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