Assessing the NASA Senior Review Approach to Mission Extension
NASA currently plans and implements extensions of science missions on the basis of the mission-extension paradigm. A formal and structured biennial process known as the Senior Review is used to review candidates for mission extension and to decide which will be funded. This process has been used for space science missions since the mid-1990s, but it was first applied to Earth science missions following the reorganization of NASA in late 2004.
DESCRIPTION OF THE SENIOR REVIEW
A mission that is approaching the end of its nominal mission lifetime is a candidate for mission extension under the Senior Review process. To be approved for an extended mission, the mission team must submit a detailed proposal describing accomplishments to date, the scientific benefits of extension and the science to be accomplished, the plans for operating the extended mission, and the cost of extended operations. Also included are plans for continuing related education and public outreach activities.
These proposals then undergo peer review of their scientific merit and a feasibility evaluation that covers technical issues, safety, cost, and risk criteria. Selected proposals are expected to reduce their annual operating costs significantly as compared with costs during the nominal mission life period. Funding is provided on a biennial basis, with proposals required every 2 years for renewal. Historically, a substantial majority (around 80 percent) of candidate missions have been approved for extension during any Senior Review cycle, with levels of funding that may be modestly or even drastically reduced compared with funding levels during the prime mission lifetime.
The funding for all extended missions is held in a single line within the NASA budget. For the space sciences, the committee estimates that the average total of extended-mission funding for the 5-year period from fiscal year (FY) 1998 to FY 2003 was approximately $60 million per year. Funding of extended missions under this approach provides for advanced budget planning that is consistent with the needs of the federal budget process, but it allows NASA to make decisions regarding individual mission extensions as the needs arise.
ASSESSMENT OF THE SENIOR REVIEW
The committee found that the Senior Review provides an excellent starting point for a mission-extension process, although it does not fully address the particular needs of Earth science missions. In particular, the committee believes that the Senior Review’s reliance on an open, structured, and documented process is highly commendable. The strong emphasis on peer review and community involvement is an essential element of the process. The use of fair and open competition among all missions requesting funding further establishes community confidence that all missions will receive an objective hearing. The requirement for reduced operations cost during the extended mission appropriately emphasizes that the primary science acquisition occurred during the nominal mission life. Finally, NASA’s establishment of a funding line to support all mission extensions has resolved the conflict between advanced budgeting and last-minute decisions. If, as recommended in the following chapter,
NASA elects to tailor the Senior Review to the particular needs of Earth science missions, these attributes of the process should be carefully protected.
Finding. The Senior Review, currently used as the basis for all NASA decisions on space and Earth science mission extensions, is a thorough and well-run process, but it does not adequately satisfy the unique considerations of Earth science missions.