Draft Findings: 9th Meeting of the NASA Small Bodies Assessment Group


image Editor's note: although this document has been widely circulated, these are DRAFT findings and are subject to change. A final version will be issued next week and will replace this draft version.

(1) Draft Finding - Decadal Survey Compliance

The planetary decadal survey states the importance of a balanced portfolio of mission classes when the budget is adequate to support this. The decadal survey also makes clear recommendations for how programs should be prioritized if fiscal conditions are worse than anticipated: "It is also possible that the budget picture could turn out to be less favorable than the committee has assumed. This could happen, for example, if the actual budget for solar system exploration is smaller than the projections the committee used. If cuts to the program are necessary, the committee recommends that the first approach should be descoping or delaying Flagship missions. Changes to the New Frontiers or Discovery programs should be considered only if adjustments to Flagship missions cannot solve the problem. And high priority should be placed on preserving funding for Research and Analysis programs and for technology development." (Bolded in the report). The focus on flagship missions in the current fiscal environment at the expense of restoring the Discovery cadence, and the continuing funding stress experienced by the Research and Analysis programs, is inconsistent with the decadal survey recommendations.

(2) Draft Finding - Travel Restrictions

The current NASA and government restrictions on travel and attendance at workshops, conferences, science team meetings, etc. is severely impacting the ability of the planetary science and engineering communities to conduct their work. The increased level of oversight forces a disproportionate amount of time and effort by agency personnel to comply with the necessary waivers and forms to attend such functions at the expense of focusing on NASA goals and objectives. In addition, these travel restrictions undermine the effective planning of domestic and international meetings by suppressing attendance in a manner that is difficult to predict, limiting vital interactions of individuals working on projects and missions relevant to NASA interests.

(3) Draft Finding - Planetary Defense Office

NASA recently announced a Grand Challenge to protect the Earth's population from extraterrestrial impacts. This involves many aspects of detection, characterization, and mitigation of potentially hazardous objects (asteroids and comets). The SBAG notes that currently there is only one expert at NASA HQ who is conversant with the issues of planetary defense. Given that emphasis is now going to be placed on this Grand Challenge and that this effort will involve multiple NASA directorates (SMD, HEOMD, and STMD), US agencies (DHS, FEMA, DoD, DoE, State, etc.) and international partners, the SBAG finds that establishing a Planetary Defense Office would help NASA to more effectively interface with all these entities and cover the necessary expertise required to implement the Grand Challenge.

(4) Draft Finding - NEO Survey Telescope

NASA's Asteroid Initiative combines aspects of human exploration, science, resource utilization, and planetary defense. A NEO survey telescope is a foundational asset that will significantly enhance the ability of NASA to properly evaluate its human exploration objectives, perform valuable science, identify potential candidates for in situ resource utilization, and achieve its Grand Challenge with respect to defending Earth's populations from hazardous asteroids. The SBAG reiterates its previous findings that support the importance of a space-based survey telescope to NASA SMD and HEOMD goals and objectives. The new Asteroid Initiative only serves to highlight the importance of this foundational asset. Any reliance solely upon outside entities to fund, build, and operate such an asset, whose success is beyond NASA control, places NASA's goals and objectives at risk. In addition, SBAG finds that making such an asset a NASA priority would be more consistent with the agency's acceptance and implementation of its Grand Challenge for planetary defense.

(5) Draft Finding - Comet ISON Campaign

Comet ISON presents a rare opportunity to study a potentially bright, sun-grazing comet for many months prior to perihelion and potentially after perihelion. The SBAG finds that the willing coordination across NASA's Science Mission Directorate to support the unique observational campaign through the use of spacecraft assets, ground-based facilities, and the rapid response of an airborne balloon platform is moving apace and should help to to maximize the scientific return from this uncommon event.

(6) Draft Finding - Impactor for Surface and Interior Science (ISIS) mission

JPL is leading a study for a non-competed mission to be co-manifested with the Mars InSight spacecraft. ISIS will impact at hypervelocity speed the OSIRIS-REx target asteroid Bennu, creating a crater and modifying the orbit of that object as a planetary defense demonstration. OSIRIS-REx will be used to gather detailed information about the impact, ejecta, the crater formed, and the effect on asteroid motion. Significant savings are realized in launch vehicle costs (by the co-manifest) and use of OSIRIS-REx (mitigating the need of a second spacecraft component to study the impact results). While total mission cost is estimated at less than $200M, such cost estimates are historically very uncertain for non-competed missions in comparison to the rigorous cost evaluations applied to competed missions. While studying a full-scale hypervelocity impact event for the first time and testing a basic planetary defense scenario are important, the benefit of ISIS has not been determined to exceed those gained from Planetary Science Division funds being used to support the priorities outlined in the Decadal Survey, such as a regular cadence of competed Discovery missions.

(7) DRAFT FINDING - Planetary science

While the SBAG committee finds that there is great scientific value in sample return missions from asteroids such as OSIRIS-Rex, the Asteroid Redirect & Return Mission (ARRM) has been defined as not being a science mission, nor is it a cost effective way to address science goals achievable through sample return. Candidate ARRM targets are limited and not well identified or characterized. Robotic sample return missions can return higher science value samples by selecting from a larger population of asteroids, and can be accomplished at significantly less cost (as evidenced by the OSIRIS-REx mission). Support of ARRM with planetary science resources is not appropriate.

(8) DRAFT FINDING - Searching for Potentially Hazardous Objects

There is great value in enhancing NASA's capabilities in small body discovery and characterization. The enhancement to NEO discovery and characterization efforts proposed as part of the Asteroid Initiative would be greater still if it were to be continued for more than one year. The discovery of smaller asteroids (i.e. potential ARRM targets) is an expected byproduct of this campaign expansion. There is concern that a focus on acquiring ARRM targets, and ARRM itself, can come at the expense of the detection rate and follow-up observations of 140m and larger asteroids.

(9) DRAFT FINDING - Relevance of ARRM to Planetary Defense

Given the size of the ARRM target (< 10m), ARRM has limited relevance to planetary defense. Retrieving a NEO this small only tangentially benefits planetary defense, as the stated target body may not be representative of the larger, hazardous bodies.

(10) DRAFT FINDING - Mission Objectives

ARRM does not have clearly defined objectives, which makes it premature to commit significant resources to its development. The mission description/objectives fidelity appears to be lower than a "selectable" Discovery mission. NASA statements that deployment of a solar power array is sufficient for mission success, but capture and return of an asteroid to lunar orbit is not, brings into serious question the importance of investment in the asteroid capture and return portion of the mission plan. Firm baseline and minimum requirements must be set in order to assess the cost-effectiveness of achieving those requirements and to assess the value of the mission with respect to exploration goals. The Mars 2020 Science Definition Team released a 150+ page document outlining the mission objectives and merits. There is little comparable justification provided with respect to ARRM, yet ARRM is expected (by some estimates) to be a higher cost mission. The SBAG finds that formation of an independent Mission Definition Team (MDT) prior to commitment of significant resources and mission confirmation would allow for community participation in the relevant fields for the mission (including small body science) and provide a non-advocate peer review of the expected benefit if mission success criteria are met. In place of science objectives and traceability, the strategic knowledge gaps (for HEOMD) and technology roadmap (for STMD) can be used to provide traceability necessary for successful mission implementation.

(11) DRAFT FINDING - Target issues

The population and physical characteristics of low delta-velocity targets having diameters less than 10m are poorly constrained by observations. Because of their intrinsic faintness and long synodic periods, characterization must be undertaken over a short time period primarily during the discovery apparition. Such small objects may be rapidly rotating rubble piles, which could be hazardous to spacecraft during interactions with the target object. The mission must be designed to account for these large uncertainties in the properties of potential targets, which could greatly increase the complexity and cost of the mission. It is impractical to begin the planning and design of any mission to capture such an asteroid in the absence of a pre-existing study on the population and the physical characteristics of its members. Such a study would necessarily take a number of years if commenced now, assuming it is adequately resourced. A robust characterization campaign is imperative. Target characterization will be challenging and is expected to be of the utmost importance to mission success.

(12) DRAFT FINDING - Schedule risks

Because of long-synodic periods, a missed launch window will not be recoverable for the same ARRM target. Therefore, multiple targets meeting orbital and physical characteristic requirements and having appropriately phased launch windows will need to be discovered. Given the poor knowledge of the population of these objects, this is a significant mission risk. The stated schedule for the ARRM, which posits funding of a ~$100M study in FY14 and launch in 2017, is unrealistic.

(13) DRAFT FINDING - Cost risks

As a mission that serves as a technology and operations demonstrator, the management approach and acceptance of risk needs to be better defined to determine the feasibility of the aggressive schedule and its impact on cost and mission success criteria. The full-cost target, funding profile, and funding sources are not provided and limits any credible assessment of the schedule and mission cost to the various directorates. Lack of clarity of both resources available and resources required limits any determination of mission value, merit, and/or whether the mission is the most efficient use of available resources to achieve NASA's objectives.

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