TPF-I SWG Report - Exoplanet Exploration Program - NASA

C HAPTER 4
The full set of metrics and scores for each combination of option and discriminator is listed in Lay et al.
(2005). The final scores are tabulated in Table 4-3, with the breakdown into performance and cost/risk.
The X-Array scored the highest, followed by the Linear Dual Chopped Bracewell. Table 4-4 gives a
breakdown of the key discriminators, ie. those responsible for most of the differentials in the final scores.
4.10 Structurally Connected Interferometer
Prior to 2004, the TPF-I project developed designs for both a formation-flying interferometer (FFI) and a
structurally connected interferometer (SCI) architecture. In the following we briefly describe the SCI
design and summarize a 2006 reassessment of its planet-finding performance.
4.10.1 Baseline design
The SCI architecture created by the TPF-I Design Team has four 3.2-m diameter collectors, spaced along
a 36-m linear structure as depicted in Fig. 4-24. The light from the collectors can be phased as a Dual
Chopped Bracewell Nuller in two different ways. Configuration A has longer nulling baselines and
therefore a small inner working angle, but the short imaging baselines result in poor angular resolution.
a)
b)
c)
Figure 4-25. (a) SCI with deployed thermal shade. (b) SCI with thermal shade removed. (c) End view to illustrate
the ±45 degree solar shading limit.
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