MISSION DESIGN ACTIVITY
The initial science assessment and prioritization effort yielded 12 mission concepts, with 4 concepts put forward by each of the three science discipline panels. Each of the concepts were then organized and systematized using a standard design questionnaire intended to provide a relatively uniform set of design parameters as an input to the mission design process. The 12 mission designs were then produced over a 5-week period in February and March of 2011 at the Concept Design Center (CDC) of the Aerospace Corporation in El Segundo, California. The CDC team consisted of experts who were “firewalled” from the CATE process. Each mission was supported by a group of both shared and dedicated CDC team members, one or more members of the survey committee, and a “champion” designated by the science panels to represent each investigation concept.
The cornerstone assumption for the mission design process was that cost-effective mission concepts demand a requirements-focused design combined with overall system simplicity. The general system design baseline resulting from these assumptions was a single-string (with selective redundancy in some cases) architecture using commercially available spacecraft bus designs similar in size to a medium Explorer. The bus structure and specific capabilities such as power and pointing were sized to accommodate the required science instrumentation. Mission-unique features were also incorporated to meet requirements for orbit and downlink, radiation hardness, magnetic cleanliness, deployable subsystems, dispensing functions, and de-orbit capability (if determined to be necessary). To constrain the system design and control cost, the system architecture was also scaled such that all missions were both sized and intended for orbits so as to be compatible with a launch on a medium-size launch vehicle or smaller. The largest launch vehicle required for any mission concept was the Falcon 9.
The design process was intense but also effective at developing a realistic set of concepts consistent with the above requirements and constraints. The effort was well supported by all stakeholders in the process, with detailed standardized reports prepared for each of the resulting system designs. The quality and consistent nature of the reports allowed for a straightforward comparison of missions leading into the subsequent down-select process. The reports were also designed to be compatible with the input parameters required by the CATE process.
Following distribution of the mission design reports, the science panels performed an initial review and made recommendations to the committee for the CATE down-select from 12 to 6 missions. The recommendations were based on science objectives, complexity factors, and relative cost assumptions. The following recommended concepts were presented by the science panels, endorsed by the committee, and moved forward into the first stage of the CATE process:
1. Dynamical Neutral Atmosphere-Ionosphere Coupling (DYNAMIC) mission,
2. Interstellar Mapping and Acceleration Probe (IMAP),
3. Solar Eruptive Events (SEE),
4. Magnetosphere-Ionosphere Source Term Energetics (MISTE),
5. Magnetosphere Energetics, Dynamics, and Ionospheric Coupling (MEDICI) mission, and
6. Geospace Dynamics Constellation (GDC).
The CATE process has been discussed at length in previous reports and is based on the following principles, which have remained consistent between recent past surveys and this survey. The CATE flow