A star shade has to be refueled, perhaps every three to four years. A telescope with a built-in coronagraph that serves the same observational function will not require such an expense or an in-flight fueling system. It also should be noted that the star shade works best at a single central wavelength. This is also true for a coronagraph, but multiple coronagraphs can be packed onto a telescope allowing selection of the wavelength bands under study. You can't change out a star shade unless you launch more of them. <br><br>That said, a 30 meter platform with edge to edge accuracy of a millimeter or less like the star shade has other uses. For example, if the surface was a large diffraction grating, the collected light would be conveniently broken in wavelengths where the secondary telescope could examine stars with exquisite spectrographic detail, and with its built in coronagraphs then isolate exoplanets for their albedos where the surface spectra contain the clues that Seager seeks. Refueling would not be required, since solar powered reaction wheels could gimbal the platform to present the spectral bands under study.