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1 Introduction
Pages 8-14

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From page 8...
... Many NASA science ­spacecraft -- including but not limited to the Chandra X-Ray Observatory and the Kepler telescope; the Opportunity rover, the Lunar Reconnaissance Orbiter, and Cassini; the Aura, Aqua, and Terra Earth sciences spacecraft; the ACE and Wind spacecraft in interplanetary space between Sun and Earth, the THEMIS magnetospheric orbiter, and the SOHO and STEREO solar observatories -- have provided incredible scientific value long after their pri mary missions. These lengthy missions and their incredible scientific productivity are not simply due to happenstance or the unexpected longevity of some spacecraft: Extended missions are a mainstay of NASA's scientific endeavor, a major part of the agency's science portfolio, and the result not only of impressive engineering but also of careful management and effective planning.
From page 9...
... These spacecraft are sponsored by the Astrophysics, Heliophysics, Earth Science, and Planetary Science Divisions. Table 1.1 provides budget details for each of the four SMD divisions, along with data for the James Webb Space Telescope (JWST)
From page 10...
... 2015 Actual 2016 Enacted NASA Total 18,010.2 19,285.0 SMD 5,243.0 5,589.4 Earth Science 1,784.1 1,921.0 Planetary Science 1,446.7 1,631.0 Astrophysics 730.7 730.6 James Webb Space Telescope 645.4 620.0 Heliophysics 636.1 649.8 TABLE 1.2  The 45 NASA Missions in Extended Phase as of February 2016 Heliophysics Earth Science Planetary Science Astrophysics ACE Aqua Cassini Chandra AIM Aura LRO Fermi Geotaila CALIPSO Mars Expressa Hubble Hinodea CloudSat Mars Odyssey Kepler IBEX EO-1 MAVEN NuSTAR IRIS GRACE (1/2) MER Opportunity Spitzer RHESSI LAGEOS (1/2)
From page 11...
... Additional details describing how the Senior Reviews vary between divisions are described in Chapter 3. Most missions entered their extended mission phase after being recommended to do so by a Senior Review panel conducted within their division.
From page 12...
... Some of this research would be supported under R&A even if the relevant extended mission were to end, whereas some of it is tied to new observations acquired as an extended mission continues. The committee heard that extended science mission budgets have fluctuated over time and will continue to do so based on many factors, including spacecraft health, the results of the Senior Reviews undertaken by the divisions, and other agency considerations.
From page 13...
... According to former congressional staffers who spoke to the committee, the Authorization Act language calling for biennial reviews was based in part on this previously established cadence and was in part somewhat of a guess, with one former staffer suggesting that, in Washington, D.C., "two is the average between one and infinity." NASA's overall policies for extending science missions are outlined in the agency's management plan. The 2013 Science Mission Directorate Management Handbook states that after a mission's prime phase, entry into an extended phase "is possible if part of a compelling investigation that contributes to NASA's goals" (NASA, 2013)
From page 14...
... The following chapters in this report review in greater detail the scientific return secured from extended missions, the process that is in place to ensure that extended missions are productive contributors to NASA's science goals, how the relatively modest costs associated with supporting extended missions compares to the support required for new mission development and the potential for science lost if extended missions are not supported, and the potential ways in which extended missions may realize cost savings relative to their prime phase.


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