thermoelectric power conversion
  materials
• High capacity, low T Li-ion batteries for mobile
  applications
• High density hydrogen storage, e.g. rev. complex
  hydrides

36
50kWe static power system options(1) NASA solar
electric design
ftp//ftp-letrs.lerc.nasa.gov/LeTRS/reports/1999/T
M-1999-209288.pdf
37
NASA assumptions

• Deployment of tents by articulated mast /
  inflatables / rovers
• No wind effect on tent stability
• RFC fuel cell power storage optimistic Wh/kg
  values, unclear about electrolyser power
  requirements
• Dust removal degradation only 5 of Pathfinder _at_
  0.3/day
• 18 BOL eff. from ?-Si PV / CIS arrays assumed
  optimistic
• 2 major dust storms/Martian year, severe power
  storage depletion 100 day max. endurance
• ISRU plant switched off during dust storms
  reliabilty issue?
• 600V power generation transmission, DC switched
  to 120V
• Precision landed at 200m from habitation

38
50kWe static power system options(2) Solar
electric design for this study
39
Solar-electric power - further details

• Dust storms (OD 3.0) increase array area / mass
  by 3x. More severe dust storms make PV power
  unadvisable
• Array area 2000-7000m2 poses major deployment
  questions
• AEC-Able may offer a possible solution Ultraflex
• Note ISS arrays 2 x 400m2, required astronaut
  deployment, in ?g
• Design relies on cell performance, dust
  mitigation,
• resistance to environment, etc etc.

• 4450m2 requires
• 15 x 10m rad modules, or
• 57 x 5m rad. modules

40
50kWe static power system options(3)
Solar-wind-electric power

• Balloon tethered horizontal axis turbines
• 3 turbines, each sized to generate 10kWe
• Array to generate 20kWe under OD 3.0
• ? Total mass 8700kg, array area 2850-5600m2
• inc. 1-2t vessel for storage of hydrogen
  lifting gas
• BUT
• Accurate long term wind forecasting needed to
  reduce risk
• Limited locations where adequate wind speed
  (10m/s year round)
• Immature technology
• Hydrogen lifting gas adds signifcant mass (v.
  tower erection)

41
50kWe static power system options(4) Alternative
power systems

• Geothermal energy
• Power beaming from orbit
• Temperature gap power generation

• Requires thermal reservoir as yet unproven on
  Mars
• Power loss on tranmission thr. dust storm may be
  significant
• Low efficiency, very large buried area required
  variable power

Nuclear fission reactors are the only low risk
solution to providing significant quantities of
power on the Mars surface
42
Backup power system for greenhouse

• 1kWe for 10 hours
• PEM or Solid Oxide fuel cell (combined heat /
  power)
• 10kWh ? 0.5kg H2, 3.75kg O2
• HP gas storage in composite tanks ? 20kg,
  37litres
• or
• H2 stored as C nanofibres (25wt, O2 as sodium
  chlorate ? 17kg, 16 litres
• Li-ion battery
• Secondary 70kg, 30litres Primary 26kg,
  14litres
• Ni-MH battery
• 177kg, 50litres

43
Mobile power system optionsMicro inspection rover

• 7W mean, 14W peak, 45Wh rover max. size
  600x400x300mm, 15-20kg
• Lowest mass option has 14W PV array for day ops,
  0.25-0.4m2 fuel cell night ops, total mass
  1.9-3kg. Array too large for envelope! (600 x
  670mm req.)
• Next best option uses 7W array and battery, peak
  loads supplied from both. Array area required
  0.2-0.3m2, i.e. just within envelope, Mass 3kg,
  OK. However, dusty conditions (100W/m2) require
  larger array, exceeding envelope.

? PV arrays not optimal for all-weather operation
if body mounted ? Fuel cell 0.35-1.15kg, but
large store required. ? Rechargeable battery
1.5-1.8kg.
44
Mobile power system optionsLong range
exploration rover

• 25-200W, est. 160-190kWh total rover max. size
  not specified, 200kg total
• Optimal system for good weather has
• PV array, 2.2-3.3m2 deployable recommended
• Fuel cell for peak power, 7.5-20kg mass
• Battery for night operations, 2.8kg mass
• Bad weather (100W/m2) requires
• PV array, 7-10.5m2 deployable may be difficult
• Fuel cell 7.5-20kg
• Battery, 2.8kg

Total mass 16-36kg Deployable array required
Total mass 26-62kg LARGE deployable array required
Operation without PV array requires 90-140kg fuel
cell system due to high mass H2 / O2 storage.
45
Mobile power system optionsDrilling station

• 500-2000W, est. 920kWh total max. size
  150x150x300mm, 300kg total, 45hrs peak power
• Optimal system has
• PV array for mean power (500W), min. area 25m2 in
  dusty conditions.
• Fuel cell for peak power, 85-145kg mass
• Battery for night operations, 3kg mass
• Total mass 147-316kg.
• Alternative system with PV array / nightime
  battery only
• 215kg / 250m2 using current CIS technology
• 45kg / 130m2 using future technology

EITHER a high total mass OR a very large array
area
46
Mobile power system optionsMobile Pressurised
Laboratory APU

• 2800kWh energy, 98kWe peak power (20kWe mean), 20
  day durn, 500km range, 1500kg mass limit (power
  cart)
• Fuel cells are the ONLY practical option for this
  energy requirement
• Currently GH2 / GOX storage gives 4600kg /
  7.1m3. NOT REALISTIC.
• Near term developments may allow LOX / LH2
  storage for 20 day mission 2600kg, 4m3.
• Longer term H2 in CNFs, LOX may allow 2300kg,
  2m3. STILL TOO HEAVY.

APU, 1 day ops, 5km range, 7kWe peak, 19kWh
energy ? 2 battery 134kg, 61litres or RFC
45-220kg, 18l PV array
1500kg mass limit ? 1650kWh limit. Severe energy
limitation, unless alternative power sources
developed (e.g. In-Situ oxygen useage, NASA DIPS)
47
Mobile power system optionsUtility Truck
Emergency power unit

• 1500kWh energy 1 way trip, 292km 2x this for
  return. 48kWe peak power, 120kWh emergency power
  supply.
• Fuel cells are the ONLY practical option for this
  energy requirement
• As per MPL Near term 2600kg, 4m3.
• Longer term 2300kg, 2m3. Acceptable.
• A 1500kg power supply limit ? restricts
  operations radius max. 150km.

• Emergency power
• RFC is best option.
• High power electrolyser can be reduced in size if
  6-10 days to charge
• 270kg / 420l / 62m2 (PV array covering load
  floor)

Limited range reduced payload capacity with
conventional power source. RFC may have potential
but requires analysis of mission profile in more
depth.
48
ISRU proposed system design
Mars atmosphere 95.3 CO2 2.7 Ar 1.6 N2 _at_
7mBar, 200K
CO2
Buffer gas separator (e.g. CO2 solidifier)
Heater
Centrifugal compressor
Ar N2
420K
CO2, 420K
CH4
Cryocooler
Sabatier reactor
H2, 420K
Counter current heat exchanger
H2O
O2, 270K
Ar N2, 70K
CH4, 111K
Liquid O2, 90K
H2O electrolyser
H2, 270K
Liquid H2, 20K
CO (vented)
H2O
Heater
670K
H2
RWGS reactor
CO2
49
ISRU summary

• Power 28-43kWe Mass 1.8-2.7t
• More detailed comparison of
• RWGS
• Methane pyrolysis
• Catalytic decomposition of methane
• Direct reduction of CO2.
• For additional oxygen generation.
• Better understanding of
• Amine absorbers, v.
• Zeolite bed extraction, v.
• Solid phase separation
• For buffer gas separation.

Suggest experimental programme.
Suggest futher study
50
Technology development suggestions2002 2006
(0-5 years)

• PV array power generation Testing using high
  efficiency (GaAs based, or crystalline Si Hi-ETA
  and LILT) cells, under simulated Martian
  conditions, investment in CIS cell manufacturing.
• Power storage development batteries and fuel
  cell systems . Need to be (a) tolerant to CO2 and
  CO, (b) integrated into combined heat and power
  systems, and (c) optimised for performance under
  Mars environmental conditions. Flywheel
  investigation
• Space rated long duration Liquid hydrogen
  storage.
• ISRU technology, subsystem level. Determination
  of preferred chemistries.
• Novel means of powering mobile mision elements.
• Nuclear power systems refinement of system
  designs (more detailed trade-off between gas and
  liquid metal cooled reactors). Investigation of
  means of shielding, experiments to verify
  convective CO2 atmosphere heat rejection

51
Technology development suggestions2007 2016
(5-15 years)

• PV array based systems capable of generating
  gt100kWe under OD 3.0 or more, and a reliable
  means of deploying them.
• ISRU breadboarding, reactor optimisation.
• PMAD development 120V ? 600V, low mas
  (superconducting?) cables
• Advanced hydrogen / oxygen storage for fuel
  cells, e.g. carbon nanofibres.
• Long life Li-ion power storage systems, trade-off
  v. flywheels for preferred Mars surfa option
  where fuel cells not appropriate.
• Low energy means of reducing CO2 to CO / O2
  in-situ oxygen generation for fuel cells.
• Active thermal control systems for high heat
  loadings.
• Terrestrial test of complete, 50kWe nuclear
  reactor system. Planning and safety work for
  space test.

52
Technology development suggestions2016 2030
(15-30 years)

• Space test of 50-200kWe nuclear reactor system.
  Design for integreated nuclear power / ISRU
  system for Mars surface.
• Supporting robotic systems for deployment of
  reactors / large structures (e.g. PV arrays)
• Demonstration / test of power beaming to Mars
  surface as alternative.
• Development of mciroturbines for small mobile
  mission elements
• Integrated system tests of key technologies in
  Mars environment / on Mars. Direct precursor to
  1st human missions.

53
Key technology issues

• Static mission elements
• energy rich power sources - power limited
• Continuous power
• Highly reliable power
• Mobile mission elements
• Compact power sources - energy limited
• Lightweight power sources
• Rechargeable / renewable energy

54
Conclusions

• 50kWe static power system nuclear is the ONLY
  viable option
• Mobile mission elements various power systems
  presented. Most require fuel cells and large
  solar arrays to operate in dust storms.
• Wind energy may have significant potential on
  Mars - further research required.
• Key technologies for development are
• Fuel cells with compact oxygen / hydrogen storage
• Mars qualified nuclear reactor
• Wind energy systems
• Flywheels for energy storage, as an alternative
  to Li-ion

55
Effective human Mars exploration can only be
carried out in an energy rich environment, i.e.
one with nuclear power sources

• - Bob Zubrin, Mars Society founder and
  visionary, detailing his experiences in the
  Flashline Mars arctic research station, summer
  2001