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Minimalist Mars Mission

Establishing a Human Toehold on the Red Planet

January 2011 Review

DevelopSpace MinMars Team

Agenda• Introduction and motivation• Overall architecture• Transportation: cargo and crew• Surface infrastructure and mobility• Life support, ISRU, and resupply logistics• Launch manifest• Notional net-present-cost analysis• Expanding the toehold into a colony• Impact of new technologies on the architecture• Interesting topics for future work

Project Motivation• For manifold reasons, it is our destiny as humans to

expand our presence:– Since the existence of our species, we have expanded our

habitat over almost the entire Earth– This expansion was enabled by using technology (e.g. living in

central Europe or northern Minnesota and surviving the winter)

• The next logical step is to go beyond Earth– Requires more significant reliance on technology

• In addition to expanding our presence, there may be numerous other benefits from this:– Rekindling of frontier spirit, societal invigoration– Generation of new technologies, now knowledge– Backup of our species and its achievements

There are people who want to make it happen

Why Mars?• Why would we want to expand to Mars, instead of other

destinations such as the Moon?• Of all the bodies of the inner solar system eligible for

near-term colonization, Mars is the most suitable– Mars has an atmosphere, specifically a CO2 atmosphere (GCR /

SPR protection, feedstock for ISRU)– All the other elements necessary for sustained human existence

are present in one for or another on the Martian surface• Nitrogen, hydrogen, oxygen, carbon, iron, aluminum, etc.

– From a mass / energy perspective, the Martian surface is about as hard to reach as the lunar surface

– Higher gravity level than on the Moon

• Major challenges of Mars are that it takes longer to get there and aeroentry / aerocapture is required

MinMars Outpost Architecture Overview• Initial crew size: 4• Location:

– 20-40 deg northern latitude – Longitude not specified, preferably

close to sites of scientific interest– Surface altitude < -2 km

• Outpost initial operational duration: 20 opportunities

– Build-up of a colony should be possible during that time

• Use of commercial launch vehicles (e.g. Falcon 9 Heavy) for deployment and re-supply

• Use of Mars in-situ resources (in particular the Mars atmosphere) as a means of reducing re-supply needs

• Use of existing technologies or near-term extrapolations thereof (in particular for Mars EDL)

• Use of solar power generation

Mars Surface Water Content

• While in-situ production of water is not planned for the initial stage of the MinMars outpost operations, it may be essential for a full colony

• Within the outpost location zones dictated by solar power generation and Mars EDL considerations there seems to be a minimum water mass fraction of 4% in the Mars surface soil

Overall MinMars Outpost Arrangement

Habitat andISRU equipment

Solar arraydeployment area

Land

ing

zone

App

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1-2 km

Cargo Transportation

Earth

Mars

Low Mars Orbit

Highly Elliptic Earth Orbit (e.g. GTO)1-13 monthsof loitering

Direct Mars entry (lifting) using anextension of Viking EDL technology

Commercial Earth launch(e.g. on a Falcon 9 Heavy)

Trans-Mars coast (~ 6-8 months)

2 mt of useful payload on the surfaceof Mars; 1 km landing accuracy

Pre-deployed beacon

Mars EDL Concept• Analyses indicate that existing Mars EDL technology can be

extended to a payload mass of 2000 kg– See NASA Mars Design Reference Architecture 5.0

– Existing Mars EDL technology was developed for Viking

• => Extension of the MSL EDL system (however, no skycrane, lander stage instead):

– MSL ballistic coefficient: 115 kg/m2

– MSL reference area (4.6 m diameter): 16.62 m2

– Payload mass fraction on entry: 775 kg / 2800 kg = 0.28

– MSL hypersonic drag coefficient: 2800 kg / (115 kg/m2 x 16.62 m2) = 1.46

– MSL propellant mass estimate: 8 x 50 kg = 400 kg

• MinMars EDL system characteristics:– Entry mass: 2000 kg / 0.28 = 7143 kg

– Reference area: 7143 kg / (1.46 x 115 kg / m2) = 42.54 m2

– Aeroshell diameter: 7.36 m

– Lander propellant mass: 2000 kg / 775 kg x 400 kg = 1032 kg

– EDL system dry mass (including the cruise stage):8000 kg – 2000 kg – 1032 kg = 4968 kg

Ballisticcoefficient:

MSL scaled up

7.36 m

MinMars aeroshell

Payload envelope(cylinder):1.5 m diameter,2.5 m height

NASA MSL

Launch and Earth Departure for Cargo

• Trans-Mars injection Δv: 4000 m/s (from LEO); 1500 m/s (from GTO)

• Falcon 9 heavy payload performance to GTO: 19500 kg

• Trans-Mars injection payload mass:8000 kg (including cruise stage)

• Kick stage design– Propellant combination: MMH + N2O4

(hypergolic + storable); Isp = 316 s

– Propellant mass: 5687 kg

– Structure mass: 1137 kg (20% of propellant mass)

• Total Falcon 9 Heavy payload mass to GTO: 14824 kg

Earth

“Storage” orbit (GTO)

Trans-Marsdeparturehyperbola

Crew Transportation (for 2 Crew)

Earth

Mars

Low Mars Orbit

Low Earth Orbit (e.g. GTO)

1-5 months of loitering forEarth departure stages

Direct Mars entry (lifting) using anextension of Viking EDL technology

Commercial cargo launch(e.g. on a Falcon 9 Heavy)

Trans-Mars coast (~ 6 months)

2 crew members on the surfaceof Mars; 1 km landing accuracy

Pre-deployed beacon

Mars lander

ITH Earthdeparturestage 2

Earthdeparturestage 1

Commercial crew launch(e.g. Falcon 9 / Dragon)

Earth departure stages discarded

ITH discarded

Interplanetary Transfer Habitat (ITH)

• The ITH design is based on a NASA habitat design for a Sun-Earth L2 mission habitat (100-day mission with a crew of 4)

• The MinMars version of this habitat would house a crew of 2 for 200 days (twice the pressurized volume available per crew member)

• Habitat total wet mass at launch: 14540 kg• Habitat envelope during launch (deflated): 4 m diameter, 10 m length• Minimum consumables mass: 800 kg (food) + 200 d x 2 p x 3 kg / p / d = 2000 kg• => Conservative estimate of ITH inert mass (for estimating cost): 12540 kg• Total launch mass of ITH and Mars Crew Lander: 14540 kg + 7143 kg = 21683 kg

NASA hab design

Mars Crew Lander

• The crew lander consists of the cargo lander aeroshell, propulsion and landing system, and a 2 mt crew landing module (as payload)

• The crew landing module design is adapted from an Apollo-era lunar surface shelter design

• The crew landing module provides post-landing life-support for 2 crew for 10 days (also includes and airlock)

• Module may be reused as overnight shelter for excursions (after relocation)

Earth Departure Stage: Adapted Centaur V1

Earth Departure Propulsive Capability

4 Centaur V1 stages3 Centaur V1 stages

2 Centaur V1 stages

1 Centaur V

1 stage

Habitation Infrastructure

H

H

H

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Surface Hab Module

• The surface hab module design is adapted from an Apollo-era lunar surface shelter design

• Each hab module provides life-support, thermal control, and crew systems

• Each hab module has an airlock and 3 interfaces for connection to other modules (re-supply, inflatable, etc.)

• 4 hab modules are delivered to the Martian surface and connected linearly

Image credit: NASA

Resupply Module

• The resupply module design is adapted from an Apollo-era lunar surface shelter design (airlock included)

• Each module has one interface for connection to a hab module

• Based on the adapted design, each module can deliver a total of 853 kg of usable resupply (very conservative estimate)

• 8 modules are required to deliver the press. resupply for one opportunity

• Modules are also used for storing trash or as shelters for surface excursions

Image credit: NASA

Inflatable Module• Antarctic Habitat Demonstrator

– 8 ft max head room– Floor Area: 384 sq ft (24 ft x 16 ft) [35.7 m2]– Packed System: 1000 lbs [455 kg]

• 2 packages (3 ft by 4 ft by 8 ft)

Source: Spampinato, P. “Expandable Habitat Structures for Long Duration Lunar Missions”. 3rd Space Exploration Conference & Exhibit. Feb 2008. ILC Dover.

Source: Four Seasons Hotel. Boston. 380 sqft Superior Room

MinMars version assumedto be about 1000 kg per

inflatable module (no airlock)

Mobility / Offloading Elements

• CMC (Crewed Mobility Chassis)– NASA’s current estimate for the CMC is 969 kg dry

vehicle mass (3 mt payload)• Source: Culbert, C. “Lunar Surface Systems Project

Overview.” USCC Programmatic Workshop on NASA Lunar Surface Systems Concepts. NASA. Feb 2009.

• LSMS (Lunar Surface Manipulator System)– NASA’s current estimate for the LSMS is 190 kg (6 mt

capability)• Source: Culbert, C. “Lunar Surface Systems Project

Overview.” USCC Programmatic Workshop on NASA Lunar Surface Systems Concepts. NASA. Feb 2009.

• Mobility elements used for both crew exploration and infrastructure deployment

• Two CMC + LSMS are prepositioned on the Martian surface; in each resupply opportunity one CMC + LSMS is sent to Mars Image credit: NASA

Unpressurized Mobility Capabilities2 identical unpressurized vehicles on traverse,each capable of transporting the entire crew

Image credit: NASA

Mars Surface Power System Metrics• Metrics for performance-

based analysis:– Mass-specific average

power [W/kg]– Volume-specific average

power [W/m3]

• Two options for evaluation:– Equal-power analysis: all

architectures provide the same power to the user at any time

– Equal-energy analysis: each architecture provides the same energy per day to the user

Power output to user during typical Martian day(solar power generation, non-tracking arrays)

Day

Night

Energyrequired to

chargeenergystorage

Energyavailable fordaytime use

• Nuclear fission and dynamic RTG systems insensitive to evaluation option• Photovoltaic systems with energy storage very sensitive to evaluation options• Comprehensive analysis based on equal-energy analysis and evaluation

Po

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Mars Surface Power Architectures

Latitude-Dependence of Performance for Solar Power

Considerations for Large Solar Array Fields on Mars• Mars surface deployment (manual after crew arrival):

– Considered a 10,000 m2 rollout array field which will provide 63 kW average power for about 100 kW daytime power

– Assume array blankets are 2 m wide for easy storage and handling by two astronauts, need 14 blankets total

– Assume astronauts can unroll array at a walking speed of 1 m/s, requires only 3 hrs for unrolling; total deployment time about 17 hours for 2 crew

– Robotic deployment technology would enable solar power for in-situ propellant production; nuclear fission power requires robotic deployment

• Power generation during manual deployment following landing:– Mars surface energy storage system is brought with crew, charged full during

Earth Mars cruise and / or Mars orbit loiter– System can provide 20 kW for 14 hours; 10 kW for 28 hours

• Dealing with global dust storms and dust removal:– Experience with the Mars Exploration Rovers suggests that during a global dust

storm, arrays provide 10% or more of clear skies power output– For full power, crew needs to clean arrays periodically (~once every 30 days)

• Array degradation due to radiation, dust:– Reuse of arrays from mission to mission requires new arrays to make up for degradation

MinMars Surface Power System• For the MinMars toehold, a power system based on thin-

film amorphous silicon arrays and Li-Ion batteries was selected (30 degree northern lat.):– Usable energy per day: 63 kWe x 24.5 h = 1543.5 kWhe– Peak power: ~200 kWe Nighttime power: 12 kWe– Mass: 6000 kg– Volume (stowed): 36 m3

• Replacement units with an additional 20000 kWe are brought every opportunity (1000 kg, 6 m3)

• This is a conservative estimate, because the reuse of batteries from landers and from mobility chassis in the surface power system is not considered and nighttime power demand is assumed to be 16 kWe (high)

MinMars Surface Energy Usage• Total energy provided:

– 63 kWe x 24.5 h = 1543.5 kWhe

• Energy consumption by habitation and ISRU: – ISRU: 20 kWe x 24.5 h = 490 kWhe– Life support: 4 kWe x 24.5 h =

= 98 kWhe– Crew systems: 2 kWe x 24.5 h =

= 49 kWhe– Other habitation (avionics, comm,

etc.): 2 kWe x 24.5 h = 49 kWhe– Battery charging: 12 kWe x 2 x 14 h

= 336 kWe– Total: 1071 kWhe

• Energy available for mobility and science: 472.5 kWhe

Battery charging

Life support, habitation

ISRU

Mobility+

science

Life Support System Design

In-Situ Resource Utilization• ISRU system provides oxygen and buffer

gas production for habitation and EVA:– Oxygen: 10 kg / d

– Buffer gases (Ar, N2): 0.72 kg / d

• System design is based on the NASA Mars DRM 1.0 ISRU system design

– Design is scaled down, 4 units, operated only during the day

– No methane production using Sabatier or water electrolysis

– System mass: 4 x 828 kg = 3312 kg– System volume: 3 x 10 m3 = 40 m3

– System power demand: 60 kWe for 8 hours during the day

– One additional ISRU unit is brought every opportunity (sort of a spare part)

• No water ISRU initially

Image credit: NASA

Consumables and Spare Parts

Manifest Opportunity 1 (Prepositioning)• Launch 1 / Flight 1:

– Hab module #1

• Launch 2 / Flight 2:– Hab module #2



• Launch 5 / Flight 5:– Mobility chassis #1– ISRU unit #1

• Launch 6 / Flight 6:– Mobility chassis #2– ISRU unit #2

• Launch 7 / Flight 7:– Power system #1– ISRU unit #3

• Launch 8 / Flight 8:– Power system #2– ISRU unit #4

• Launch 9 / Flight 9:– Power system #3– Inflatable module #1

• Launch 10 / Flight 10:– Power system #4– Inflatable module #2

• Launch 11 / Flight 11:– Power system #5– Emergency spares

• Launch 12 / Flight 12:– Power system #6– Emergency spares

Manifest Opportunity 2 (Prepositioning)• Launch 1 / Flight 1:

– Resupply module #1

• Launch 2 / Flight 2:– Resupply module #2







• Launch 9 / Flight 9:– Water resupply #1– Mobility chassis #3

• Launch 10 / Flight 10:– Water resupply #2– Inflatable module #3

• Launch 11 / Flight 11:– Water resupply #3– Inflatable module #4

• Launch 12 / Flight 12:– Water resupply #4– Emergency spare parts

Manifest Opportunity 3 (Crew Transfer)• Launch 1:

– ITH #1

• Launch 2:– ITH #2

• Launch 3:– Earth departure stage #1




• Launch 7:– Delivery of the crew to the ITHs

• Launch 8:– Mobility chassis #3– Emergency spare parts

• Launch 9 / Flight 9:– Emergency food– Emergency water




Manifest Opportunity 4 (Resupply)• Launch 1 / Flight 1:










• Launch 10 / Flight 10:– Water resupply #2– ISRU unit #5

• Launch 11 / Flight 11:– Water resupply #3– Power unit #7

• Launch 12 / Flight 12:– Water resupply #4– Discretionary

Manifest Opportunity 5 (Resupply)• Launch 1 / Flight 1:










• Launch 10 / Flight 10:– Water resupply #2– ISRU unit #6

• Launch 11 / Flight 11:– Water resupply #3– Power unit #8

• Launch 12 / Flight 12:– Water resupply #4– Discretionary

Net-Present-Cost (NPC) Analysis Assumptions

• Cost estimates for spacecraft, surface infrastructure, and propulsion systems carried out with mass-based CERs– All estimates in FY04 $ Mn

• Launch cost for a Falcon 9 Heavy class launch vehicle assumed to be FY04 $ 150 Mn

• Learning rates (and associated reduction of unit costs) not included in the analysis presented here

• Non-discounted as well as discounted analyses (sensitivity analysis to discount rate)

• Time horizon for DDT&E: 5 opportunities (~ 10 years)

Notional

NPC Results (5% Discount Rate)Notional

NPC Results (10% Discount Rate)Notional

NPC by Category

Non-discounted 5% discount rate 10% discount rate

Notional

MinMars Conclusions

• Establishing a permanently inhabited toehold outpost for 4 crew is feasible with existing technologies or modest extensions thereof– 12 Falcon 9 Heavy class launches required per opportunity

• With a limitation of “chunk size” to 2 mt of payload on the surface of Mars, a number of assembly operations are required in order to establish and maintain the toehold– 7 assembly operations for assembling the habitat– 12 assembly operations per opportunity for resupply (roughly 1

assembly operation every two months)

• Notional cost analysis indicates that the NPC of a4-person toehold may be on the order of $ 20 – 40 bn

Toehold Expansion• The toehold is intended as the nucleus for the

development of a full, mostly self-sustained colony– Expanding the crew size may also be a “must” from the

perspective of psychology

• It is unlikely that the toehold would be expanded before re-supply cost can be reduced (i.e. fewer re-supply launches are required per person per opportunity)– The next slide shows an example of expansion without reduction

of resupply cost

• Following section provides suggestions for technology investments to reduced resupply needs (as well as operational risk)

NPC Results (5% Discount Rate)

4 additional crewmembers join

the toehold every3 opportunities

Technology Investment Options• In-situ food production

– Could significantly improve resupply cost and risk (dependence on Earth-based supply)

• In-situ water production– Could significantly improve resupply cost and risk (dependence

on Earth-based supply)

• In-situ production of spare parts– Could significantly improve resupply cost and risk (dependence

on Earth-based supply)

• Higher-payload-mass EDL systems + HLLV– Reduces the number of landings, assembly operations– Makes most sense when combined with a higher-payload Earth

launch capability (50 – 70 – 100 mt to LEO)

• Advanced EVA suits for Mars surface environment– Could significantly improve resupply cost (no metal oxide)

Interesting topics for future work• Fix a couple things after this review (power, ISRU)• Write a journal paper on the toehold?

• Mars surface power– solar power deployment– energy storage– integrated system design and test

• Financial analysis • Surface space suits • In-situ production topics

– In-situ production / spare parts

• EDL– Challenging and hard to test on ground, looking for people who can test

and/or have ways around this– Setup a good forum for people involved in research in this area– Literature review and system analysis of applicability to MinMars