Unless otherwise cited, the information presented herein and the assessments of the committee were based on information supplied by the candidate mission teams in response to the committee’s Request for Information (RFI) (see Appendix E) and the subsequent written answers provided in response to additional questions from the committee.

Disparity of Scale and Maturity

The five Beyond Einstein mission areas include two, Constellation-X (Con-X) and Laser Interferometer Space Antenna (LISA), that are of the scale of a Great Observatory, have a single mission concept, and were funded at the multimillion-dollar level over a number of years prior to the initiation of the study. The three probe mission areas, Black Hole Finder Probe (BHFP), Joint Dark Energy Mission (JDEM), and Inflation Probe (IP), are about one-third to one-half the scale of the other two. Each has multiple mission concepts and was funded at a variety of levels and over various time frames. Most of them received NASA funding of only $200,000 over 2 years, although one of the JDEM missions, Supernova Acceleration Probe (SNAP), has had substantial time and funding invested in its definition by the Department of Energy (DOE). This disparity of scale and maturity among the five mission areas is a fact that cannot be ignored in the assessment and is the key reason that the assessment must be comparative. Indeed, to try to normalize the missions in order to judge them against an absolute scale would mask the very information needed for a realistic assessment.

The spacecraft bus or particular spacecraft components are included in some of the instrument technology tables because the mission team included them it its technology listings. The committee decided to keep the same lists as those of the mission teams. In a few cases there was insufficient information to do a complete assessment of a particular mission concept within a mission area.

Technology Readiness and Degree of Difficulty

As part of the technical readiness assessment, the standard NASA definitions of TRLs were used in the assessments (see the list of definitions below).3 TRL definitions are open to some interpretation and are often interpreted differently by different people (e.g., by technology or project personnel versus independent assessors). Because TRL overestimation has led to schedule and cost issues for many space programs in the past, the definitions were applied rigorously and conservatively in this assessment. That is, if there was any uncertainty in the assignment, the committee selected the more conservative (lower) TRL level or assigned a range (e.g., TRL 3-4). The normal NASA standard is that a TRL of 6 or higher should be achieved prior to proceeding into development.4 The simplified definitions of TRLs that the committee used are as follows:

TRL 1. Basic principles observed and reported.

TRL 2. Technology concept and/or application formulated.

TRL 3. Analytical and experimental critical function and/or characteristic proof-of-concept completed.

TRL 4. Component and/or breadboard validated in laboratory environment.

TRL 5. Component and/or breadboard validated in relevant environment.

TRL 6. System/subsystem model or prototype demonstrated in a relevant environment (ground or space).

TRL 7. System prototype demonstrated in a space environment.

TRL 8. Actual system completed and “flight-qualified” through test and demonstration (ground or flight).

TRL 9. Actual system “flight-proven” through successful mission operations.


NASA, NASA System Engineering Processes and Requirements, NPR 7123.1A, March 26, 2007. Available at http:\\nodis3.gsfc.nasa.gov.



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