Small Body Mission andSpacecraft Design

John DankanichSteve Oleson

Presented at Small Body Technology ForumJanuary 24, 2011y ,

Decadal Survey and SBAG

The SMD PSD is currently developing a mission prioritization through the National Academies Space Studies Board.

- Missions from 2013 – 2022

SBAG community completed a survey for prioritization of small body missions.- Provided recommendations to the decadal survey and NASA SMD- There is concern decadal may not adequately address Discovery classThere is concern decadal may not adequately address Discovery class

- Dedicated studies on New Frontiers and larger missions- High priority small body science available in Discovery

Missions of Interest

Science priorities and mission recommendations provided through community white papers and the SBAG.

Near-Earth Objects Near Earth Objects- Mega-multi-flyby- Multi-rendezvous- Sample return

Main belt asteroids and Jupiter Trojans- Main belt sample return- Multi-asteroid rendezvous- Jupiter Trojan rendezvousJupiter Trojan rendezvous

Comets- Comet Surface Sample Return and CNSR (Flagship)

Small SatellitesPh b d Di l t *- Phobos and Diemos sample return *

Dwarf Planets- Haumea flyby (Rendezvous preferred)

Centaurs and Trans-Neptunian Objectsp j- Flyby (Rendezvous preferred)

Wide range of targets and lack of appreciable gravity ideal for EP.

Spacecraft Design and Mission Designare Strongly Coupled

A complete spacecraft design in required to accurately predict mission performance.

Dankanich, J. W., Kamhawi, H., Mathers, A., “HiVHAC Maximum Operating Power Mission Impacts,” 31st IEPC, Ann Arbor, MI, September 20-24, 2009.

Mission Design Margins

Electric propulsion margins have interdependencies

Must have robust mission against missed thrust periodg p

There is no formal standard for EP mission design margins.Oh, D. Y., Landau, D., Randolph, T., Timmerman, P., Chase, J., Sims, J. and Kowalkowski, T., “Analysis of System Margins on Deep Space Missions

Utilizing Solar Electric Propulsion,” AIAA 2008-5286, 44th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Hartford, CT, July 21-23, 2008.

Recent Detailed Designs Completed(By COMPASS)

Ceres Sample ReturnDefinition: New Frontiers Class Mission.Customer: By request of In-Space ProgramSummary: Feasibility of gathering a sample from this asteroid and staying within the New Frontiers cost and mission cap After several

Scarlatti – Discovery class Asteroid mission

staying within the New Frontiers cost and mission cap. After several propulsion and power trades, selected mission design utilizes a 2+1 NEXT ion propulsion system and two Orion derived solar arrays. Study Dates: May 2010

Definition: Discovery class science mission

Summary: 1+1 NEXT thrusters, trajectory built around asteroid tour. flyby maneuver of binary asteroid system, and explore two triple asteroid systems, 8 yr science mission, payloads chosen from similar small body missions, avail launch margin on Atlas 401 for 2nd S/C,launch end 2016.2nd S/C,launch end 2016.Study Dates: December 2009

SAMBA - Sample Return Main Belt AsteroidD fi i i M i b l id l i iDefinition: Main belt asteroid sample return missionCustomer: By request of In-Space Program, Collaboration with APLSummary: Demonstrates the feasibility of landing on an L-type asteroid, launch 2021, SAMBA lands on asteroid 234 Barbara, collects surface samples, lifts off, 2029 return sample capsule to Earth for scientific review.

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Study Dates: January 2010

Recent Detailed Designs Completed(By COMPASS)

Chiron Orbiter – Decadal Survey MissionDefinition: Decadal study - trade EP and ASRG power technologies in a Centaur Chiron science missionCustomer: By request of In-Space Program Designs for Decadal Planning - Collaborative design with GSFCPlanning Collaborative design with GSFCSummary: REP powered EP science orbiter to Chiron, traded ASRG technologies. GSFC performed Chem, 2024 launch, 11-13 yr trip-times, 2+1 High throughput BPT-4000 Hall thrusters, 2+1 PPUs, 76 kg delivered science payload.Study Dates: January 2010

REP Centaur OrbiterReporting: COMPASS Report Complete, Paper presented at JPC 2008

S D i d t t th f ibilit f REP fSummary: Design demonstrates the feasibility of REP for Orbiting Small, Deep Space Bodies. The Concept can be proposed once the SRGs are matureStudy Dates: December 2009

REP Trojan LanderDefinition: Evaluate technology requirements and readiness for REP Trojan Lander mission, feasibility studyCustomer: Collaboration with APLSummary: Developed technology requirements for REP and ASRG subsystems evolved into Ilion design led by APL for chemical

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subsystems, evolved into Ilion design led by APL for chemical alterative, also evaluated under Decadal Survey

Recent Detailed Designs Completed(By COMPASS)

Multi-Near Earth Asteroid Sample ReturnDefinition: New Frontiers Class Mission.Customer: By request of In-Space ProgramSummary: Feasibility of multiple samples return from distinct NEO targets with a single mission. Mission was feasible using NEXT 1+1 system. However, could not fit within a Discovery class mission.

Estimated cost of $530M

Phobos and Diemos Sample ReturnDefinition: New Frontiers Class MissionE l t f ibilit f i l ft f t t

Estimated cost of $530M

Evaluate feasibility for single spacecraft for to return multiple samples from multiple locations on both Phobos and Diemos

Summary: BPT-4000 Hall thrusters work well due to high thrust level and limited return opportunities. Missionthrust level and limited return opportunities. Mission could not fit within Discovery class. Mission was able to fit within the New Frontiers category.

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Performance : Thrust vs. Isp

There is a belief that higher ISP is always better.

The EP system that can best use the available power will have the highest

Missions where ΔV is highly dependent on thrust can optimize to low specific impulse.

The EP system that can best use the available power will have the highest performance.

Hofer, R. R., Randolph, T. M., Oh, D. Y., Snyder, J. S., and deGrys, K. H., “Evaluation of a 4.5kW Commercial Hall Thruster System for NASA Science Missions,” AIAA 2006-4469, 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Sacromento, CA, July 10-12, 2006.

Near-Earth ObjectsMega-multi Flyby

NEOs sample the main-belt and comet reservoirs, present resource opportunities and represent hazard concerns.

The GTOC demonstrated more than 40 targets in < 10 years

- Questionable spacecraft design

Example solution more 12 targets, ~6 yearstargets, 6 years

EP can enable multi-flyby missions; provide insight into the diversity of NEOs.

Near-Earth ObjectsInclined Rendezvous

Some NEOs are easier to get to than the moon… not all. Inclined targets are of unique scientific interest; potentially dead comets,

Earth crossingEarth-crossing. ∆V = 2V sin (θ/2)Cacus @ 26o

Tantalus @ 64oTantalus @ 64o

Inclination change is a costly propulsive maneuver

Earth’s heliocentric orbital speed = 29.7 km/s

Tantalus chemical mass fraction ~1%

Electric propulsion can enable missions to a wide range of targets.EP Mass fraction ~ 44%

Near-Earth ObjectsSample Return

With more than 4000 NEAs examined, the ESA report states “a limited number of targets (a few dozen) are within reach of a chemically propelled spacecraft while solar electric propulsion opens up many more opportunities.”solar electric propulsion opens up many more opportunities.

JAXA completed the Hayabusa SR mission in June with primary electric propulsion.

Electric propulsion can enable more targets or multi-sample return.

Agnolon, D., et al., “Study Overview of the Near Earth Asteroid Sample Return,” SCI-PA/2007/004/DA, ESA Technology Reference Study, May 30, 2007.

Phobos and Diemos SR

C3 ~ 10 km2/s2

Electric propulsion enables Falcon 9 class launch vehicle mission for Deimos or Phobos SR.

C3 ~ 5 - 23 km2/s2

Electric propulsion allows either twin spacecraft or a single vehicle to land and return from bothDeimos and Phobos. (30kg spiral penalty)

Mission can be completed chemically

- Russian Phobos-Grunt Planned

- Spacecraft ~ 75% propellant

- Requires chemical staging

- Requires larger launch vehicle© L hki A i i

q g© Lavochkin Association

Electric propulsion enables a single SR mission from both Deimos and Phobos.

Main Belt AsteroidsMulti-Rendezvous

Electric propulsion can enable mission to multiple targets with a single s/c.Dankanich, J. W., Drexler, J. A., and Oleson, S. R., “Electric Propulsion Mission Viability within the Discovery Class Cost Cap,” 46th AIAA/ASME/SAE/ASEE

Joint Propulsion Conference and Exhibit, Nashville, TN, July 25-28, 2010. – Tuesday at 10:00 AM

Main Belt AsteroidsSample Return

The ISPT project evaluated main-belt sample return missions to evaluate any required propulsion technologies.

SOA electric propulsion enables a main belt sample return mission.Dankanich, J. W., Landau, D., Martini, M. C., Oleson, S. R., and Rivkin, A., “Main Belt Asteroid Sample Return Mission Design,” 46th AIAA/ASME/SAE/ASEE

Joint Propulsion Conference and Exhibit, Nashville, TN, July 25-28, 2010.. – Wednesday at 10:30 AM

Comet Surface Sample Return

NASA directed a study to APL to evaluate the Comet Surface Sample Return (CSSR) mission and stated that “The low-thrust mission is much more forgiving and provides access to many more targets and regular launch opportunities.”

Fountain, G. H., et al., “Comet Surface Sample Mission Study,” SDO-11998, Prepared for NASA’s Planetary Science Division, April 30, 2008.

Electric propulsion enables additional targets for CSSR with greater flexibility. Electric propulsion will enable the CNSR mission.

Jupiter Trojan Rendezvous

While chemical Trojan rendezvous is possible, electric propulsion allows for multi-target rendezvous and wider target capture.

REPREP

SEP

SOA electric propulsion enables multi-Trojan rendezvous.

Centaur Orbiter

Centaur rendezvous cannot be completed with chemical propulsion. A chemical flyby mission or an REP rendezvous missions are both New Frontiers.

Radioisotope electric propulsion enables a centaur rendezvous mission.Dankanich, J. W., and Oleson, S. R., “Radioisotope Electric Propulsion (REP) Centaur Orbiter Mission Design,” AIAA-2008-4518, 44th

AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Hartford, CT, July 21-23, 2008

Centaur Orbiter

Practical propulsion system performance can enable a range of targets.

26 feasible targets with REP

- As of study date

700 Watts into the thruster

- 45% η at 2000s Isp

- 250 – 400kg of throughput250 400kg of throughput

- @ ASRG alpha ~ 8 W/kg

Radioisotope electric propulsion has lifetime requirements beyond SOA.Dankanich, J. W., and Oleson, S. R., “Radioisotope Electric Propulsion (REP) Centaur Orbiter Mission Design,” AIAA-2008-4518, 44th

AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit, Hartford, CT, July 21-23, 2008

Dwarf Planet Rendezvous

In 2009, NASA GRC and JPL teamed to evaluate flagship REP missions to KBOs.- Perihelion > 33AU- Delta IVH w/ Star 63Delta IVH w/ Star 63- 16 Year Transfer- 3 kW EP system - ~1000 kg of throughput

Beyond Ceres Dwarf planets are very high AUBeyond Ceres, Dwarf planets are very high AU- Haumea > 43 AU, i = 28o

- Larger LV Desired- Requires total spacecraft power density

better than 1.6 W/kg, SOA ~0.7 W/kg

Far-term REP with advanced ASRG may enable rendezvous > 30 AU.Oleson, S. R., McGuire, M. L., et al., “COMPASS Final Report: Kuiper Belt Object Orbiter Using Advanced Radioisotope

Power Sources and Electric Propulsion,” CD-2009-32, July – August, 2009.

Propulsion Technology Status

Chemical propulsion systems are available as COTS or TRL 6 AMBR- NEO fly-by, NEO rendezvous, NEO sample return, Phobos or

Diemos SR, Trojan / Centaur Flyby, very high AU flyby

NEXT is available for technology infusion- LDT demonstrating > 530 kg, expecting ~800 kg- Preliminary integration testing completed- PPU rework environmentals and integrated testing for TRL 6PPU rework, environmentals, and integrated testing for TRL 6

- NEO fly-by, NEO rendezvous, NEO sample return, main belt rendezvous, main belt SR, Phobos and Diemos SR, Trojan rendezvous.

Hall system development is advancingy p g- HiVHAC EM thruster to begin duration testing summer 2010- Feed system TRL 6 and progressing- PPU investments through SBIR

- NEO fly-by, NEO rendezvous, NEO SR, main belt rendezvous, y y, , , ,and Phobos and Diemos SR.

REP thruster technology advancing- Thruster advancement through SBIR

T j d t d d hi h AU d

Planned investments are developing near-term technology needs.Additional investments are required for additional mission capture.

- Trojan rendezvous, centaur rendezvous, and very high AU rendezvous.

Non-Propulsion Technology

Near-term solar array technology can enhance mission performance- Ultraflex Solar Array ~175 W/kg through ST-8- Currently only expected to achieve ~100 W/kg through Orion

REP missions are driven by spacecraft power-to-mass ratio:- Current ASRG enables some targets- Larger ~500W ASRG increases REP mission capture

Sample Return Technologies – many require significant development- Site selection instruments, navigation, sensors- Samplers for touch-and-go, surface, and subsurface- drilling / coring technologies- sample handling, verification, transfer, encapsulation- Earth Entry Vehicle: Carbon phenolic availability, aero stability, hard landing, etc.

There are technology gaps for nearly all sample return mission needs. The needs increase with mission difficult: surface, subsurface, deep/stratigraphy, cryo.

Lessons Learned

Costs:- Multiple Body Orbiters using SEP fit in Discovery Class- Small body SEP sample return missions fit into New Frontiers class

missions often ith significant marginmissions, often with significant margin- Most REP missions fit well within New Frontiers Class

Sample Return:Aside from a subset of NEOs the large ΔV to arrive land and return- Aside from a subset of NEOs, the large ΔV to arrive, land and return from small bodies are enabled by SEP

- REP sample return has not completed a detailed spacecraft design / mission feasibility studyDeployed solar array (without precision tracking) can be used for surface- Deployed solar array (without precision tracking) can be used for surface operations, battery charging

Small objects beyond Jupiter cannot be orbited without REPAside from a subset of NEOs the large ΔV to arrive land and return- Aside from a subset of NEOs, the large ΔV to arrive, land and return from small bodies are enabled by SEP

EP power can be leveraged by communication subsystemSmall main antenna transponder mass grows slowly with power- Small main antenna, transponder mass grows slowly with power,

significantly decrease DSN time for cost savings

Conclusions

The community is establishing mission guidance with a wide variety of small body missionsy

The small body missions are very well suited for the use of electric propulsion

All small body missions are enhanced and most are enabled by- All small body missions are enhanced and most are enabled by electric propulsion

- REP technologies are required for high AU rendezvous

Technology are available or near-term for the majority of high priority small body missions

Large technology gaps remain for low risk sample returng gy g p p

Questions?