SBAG Meeting Minutes and Findings for January 12–13 Meeting
Small Bodies Assessment Group
January 12–13, 2009
College Park, MD
The Small Bodies Assessment Group (SBAG) held its inaugural meeting on 12–13 January 2009 at the Inn and Conference Center of the University of Maryland, College Park, Maryland. The morning sessions of both days were available to interested parties through a Webex option. Seven of the 8 members of the steering committee attended the meeting; the eighth attended by Webex. Over one and a half days, the meeting was attended by 42 people, with an additional approximately 20 people attending various parts of the meeting through the Webex internet option.
The agenda (appended below) included a variety of presentations during the two morning sessions, coupled with meetings of subgroups that considered different aspects of small bodies exploration in the afternoon of the first day. The first day began with a review of small bodies division activity by James Green, Director of the Planetary Science Division (PSD) of NASA’s Science Mission Directorate (SMD). Lindley Johnson, Discipline Scientist for NASA’s Near-Earth Object Observation program, reviewed the NEOO status. Mike A’Hearn reviewed the recently-convened National Academies’ study on Near-Earth Object detection, characterization, and mitigation. The status of existing small body spacecraft programs EPOXI (Mike A’Hearn), Stardust-NExT, Rosetta (Paul Weissman), Dawn (Lucy McFadden), New Horizons (Hal Weaver), Hayabusa (Mike Zolensky) and Stardust (Mike Zolensky) was then addressed by individual team members (in parentheses). A New Frontiers mission concept to Neptune and a Centaur, Argo, was presented by Heidi Hammel. Discussion throughout these presentations centered on future exploration and questions and implications of the presentations.
During the afternoon of the first day, the meeting attendees broke into six groups, each addressing a specific small bodies topic of interest. These subgroups with their scientific leads included Small Bodies Science Issues (Anita Cochran), Small Bodies Missions - Remote Sensing (Deborah Domingue), Small Bodies Missions - Sample Return (Mike Zolensky), Population Identification & Character Assessment (Joe Nuth), In-Situ Space Resources Utilization (Mark Sykes), and Hazard Assessment (Paul Abell). At the end of the afternoon, the attendees reconvened and each group reviewed its discussion and status.
The second day started with a review of the NExT status and COMPLEX activities, including the creation of the decadal study for Solar System exploration, from Joe Veverka. Mark Sykes presented a review of the International Primitive Bodies Exploration Working Group (IPEWG) initial meeting held in Japan in January, 2008. John Dankanich discussed in-space propulsion options offered by NASA Glenn Research Center. Luke Sollitt reviewed spacecraft options for primary and secondary payload offered by Northrup Grumman. The rest of the morning session consisted of general discussion among the participants on the objectives of the general SBAG white paper, and SBAG input and recommendations for small bodies research.
Planetary Science Division Report
Jim Green reviewed the announced launch delay of Mars Science Laboratory (MSL) to 2011. He stated that the significant costs of this delay will be borne first by JPL and the Mars program, and then would carry over to other planetary programs. Green stated that planetary research and analysis programs were off the table and would not be impacted by MSL. ESA has also slipped ExoMars to 2016. There is no NASA-led Mars lander planned for 2016. There is a possible MSL – Juno launch conflict in 2011, but NASA expects this to be resolved. Green states that impacts to other missions would be delays, not cancellations.
The upcoming New Frontiers AO will contain small bodies opportunities, including a comet sample return. The final AO release is delayed until the final budget for MSL is determined, which will be after February. A Discovery AO will follow the New Frontiers AO by about 6 months, but could be delayed further due to the MSL launch slip. RPS (Stirling engines) is being considered as part of this AO, and this decision will affect the Discovery AO release date. The Stirling engine report is due early February.
NASA has received several unfunded mandates to conduct near-Earth object (NEO) studies. The detection of objects down to diameters of 1 km has been extended down to diameters of 140 m, and remains unfunded. NEO impact mitigation studies are also unfunded at this time. NASA continues to coordinate with the NSF to leverage ground-based facilities to support NEO studies.
The first International Primitive Bodies Working Group (IPEWG) meeting was hosted by JAXA in January 2008, in Japan. NASA will sponsor the IPEWG in 2010, and meetings are planned for every two years. JAXA is maintaining an IPEWG website. Green is charging SBAG with reviewing the status and plans of IPEWG, and advising NASA on participation in IPEWG.
NASA and NSF have jointly requested the National Academies to conduct a Planetary Science Decadal Study. SBAG should provide input to this survey on small bodies, from both the ground- and space-based perspectives. This is the forum in which to make a case for any flagship small bodies missions.
NASA NEO Observation Programs
Lindley Johnson, Discipline Scientist for NASA’s Near-Earth Objection Observation program, reviewed the status of NASA’s contribution to the Spaceguard Survey, the NEO observation program. Congress initially mandated NASA to conduct a survey of 90% of the 1-km or larger diameter Potentially Hazardous Objects (PHOs) (defined as objects passing within 0.05 AU of Earth’s orbit). Twenty percent of the NEOs are PHOs. Congress has recently mandated that the limiting diameter be reduced to 140 m by the year 2020. Both of these surveys have been unfunded mandates from Congress. At the time of the SBAG meeting, the initial search has yielded 844 km-sized objects out of an estimated 940 ± 50 objects. If the diameter is reduced to 140 m, ~20000 PHOs are predicted. Three of five primary ground-based surveys have stopped operating, leaving only LINEAR and the Catalina Sky Survey. If Congress mandates smaller targets, they will need to provide an estimated $800M of dedicated assets to conduct the search. No single asset can accomplish this goal. A combination of ground- and space-based assets can accomplish this by the year 2020, but the funds to accomplish this goal are not currently in NASA’s budget. Pan-STARRS is the only telescope in the “ready now” category. A large amount of data will be generated by such an intense search, and should be widely available to astronomers addressing the NEO issue.
National Academies NEO Study
Congress considers NASA to have been unresponsive to their 2005 mandate because NASA did not recommend a specific program to Congress for identifying the PHOs down to diameters of 140 m. In response, Congress requested another study conducted through the National Academies. Co-Chair Mike A’Hearn reviewed this program, emphasizing that this is not a scientific issue but a sociological one. Mitigation strategies, and possibly some of the detection approaches, raise the question of how to effect an international effort. An RFI for proposals for the detection, categorization, and mitigation strategies is on the street with proposals due March 20.
Current Operating/Planned Missions
The current status of missions to small bodies, either planned or operational or past, was reviewed by members of each of their teams over the duration of the meeting. Mike A’Hearn reviewed the status of EPOXI and NExT; Joe Veverka also reviewed NeXT. Rosetta successfully flew past asteroid 2867 Steins (E class) on its way to asteroid 21 Lutetia (C class) on July 10, 2010. After the Lutetia encounter , there is a planned 40-month hibernation, which is unprecedented. Rendezvous with Comet 67P/Churyumov-Gerasimenko is planned for May, 2014. Dawn will fly past Mars on Feb 17, 2009. The instrument sequencing planning for observations of Vesta is beginning, and the participating scientist program for the Vesta phase of the mission will open in 2009. The return status of Hayabusa and Stardust sample analysis were reviewed briefly by Mike Zolensky.
The New Horizons mission is on schedule to reach Pluto on July 14, 2015. New Horizons will fly past one of the Lagrangian points of Neptune, so there is a chance for an encounter with a small object there. There should be sufficient fuel left after the Pluto encounter to permit the fly-by of at least one additional KBO. The mission has been running successively longer hibernations, and it is about to enter a 200-day hibernation. During hibernations, only the dust detector operates; it has been producing interesting results, following receipt of some particle counts.
Future Mission Possibilities
Heidi Hammel reviewed the Argo mission concept (Candace Hansen, P.I.) for a New Frontiers 4 mission (not the upcoming cycle) to fly by Neptune, Triton, and target a KBO. The Neptune fly-by provides a cone of accessibility of KBOs 1000 times larger than that available to New Horizons. Argo requires an RPS (Stirling engine), and gravity assists from Jupiter and Saturn. As such, the next launch opportunity is during 2017 – 2019 in order to use a Jupiter fly-by; the next opportunity would be 12 years later. This would require an AO for New Frontiers 4 no later than 2013. Their estimated science payload mass is 50 kg.
Options for in-space propulsion were discussed by John Dankanich of In-Space Propulsion Technology at NASA’s Glenn Research Center. NASA’s Evolutionary Xenon Thruster (NEXT) is now available and is optimized for large New Frontiers/Flagship class missions. The High-Voltage Hall Accelerator (HiVAC), a low-cost electric propulsion thruster now under development, could have a significant impact on low-cost mission to targets that are not in deep gravity wells. It is not yet available. Dankanich is looking for a prioritized list of targets, separated as feasible Õ executable Õ selectable. The SBAG notes that types, locations, sizes, and many other differences among the small bodies could be prioritized. The NEXT designers could provide an available phase space box, so that accessible targets can be determined, and then a mission that maximizes science return could be designed.
Mark Sykes led a discussion of the IPEWG meeting held in January, 2008, emphasizing the challenges arising from the differences in scientific culture and approach of different countries to data ownership, control and accessibility. Significant discussion ranged around how to work cooperatively with foreign countries by being upfront about these differences, which would inform the development of MOUs regarding data issues and working relationships as the best path to achieve U.S. objectives and avoid conflict and frustration flowing from unspoken, incorrect assumptions. The SBAG discussed these issues in the context of three examples: the Japanese Hyabusa mission, and the US Dawn and CONTOUR missions. The agreement with the Japanese to archive its Hyabusa data in the NASA PDS was not detailed in advance of the mission agreement, leading to delays and additional expenses in creating PDS standards-compliant formats with adequate documentation. The Dawn mission did not have a data archive plan signed off between the US and European partners until well after launch. Both CONTOUR and Dawn are examples of small bodies missions with instruments supplied by both the US and European institutions.
SBAG White Paper
Participants in the SBAG meeting broke into six groups (see below) to address different aspects of future small bodies exploration. Each team was tasked with preparing an outline by mid-February of the questions they discussed. The final products of these individual committees will both constitute the underpinning of a white paper that the SBAG will produce for PSD, as well as individually provide information to the upcoming planetary sciences decadal survey. Discussion over the approach and structure of the white paper occurred near the end of the SBAG meeting.
Throughout the meeting, participants discussed strategy for future small bodies exploration conducted by the United States through NASA. The participants were concerned that MSL overrun costs will consume any available NASA funding. Support for the continuation of PI-led missions was reiterated. Flight opportunities for new technologies should be available. Of major interest to meeting participants is a cryogenic comet sample return mission. This mission is likely in the flagship category.
The SBAG plans to meet a second time in 2009 during late summer or early fall, not to coincide with the IAU meeting. The committee will also work to produce the white paper in a timely fashion as input to the planetary sciences decadal survey.
Small Bodies Assessment Group Agenda
Monday, January 12, Chesapeake Room, Inn & Conference Center
|8:30 a.m.||Opening Remarks||F. Vilas, M. Kelley|
|8:45 a.m.||NASA SMD Small Bodies
|9:45 a.m.||NASA NEO Program||L. Johnson|
|10:15 a.m.||National Academies NEO Study||M. A’Hearn|
|10:45 a.m.||EPOXI status, comet missions||M. A’Hearn|
|11:00 a.m.||Rosetta status||P. Weissman|
|11:15 a.m.||Dawn status||L. McFadden|
|11:30 a.m.||New Horizons status||H. Weaver|
|11:45 a.m.||New Frontiers Mission Proposal||H. Hammel|
|12:10 p.m.||Working Lunch|
|12:30 p.m.||Stardust, Hayabusa||M. Zolensky|
|1:00 p.m.||Break-out groups in afternoon|
|Small Bodies White Paper (Topic Leads):|
|Small Bodies Science Issues||A. Cochran|
|Small Bodies Missions - Remote Sensing||D. Domingue|
|Small Bodies Missions - Sample Return||M.Zolensky|
|Population Identification & Character Assessment||J. Nuth|
|In-Situ Space Resources Utilization||M. Sykes|
|Hazard Assessment||P. Abell|
|4:30 p.m.||Review - 6 panels -10 min. each
|Tuesday, Jan 13 Chesapeake Room|
|8:45 a.m.||NeXT status, Complex update||J. Veverka|
|9:00 a.m.||IPEWG discussion and review||M. Sykes, All|
|9:30 a.m.||In-Space Propulsion Technologies for
|10:00 a.m.||Northrup Grumman spacecraft options||L. Sollitt|
SBAG Findings from January 2009 Meeting
- There are compelling small body missions for all three classes of Solar System exploration missions: Discovery, New Frontiers and Flagship. While the Europa Jupiter System Mission has been selected as the next Flagship mission, consideration should be given to a small body mission for the next Flagship opportunity.
- Small bodies represent ubiquitous flyby targets of opportunity for NASA planetary missions during interplanetary cruise. Assessment of serendipitous science to be gained from such flybys, and reasonable support for the associated cost of acquiring the data, should be a standard part of mission planning. In addition, NASA should create a mechanism by which PIs can propose for the funding of cruise-phase serendipitous science of small body targets.
- The planetary and astrophysics communities should collaborate to identify small body science opportunities that can be accomplished with astrophysics missions, and how these translate to requirements that are practical within the context of a given mission. These opportunities could include requirements for non-sidereal tracking and spacecraft pointing near to the Sun and the Moon, as well as modifications to the data pipeline. This needs to be done early in the overall mission lifetime to identify investments that planetary science should be making in the astrophysics missions.
- Technology development is needed to support small body missions. This includes instrumentation for remote and in situ study, sample acquisition and recovery, low-thrust propulsion systems, autonomous operations, and nuclear power sources.
- Missions to small bodies afford frequent opportunities for international collaboration and the enhancement of science return as a consequence of sharing resources. Such cooperative opportunities should be pursued. The SBAG encourages NASA to participate in the newly-forming International Primitive Bodies Exploration Working Group (IPEWG), being mindful of the different approaches to data ownership and sharing that individual countries and cultures possess. In order to craft cooperative agreements, there must be an effort in advance to identify and acknowledge differences in culture and philosophy among international partners towards mission science, data accessibility, and data ownership. This allows for maximum scientific benefit to be realized while minimizing unplanned delays and the increased cost of dealing with post-facto disagreements arising from these differences. The SBAG endorses NASA’s sponsorship of the next IPEWG meeting.
- NASA Research and Analysis programs are critical, mission-enabling activities for small body missions. Data analysis programs for small body mission data provide essential results that help justify those missions, as well as enable future missions. The SBAG strongly supports enhancement of the NASA R&A programs.
- Small bodies are numerous and diverse. The fraction of these bodies for which we have spectroscopic and other physical information is small. This includes the changing characteristics of comets over their entire orbits. NASA should commit to providing long-term support for the acquisition of such information for as many of these bodies as possible, which likely number hundreds of thousands of objects over a period of decades. This would involve the use of small, medium and large aperture ground-based telescope facilities. This need not be a crash program, but rather something for which a baseline of ongoing activity should be established and maintained. This affords potential substantial mission cost savings by identifying more dynamically accessible targets for given science goals, and increases mission science return by creating a deeper context within which the data can be interpreted.
- The SBAG endorses the concept that the large amount of observational data that will be produced by the mandated searches for the > 140m diameter Potentially Hazardous Objects (PHOs) should be easily accessible to the scientific community to encourage expanded study of these objects. This volume of data, generated with NASA support, should be archived in the NASA Planetary Data System. The PDS Small Bodies Node is responsible for ingesting and curating small body data, as well as facilitate access to these data by the scientific community. Access to small body data holdings in the PDS should be reviewed, and recommendations addressing the interfaces and tools that are made available to the community, particularly with regard to the large future volumes from PHO searches, should be identified. NASA should provide the resources necessary to implement these recommendations to provide easy identification and access to PHO and other small body data within PDS.
- The SBAG reiterates the need for continued support of NASA’s Deep Space Network in the future, including supporting both Ka band and X band capabilities. This capability is necessary for future, successful deep space probe operations.