Glenn Research Center Radioisotope Electric Propulsion: Enabling the Decadal Survey Science Goals for Primitive Bodies
R. 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 Laboratory 11100 Johns Hopkins Road, Laurel, MD 20723, USA 2QSS Group, Inc., NASA Glenn Research Center21000 Brookpark Rd, Cleveland, OH 44135, USA 3NASA Glenn Research Center21000 Brookpark Rd., Cleveland, OH 44135, USA
Space Technology and Applications 23nd Symposium on Space Nuclear International Forum (STAIF) Power and Propulsion Albuquerque, New Mexico C07. Electric Propulsion 12 - 16 February 2006 Systems/Concepts
14 February 2006 RLM - 1 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Glenn Research Center For Any Mission There Are Four 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 approach incorporating all key elements is required to promote and accomplish a successful exploration plan
14 February 2006 RLM - 2 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Solar System Science Exploration is
Glenn Research Center Guided by the Decadal Survey • There are two general issues regarding primitive bodies in the solar system:
– What is the role of primitive bodies as building blocks of the solar system? – What is the role of primitive bodies as reservoirs of organic matter raw materials for for the origin of life?
14 February 2006 RLM - 3 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). PRIMITIVE BODIES AS BUILDING BLOCKS OF THE SOLAR SYSTEM Glenn Research Center
Fundamental Issues Important questions Where in the SS are the primitive bodies found, Are there Pluto-size and larger bodies beyond Neptune? and what range of sizes, compositions and other physical characteristics do they represent?
What processes led to the formation of these · How do the compositions of Pluto-Charon and Triton relate to those of objects? Kuiper Belt objects? Since their formation, what processes have altered · What are the basic physical properties (mass, density, size) of Kuiper Belt the primitive bodies? objects,Centaurs, and comets?
How did primitive bodies make planets? · What are the interior properties of all these bodies, and how do they differ from the surface compositions and properties? Are they differentiated?
How have they affected the planets since the · What are the surface properties and compositions of these bodies, and how epoch of formation? do endogenous and exogenous processes affect them?
· Do Pluto and/or large Kuiper Belt objects show internal activity, as Triton does? · What are the compositions of comet nuclei, and how do they relate to Kuiper Belt objects · What is the origin of the organic matter in carbonaceous meteorite parent bodies, and what are the parent bodies of the many different types?
What organic materials occur in primitive bodies at various heliocentric distances? · What is the origin of hydrated minerals in the meteorite parent bodies, and what do fluid inclusions in meteorites tell us about conditions in the solar nebula and parent bodies? · What is the origin of micrometeorites? · What are the albedo and color statistics of Centaurs, Kuiper Belt objects, and comets?
14 February 2006 RLM - 4 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). PRIMITIVE BODIES AS RESERVOIRS OF ORGANIC MATTER RAW Glenn Research Center
Fundamental Issues Important questions
What is the composition, origin What is the composition and structure of primitive and primordial distribution of organic matter in the solar system? solid organic matter (OM) in the solar system? What is its present day Where and under what conditions did organic matter distribution? originate? What processes can be identified What are the relative fractions of organic matter in that create, destroy, and modify meteorites and comets that are interstellar and solar solid organic matter in the solar nebula in origin? nebula, in the epoch of the faint early Sun, and in the current Solar System?
How did organic matter Was primitive organic matter racemic? influence the origin of life on Earth and other planets? Is organic matter similarly Is organic matter similarly distributed among distributed among primitive primitive bodies in other planetary systems? bodies in other planetary systems?
14 February 2006 RLM - 5 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). What are “Primitive Bodies”? Glenn Research Center • Neptunian satellites – Triton – Nereid • Kuiper Belt Objects – Charon – Quaoar – UB313 • Trojan Asteroids • Centaurs – Chiron – Pholus Neptunian satellites
• Thousands of small objects • A long way off
14 February 2006 RLM - 6 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). How Do We Get There? Glenn Research Center The past: The future:
PARIS Missions (Planetary Access with Radioisotope Ion-drive System)
Jupiter Icy Moons Orbiter - I2E - The improbable dream Innovative Interstellar explorer
14 February 2006 RLM - 7 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). REP Enables New Missions Glenn Research Center High efficiency power sources are the key to new and fundamental science, especially in the outer solar system, on reasonable timescales
14 February 2006 RLM - 8 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Fundamental Science Issues Glenn Research Center The NRC Space Studies Board Decadal Survey highlighted fundamental questions concerning primitive bodies:
• What range of sizes, compositions, and other physical characteristics 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) 14 February 2006 RLM - 9 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Potential Missions Glenn Research Center • Joint teams of APL, GRC, JPL, USC, and other institutions have been exploring radioisotope powered 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 power sources ≥ 6W/kg – Some missions require ≥ 8W/kg
14 February 2006 RLM - 10 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Glenn Research Center Answering the Science Questions is a “System of Systems” Problem
DRIVERS Science Questions Probe Science Objectives Distance Objective Questions and time for the Science Measurement Objectives mission Required Instruments Instrument Resources and Requirements Return data Mission and Spacecraft Requirements Data Product Operate Analysis Product for required Science Result time
14 February 2006 RLM - 11 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Traceability Matrix Guides
Glenn Research Center Concept Definition
Science Questions PARIS Objectives Science Measurement Objectives Analysis Product Science Results
Surface elemental abundances GRNS: Fe, Si, H, Global maps by element Comparison of elemental and Did the Trojans form in the Jovian environment K, U, Th, O. Mapping of ice abundance (?) Map the elemental and mineralogical mineralogical abundances with or were they formed in the Kuiper Belt and composition of the Trojans those predicted from solar transported inward? Spectral measurements of surface: MASCS nebula Spectral unit maps Visible and near-IR absorption bands
Characterize presence and What can the Trojans tell us about primitive Composition of early solar distribution of organic molecules ??? MASCS, GRNS??? ??? organics, the building blocks of life? nebula (OM)s on Trojans
Global monochrome imaging of impact craters to Monochrome high Average surface age; location determine cratering rate: MDIS resolution map of units of different age Determine collisional history Global shape from imaging; MDIS Global shape model Ties in gravity and topography models, helps elucidate Gravity measurements using Doppler ranging to history. Comparison with other Characterize interior configuration spacecraft; characterization of structural features Global gravity map small bodies. and overall shape: MDIS
Monochrome imaging of impact crater and Monochrome image catalog How have the Trojan asteroids evolved over structural feature morphology: MDIS time? Are the geological processes which have Constraints on surface strength Characterize physical surface occurred on the Trojans the same as those that Topography from stereo imaging: MDIS Slope map and regolith properties; properties have affected asteroids in the Main Belt? collisional history
Regolith processes and distribution: MDIS Regolith distribution map
Multispectral global map, High-resolution multispectral mapping of craters: mulstispectral image MDIS Characterization of space Investigate space weathering effects catalog weathering effects at 5 AU Composition of pickup ions in the solar wind from Pickup ion species (?) sputtered neutrals: EPPS Moon images and orbital Constraints on geological Search for moons Image vicinity of target Trojan: MDIS information history
Surface elemental abundances GRNS: Fe, Si, H, Global maps by element Are the L4 and L5 populations the K, U, Th, O. Mapping of ice abundance (?) Constraints on origin of Trojans same? Spectral measurements of surface: MASCS Spectral unit maps Visible and near-IR absorption bands How homogenous is the Trojan population? Surface elemental abundances GRNS: Fe, Si, H, Global maps by element K, U, Th, O. Mapping of ice abundance (?) Constraints on evolution of Do Trojan families exist? Trojans Spectral measurements of surface: MASCS Spectral unit maps Visible and near-IR absorption bands 14 February 2006 RLM - 12 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Trojan Asteroids Glenn Research Center These questions can be addressed by using REP technology to explore the Trojan asteroids • Jupiter’s ~1100 Trojan asteroids orbit in elongated regions around the L4 and L5 Lagrange points at 5.2 AU • Trojan regions contain only low albedo, primarily D-type asteroids • Relatively pristine remnants of the early Solar System; may have organics, silicates, opaque minerals • Could be a source of short-period comets • No known analogs in meteorite collection (except possibly Tagish Lake meteorite) • New breaking results (Morbidelli et al., ACM, 2005) suggest that the Trojans may have originated in the Kuiper Belt
14 February 2006 RLM - 13 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Radioisotope Electric Propulsion (REP)
Glenn Research Center Enabling Primitive Body Decadal Survey Science Example: PARIS to Hektor Orbiter Mission Rationale for Jovian Trojans Mission Concept • Pristine remnants of early Solar System • Ion Propulsion • No known meteorite analogs • High Delta-V (8.5 km/s) • Relation to other asteroid groups and • Radioisotope Stirling Power - develop other small bodies • Existing Low Mass Components - existing • Primitive composition • High energy launch (Atlas V 551 - proven) • Organic constituents • Spacecraft slows to target speed • Isotopic ratios • Jovian System impactors? Spacecraft • In Decadal Survey • Launch Mass 690 kg, Power 750 W, 50 Community Interest kg payload (inc. margin) • Flyby in the Decadal Survey; orbital Mission Design Mission not deemed feasible • Orbit at least 2 Trojans • 5 yr cruise time, 2 yr orbital operations • Launch any year Propulsion exists; continuing radioisotope power source development required. MMRTG optimized for Mars (2.5 W/kg); too heavy for the outer solar system. Evolve old technology to achieve at least 6 W/kg (required, Cassini RTG ~ 5 W/kg) 14 February 2006 RLM - 14 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). PARIS to Hektor Payload Glenn Research Center
REP enables a capable payload well suited to studying asteroids
MASS PWR D/R (bps) Mercury dual imaging system (MDIS) 6.8 6.7 12000 Mercury atm & surface comp spectr (MASCS) 3.1 5.9 1000 Gamma-ray & neutron spectrometer (GRNS) 13.4 23.6 1000 Energetic particle and plasma spec (EPPS) 2.6 6.4 1000 Data 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
14 February 2006 W. K. HartmRLaMn n- 15 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Chariklo Orbiter with Eurysaces
Glenn Research Center Flyby Mission
• Flyby Trojan Asteroid 8317 Eurysaces • Orbit Centaur 10199 Chariklo Launch • Launch on Atlas V 551/Star 48 to February 10, 2016 2 2 C3 of 112.0 km /s , launch mass of 1135 kg • 1 year 3 months to flyby of Eurysaces at relative speed of ~15 km/s Flyby Eurysaces • 10 years more to orbit of Chariklo May 7, 2017 • Total mission time of 11 years 3 months Orbit Chariklo • Final mass at Chariklo of 791 kg May 2, 2027 • Consistent with conservative S/C Model (with 30% contingency) • 85 kg Instrument payload (includes 30% contingency) • Utilizes NSTAR thruster at ~2500
seconds ISP (3 + 1 thrusters) • With optimized EP Requires 750 W of power into EP • e system, ISP of ~2100 system and ~350 kg of propellant seconds, 10.2 year trip time to Chariklo is possible
14 February 2006 RLM - 16 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Chariklo Trade Space Glenn Research Center
• Examined launch opportunities throughout 1 Chariklo orbit of the 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 L5 Trojan Asteroids assessed visually knowing location of Earth, L4/L5 point, and Chiron – Only the 2015-2017 opportunities with Trojan flyby have been optimized with DTOM (previous chart shows 2016 opportunity) – Other Trojan flyby opportunities highlighted here may or may not • Three Trojan asteroids in reach between exist, full optimization required 2015 and 2017 • Best opportunities exist in the – 2015: 10247 Amphiaraos 2010s and after 2050 – 2016: 8317 Eurysaces – 2017: 20947 Polyneikes 14 February 2006 RLM - 17 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Chariklo Flyby Analysis Glenn Research Center • 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?
14 February 2006 RLM - 18 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Chiron Orbiter with Eurysaces
Glenn Research Center Flyby Mission
• Flyby Trojan Asteroid 8317 Eurysaces • Orbit Centaur 2060 Chiron Orbit Chiron June 9, 2031 • Launch on Atlas V 551/Star 48 to Near Aphelion 2 2 C3 of 102.6 km /s , launch mass of ~1200 kg • 1 year 4 months to flyby of Eurysaces at relative speed of ~14 km/s • 11 years 9 months more to orbit of Chiron
• Total mission time of 13 years 2 Launch April 22, 2018 Flyby Eurysaces months August 12, 2019 • Final mass at Chiron of 766 kg • Consistent with conservative S/C Model (with 30% contingency) • 85 kg Instrument payload (includes 30% contingency) • With optimized EP • Utilizes HiVHAC thruster at ~1440 system, I of ~2000 seconds I (5 + 1 thrusters) SP SP seconds, 11.6 year Requires 750 W of power into EP • e trip time to Chiron is system and ~540 kg of propellant possible
14 February 2006 RLM - 19 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Chiron Trade Space Glenn Research Center
• Examined launch opportunities throughout 1 Chiron orbit of the Sun (~50 years) – 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 assessed visually knowing location of Earth, L4/L5 point, and Chiron – Only the 2018 opportunity with Eurysaces flyby has been optimized with DTOM (previous chart) • Best opportunities exist in the 2030s and 2050s – Other Trojan flyby – Possibility of trip times between 7 and 10 years opportunities highlighted including Trojan flyby here may or may not exist, • Should further analyses of these opportunities be full optimization required completed now?
14 February 2006 RLM - 20 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Okyrhoe Orbiter with 2002 GK147 Flyby Mission Glenn Research Center
• Flyby Trojan Asteroid 2002 GK147 • Orbit Centaur 52872 Okyrhoe • Launch on Atlas V 551/Star 48 to 2 2 C3 of 100.8 km /s , launch mass Orbit Okyrhoe of ~1300 kg June 7, 2024 Launch • 1 year 5 months to flyby of 2002 March 15, 2017 GK147 at relative speed of ~13.5 km/s • 5 years 11 months more to orbit of Okyrhoe • Total mission time of 7 years 3
months Flyby 2002 GK147 • Final mass at Okyrhoe of 770 kg August 3, 2018 • Consistent with conservative S/C Model (with 30% contingency) • 85 kg Instrument payload (includes 30% contingency) • Utilizes HiVHAC thruster at ~1350
seconds ISP (4 + 1 thrusters)
• Requires 750 We of power into EP system and ~570 kg of propellant
14 February 2006 RLM - 21 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Hardware Constraints Glenn Research Center
• Missions are mass-constrained • Requires innovative approaches to spacecraft design – Efficient, lightweight electric propulsion – Lightweight power system – Small science payload (~50 kg) – Lightweight structures, communications, attitude control – Total dry mass of approximately 500 kg
14 February 2006 RLM - 22 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Launch Vehicle Constraints Glenn Research Center • Atlas V 551/Star 48 used as baseline launch vehicle • Delta IV Heavy used with multiple stages can improve mission performance for more distant targets.
10000
9000
8000
7000 kg 6000
Mass, 5000 Delta IVH/Star 48/Star 37 4000
Delivered 3000 Atlas V 551/Star 48 2000 Atlas V 551 1000
0 0 20 40 60 80 100 120 140 160 180 2 2 Excess Escape Energy (C3), km /s
14 February 2006 RLM - 23 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Configuration 1:
Glenn Research Center Axial RTG Mount with 4-m Fairing Science HGA Instruments
Star cameras Hydrazine
Upper stage Xe tank Electric Engines
14 February 2006 RLM - 24 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Configuration 2:
Glenn Research Center Radial RTG Mount with 5-m Fairing
Science Instruments HGA
Star Hydrazine cameras
Upper stage Xe tank Electric Engines
14 February 2006 RLM - 25 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Glenn Research Center For Any Mission There Are Four Key Elements • Science the case for going • Technology the means to go • Strategy all agree to go • Programmatics money in place Needs work! A well-thought-out systems approach incorporating all key elements is required to promote and accomplish a successful exploration plan
14 February 2006 RLM - 26 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). It Worked for New Horizons… Glenn Research Center
14 February 2006 RLM - 27 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). …and We Have Pencils Glenn Research Center
14 February 2006 RLM - 28 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8). Next IAC Meeting Glenn Research Center • Valencia, Spain • 2-6 October 2006
•• SessionSession D3.5D3.5 ScienceScience MissionsMissions EnabledEnabled byby NuclearNuclear ElectricElectric PropulsionPropulsion • Abstract deadline 10 March 2006
14 February 2006 RLM - 29 PUBLIC DOMAIN INFORMATION. NO LICENSE REQUIRED IN ACCORDANCE WITH ITAR 120.11(8).