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2/12/01
Exploration Requirements for Earth to Orbit
Doug Cooke5/14/2002
2/12/01
Sustainable PlanetarySurfaces
Go anywhere, anytime
Accessible Planetary Surface
Earth’sNeighborhood
Stepping Stones
Earthand LEO
2/12/01
Core Capabilities & Technologies
TechnologyBuilding BlocksCommon CapabilitiesPotential Destinations
from Science Objectives
Wireless PowerTransmission
RegenerativeAerobraking
Revolutionary ETORockets
Efficient In-SpaceProp..Aeroassist
Low-cost EnginesCryo FluidManagementRobust/Efficient
PowerLightweightstructures systems,sensors, micro/nanoelectronics
Radiation ResearchZero/Low-g Research
Regenerable LifeSupportAdvanced
Lightweight EVA
Innovative MissionConcepts
MissionAnalyses
SystemDesign(s)
“Breakthrough” Technologies
(Examples)
2/12/01
20
0
30
40
50
60
70
80
90
100
Cum
ulat
ive
Mas
s Sa
ving
s (P
er C
ent)
The Value of Technology InvestmentsMars Mission Example
+ Advanced Materials (14%)+ Maintenance &
Spares (21%)
+AdvancedAvionics (11%)
+Closed Loop Life Support (19%)
+Advanced Propulsion (EP or Nuclear) (46%)
+Aerocapture (50%)
All Propulsive, Chemical
Today’sTechnology
10
2/12/01
Libration Points and New Ideas
• Libration Points are relatively stablelocations in space oriented to orbitingplanetary bodies
• Access to all locations on moon andMars is equivalent
• Very low energy transfers betweenlibration points are possible
L4 L2
L1
L3
L5
Sun - EarthL1
Sun - EarthL2
1.5 million km 1.5 million km
Moon’s Orbit
150 million km
Sun – MarsL1
Sun – MarsL2
1.1 m km1.1 m km
2/12/01
Gateway Architecture
Crew departsfrom and returns
to ISSL1 Gateway
GPSConstellation
Lunar Lander
Crew Transfer Vehicle•Transports crewbetween ISS andGateway•Nominal aerocaptureto ISS, or direct Earthreturn contingencycapability
“Earth’s Neighborhood”
LunarHabitat
L1 Gateway•“Gateway” to the Lunarsurface•Outpost for stagingmissions to Moon, Marsand telescopeconstruction•Crew safe haven
Lunar Lander•Transports crewbetween Gateway andLunar Surface•9 day mission (3 dayson Lunar surface)
Lunar Habitat•30-day surface habitatplaced at Lunar SouthPole•Enables extended-duration surfaceexploration and opsstudies
Crew TransferVehicle
2/12/01
Lunar L1 “Gateway”
Key Attributes
• Earth-Sun Telescopeassembly and servicing
• Gateway serves as“stepping stone” -opportunity to testtechnology and operationalconcepts
• Architecture can be bought“by the yard” - increasingcapabilities and operationalexperience
• Employs existing andmodest augmentation ofexisting launch vehicles
• Common architectureelements for all Earth’sNeighborhood missions
• Potential for repairingoutbound planetaryspacecraft
TM-50 Hall Effect Thruster(6x50kWe each)“Transhab”- class inflatable
pressure shell (1/2 length)
NGST sunshield inflatabledeployment concept
2/12/01
Earth’s Neighborhood Evolution in Vehicle Designs
0.0
1.0
2.0
3.0
4.0
5.0
Nor
mal
ized
Mas
s
+ AdvancedPropulsion(EP) (45%)
+ Closed LifeSupport (34%)
+ Advanced Materials (17%)
+ Maintenance & Spares (18%)
+ Advanced Avionics (7%)
Today
+ Aerobraking (42%)
+ Advanced Materials (17%)+ Maintenance & Spares (18%)
+ Advanced Avionics (7%)
Today
Crew Transfer Vehicle(First Flight)
Gateway(Including Deployment)
Crew Transfer Vehicle Gateway
2/12/01
5) LUNARTRANSFERVEHICLE(LTV) TO ISS
Mission Architecture Summary
LEO
L1
LUNAR SURFACE
1) GATEWAY WITHSOLAR ELECTRICPROPULSION STAGETO L1
2) SOLARELECTRICPROPULSIONSTAGE TO LEO
4) L1 LUNAR LANDER TOGATEWAY
7) KICKSTAGE TOISS VICINITY
8) LTV, LOGI-PACK AND KICK
STAGE, ANDCREW TOGATEWAY
9) CREW AND L1Lunar Lander TOLUNAR SURFACE
10) CREW AND L1 LunarLander TO L1
12) CREW AND LOGI-PACK TO EARTH VIA
SHUTTLE3) L1 LUNARLANDER TOLEO, AUTORNDZ & DOCK
11) CREW AND LTVAEROBRAKE TO ISS
DELTA IV HEAVYS SHUTTLE DELTA IV HEAVY
13) SOLARELECTRICPROPULSIONSTAGE TO LEO
14) LUNARHABITATLANDER TO LEO,AUTO RNDZ &DOCK
15) TO LUNARSURFACE
DELTA IV HEAVYSSHUTTLE
6) LOGI-PACK ANDCREW TOISS
2/12/01
Simplifying Exploration Infrastructure
Mars
Earth-Moon L1Gateway
Moon
Earth-Sun L2 ScienceInstruments
Simplified
Earth-Moon L1Gateway
Mars
HighEarthOrbit
Moon
PreviousEarth-Sun L2
,Transfer Vehicle &Science Instruments
• Space Super Highways are corridors through theSolar System that balance the gravitational forcesof the Sun and the Planets.
• Vehicles require minimal thrust and mass to movefrom one Libration point to another
• Earth System to Mars System transfers have thepotential to transfer cargo at significant costreduction over previous trajectory designs
2/12/01
Potential “Earth’s Neighborhood” Destinations
InterplanetaryDestinations
Earth-MoonGateway
Earth-SunL1
Construct and DeploySolar Sentinels
• Understand Origins of SolarVariability
• Understand Effects on SolarAtmosphere and Heliosphere
• Understand Space Environmentof Earth and Other Planets
• Improve Space WeatherForecasting
Earth-SunL2
Lunar Science• Establish Impact History in
Inner Solar System• Determine Composition of
Lunar Mantle• Insight into Past and Current
Solar Activity• Poles - History of Volatiles in
Solar System
LunarSurface
Construct, Deploy, andService Advanced
AstronomicalInstruments
• Determine PhysicalCharacteristics of PlanetarySystems of other Stars
• Search for Worlds that Could orDo Harbor Life
2/12/01
Trajectory Options Under Consideration
•One-Year Mission– Missions with short Mars surface stays with total
mission duration of one year or less
!SUN
!
•Opposition Class Mission– Variations of missions with short Mars surface
stays and may include Venus swing-by
!SUN
•Conjunction Class Mission– Variations of missions with long
Mars surface stays.
OutboundSurface StayInbound
Ref. Johnson Space Center
2/12/01
0
10
20
30
2000 2001 2004 2005 2008 2009 2012 2013 2016 2017 2020
Earth Departure Date
Min
imu
m T
ota
l P
rop
uls
ive
DV
(K
m/s
ec)
Round-Trip Mars Mission Energy (Delta-V) Variations
2002 2004 2006 2008 2010 2012 2014 2016 2018 2020
3600
3700
3800
3900
4000
12/1/13 12/11/13 12/21/13 12/31/13 1/10/14 1/20/14 1/30/14 2/9/14Earth Departure Date
Earth
Dep
artu
re D
elta
-V (m
/s)
Long-Stay Missions(Conjunction Class)
Minimum delta-v
Short-Stay Missions(Opposition Class)
Minimum delta-v for a 40-day stay
2/12/01
0
200
400
600
800
1000
1200
1400
1600
Init
ial
Ma
ss i
n L
ow
Ea
rth
Orb
it (
Metr
ic T
on
nes)
1 2 3 4 5 6 7 8 9
Mars Architecture Mass Comparison
1 Short Stay, Chem/Aerocapture2 Short Stay, Chem/Aerocapture3 Short-Stay, Nuclear Thermal Rocket (NTR)4 Short Stay, NTR5 Long Stay, NTR, ISRU, Dual-Hab6 Long Stay, NTR, ISRU, Single-Hab7 Long Stay, DRM 4 Refinement (NTR or SEP)8 Long Stay, Dual Landers, Solar Electric (SEP)9 Short Stay (Best Opp.) (NTR or SEP)
ISS @AssemblyComplete(470 tons)
2/12/01
2.4 MWe BOL
1.7 MWe EOM1(Estimated Size)
Central Hub Detail
ISS Mass ! 470 MTSEP-TV dry mass ! 36 MT
• Array sized to provide 1700 kWethroughout first mission
• 14700 m2 CuInS2 array area• 171 m span (wingtip-wingtip)• 17 x 100 kWe Hall Thruster
Propulsion• Articulated boom thruster
Solar Electric Propulsion Concept
2/12/01
Mars Mission Vehicle Concepts
HEO Configuration
Mars Transit Vehicle• Supports mission crew of six
for up to 200-day transits toand from Mars
• Return propulsion stageintegrated with transit system
• Provides return-to Earth abortcapability for up to 30 hourspost-TMI
• Total Vehicle Mass in High-Earth Orbit = 188 mt
Mars Surface Configuration Mars Surface Configuration
Descent/Ascent Vehicle• Transports six crew from Mars
orbit to the surface and back toorbit
• Provides contingency abort-to-orbit capability
• Supports six crew for 30-days• Vehicle capable of utilizing
locally produced propellants• Total Vehicle Mass in High-
Earth Orbit = 103 mt
HEO Configuration
Mars Surface Habitat• Vehicle supports mission crew
of six for up to 18 months onthe surface of Mars
• Provides robust exploration andscience capabilities
• Descent vehicle capable oflanding 36,000 kg
• Total Vehicle Mass in High-Earth Orbit = 99 mt
2/12/01
Lander Dimensions
9’
8’
8’
8’
8’
26’
16’
9’
12’
30’
16’
57’
Habitat Lander
Descent / Ascent Vehicle
Inflatable Habitat
Crew Module
2/12/01
Mars Mission Overview
Habitat Lander and Ascent/DescentVehicles delivered to Low Earth Orbit
with Magnum. Solar ElectricPropulsion stage spirals cargo to HighEarth Orbit. Chemical injection usedat perigee. SEP spirals back to LEO
for reuse.
Surface Habitat andexploration gear
aerocaptures into Marsorbit
Ascent/Descent Vehicleaerocaptures and
remains in Mars orbitfor the crew
Surface Habitat landsand performs initial
setup and checkout -Initial outpostestablished
Transit Habitat vehicle delivered to LEOwith Magnum. SEP spirals Transit Habitat
to High Earth Orbit. Crew delivered tovehicle via crew taxi. SEP spirals back to
LEO for reuse.
Crew travels to Mars in“fast transit” 180-day
transfer. Aerobrakes intoMars orbit
Crew rendezvous withDescent/Ascent Vehicle in Mars
Orbit then lands in vicinity of HabitatLander
Habitatremains inMars orbit
Mars Surface
Earth Orbit
Crew ascends andrendezvous with
waiting Transit Habitat
Crew returns to Earth on“fast transit” 180-day
transfer. Direct entry atEarth
30 daysprovided to
satisfy “long-stay” criteria.
2/12/01
Mars Mid-term Case Study Set 2 ResultsMars Mid-Term Mass Summaries
162 142 161 141 163 142
132133
212
155 131114
169160
199
137 152
125
24 24
24
0
100
200
300
400
500
600
Ca
se 6
.13
NT
R
Ven
us
Sw
ing
-By
Ca
se 6
.15
SE
P
Ven
us
Sw
ing
-By
Ca
se 6
.17
NT
R
On
e-Y
ear
Ca
se 6
.19
SE
P
On
e-Y
ear
Ca
se 6
.21
NT
R
Lo
ng
-Sta
y
Ca
se 6
.23
SE
P
Lo
ng
-Sta
y
Init
ial
Ma
ss i
n L
EO
(m
t)
Crew Taxi
Transit Habitat
Surface Habitat
Earth Return Vehicle
Descent / Ascent Vehicle
Ref. Johnson Space Center
2/12/01
“Shuttle Class” 1Transit Habitatlaunched to lowEarth orbit
STS 1 & 2Transit Habitatoutfittingmissions
“Shuttle Class” 5Transit HabitatSEP vehiclelaunched to lowEarth orbit
“Shuttle Class” 6Transit Habitatpropulsion stageslaunched to lowEarth orbit
SEP vehicle boostsTransit Habitat toHigh Earth Orbit
STS 3 / TaxiTransit Habitatservicing mission inHigh Earth Orbit
Mission SequenceHigh Earth Orbit Boost Phase
SEP vehicles boostDescent/Ascentand Surface Hablanders to HighEarth Orbit
STS 4 / TaxiServicing missionin High EarthOrbit
“Shuttle Class” 2SEP launched tolow Earth orbit
UNPILOTED VEHICLES
PILOTED VEHICLES
Bret Drake / EX
“Shuttle Class” 3Descent/Ascentvehicle, aerobrake,and TMI stagelaunched LEO
“Shuttle Class” 4Surface HabitatLander, aerobrake,and TMI stagelaunched LEO
2/12/01
0
10
20
30
40
50
0 20 40 60 80 100 120
Payload per Launch (Metric Tonnes)
Nu
mb
er
of
La
un
ch
es
Re
qu
ire
d
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Cu
mu
lativ
e L
au
nc
h R
elia
bilityLOSS OF COMMONALITY WITH
STS INFRASTRUCTURE
- INTEGRAL AEROBRAKES LOST
- INTEGRAL INJECTION STAGES LOST
- PACKAGING INEFFICIENCIES INCREASE
- ONORBIT INTEGRATION COMPLEXITY INCREASEs
NO AERO-
CAPTURE
ISS-SCALE
PACKAGING
EFFICIENCIES
IDEAL
PACKAGING
EFFICIENCY
94% (World-wide
Reliability)
97% (EELV
Reliability Req.)
Launch Reliability = 99.7%
(STS Reliability)
TOTAL LAUNCH MASS
- 450 Metric Tonnes
2/12/01
Effects of “Launch Package” Size
• Range of individual launch package masses have been assessed for exploration missions• Package sizes in the range of current launch capabilities show significant disadvantages
– Mass efficiency losses due to non-optimal packaging - ISS experience is ~70%utilization
– Design inefficiencies for large volumes (prop tanks, habitat module)• Increase in interfaces• Excessive mass for bulkheads, docking mechanisms, plumbing
– Increased reliance on on-orbit construction of flight-critical structures• Heat shields, aerobrakes
– Reliability of launch vehicle would need to be extremely high for successful launchof all components
• Payloads consistent with STS-level GLOW launch vehicle could orbit 80-100 metric tons– Could relieve these concerns– Could have small impact to current launch infrastructure
2/12/01
Exploration Requirements
• Payload Mass- 80 to 100 metric tons (100 preferred)• Delivery to 28.5 degree inclination, 407 km altitude• Rendezvous with pre-deployed assets in Earth orbit• Volume- 8m dia. X 30m length• Reliability- 99.7% or better (Shuttle Equivalent)• Goal- $1000 per pound• Cargo launch Shroud= Mars entry heat shield
2/12/01
Summary
• NASA has conducted human Mars mission studies for more than 12 years– Variety of mission goals– Variety of mission durations– Variety of assumptions in technology employed
• Total initial mission mass in low earth orbit has varied from 400 to 1400metric tons to send a crew to Mars
• Current estimated mass~ 450 metric tons• Launch package sizes on the order of 80 to 100 metric tons allow for simplest
interfaces between vehicle components