Near-Term Mars Colonization
-A DevelopSpace ProjectMay 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)
Chemical Propulsion
Payload Mass vs Delta V Requirement
Payload Mass / Initial Mass [%]
Payload Mass / Initial Mass [%]
Payload Mass vs.
Propellant Mass Fraction
40
35
30
25
20
0.05
0.1
0.15
0.2
0.25
Propellant Mass Fraction (PMF)
40
38
36
34
32
30
28
26
24
22
20
3500
3700
3900
4100
4300
Delta V [m/s]
Payloadd Mass / Initial mass [%]
Payload Mass vs. Specfic Impulse
40
38
36
34
32
30
28
26
24
22
20
• Baseline
• Delta-V = 4000 m/s
• PMF = 0.125
• Specific Impulse = 450 sec
340
360
380
400
420
Specific Impulse [sec]
440
460
4500
Mass to TMI vs IMLEO
40000
35000
TMI Payload Mass [kg]
30000
25000
20000
15000
10000
5000
0
20000
30000
40000
50000
60000
70000
IMLEO [kg]
80000
90000
100000
110000
120000
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 2833% 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]
TMI Stage "Dry" [kg]
100000
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
Surface Infrastructure Masses for
DRM-4
35000
Crew
30000
Food
Payloads and Systems
1.0 Power Systems
2.0 Avionics
10.0 Structure
3.0 Environmental Control & Life
Support System
9.0 Science
4.0 Thermal Management System
5.0 Crew Accommodations
8.0 Mobility
6.0 EVA Systems
7.0 In-situ Resource Utilization
7.0 In-situ Resource
8.0 Mobility
Utilization
9.0 Science
6.0 EVA Systems
10.0 Structure
Margin (15%)
5.0 Crew Accommodations Food
Crew
4.0 Thermal Management
System
Margin (15%)
25000
Mass [kg]
20000
15000
10000
3.0 Environmental Control
& Life Support System
5000
2.0 Avionics
0
1.0 Power Systems
Mars Habitat
Mars
Descent/Ascent
Vehicle
Element Name
Mars
Habitat
30325.2
5988
153
Mars
Descent/Ascent
Vehicle
13467.2
4762
153
3948.9
2912.1
3502.9
1174.4
165
0
829.9
1861.3
1775.1
6840
0
1037.6
527.4
727.7
1085
0
1200.4
301.2
1339.8
1415.1
360
558
Mobility Strategies
Advantages
EVA Suits
Simplest
Comments
Not feasible with multiple stationary
Very limited range landers/habitats
Unpressurized
Rovers
Simple
Increased range vs. EVA
Limited range
Pressurized
Rovers
Simple
Multi-day trips
Higher mass than
UPR
Range limited by
capacity
Being developed for lunar exploration
Aircraft
Increased range
Untested
Is this even possible?
Untested
Complex
Use of ISRU a possibility
Mass intensive
Either by roving or ballistic
Ballistic
Vehicles
Mobile Base
Increased range
Move entire habitats to
desired locations
Disadvantages
Being developed for lunar exploration
Minimalist Transportation Concept
Transportation Challenges
Falcon 9
Heavy
• 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 Exploration
Technologies, Inc.
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
8400
• 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
Cargo Transportation Concept
•
Earth-Mars transit configuration
Solar array
Entry body 2
– Reduces ballistic coefficient per entry
body (~ 600 kg/m2)
– Allows for simple blunt-body shape
Solar array
•
Entry body 1
8400
TMI stack
6500
Earth
departure
stage 2
•
6500
2 Earth departure stages are launched
after the entry bodies
– Stages dock to entry bodies for dual burn
Earth departure
4000
Earth
departure
stage 1
Entry bodies are launched together with
additional cruise systems
– Solar arrays, batteries, radiators
– Entry bodies separate prior to
aerocapture and aeroentry
22600
Launch configuration
Transportation concept based on dual
blunt-shaped entry bodies
•
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)
Crew Transportation Concept
Earth-Mars transit configuration
Solar arrays
Transit
hab
•
– 2 sets of solar arrays, batteries, and
radiators
– Transit habitat is jettisoned prior to
aerocapture
Solar array
Entry body
•
22600
22600
TMI stack
22600
Earth
departure
4000
stage 1
4000
4000
6500
6500
8400
Earth
departure
stage 2
6500
8400
8400
Launch configuration
Crew transportation with entry body
(cargo) and additional transit habitat
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
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
Primary
energy
generation
Secondary
energy
generation
Energy
storage
Tracking
arrays?
Photovoltaic
conversion (“solar”)
Nuclear fission
Not required
Batteries
Fuel cell +
electrolysis
Batteries +
radioisotope
Fuel cell +
electrolysis +
radioisotope
Radioisotope
Not required
Batteries
H2 + O2
Batteries
H2 + O2
Not required
N/A
Yes
No
Yes
No
Yes
No
Yes
No
Yes
No
• 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)
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
Daily Solar Incidence Energy Levels
– Mars analysis done for an
(Tracking Arrays, No Atmosphere)
equatorial location (actually
not optimal location for
solar power on Mars):
• Optimal location at 31° N, with
a minimum of 6.57(kW-h/m^2/sol)
and 49% daylight/sol for a
period of 100 sols
• Northern latitudes better than
corresponding southern latitude
kW-h (solar) / m^2 / sol
12
10
8
6
4
Equator
45-degrees North
2
45-degrees South
0
0
100
200
300
400
500
Date in Sols (Perihelion = 0)
600
700
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 Results
Mass Specific Power vs. Average Power Level On Mars
Mass Specific Power (W/kg)
30
Non-Tracking+RFC
Non-Tracking+Li-Ion batteries
25
Nuclear+stirling
Nuclear+Brayton
20
Tracking+RFC
Tracking+Li-Ion
15
Non-Tracking+RFC+RTG(5kW)
Tracking+RFC+RTG(5kW)
10
Non-Tracking+Li-Ion+RTG(5kW)
Tracking+Li-Ion+RTG(5kW)
5
Non-Tracking+RTG(20kW)
Tracking+RTG(20kW)
2xMass Non-Tracking+RTG(20kW)
0
25
35
45
55
Avg Power (kW)
65
75
Mars Results Continued
Volume Specific Power vs. Average Power Level On Mars
Mass Specific Power (W/m^3)
8000
Non-Tracking+RFC
7000
Non-Tracking+Li-Ion batteries
6000
Nuclear+stirling
5000
Tracking+RFC
Nuclear+Brayton
Tracking+Li-Ion
4000
Non-Tracking+RFC+RTG(5kW)
Tracking+RFC+RTG(5kW)
3000
Non-Tracking+Li-Ion+RTG(5kW)
2000
Tracking+Li-Ion+RTG(5kW)
Non-Tracking+RTG(20kW)
1000
Tracking+RTG(20kW)
2xMass Non-Tracking+RTG(20kW)
0
25
35
45
55
Avg Power (kW)
65
75
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
July 15, 2008
Mid-May 2008
Focus on fixed crew-size “toehold” on
Mars as alternative to exploration program
Early September 2008
Focus on expansion of “toehold”
to mostly self-sustained colony
In-Space Transportation
(lead: Arthur)
Surface Infrastructure
(lead: Arthur)
Surface Operations
(lead: Arthur)
Project
Definition
Surface Power & Thermal
(lead: Chase)
Outpost re-supply
(lead: Wilfried)
Finance and costing
(lead: ?)
Integration of results
(lead: Wilfried)
Expansion analysis
Follow-on
projects
Operational Architecture
Mars
orbit
Earth
orbit
Earth departure
architecture
Earth departure
architecture
26 months
Earth departure
architecture
26 months
• The overall operational architecture for the initial toehold is based on oneway 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
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 resupply mass reduction
– Carry out initial modeling and testing of these technologies
• Formulate plan for further technology development
Mars Surface Habitat Architectures 1-5
Open loop
Water regeneration (95%)
Regenerative CO2 removal
Completely dehydrated food
Washing machine
Mars Surface Habitat Architectures 5-9
Cryogenic oxygen
Water electrolysis
Water electrolysis
+ Sabatier reactor
Water electrolysis
+ Sabatier reactor
+ methane pyrolysis
Mars Surface Habitat Architectures 9-13
Zirconia electrolysis +
water electrolysis
+ Sabatier reactor
+ methane pyrolysis
Zirconia electrolysis,
no water electrolysis,
Sabatier reactor,
methane pyrolysis
Zirconia electrolysis, scaled-up
Zirconia electrolysis, scaled-down
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
Habitat Module Structure
Furniture and Interior
Life Support System
Comm/Info
Hydrogen and Hab ISRU
Health Care
Thermal
Crew accommodation
Spares and Margin
Science
Crew
Surface power (reactor)
Power Distribution
EVA Suits
Open Rovers
Pressurized Rover
Consumables
EVA Consumables
Descent fuel cell
Reaction Control System
Total Landed
Mars Direct DRM-3 MSM
5
5.5
4.8
1
0
1.5
3
4.7
3.8
0.2
0.3
0.3
0.4
0
0
1.3
0
0
0
0.6
0.5
0
11.5
0
3.5
0
0
1
0
0
0.4
0.5
0.4
0
1.7
5
0
0.3
0.3
0.4
1
1
0.8
0.5
0
1.4
0
0
7
0
3.2
0
2.3
0
1
3
1.3
0.5
0
0.5
26.9
31.9
22.6
Explanation for MSM figures
Scaled from DRM-3
NASA model for crew of six
DRM-3
DRM-3 Scaled
Included in individual listings
At least 25 kWe needed
DRM-3 Scaled
DRM-3
Mass budgeted with surface power
98% closed H20/02 + food (=0.630 kg/per/day for 600 days)
Produced by ISRU on MAV and Hab
Mars Direct
Total of Above
Mass allocations for Mars Direct
components on surface of Mars
ERV components
ERV cabin structure
Life Support System
consumables
Solar Arrays (5 kW)
Reaction Control System
Communications and Information Management
Furniture and Interior
Space Suits (4)
Spares and Margin (16%)
Aeroshell (for Earth Return)
Rover
Hydrogen Feedstock
ERV Propulsion stages
Propellant Production Plant
Nuclear reactor (100 kW)
mT
3
1
3.4
1
0.5
0.1
0.5
0.4
1.6
1.8
0.5
6.3
4.5
0.5
3.5
Total Mass
28.6
Habitat components
Habitat strucure
Life Support System
Consumables
Solar Arrays (5 kW)
Reaction Control System
Communications and Information Management
Furniture and Interior
Space Suits (4)
Spares and margin (16%)
Pressurized Rover
Open Rovers (2)
Lab Equipment
Field Science Equipment
Crew
mT
5
3
7
1
0.5
0.2
1
0.4
3.5
1.4
0.8
0.5
0.5
0.4
25.2