3

Review of Extended Missions by NASA

NASA ensures that its fleet of extended science missions provides good value and remains in balance with other science-motivated pursuits by periodically reviewing operating missions. Extended missions generally provide excellent, cost-effective science value by leveraging existing assets. Although the resource levels required to operate extended missions are generally much lower than those required for developing comparable new prime missions, the required investment levels are substantial enough that careful stewardship is warranted.

NASA reviews its extended missions biannually in accordance with Public Law 109-155 (passed in 2005 and renewed in 2010 as part of the NASA Authorization Act). Because that law does not prescribe implementation details, NASA has designed and implemented a review process in each of the Science Mission Directorate (SMD) divisions. The review process was described to the committee through presentations by the SMD associate administrator and each of the SMD division directors. The committee received further information in the form of archival documents and data. The overall approach to the reviews is based on peer-review principles commonly used to assess scientific merit. The reviews are called Senior Reviews, and each of the four SMD divisions conducts its own Senior Review using its own processes and criteria. Many aspects of the reviews are shared across the divisions, but each division implements processes and criteria tailored to its own characteristics and needs. The present-day Senior Reviews are derived from those that began in the 1990s within what are now called the Astrophysics Division and the Heliophysics Division. The Planetary Science Division also began conducting Senior Reviews in the 1990s, and the Earth Sciences Division has been conducting them since 2005. All SMD divisions therefore have extensive experience with conducting Senior Reviews.

NASA uses the Senior Reviews as key guidance for managing extended missions. The reviews are the primary gauges of the scientific value of each mission, and the findings resulting from these reviews play a central role in NASA’s decision-making and resource allocation planning. Guidance from the Senior Reviews is used, along with other significant factors that are taken into account, for any NASA activity, including “the budget, programmatic considerations, agency or national policy, and international partnerships.”¹

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¹ Clarke, S., NASA Science Mission Directorate. 2016. “Heliophysics Division,” presentation to the Academies’ Committee on NASA Science Mission Extensions, February 1, Washington, D.C.

This chapter describes NASA’s present implementation of Senior Reviews. It discusses elements that are common to the four SMD divisions and highlights aspects that differ among the divisions. It presents perspectives on the process gleaned from presentations by and conversations with a cross section of stakeholders. The chapter discusses evolution of the Senior Review process through incorporation of experiences from previous reviews, and it presents a summary history of the missions that have been reviewed since 2005. This chapter also compares NASA’s process to that practiced by the European Space Agency (ESA) for reviewing its extended missions.

SMD-WIDE CHARACTERISTICS OF SENIOR REVIEWS

The Senior Review process is based on a proposal-driven paradigm. It begins with a division director issuing a call for proposals to the teams that operate missions under the management of that division. The call is timed such that the results can be used as input to NASA’s annual budgeting process. The call contains instructions for proposal preparation and submission and explains how the proposal will be reviewed by a Senior Review panel convened for this purpose. It delineates the criteria to be used by the panel in its assessment. It explains that a budget guideline for the amount of funding available for each mission has been developed by NASA within the Planning, Programming, Budgeting, and Execution (PPBE) process and specifies a period of performance. It contains the schedule for submission, typically about 4 months after the release of the call, and discusses how each team is to make an oral presentation to the panel. The call also contains links to supporting documents. Proposals are typically 30 pages in length, plus appendices, although the guidelines have varied from division to division and review to review over the years.

Senior Reviews are nominally conducted on a biannual basis, with Astrophysics and Planetary Science reviews occurring in even-numbered years and Earth Science and Heliophysics reviews occurring in odd-numbered years. Although the reviews happen on a regular basis, science missions are subject to different events and timelines, which can affect how recommendations are implemented or when individual reviews take place. For example, a launch failure of a new mission might occur after a Senior Review recommended termination of an earlier mission, thus requiring the earlier mission to be extended to avoid a gap in data continuity. Another possibility is that a spacecraft may be due to run out of fuel a few months after a scheduled review, and it would make little sense to hold a new review for only a short life extension. Perhaps most importantly, mission teams spend up to 6 months preparing for a Senior Review, and if the review and a major mission event are scheduled to occur around the same time, this could jeopardize the mission’s success by diverting the team members’ attention when they should be focused on mission operations. Specific examples of missions that were reviewed off-cadence are given later in this chapter.

Within each division, a panel of experts evaluates the division’s extended-mission portfolio. Strategic or directed missions like NEOWISE (Near-Earth Object Wide-field Infrared Survey Explorer), principal investigator-led missions, and foreign partner-led missions to which SMD contributes, like Mars Express, are commonly, but not always, considered together. After its deliberations have concluded, the Senior Review panel issues a report containing its findings to the division director. A typical report contains an executive summary, an overview, and a digest of findings for each mission. Grades for the overall scientific merit of each mission are given. Occasionally, areas of special concern for some missions are called out and explained. The division uses this report as a basis for managing its portfolio of extended missions, including the following:

1. Prioritizing the operating missions and projects;
2. Defining an implementation approach to achieve division strategic objectives;
3. Providing programmatic direction to the missions and projects for years 1 and 2 following the review; and
4. Issuing initial funding guidelines for years 3 and 4 following the review.

DIVISION-SPECIFIC CHARACTERISTICS OF SENIOR REVIEWS

Each SMD division tailors its Senior Reviews to take into account special conditions and aspects of the division and the way it performs its overall undertaking. Thus, there are differences in the reviews across the divi-

sions. This section describes the division-specific aspects of the Senior Reviews and explains the rationales for these differences.

Astrophysics

Unlike the other divisions, the Astrophysics Division does not review all missions in the same manner. It has a different process for the Hubble Space Telescope and Chandra X-Ray Observatory than for the other astrophysics missions. These missions, as members of the Great Observatories, are treated as general-purpose facilities capable of addressing wide areas of astrophysics research and therefore are not tied to specific scientific goals. Thus, the Hubble and Chandra reviews are incremental or “delta” reviews that focus on changes since the previous review, with an emphasis on mission efficiency.

Reduced funding guidelines provided to extended missions and to the Senior Review panels in recent years has become a key concern. For example, in its 2014 Senior Review,² Spitzer was ranked highly enough to be fully funded, yet the projected budget for the set of extended missions would not accommodate that. Two lower-ranked missions would not add up to the required cut, so one option recommended by the Senior Review committee was to zero out Spitzer. In response, the Astrophysics Division provided some additional funding and allowed the Spitzer team to propose for an extension with reduced operations and higher risk. The reduced mission was approved and has delivered excellent science at lower cost. For the 2016 Astrophysics Senior Review, the guideline budgets were again insufficient to fully fund all of the missions under review. Following recommendations from the review panel to continue funding all of the missions, the Astrophysics Division reworked its constrained budgets to enable ongoing operation for all of the proposed missions. Some missions, however, are required to find further operating efficiencies to deal with reduced funding, and one mission is allocated a modest over-guide budget to augment its guest observer program.

Earth Sciences

Earth Science Division (ESD) Senior Reviews³ begin with an assumption that a mission will be continued if its unique contributions are still rated highly and if the health of the instruments and spacecraft are still very good. An additional consideration for long-term Earth Science missions is the NASA policy requirement (NASA NPR 8715.6A) that maneuverable spacecraft that are terminating their operational phases at altitudes of less than 2,000 km above Earth shall have fuel and capability to reduce their remaining orbital lifetime to 25 years.

The Earth Science Senior Reviews explicitly acknowledge the importance of long-term data sets and the overall value of data continuity for Earth science research. This importance leads to a different risk posture for Earth Science missions in comparison to other SMD missions. The other divisions explicitly tolerate higher risk in

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² The Astrophysics Division Senior Reviews are available at NASA Science, “Astrophysics: Documents,” http://science.nasa.gov/astrophysics/documents/.

³ The Earth Science Division Senior Reviews are available at NASA Science, “Earth: Missions: Operating,” http://science.nasa.gov/earth-science/missions/operating/.

extended missions than they do for prime missions, with the idea that costs can be reduced by accepting higher risk levels. Because of national interests and needs, Earth Science has more stringent requirements for data continuity and cannot accept additional risk for extended missions as a way to reduce costs.

The Earth Science Division explicitly takes into account national operational objectives in its Senior Review process. The 2005 National Research Council report Extending the Effective Lifetimes of Earth Observing Research Missions recognized that Earth science missions “have unique considerations, such as future operational utility and interagency partnerships, that distinguish them from space science missions” (NRC, 2005, p. 1), and the same report contained a recommendation that NASA consider the operational use of NASA Earth science missions in the mission-extension process. As a result, a National Needs Panel has been included in ESD Senior Reviews since 2007 (being more recently renamed the National Interests Panel). The findings of the National Interests Panel provide a secondary evaluation criterion; the primary evaluation criterion is the scientific merit of the mission. The National Interests Panel determines the value of the data sets for applied and operational uses that serve national interests—including operational uses, public services, business and economic uses, military operations, government management, policy making, and nongovernmental organizations’ uses. The organizations that were represented during the 2015 Senior Review are as follows:

• National Oceanic and Atmospheric Administration National Weather Service,
• National Oceanic and Atmospheric Administration National Ocean Service,
• Federal Aviation Administration,
• U.S. Department of Agriculture,
• Naval Research Laboratory,
• U.S. Army Corps of Engineers,
• Environmental Protection Agency,
• U.S. Geological Survey,
• Department of Homeland Security Federal Emergency Management Agency,
• Centers for Disease Control and Prevention,
• Alliance for Earth Observations,
• International Association of Wildland Fire,
• Conservation International,
• National States Geographic Information Council,
• U.S. Geospatial Intelligence Foundation, and
• Urban and Regional Information Systems Association.

ESD also supplements the Senior Review with an annual Operations Review. This review evaluates spacecraft and instrument health, mission operations functionality, anomalies, new or monitored risks, and science data product production for all division missions.

Heliophysics

The Heliophysics Division recognizes the interconnectedness of its discipline by explicitly considering the contributions each mission makes to the Heliophysics System Observatory (HSO). The HSO consists of all operating Heliophysics missions, and its purpose is to investigate the behavior of the entire interconnected heliophysics

domain through simultaneous multipoint sampling throughout that domain. The Senior Review panel evaluates the contributions of each mission to the HSO and reflects these evaluations through a separate set of scores reported alongside the scores of overall scientific merit.

Heliophysics extended mission proposals include a 10-page Mission Archive Plan as an appendix. This appendix describes the data products of the mission and how they will be archived for use by the research community. (Similar data archiving plans are required for the other divisions’ extended mission proposals as well.)

Like the missions of the Earth Science Division, the missions of the Heliophysics Division collect data that are used by other agencies. The Senior Review includes a mechanism to include input from these agencies. Because data from some current missions are being used by the National Oceanic and Atmospheric Administration (NOAA), the 2015 Senior Review panel included a scientist from NOAA’s Space Weather Prediction Center.⁴

Planetary Science

The Planetary Science Division incorporates flexibility into its regimen of mission review with occasional mission-specific adjustments to review timing due to the special constraints of planetary missions, such as target body encounters and critical mission events that require the undivided attention of the team members who would also be charged to write the Senior Review proposal. Flexibility has also been employed to recognize other aspects of planetary missions. For example, a 3-year proposal was requested from Cassini in the 2014 Senior Review in recognition that the mission’s “Grand Finale” scenario would require slightly more than the nominal 2-year extension period, but the mission would then be terminated due to lack of fuel and the need to dispose of the spacecraft for reasons of planetary protection. Therefore, Cassini was not reviewed in the 2016 Senior Review.⁵ The Planetary Science Division also convenes out-of-sequence reviews as needed for missions that enter into extended operations off-cycle.

The Planetary Science Senior Review panels are sometimes split into separate subpanels by subject matter. In 2014, the Mars Exploration Program missions under review were considered by a separate group of reviewers from the other missions, and this separation was retained in 2016. The division indicated that separate review panels are used primarily because the Mars missions are parts of an integrated program, where the value of each mission is not independent of the other. The non-Mars Exploration Program missions are viewed as independent from one another.

STAKEHOLDERS

As part of its assessment process, the committee heard from various Senior Review stakeholders, including the NASA SMD associate administrator and the four division directors, panel chairs from the most recent Senior Reviews in each division, and principal investigators or science team leads for at least one large and one small mission currently in extended phase in each of the divisions. These presenters represent the immediate stakeholders of the Senior Review process—that is, the NASA Headquarters program executives, the review panels, and the mission teams. Each of the stakeholders has their own interests and perspectives on various aspects of the Senior Review process and on the overall value of Senior Reviews.

NASA Headquarters

The Senior Reviews are essential for NASA assessment of the scientific return and costs of missions in extended phases. In some cases, it is obvious that a mission has reached the end of its scientific productivity, but in most cases missions remain healthy with continued scientific return. In a cost-constrained environment, infor-

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⁴ The Heliophysics Division Senior Reviews are available at NASA Science, “Heliophysics: Missions: Senior Review Reports,” http://science.nasa.gov/heliophysics/senior-review/.

⁵“Report for Planetary Mission Senior Review 2016,” letter from J. Douglas McCuistion to James Green, Planetary Science Division Director, NASA Headquarters, June 17, 2016, http://solarsystem.nasa.gov/missions/2016seniorreview.

mation is needed on the absolute worthiness of the missions and the relative importance of their future scientific promise. Implementation and cost information from the mission teams also is important for planning future budgets.

Review Teams

The review panels represent the community in assessing the NASA portfolio of missions in extended phase. There are trade-offs between the cost and benefit of operating current missions and applying the funding to other areas of NASA science, and the SMD divisions utilize the reports from the Senior Review panels to refine initial allocations of funding among the extended missions as well as for deciding whether to allocate additional funding from elsewhere in the science portfolios. There is significant work involved for the panel members, who must carefully assess each mission and prepare the final report. Recent panel chairs indicated that they believed that a minimum period of 6 to 8 weeks between receipt of proposals and the panel meeting with the mission teams was required to effectively review and assess the proposals. They recommended that the panels have at least four weeks to read the proposals and to formulate questions for the mission teams. The committee considered the substantial workload on the community in formulating its assessments below. The panel members serve without compensation. The community and NASA Headquarters owe a huge debt of gratitude to the review panels for this essential work.

Mission Teams

For the mission teams, the preparation of Senior Review proposals and presentations requires a tremendous amount of work. Some of the work may be needed in any case for future planning, but substantial extra effort is needed to prepare formal proposals for the Senior Review. According to many of the mission team members who met with the committee, it typically requires up to 6 months of every 2-year period to prepare for and present at a Senior Review, which diverts mission teams from producing scientific results with their spacecraft during that period. Representatives from mission teams reported that there are commonly a large number of questions from the panel with very limited time for the mission teams to prepare responses. They suggested that the review panels should provide the questions to the proposers a minimum of 2 weeks before the panel meets with the teams. It is clear that this process presents a workload on the mission teams that could reasonably be called burdensome and therefore represents an important consideration for the committee.

In summary, the reviews are a huge amount of work for all stakeholders. NASA invests considerable resources on the reviews. A substantial amount of effort goes into choosing panels without conflicts of interest and in preparing the call for proposals. The mission teams spend a significant fraction of their time and effort preparing proposals, answering questions, and presenting to the Senior Review panels. The review panels devote a significant amount of time to reading and accurately reviewing the proposals.

The committee recognizes that some of these recommendations have already been in practice for some divisions (such as the length of time allocated to a panel to review the proposals) and believes that they should be adopted in general for all Senior Reviews regardless of the division. These minimums are essential for obtaining the best quality recommendations from the review panels, and considering that NASA holds Senior Reviews on a regular cadence, the agency can plan for the reviews well in advance.

The committee recognizes that because the 2-year cadence is established in congressional budget authorization language, NASA alone cannot change to a 3-year cadence. The committee believes that NASA will have to work with Congress to seek a change in the requirement for Senior Reviews, but that the advantages of such a change are significant and can save money and effort while continuing to maximize scientific return from the space agency’s extensive fleet of science missions.

As the recommendation indicates, an important component of this revised 3-year cadence is conducting regular assessments of the health of the spacecraft and instruments. This is necessary so that both the agency and proposers are aware of any potential issues that might result in shorter useful lifetimes and can plan accordingly. NASA’s science divisions already have provisions for doing this. These assessments do not need to be extensive, and their primary focus can be assessing changes since the last review.

The committee heard from the division director of the Earth Science Division that continuity of scientific measurements is a priority, because climate and other studies benefit most from similar measurements over time. Mission budgets are normally only sufficient to cover the processing, validation, and distribution of the approved standard data products. Innovative uses of current missions and the development of new data products can be, and often are, proposed through the ROSES (Research Opportunities in Space and Earth Sciences) investigation solicitations.

Conversely, in the other divisions, many mission teams believe that they must emphasize “new science,” over continuity measurements in their proposals, to be competitive. A careful reading of recent Senior Review proposal guidelines documents (Heliophysics 2015, Astrophysics 2014 and 2016, and Planetary Science 2014 and 2016) shows that new science is not required for a mission’s extension, although the potential for (or enabling of) new science may be evaluated. However, due to the emphasis on demonstrating that the primary science goals must help achieve NASA’s Science Plan or decadal survey objectives, in combination with the idea that the objectives of the prime phase of the mission have already been satisfied before proceeding into extended phase, it is easy to see how such a de facto requirement could be inferred by both the mission teams and the review panels evaluating the proposed activities. This de facto requirement is then underscored by the competitive environment of the Senior Review process. For example, in the case of the Planetary Science Division, language stating that a criterion of the evaluation is the “potential for groundbreaking science” has been widely interpreted by recent Senior Review panels and proposing mission teams as a requirement for new science and a diminution of continuity science.

INCORPORATION OF LESSONS LEARNED INTO SENIOR REVIEWS

Based on inputs from across the divisions, lessons learned include the following:

• Maximizing the number and experience of returning panel members facilitated the work of the Senior Review panels. The goal of ESD is to recruit panel members for a two-review commitment, with half of the panel returning from the prior review and half of them new. Other divisions have carry-over members, but the numbers are not specifically called out. Inclusion of some early-career panelists is also desirable in that it promotes opportunities for presentation of new perspectives as part of the review process.
• The process for developing questions for the mission teams’ oral presentations to the panel still needs improvement in some divisions. Although having a few standard questions can facilitate discussion between the panel and the missions, there also need to be mission-specific questions to fill in possible blanks and to provide essential clarifications without overloading the mission team or the review panel.
• The budget evaluation process has been improved over the years. More detail is now requested in the proposal and more support from NASA’s SMD/Resources Management Division Assessment and Evaluation Group in recent Senior Reviews greatly improved the use of the proposal budget information in decision making.
• In some instances, better coordination is needed with the PPBE (NASA’s annual budget planning) decision process and the PPBE submittal schedule.

• Are comprised primarily of senior scientists knowledgeable about and experienced in mission operations so as to ensure that the operational context of the science being proposed and evaluated is considered in the review (individuals with operations and/or programmatic expertise may also be included as needed);
• Are assembled early to avoid or accommodate conflicts of interest and ensure availability of appropriate expertise;
• Include some continuity of membership from the preceding Senior Review to take advantage of corporate memory; and
• Include some early-career members to introduce new and important perspectives and enable them to gain experience for future Senior Reviews.

Because continuity from one Senior Review to the next is valuable, introducing early-career members into the Senior Review process provides a way to ensure that future reviews will have a pool of scientists experienced in the process.

SUMMARY HISTORY OF MISSIONS REVIEWED BY THE SENIOR REVIEWS

The Senior Review process has been used by SMD to review a total of 73 science missions since 2005. Most missions have been reviewed several times in this interval, with proposals for a total of some 290 mission-years evaluated. Tables 3.1 through 3.4 present a history of these reviews for each division. The process has generally worked as it was conceived, and recommendations to terminate missions that were returning useful data have been infrequent. Exceptions for Astrophysics are GALEX and WISE in 2010 and Spitzer in 2014. Three missions were recommended for termination in Earth Sciences: ACRIMSAT in 2007 and 2009, ICESat in 2009, and EO-1 in

2009, 2013, and 2015.⁶ In Planetary Science, no missions were recommended for termination in the 2014 Senior Review. However, both the Lunar Reconnaissance Orbiter and Opportunity were eliminated from funding in the President’s fiscal year (FY) 2015 and FY2016 budget proposals. Congress later added money to continue these missions. The results of the four divisions’ Senior Reviews since 2005 are presented in Tables 3.1, 3.2, 3.3, and 3.4.

There also have been circumstances that have caused the NASA extended mission fleet to be operated in a manner that deviated from the recommendations of the Senior Reviews. Other than budgetary shortfalls, significant deviations have been necessary for a variety of reasons. An example is ACRIMSAT, which was extended after the failure of the Glory launch in 2011 to provide a backup for total solar irradiance measurements performed by SORCE. Similarly, an out-of-sequence Senior Review was convened to continue QuikSCAT when the performance of the RapidScat instrument on the International Space Station became unpredictable. These experiences underscore the value of allowing SMD to have flexibility in interpreting the Senior Review recommendations.

One thing that is apparent in Table 3.4 is that the Planetary Science Division has held a number of reviews in between the normal 2-year Senior Review cycle, such as Cassini in 2007 and 2009 and MESSENGER in 2011 and 2013. These off-year reviews were prompted by individual mission needs, indicating that a certain degree of flexibility on the cadence for Senior Reviews has been necessitated by mission operations.

EXTENSION OF EUROPEAN SPACE AGENCY SCIENCE MISSIONS

NASA is not the only agency that operates long-lasting science missions. ESA also operates a number of Earth science, heliophysics, astrophysics, and planetary science spacecraft. Like NASA, ESA has also developed a process for reviewing missions after their prime phase has been completed. ESA makes a commitment for the first 2 years of extended phase, but after that conducts Senior Reviews for the missions to extend them for 2 years at a time.

For ESA missions in which there is a NASA contribution (e.g., Rosetta), ESA approaches the international partners, such as NASA, and verifies the status of their commitment before the Senior Review. That information is then presented to the ESA Senior Review.

ESA conducts its Senior Reviews on a 2-year cadence, like NASA. According to an ESA representative who spoke to the committee, this is a compromise. This rolling process provides a sufficient continuity for managers to plan and provides checkpoints to ensure that there are sufficient reviews to change course if the mission is no longer compelling. The representative stated that some people have called for yearly reviews of ESA programs.

According to the ESA representative, there is no pressure for immediate balance across science disciplines when Senior Reviews are conducted. However, he stated that there is an understanding that the goal is a long-term balance. ESA ranks science first and foremost; the same is true for mission proposals (not just extensions).

According to the ESA representative, scientific proposals have a page limit (approximately 12 pages) that is significantly shorter than NASA’s requirements (which have varied from 20 to 50 pages). According to the ESA representative, this short length is not an excessive burden for the scientific community, but he also stated that the mission operations people would prefer longer proposals so as to provide more details of their plans and capabilities. Proposers for extended missions are asked to make an oral presentation to the peer review committee. The committee discussed the issue of page length for proposals with NASA proposal teams and determined that the NASA requirement is more appropriate for NASA missions. Some teams noted that shorter page requirements do not necessarily save preparation time because teams spend more time and effort deliberating on what should be included and excluded, and excluding important data may limit a review panel’s ability to understand the proposal.

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⁶ EO-1 was recommended for termination in 2009. However, the Senior Review specifically allowed for further consideration of the mission in the 2011 Senior Review. Utilization of EO-1’s instruments increased significantly after 2009 and by 2011 the spacecraft was increasingly used for disaster monitoring. The 2011 Senior Review recommended a continued mission, although it also called for improvements in data utilization. The 2013 Senior Review recommended an additional 2-year extension but did not recommend that the mission be allowed to propose to the 2015 Senior Review. The EO-1 team responded by indicating that there was still a demand for EO-1 data and they were allowed to propose to the 2015 Senior Review. The 2015 Senior Review recommended an additional year of operation but that EO-1 begin the termination phase by October 2016, which is the current plan.

TABLE 3.1 Astrophysics Division Senior Reviews by Year and Missions Reviewed

Mission	2006	2008	2010	2012	2014	2016
Chandra
Fermi
FUSE
GALEX
Gravity Probe B
Hubble
INTEGRAL
Kepler
MaxWISE
NuSTAR
Planck
RXTE
Spitzer
Suzaku
Swift
WISE
WMAP
XMM-Newton

NOTE: Acronyms defined in Appendix F.

TABLE 3.2 Earth Science Division Senior Reviews by Year and Missions Reviewed

Mission	2006	2008	2010	2012	2014	2016
ACRIMSAT
Aqua
Aquarius
Aura
CALIPSO
Cloudsat
ERBE
EO-1
GPS Science
GRACE
ICESat
Jason-1
OSTM
QuikSCAT
SAGE
SORCE
Terra
TOMS
TRMM
UARS

NOTE: Acronyms defined in Appendix F.

TABLE 3.3 Heliophysics Division Senior Reviews by Year and Missions Reviewed

	2005	2008	2010	2013	2015
ACE
AIM
CINDI
Cluster
FAST
Geotail
Hinode
IBEX
IMAGE
IRIS
Polar
RHESSI
SDO
SOHO
STEREO
THEMIS
TIMED
TRACE
TWINS
Ulysses
Van Allen Probes
Voyager
Wind

NOTE: Acronyms defined in Appendix F.

TABLE 3.4 Planetary Science Division Senior Reviews by Year and Missions Reviewed

	2006	2007	2008	2009	2010	2011	2012	2013	2014	2016
Cassini
Curiosity
Dawn
Deep Impact
GRAIL
LRO
MAVEN
MER
Mars Global Surveyor
Mars Express
MRO
MESSENGER
Odyssey
Phoenix
New Horizons
Stardust-NExT

NOTE: Acronyms defined in Appendix F.

During the last ESA Senior Review process, 10 missions were put up for extended missions. Eight of these were approved for extension. The two that were not extended were reaching the end of their technical lifetimes and could not be extended.

CONCLUSION

The committee did not identify major problems with NASA’s overall approach to Senior Reviews, although it did conclude that the agency needs to provide more time for its review teams in order to ensure that they can devote appropriate time to conduct quality reviews. The committee also concluded that NASA’s divisions also communicate with each other about review processes best practices and believes that this is a valuable practice.

As the divisions have performed more Senior Reviews, the details of the process have become more stable from cycle to cycle. Stability includes consistency of information requested, proposal format, timing for the various stages of the review, and so on. Maintaining best practices through regular interactions and feedback between NASA Headquarters, the mission teams, and review panels will help to ensure that this consistency is maintained while also providing opportunities for incremental improvements in the process.

REFERENCE