Near-Term Mars Colonization

-A DevelopSpace Project-May 25th, 2008

Agenda

• Transportation update

• Minimalist transportation concept

• Power update

• SVN update

Transportation Update

Solar Electric Propulsion (SEP)

• Could be used to raise from LEO to HEO• System Mass = ~120% Payload Mass• Paper by Gordon Woodcock (AIAA 2004-3643)

– Requires 41mT of Xenon (for 50 mt Payload)» (Annual world production = 53mT)

• Baseline• Delta-V = 4000 m/s• PMF = 0.125• Specific Impulse = 450 sec

Chemical Propulsion

TMI Stage Mass vs Payload Mass• From LEO, the TMI payload mass is ~50% the

mass of the TMI Stage– Ideally, the TMI payload mass would be equal to the

TMI stage mass to utilize one launch vehicle• Solutions

– Break TMI Stage into two stages• One large & one small

– Have launch vehicle place TMI stage and payload into highly elliptical orbits

• Reduce TMI Delta-V to ~2600 m/s– No analysis on feasibility done yet

Mars Orbit Insertion and EDL• Most common approach

– Aero-capture followed by aero-assist EDL

• System Masses vary greatly– DRM-1 & DRM-3 assume 28-

33% of TMI Mass required for “descent system”

– Mars Direct assumes 35% of TMI Mass required

– Robert Braun (Georgia Tech) mentions 70% of TMI Mass required for “descent system”

• 40% for orbit insertion• 30% for descent and landing

IMLEO [kg] 100000

TMI Stage "Dry" [kg] 8380

TMI Stage "Propellant" [kg] 58659

Orbit Insertion System [kg] 13184

Descent and Landing System [kg] 9888

Payload [kg] 9888

• Based on chemical propulsion & Braun’s numbers• 10% of IMLEO mass can

be landed on Mars

In-Space Crew Considerations

• How does the crew get to the surface of Mars?• Earth to LEO

– Separate launch and rendezvous– Launched in transit or Mars habitat

• LEO to Mars– Is a unique habitat required?– Zero-gravity concerns

• Artificial Gravity

 Mars

HabitatMars Descent/Ascent

Vehicle

Payloads and Systems 30325.2 13467.2

1.0 Power Systems 5988 4762

2.0 Avionics 153 1533.0 Environmental Control & Life Support System 3948.9 1037.6

4.0 Thermal Management System 2912.1 527.4

5.0 Crew Accommodations 3502.9 727.7

6.0 EVA Systems 1174.4 1085

7.0 In-situ Resource Utilization 165 0

8.0 Mobility 0 1200.4

9.0 Science 829.9 301.2

10.0 Structure 1861.3 1339.8

Margin (15%) 1775.1 1415.1

Food 6840 360

Crew 0 558

Mobility Strategies  Advantages Disadvantages Comments

EVA Suits Simplest Very limited rangeNot feasible with multiple stationary landers/habitats

Unpressurized Rovers

SimpleIncreased range vs. EVA Limited range Being developed for lunar exploration

Pressurized Rovers

SimpleMulti-day trips

Higher mass than UPRRange limited by capacity Being developed for lunar exploration

Aircraft Increased range Untested Is this even possible?

Ballistic Vehicles Increased range

UntestedComplex Use of ISRU a possibility

Mobile BaseMove entire habitats to desired locations Mass intensive Either by roving or ballistic

Minimalist Transportation Concept

Transportation Challenges• How do we transport crew and cargo to the

Martian surface using 25 mt launch vehicles?– 25 mt is “worst-case scenario”– Larger payload capabilities would facilitate

transportation and also lead to scaling benefits• Specific challenges:

– Launch and LEO orbit assembly– Mars aerocapture and EDL

• Ballistic coefficient (entry body mass, diameter, shape)• Altitude at Mach 3 / aeroshell separation

– Propulsive descent (800 m/s assumed for now)– Final landing GN&C, landing error reduction– Hazard avoidance

• Falcon 9 Heavy assumed as reference LV– ~28 mt to 300 km LEO– ~4 m x ~10 m cylinder of usable volume in shroud

Image credit: Space ExplorationTechnologies, Inc.

Falcon 9Heavy

Mars Aerocapture and Entry Vehicle• Entry vehicle is based on conic

blunted body– 20 degree side-wall angle– Drag coefficient: ~1.6– L/D: ~0.3

• Total mass is 12 mt, leading to a ballistic coefficient of around 600 kg/m2– Mach 3 altitude ~ 5 km

• Final descent propulsion based on MMH / N2O4– Isp = 320 s– 8 tanks (4 fuel, 4 oxidizer)

• Cargo to surface: ca. 5 mt

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Cargo Transportation Concept• Transportation concept based on dual

blunt-shaped entry bodies– Reduces ballistic coefficient per entry

body (~ 600 kg/m2)– Allows for simple blunt-body shape

• Entry bodies are launched together with additional cruise systems

– Solar arrays, batteries, radiators– Entry bodies separate prior to

aerocapture and aeroentry• 2 Earth departure stages are launched

after the entry bodies– Stages dock to entry bodies for dual burn

Earth departure• Initial analysis indicates that ~25 mt can

be injected towards Mars using LOX / kerosene stages

– ~10 mt useful cargo mass on Mars surface (~ 5 mt per entry body)

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Solar array Solar array

Earth-Mars transit configuration

Entry body 1

Entry body 2

Launch configuration

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TMI stack

Earthdeparturestage 1

Earthdeparturestage 2

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Crew Transportation Concept• Crew transportation with entry body

(cargo) and additional transit habitat– 2 sets of solar arrays, batteries, and

radiators– Transit habitat is jettisoned prior to

aerocapture

• 2 Earth departure stages are launched separately and docked

– Dual burn Earth departure– LOX / kerosene propulsion

• Initial analysis indicates that 2-3 crew can be delivered to Mars surface this way

– Crew can be sustained for 30+ days on surface after landing

– Unpressurized mobility delivered with crew

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Solar arrays Solar array

Earth-Mars transit configuration

Entry body

Launch configuration

TMI stack

Earthdeparturestage 1

Earthdeparturestage 2

Transithab

Transportation Results & Forward Work

• 4-6 crew can be transported to Mars with 6 Falcon 9 heavy launches– Launch cost of ca. $ 600 Mn (ca. $ 100 Mn per launch)

• 3 Falcon 9 heavy launches can deliver a minimum of 10 mt of useful mass to the Martian surface– Equivalent to 26-month consumables demand for 4 crew

• Forward work:– More detailed design of aeroshell and descent stage– More detailed design of Earth departure propulsion

• Including propellant type trade

– Investigation of different entry body shapes

Power Update

Surface Power Architecture Tree

• The basic type of analyses that was carried out:– Equal energy analysis: all systems provide the same usable

energy per day (for photovoltaic systems this means increased power generation during the day)

Primaryenergy

generation

Nuclear fission Photovoltaicconversion (“solar”)

Secondaryenergy

generation

Not required Batteries Fuel cell +electrolysis

Energystorage

Not required Batteries H2 + O2

Batteries +radioisotope

Batteries

Fuel cell +electrolysis +radioisotope

H2 + O2

Trackingarrays?

N/A Yes No Yes No Yes No Yes No

Radioisotope

Not required

Yes No

Modeling• Created model for Mars solar arrays based on following major

requirements:– Array must be sized for end-of-mission power requirements– If several missions go to same site, supplementary arrays are brought each

mission to make up for degradation– Array must be sized to provide the required power during the year’s

minimum incident solar energy period• Model Assumptions:

– On Mars, optical depth of 0.4 (equivalent to hazy skies)– Tracking arrays at both locations are multi-axis and keep incident flux

perpendicular to array over the day– Nighttime power of 20 kW, with daytime power enforced when sun is 12

degrees above the horizon– Mars analysis done for an

equatorial location (actuallynot optimal location forsolar power on Mars):

• Optimal location at 31° N, witha minimum of 6.57(kW-h/m^2/sol)and 49% daylight/sol for aperiod of 100 sols

• Northern latitudes better than corresponding southern latitude

Daily Solar Incidence Energy Levels (Tracking Arrays, No Atmosphere)

0

2

4

6

8

10

12

0 100 200 300 400 500 600 700

Date in Sols (Perihelion = 0)

kW

-h (

so

lar)

/ m

^2

/ s

ol

Equator

45-degrees North

45-degrees South

Model Inputs and Outputs• Inputs:

– Minimum solar energy– Eclipse Time– Daytime/nighttime power

req.– Power distribution eff.– Solar array eff.– Degradation per year– Array lifetime– Optical depth– Latitude– Array packing density– Battery type

• Outputs:– Array area– System mass– System volume

Mars ResultsMass Specific Power vs. Average Power Level On Mars

0

5

10

15

20

25

30

25 35 45 55 65 75

Avg Power (kW)

Mas

s S

peci

fic P

ower

(W/k

g)

Non-Tracking+RFC

Non-Tracking+Li-Ion batteries

Nuclear+stirling

Nuclear+Brayton

Tracking+RFC

Tracking+Li-Ion

Non-Tracking+RFC+RTG(5kW)

Tracking+RFC+RTG(5kW)

Non-Tracking+Li-Ion+RTG(5kW)

Tracking+Li-Ion+RTG(5kW)

Non-Tracking+RTG(20kW)

Tracking+RTG(20kW)

2xMass Non-Tracking+RTG(20kW)

Mars Results ContinuedVolume Specific Power vs. Average Power Level On Mars

0

1000

2000

3000

4000

5000

6000

7000

8000

25 35 45 55 65 75

Avg Power (kW)

Mas

s Spe

cific

Pow

er (W

/m̂3)

Non-Tracking+RFC

Non-Tracking+Li-Ion batteries

Nuclear+stirling

Nuclear+Brayton

Tracking+RFC

Tracking+Li-Ion

Non-Tracking+RFC+RTG(5kW)

Tracking+RFC+RTG(5kW)

Non-Tracking+Li-Ion+RTG(5kW)

Tracking+Li-Ion+RTG(5kW)

Non-Tracking+RTG(20kW)

Tracking+RTG(20kW)

2xMass Non-Tracking+RTG(20kW)

Other Considerations for Large Solar Array Fields on Mars

• Deployment time:– Considered a 10,000 m^2 rollout array field which will provide 63kW average power for

about 100kW daytime power– Assume array blankets are 2m wide for easy storage and handling by two astronauts– Assume each blanket weighs 100lbs again for easy handling– With 0.06 kg/m^2 expected array density, need only 14 blankets total– Assume astronauts can unroll array at a walking speed of 1m/s, requires only 3hrs for

unrolling– Most time will be needed for unloading positioning and hookup, if assume 1hr for this

for each array, total deployment time approximately 17 work hours for 2 crew

• Power delivery during deployment:– If we are conservative and say deployment takes 1 week, we need either a 10kW RTG or

fuel cell system to provide 10kW power over the week– RTG system would be approximately 1200kg and 0.6 m^3– If use RFC, need 2400kg system with volume 8.4 m^3

Future Work

• Reassess architecture options in MinMars colony context. Previous power analysis for shorter round trip mission.

• Operations considerations such as dust removal and maintenance.

• Dust storm power generation.

SVN Update

Current SVN Folder Structure

• Meetings– Folders with telecon slides

• Models & Analysis– Folders with individual models and results

(spreadsheets, presentations, CAD files, etc.)

• Users– Folders for individual users

Backup Slides

ProjectDefinition

Mid-May 2008 July 15, 2008 Early September 2008

Focus on fixed crew-size “toehold” onMars as alternative to exploration program

Focus on expansion of “toehold”to mostly self-sustained colony

Follow-onprojects

Integration of results(lead: Wilfried)

Finance and costing(lead: ?)

Outpost re-supply(lead: Wilfried)

In-Space Transportation(lead: Arthur)

Surface Infrastructure(lead: Arthur)

Surface Operations(lead: Arthur)

Surface Power & Thermal(lead: Chase)

Expansion analysis

Operational Architecture

• The overall operational architecture for the initial toehold is based on one-way flights delivering cargo and crew to the Martian surface– Potentially with an emergency return capability

• Mars capture is assumed to be accomplished by aerocapture• Subsequent lifting entry and propulsive descent are used to deliver

payloads to the single surface outpost site– Outpost location is subject to a variety of factors (insolation, water, elevation)

• The exact size and payload capability of each lander depends on the Earth departure architecture and entry body chosen

Marsorbit

Earthorbit

Earth departurearchitecture

Earth departurearchitecture

Earth departurearchitecture

26 months 26 months

Toehold Location: Topography

Toehold Location: Solar Power

Toehold Location: Water

General Study Objectives

• Carry out an assessment of re-supply needs for the outpost given different technologies– Including high-closure life support, ISRU

• Identify key re-supply drivers and carry out in-depth analyses

• Identify interesting technologies with high payoff in re-supply mass reduction– Carry out initial modeling and testing of these technologies

• Formulate plan for further technology development

Mars Surface Habitat Architectures 1-5Open loop

Water regeneration (95%)

Regenerative CO2 removal

Completely dehydrated food

Washing machine

Mars Surface Habitat Architectures 5-9

Cryogenic oxygen

Water electrolysis+ Sabatier reactor

Water electrolysis

Water electrolysis+ Sabatier reactor

+ methane pyrolysis

Mars Surface Habitat Architectures 9-13

Zirconia electrolysis, scaled-up Zirconia electrolysis, scaled-down

Zirconia electrolysis +water electrolysis+ Sabatier reactor

+ methane pyrolysis

Zirconia electrolysis,no water electrolysis,

Sabatier reactor,methane pyrolysis

Preliminary Insights• Existing technologies allow for re-supply

masses per opportunity of ~2 mt / person– This includes fairly conservative tare fractions on

pressurized logistics and fluid re-supply

• Remaining high-mass re-supply items are:– Food– Spare parts (fans, multi-filtration beds, etc.)– Hygiene & health re-supply (soap, first-aid, etc.)– Hydrogen for ISRU

Food Logistics Reduction• Many options for closure of the food loop

have been investigated over the decades• Two major families of options:

– 1. Chemical regeneration of food from waste• Synthesized chemicals suitable for long-term ingestion

include: glucose, glycerin, ethanol, formose sugars

– 2. Biological regeneration of food from waste• Algae (also for CO2 regeneration)

• Higher plants (wheat, corn, vegetables, etc.)• Animals (fish, chicken)

Mars Wish List

Transportation• Automated Mars landing and hazard avoidance

navigation systems • Mars in-situ propellant production friendly rocket

combustion / performance characterization (C2H4/LOX; CH4/LOX); more important if people want to come back

• Large-scale (20mt+) Mars aero-entry (and EDL more generally) technology

• Low mass, cost, power and ideally autonomous deep-space (out to at least ~2 AU) navigation systems (software, hardware)

Power

• Automated, large scale (football field+) solar array transport, surface deployment, and maintenance systems

• High energy density electrical power storages systems (aiming in particular towards high energy density relative to Earth imported mass)

• Mars surface internal combustion engines (LOX, plus various fuels, e.g., C2H4, CH4, CO, etc), possibly with water exhaust reclamation.

Life Support, Logistics, ISRU• Mars atmosphere collection systems (at minimum CO2; adding N2 and Ar is useful;

H2O depends on energy/mass intensity relative to other options) • Mars permafrost mining systems (for varying wt% H2O); note, this is much easier

than mining putative lunar ice • Good, high capacity Mars surface cryocoolers (options for just soft/medium

cryogens (e.g., LOX, CH4, C2H4), or also for hard cryogen (LH2)) • Earth-Mars hydrogen transport systems (not necessarily as LH2) • Basic ISRU chemical processing systems (e.g., H2O electrolysis, Sabatier, RWGS,

CO2 electrolysis, ethylene production, etc.) • High closure physical-chemical life support systems (e.g., air revitalization, water

recycling) • "Food system" for food supplied from Earth. Consider being able to survive on

food shipped 5 years ago. • Mars surface food production systems • Simple in-situ manufacturing systems (e.g., for spare parts) • Simple raw materials production (e.g., plastics such polyethylene, epoxies,

ceramics, etc.)

Outpost Ops and Surface Exploration

• Mars surface communication and navigation systems (e.g., for rovers), sans extensive satellite constellation

• Very high data rate Mars-Earth back-haul comm system

• Good Mars surface EVA suits • Data collection, analysis in support of landing site /

outpost location selection • Very long distance surface mobility systems

(including with people) • Solar flare / SPE warning systems

Mass Budget for Habitat-1

  Mars Direct DRM-3 MSM Explanation for MSM figuresHabitat Module Structure 5 5.5 4.8 Scaled from DRM-3Furniture and Interior 1 0 1.5  Life Support System 3 4.7 3.8 NASA model for crew of sixComm/Info 0.2 0.3 0.3 DRM-3Hydrogen and Hab ISRU 0.4 0 0  Health Care 1.3 0 0  Thermal 0 0.6 0.5 DRM-3 ScaledCrew accommodation 0 11.5 0  Spares and Margin 3.5 0 0 Included in individual listingsScience 1 0 0  Crew 0.4 0.5 0.4  Surface power (reactor) 0 1.7 5 At least 25 kWe neededPower Distribution 0 0.3 0.3 DRM-3 ScaledEVA Suits 0.4 1 1 DRM-3Open Rovers 0.8 0.5 0 Mass budgeted with surface powerPressurized Rover 1.4 0 0  Consumables 7 0 3.2 98% closed H20/02 + food (=0.630 kg/per/day for 600 days)EVA Consumables 0 2.3 0 Produced by ISRU on MAV and HabDescent fuel cell 1 3 1.3  Reaction Control System 0.5 0 0.5 Mars DirectTotal Landed 26.9 31.9 22.6 Total of Above

Mass allocations for Mars Direct components on surface of Mars

ERV components mT Habitat components mTERV cabin structure 3 Habitat strucure 5Life Support System 1 Life Support System 3consumables 3.4 Consumables 7Solar Arrays (5 kW) 1 Solar Arrays (5 kW) 1Reaction Control System 0.5 Reaction Control System 0.5Communications and Information Management 0.1 Communications and Information Management 0.2Furniture and Interior 0.5 Furniture and Interior 1Space Suits (4) 0.4 Space Suits (4) 0.4Spares and Margin (16%) 1.6 Spares and margin (16%) 3.5Aeroshell (for Earth Return) 1.8 Pressurized Rover 1.4Rover 0.5 Open Rovers (2) 0.8Hydrogen Feedstock 6.3 Lab Equipment 0.5ERV Propulsion stages 4.5 Field Science Equipment 0.5Propellant Production Plant 0.5 Crew 0.4Nuclear reactor (100 kW) 3.5           Total Mass 28.6   25.2