Assessment of Mission Size Trade-offs for NASA's Earth and Space Science Missions (2000)

To obtain the information needed to carry out the three tasks assigned to it (Appendix B), the Ad Hoc Committee on the Assessment of Mission Size Trade-offs for Earth and Space Science Missions asked four of the Space Studies Board’s discipline committees (the Committee on Astronomy and Astrophysics, the Committee on Earth Studies, the Committee on Planetary and Lunar Exploration, and the Committee on Solar and Space Physics) and one of the interdisciplinary committees (the Committee on International Space Programs) to answer the following questions:

1. Are there arguments for having a spectrum of mission sizes to achieve near-term (10 years) and far-term (10 to 20 years) goals in your discipline?¹ What are these arguments? Please cite relevant SSB strategy reports or other reports where appropriate. Relevant arguments might include laws of physics, cost and budget, timeliness and time-to-flight, institutional opportunities to participate, technology and technology readiness, and risk tolerance.

2. What are examples of existing, planned, or proposed missions along that spectrum of mission sizes? Examples should relate to missions that address high-priority science goals.

3. What criteria would you develop for evaluating the mix of missions you have chosen as examples?

• Is the mix affected by the availability of off-the-shelf hardware?

• Has the recent emphasis on various low-cost missions influenced your perceptions of what the best mix should be?

• Has the recent support for low-cost missions improved or weakened near-term science in your discipline?

• What is the impact of international cooperation on the mix of missions you chose? Criteria for evaluating the mission mix might include resilience, robustness, and satisfactory rates of progress against established science goals.

4. In applying these criteria to NASA’s portfolio of missions in the NASA strategic plan for your discipline, what do you observe? To what extent do the projects planned or sponsored by other national space agencies

address discipline strategic goals not currently addressed in NASA’s strategic plans? Where do such projects fit in the spectrum of missions defined below?

The discipline committees were asked to provide written responses to these questions as input to the ad hoc committee’s information gathering and subsequent deliberations.