The latest criticism to be directed against the current NASA plan to retrieve an asteroid, move it into lunar orbit, and visit it with astronauts is coming from the Small Bodies Assessment Group, according to a July 31, 2013 post on NASA Watch.
SBAG developed a series of findings on a variety of missions and NASA programs during a July10-11 meeting. On the asteroid mission, it made the following observations.
The asteroid mission has less scientific value than would a robotic sample return mission, such as OSIRIS-Rex, because there would be a wider variety of asteroids to select from.
The small size of the target asteroid reduces its relevance to planetary defense and the detection of hazardous objects.
Target asteroids will be difficult to detect and may be hazardous for a spacecraft to approach because, “small objects may be rapidly rotating rubble piles.”
The proposed schedule and the estimated costs are either vague or unrealistic.
SBAG also found that the mission requirements were ill defined.
“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.”
In other words, SBAG has found that the latest asteroid mission was not properly planned or defined and has lower value than other comparable missions.