Powering Science NASA's Large Strategic Science Missions (2017) / Chapter Skim
Currently Skimming:
2 Balancing Strategic Missions
2 Balancing Strategic Missions
Pages 24-46
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 24... ...
However, although both heliophysics and Earth science generally rely more on smaller missions than large strategic missions than do astrophysics and planetary science, they have operated large strategic missions, and these missions, as well as future ones, are still considered by some members of their communities to be vital for some major scientific breakthroughs in their respective fields. Furthermore, both Earth science and heliophysics are likely to operate constellations of multiple smaller spacecraft pursuing strategic science goals and having the cost and complexity common to large strategic missions.
|
From page 25... ...
42. 3 NASEM, Space Science Decadal Surveys, 2015, pp.
|
From page 26... ...
almost did not happen, because its initially planned 2004 launch was canceled in the aftermath of the 2003 Columbia space shuttle accident. The high-profile nature of the Hubble mission resulted in considerable controversy over its planned demise and led to several studies, including a 2005 National Research Council report: Assessment of Options for Extending the Life of the Hubble Space Telescope.
|
From page 27... ...
SOURCE: NASA. With the retirement of the space shuttle program in 2011, Hubble can no longer be serviced, but due to the efforts of SM4, NASA is hoping to keep it operational until at least 2020 to allow for at least one year of overlap with the James Webb Space Telescope (JWST)
|
From page 28... ...
, within the Astrophysics Science Division large strategic missions support a range of science through a vast user community. Each year, there are hundreds of programs allocated to small principal investigator (PI)
|
From page 29... ...
Certainly, a balanced program in astrophysics will always have a role for large strategic missions. EARTH SCIENCE DIVISION In the Earth science field, large strategic missions provide a centralizing and organizing force around which research and development activities can coalesce.
|
From page 30... ...
In Earth science the ability to collect consistent, well-calibrated, validated data over decadal timescales is critical for understanding Earth's climate, physical, and biogeochemical systems. This remains a primary requirement for Earth science and the large strategic missions that generate hundreds of community-defined science products, and continuously receive very high marks in the senior review process.5 Currently, NASA's Earth Science Division operates three large strategic missions: Terra, Aqua, and Aura.
|
From page 31... ...
Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) , contributed by the Japanese Ministry of Economy, Trade, and Industry with a U.S.-led science team at the Jet Propulsion Laboratory (JPL)
|
From page 32... ...
. In addition to creating a very large library of measurements supporting the objectives listed earlier, highlights of the Terra mission (shared with other Earth science missions)
|
From page 33... ...
Announcements of opportunity issued through NASA/HQ were specifically designed to address the mission and its science requirements. In extended mission phase, efforts were made to reduce mission operations costs, and the R&A portion of the Terra mission not directly tied to mission science management or PI instruments was folded back into the Earth science budget.6 Alternatives to Large Strategic Missions in Earth Science The Earth science community has grown out of a broad set of academic disciplines distributed over the focus areas in Earth science that include climate variability and change, atmospheric composition, carbon cycle and ecosystems, water and energy cycle, weather, and Earth surface and interior.
|
From page 34... ...
As this study was concluding, the second Earth science decadal survey was still under way. This committee concluded that the issue of the future role of large strategic missions in Earth science was best left to the decadal survey to address.
|
From page 35... ...
The development and integration of dozens to potentially hundreds of small spacecraft can result in a mission that is both strategic -- vital to the development of the science discipline -- and also large in terms of cost and complexity. As in Earth sciences, the study of fundamental heliospheric processes requires studying an enormous range of spatial and temporal scales that can sometimes be accomplished only by using large strategic mission capabilities.7 To understand why the solar wind exists, for example, requires placing a spacecraft into the atmosphere of the Sun, within at least 11 solar radii of the Sun's center.
|
From page 36... ...
distance from the Sun, the spacecraft will have to complete seven flybys of Venus and plans its first approach of the Sun is to be concluded in the winter of 2024. The goals of the Parker Solar Probe mission include the following: • Determining the structure and dynamics of the magnetic fields at the sources of solar wind, • Tracing the flow of energy that heats the Sun's corona and accelerates the solar wind, and • Determining what mechanisms accelerate and transport energetic particles.
|
From page 37... ...
PLANETARY SCIENCE DIVISION Planetary science is conducted with large strategic as well as competed missions. Planetary science requires large strategic missions for several reasons: because the destinations/targets are difficult to reach and because of a need to carry a comprehensive instrument suite to a far or difficult destination to make multiple observations.
|
From page 38... ...
The value and breadth of large strategic missions for planetary science is demonstrated by NASA's Cassini mission to Saturn. Cassini At the time this report was being written, NASA was preparing the end of life for the Cassini spacecraft.
|
From page 39... ...
Huygens and Cassini had different prime mission science FIGURE 2.4 The Cassini-Huygens spacecraft during final integration and testing in the late 1990s. The Huygens atmospheric probe is the large gold disk at center.
|
From page 40... ...
In addition, European funding prevented Cassini from being canceled in the 1990s, and later, U.S. support enabled extended mission funding for European scientists.
|
From page 41... ...
. CubeSats, or even small satellites like those being evaluated as part of the PSDS3 program, are unlikely to conduct planetary science missions on their own, but will probably be carried to their destination aboard larger spacecraft.
|
From page 42... ...
to trade off within limited budget between development and operation of large strategic missions and the cadence and or/cost caps of medium-size and small principal investigator (PI) -led mission lines." After much deliberation, the committee concluded that there is no single figure-of-merit approach that could be developed to apply to all four scientific disciplines, nor was it appropriate for this committee to seek to supersede the guidance that is already provided to NASA by the decadal surveys.
|
From page 43... ...
For example, the National Aeronautics and Space Administration Transition Authorization Act of 2017 states that "the Administrator should set science priorities by following the guidance provided by the scientific community through the National Academies of Sciences, Engineering, and Medicine's decadal surveys." Each division is charged with advancing the state of knowledge in the relevant fields of astrophysics, Earth science, heliophysics, and planetary science. To accomplish that goal, each division is also charged with advancing the state of technology, as appropriate, which may include both hardware (e.g., instrumentation and techniques)
|
From page 44... ...
RECOMMENDATION: The decadal surveys should formulate mission concept variants or other means to assess the boundaries of cost and technical risk and recommend the application of decision rules to provide flexibility to the NASA science divisions and most importantly to the scientific community. This will enable further refinement of mission concepts when pursuing the scientific priorities identified by the decadal surveys.
|
From page 45... ...
RECOMMENDATION: In preparation for the decadal surveys, large strategic mission proposal teams should consider describing ranges of scientific scope for their recommended large strategic missions, such as minimum science goals and maximum budgets, as well as identifying what science goals are most desirable at different budget levels. This approach may allow the scientific community and NASA to develop less expensive implementation strategies for mission concepts that do not exceed current budget limitations.
|
From page 46... ...
That is the subject of the next chapter. 13 For further information, see NASEM, Space Science Decadal Surveys, 2015.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.