Radioisotope Electric Propulsion: Enabling the Decadal Survey … · 2006-03-08 · 2QSS Group, Inc., NASA Glenn Research Center21000 Brookpark Rd, Cleveland, OH 44135, USA 3NASA

14 February 2006PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8).

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Glenn Research Center

Radioisotope Electric Propulsion:Enabling the Decadal Survey Science

Goals for Primitive BodiesR. L. McNutt, Jr.1, R. E. Gold1, L. M. Prockter1, P. H. Ostdiek1, J. C. Leary1, D. I. Fielher2,

S. R. Oleson3, and K. E. Witzberger3

1The Johns Hopkins University Applied Physics Laboratory11100 Johns Hopkins Road, Laurel, MD 20723, USA

2QSS Group, Inc., NASA Glenn Research Center21000 Brookpark Rd, Cleveland, OH 44135, USA3NASA Glenn Research Center21000 Brookpark Rd., Cleveland, OH 44135, USA

Space Technology and ApplicationsInternational Forum (STAIF)Albuquerque, New Mexico12 - 16 February 2006

23nd Symposium on Space NuclearPower and Propulsion

C07. Electric PropulsionSystems/Concepts


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For Any Mission There AreFour Key Elements

• Science the case for going• Technology the means to go• Strategy all agree to go• Programmatics money in place

A well-thought-out systems approachincorporating all key elements isrequired to promote and accomplish asuccessful exploration plan


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Solar System Science Exploration isGuided by the Decadal Survey

• There are two general issuesregarding primitive bodies in thesolar system:

– What is the role of primitive bodies asbuilding blocks of the solar system?

– What is the role of primitive bodies asreservoirs of organic matter rawmaterials for for the origin of life?


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PRIMITIVE BODIES AS BUILDINGBLOCKS OF THE SOLAR SYSTEM

· What are the albedo and color statistics of Centaurs, Kuiper Belt objects,and comets?

· What is the origin of micrometeorites?

· What is the origin of hydrated minerals in the meteorite parent bodies, andwhat do f luid inclusions in meteorites tell us about conditions in the solarnebula and parent bodies?

What organic materials occur in primitive bodies at various heliocentricdistances?

· What is the origin of the organic matter in carbonaceous meteorite parentbodies, and what are the parent bodies of the many different types?

· What are the compositions of comet nuclei, and how do they relate toKuiper Belt objects

· Do Pluto and/or large Kuiper Belt objects show internal activity, as Tritondoes?

· What are the surface properties and compositions of these bodies, and howdo endogenous and exogenous processes affect them?

How have they affected the planets since theepoch of formation?

· What are the interior properties of all these bodies, and how do they differfrom the surface compositions and properties? Are they differentiated?

How did primitive bodies make planets?

· What are the basic physical properties (mass, density, size) of Kuiper Beltobjects,Centaurs, and comets?

Since their formation, what processes have alteredthe primitive bodies?

· How do the compositions of Pluto-Charon and Triton relate to those ofKuiper Belt objects?

What processes led to the formation of theseobjects?

Are there Pluto-size and larger bodies beyond Neptune?Where in the SS are the primitive bodies found,and what range of sizes, compositions and otherphysical characteristics do they represent?

Important questionsFundamental Issues


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PRIMITIVE BODIES AS RESERVOIRS OFORGANIC MATTER RAW

Is organic matter similarly distributed amongprimitive bodies in other planetary systems?

Is organic matter similarlydistributed among primitive

bodies in other planetarysystems?

Was primitive organic matter racemic?How did organic matterinfluence the origin of life onEarth and other planets?

What are the relative fractions of organic matter inmeteorites and comets that are interstellar and solarnebula in origin?

What processes can be identifiedthat create, destroy, and modifysolid organic matter in the solarnebula, in the epoch of the faintearly Sun, and in the currentSolar System?

Where and under what conditions did organic matteroriginate?

What is its present daydistribution?

What is the composition and structure of primitiveorganic matter in the solar system?

What is the composition, originand primordial distribution ofsolid organic matter (OM) in thesolar system?

Important questionsFundamental Issues


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Glenn Research CenterWhat are “Primitive Bodies”?

• Neptunian satellites– Triton– Nereid

• Kuiper Belt Objects– Charon– Quaoar– UB313

• Trojan Asteroids• Centaurs

– Chiron– Pholus

• Thousands of small objects• A long way off

Neptunian satellites


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Jupiter Icy Moons Orbiter -The improbable dream

The past: The future:PARIS

Missions(Planetary

Access withRadioisotope

Ion-driveSystem)

I2E -InnovativeInterstellar

explorer

How Do We Get There?


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Glenn Research CenterREP Enables New Missions

High efficiency power sources are the key to new andfundamental science, especially in the outer solar

system, on reasonable timescales


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Glenn Research CenterFundamental Science Issues

The NRC Space Studies Board Decadal Survey highlightedfundamental questions concerning primitive bodies:

• What range of sizes, compositions, and other physicalcharacteristics do primitive bodies represent?

• How did they form?

• What processes have altered them?

• How are planets made from primitive bodies?

• How have they affected planets since their formation (e.g.,by impact cratering)?

Cassini montage of Saturn’s “sponge” moon, Hyperion (NASA/JPL)


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Glenn Research CenterPotential Missions

• Joint teams of APL, GRC, JPL, USC, and otherinstitutions have been exploring radioisotopepowered missions

• Two candidate missions are:– Jovian Trojan asteroid orbiter– Innovative Interstellar Explorer

• Radioisotope-electric propulsion (REP)enables this new class of deep space missions

• Mass and power constraints require powersources ≥ 6W/kg– Some missions require ≥ 8W/kg


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Answering the Science Questions is a“System of Systems” Problem

Instrument Resources and Requirements

Required InstrumentsScience Measurement Objectives

Objective Questions

Mission and Spacecraft Requirements

Probe Science Objectives

Science ResultAnalysis Product

Data Product

Science Questions

Distanceand timefor the

mission

Returndata

Operatefor

requiredtime

DRIVERS


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Traceability Matrix GuidesConcept Definition

Science Questions PARIS Objectives Science Measurement Objectives Analysis Product Science Results

Surface elemental abundances GRNS: Fe, Si, H,

K, U, Th, O. Mapping of ice abundance (?)Global maps by element

Spectral measurements of surface: MASCS

Visible and near-IR absorption bandsSpectral unit maps

What can the Trojans tell us about primitive

organics, the building blocks of life?

Characterize presence and

distribution of organic molecules

(OM)s on Trojans

??? MASCS, GRNS??? ???Composition of early solar

nebula

Global monochrome imaging of impact craters to

determine cratering rate: MDIS

Monochrome high

resolution map

Average surface age; location

of units of different age

Global shape from imaging; MDIS Global shape model

Characterize interior configuration

Gravity measurements using Doppler ranging to

spacecraft; characterization of structural features

and overall shape: MDIS

Global gravity map

Monochrome imaging of impact crater and

structural feature morphology: MDISMonochrome image catalog

Topography from stereo imaging: MDIS Slope map

Regolith processes and distribution: MDIS Regolith distribution map

High-resolution multispectral mapping of craters:

MDIS

Multispectral global map,

mulstispectral image

catalog

Composition of pickup ions in the solar wind from

sputtered neutrals: EPPSPickup ion species (?)

Search for moons Image vicinity of target Trojan: MDISMoon images and orbital

information

Constraints on geological

history









Characterization of space

weathering effects at 5 AUInvestigate space weathering effects

How homogenous is the Trojan population?

How have the Trojan asteroids evolved over

time? Are the geological processes which have

occurred on the Trojans the same as those that

have affected asteroids in the Main Belt?

Constraints on evolution of

Trojans

Constraints on origin of Trojans

Map the elemental and mineralogical

composition of the Trojans

Did the Trojans form in the Jovian environment

or were they formed in the Kuiper Belt and

transported inward?

Do Trojan families exist?

Are the L4 and L5 populations the

same?

Comparison of elemental and

mineralogical abundances with

those predicted from solar

nebula

Constraints on surface strength

and regolith properties;

collisional history

Characterize physical surface

properties

Ties in gravity and topography

models, helps elucidate

history. Comparison with other

small bodies.

Determine collisional history


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Glenn Research CenterTrojan Asteroids

• Jupiter’s ~1100 Trojan asteroids orbitin elongated regions around the L4and L5 Lagrange points at 5.2 AU

• Trojan regions contain only lowalbedo, primarily D-type asteroids

• Relatively pristine remnants of theearly Solar System; may haveorganics, silicates, opaque minerals

• Could be a source of short-periodcomets

• No known analogs in meteoritecollection (except possibly TagishLake meteorite)

• New breaking results (Morbidelli et al.,ACM, 2005) suggest that the Trojansmay have originated in the Kuiper Belt

These questions can be addressed by using REP technology to explore the Trojan asteroids


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Radioisotope Electric Propulsion (REP)Enabling Primitive Body Decadal Survey Science

Rationale for Jovian Trojans• Pristine remnants of early Solar System• No known meteorite analogs• Relation to other asteroid groups and

other small bodies• Primitive composition

• Organic constituents• Isotopic ratios

• Jovian System impactors?• In Decadal Survey

Community Interest• Flyby in the Decadal Survey; orbital

Mission not deemed feasible• Orbit at least 2 Trojans

Mission Concept• Ion Propulsion

• High Delta-V (8.5 km/s)• Radioisotope Stirling Power - develop• Existing Low Mass Components - existing• High energy launch (Atlas V 551 - proven)

• Spacecraft slows to target speed

Spacecraft• Launch Mass 690 kg, Power 750 W, 50

kg payload (inc. margin)

Mission Design• 5 yr cruise time, 2 yr orbital operations• Launch any year

Propulsion exists; continuing radioisotope power sourcedevelopment required. MMRTG optimized for Mars (2.5 W/kg);too heavy for the outer solar system. Evolve old technology toachieve at least 6 W/kg (required, Cassini RTG ~ 5 W/kg)

Example: PARIS to Hektor Orbiter Mission


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MASS PWR D/R (bps)Mercury dual imaging system (MDIS) 6.8 6.7 12000Mercury atm & surface comp spectr (MASCS) 3.1 5.9 1000Gamma-ray & neutron spectrometer (GRNS) 13.4 23.6 1000Energetic particle and plasma spec (EPPS) 2.6 6.4 1000Data processing units (DPU - 2) 3.3 4.2 30

Total 32.9 52.1 15030

(Cruise science data rate total approx. 100 bps)

Based on MESSENGER payload experience

PARIS to Hektor Payload

REP enables a capable payload well suited to studying asteroids

W. K. Hartmann


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Chariklo Orbiter with EurysacesFlyby Mission

• Flyby Trojan Asteroid 8317 Eurysaces• Orbit Centaur 10199 Chariklo• Launch on Atlas V 551/Star 48 to

C3 of 112.0 km2/s2, launch massof 1135 kg

• 1 year 3 months to flyby ofEurysaces at relative speed of~15 km/s

• 10 years more to orbit of Chariklo• Total mission time of 11 years 3

months• Final mass at Chariklo of 791 kg

• Consistent with conservative S/CModel (with 30% contingency)

• 85 kg Instrument payload (includes30% contingency)

• Utilizes NSTAR thruster at ~2500seconds ISP (3 + 1 thrusters)

• Requires 750 We of power into EPsystem and ~350 kg of propellant

LaunchFebruary 10, 2016

Flyby EurysacesMay 7, 2017

Orbit CharikloMay 2, 2027

• With optimized EPsystem, ISP of ~2100seconds, 10.2 yeartrip time to Chariklois possible


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Glenn Research CenterChariklo Trade Space

• Examined launch opportunitiesthroughout 1 Chariklo orbit ofthe Sun (~40 years)

– Max Trip Time of ~14.5 years,2032 launch

– Min Trip Time of ~9.8 years,2012 launch

• Possible flybys of L4 or L5Trojan Asteroids assessedvisually knowing location ofEarth, L4/L5 point, and Chiron

– Only the 2015-2017opportunities with Trojan flybyhave been optimized with DTOM(previous chart shows 2016opportunity)

– Other Trojan flyby opportunitieshighlighted here may or may notexist, full optimization required

• Best opportunities exist in the2010s and after 2050

• Three Trojan asteroids in reach between2015 and 2017– 2015: 10247 Amphiaraos– 2016: 8317 Eurysaces– 2017: 20947 Polyneikes


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Glenn Research CenterChariklo Flyby Analysis

• High relative velocity for the flybys– ~30 km/s for a representative Main Belt Asteroid in a circular orbit at 2.7 AU– ~15 km/s for Eurysaces (Trojan Asteroid) flyby

• Reducing flyby relative velocities will increase trip time to the Centaur• Is it worth retargeting for a Main Belt flyby at these speeds?• Can the high relative velocity be managed through instrument design?


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Chiron Orbiter with EurysacesFlyby Mission

• Flyby Trojan Asteroid 8317Eurysaces

• Orbit Centaur 2060 Chiron• Launch on Atlas V 551/Star 48 to

C3 of 102.6 km2/s2, launch massof ~1200 kg

• 1 year 4 months to flyby ofEurysaces at relative speed of~14 km/s

• 11 years 9 months more to orbitof Chiron

• Total mission time of 13 years 2months

• Final mass at Chiron of 766 kg• Consistent with conservative S/C

Model (with 30% contingency)• 85 kg Instrument payload (includes

30% contingency)

• Utilizes HiVHAC thruster at ~1440seconds ISP (5 + 1 thrusters)


LaunchApril 22, 2018 Flyby Eurysaces

August 12, 2019

Orbit ChironJune 9, 2031

Near Aphelion

• With optimized EPsystem, ISP of ~2000seconds, 11.6 yeartrip time to Chiron ispossible


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Glenn Research CenterChiron Trade Space

• Examined launchopportunities throughout 1Chiron orbit of the Sun (~50years)– Max Trip Time of ~11.5

years, 2017 launch– Min Trip Time of ~5.9 years,

2045 launch• Possible flybys of L4 or L5

Trojan Asteroids assessedvisually knowing location ofEarth, L4/L5 point, andChiron– Only the 2018 opportunity

with Eurysaces flyby hasbeen optimized with DTOM(previous chart)

– Other Trojan flybyopportunities highlightedhere may or may not exist,full optimization required

• Best opportunities exist in the 2030s and 2050s– Possibility of trip times between 7 and 10 years

including Trojan flyby• Should further analyses of these opportunities be

completed now?


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Okyrhoe Orbiter with2002 GK147 Flyby Mission

• Flyby Trojan Asteroid 2002 GK147• Orbit Centaur 52872 Okyrhoe• Launch on Atlas V 551/Star 48 to

C3 of 100.8 km2/s2, launch massof ~1300 kg

• 1 year 5 months to flyby of 2002GK147 at relative speed of ~13.5km/s

• 5 years 11 months more to orbitof Okyrhoe

• Total mission time of 7 years 3months

• Final mass at Okyrhoe of 770 kg• Consistent with conservative S/C

Model (with 30% contingency)• 85 kg Instrument payload (includes

30% contingency)

• Utilizes HiVHAC thruster at ~1350seconds ISP (4 + 1 thrusters)


LaunchMarch 15, 2017

Flyby 2002 GK147August 3, 2018

Orbit OkyrhoeJune 7, 2024


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• Missions are mass-constrained• Requires innovative

approaches to spacecraftdesign– Efficient, lightweight electric

propulsion– Lightweight power system– Small science payload (~50 kg)– Lightweight structures,

communications, attitude control– Total dry mass of approximately

500 kg

Hardware Constraints


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Launch Vehicle Constraints

• Atlas V 551/Star 48 used as baseline launch vehicle• Delta IV Heavy used with multiple stages can

improve mission performance for more distanttargets.

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0 20 40 60 80 100 120 140 160 180

Excess Escape Energy (C3), km2/s

2

Del

iver

ed M

ass,

kg

Atlas V 551/Star 48

Atlas V 551

Delta IVH/Star 48/Star 37


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Configuration 1:Axial RTG Mount with 4-m Fairing

HGA

Electric Engines

Upperstage

Xetank

Hydrazine

ScienceInstruments

Starcameras


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Configuration 2:Radial RTG Mount with 5-m Fairing

HGA

Electric Engines

Upperstage

Xetank

Hydrazine

ScienceInstruments

Starcameras


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For Any Mission There AreFour Key Elements

• Science the case for going• Technology the means to go• Strategy all agree to go• Programmatics money in place

A well-thought-out systems approachincorporating all key elements isrequired to promote and accomplish asuccessful exploration plan

Needswork!


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Glenn Research CenterIt Worked for New Horizons…


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Glenn Research Center…and We Have Pencils


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Glenn Research CenterNext IAC Meeting

• Valencia, Spain• 2-6 October 2006

•• Session D3.5 Science MissionsSession D3.5 Science MissionsEnabled by Nuclear ElectricEnabled by Nuclear ElectricPropulsionPropulsion

• Abstract deadline 10 March 2006

Documents

Radioisotope Electric Propulsion: Enabling the Decadal Survey … · 2006-03-08 · 2QSS Group, Inc., NASA Glenn Research Center21000 Brookpark Rd, Cleveland, OH 44135, USA 3NASA