Eclipse architecture

摘要

The Eclipse instrument concept is being optimized to produce direct images of cool Jovian planets around several hundred candidate nearby stars, and consists of matched large telescope, wavefront sensing and control, and coronagraphic camera modules. Designed to fully comply with a Discovery Program budger and schedule, it operates in a wavelength band from 550 nm to 950 nm, and includes an unobscured telescope 1.8 m in diameter. Spaceborne direct exoplanet imaging is now practical through deformable mirror (DM) technology that permits a hundred-fold or more quasi-static correction of a Hubble Space Telescope (HST)-level primary mirror surface error at the mid-spatial frequencies that scatter starlight over its planet. Due to the stability of the spaceborne environment, wavefront error sensing can be accomplished in calibration runs preceding planet observation. Eclipse development is aided by a Jet Propulsion Laboratory (JPL) testbed including many attributes of the flight article, and by validation of diffractive propagation algorithms that define system performance. As such, Eclipse both may serve as a pathfinder for envisioned larger instruments for terrestrial planet finding, and provide the first sensitive survey of nearby planetary systems. Eclipse is in the process of definition and design, and the results shown here may be modified with further analysis and design. The emphasis of this paper is our approach to the Eclipse Space Element, and the definition of a checklist of features for coronagraphic design. The ground element, and specific devices and a algorithms, and the next stages of design will be subjects of future papers. It is not sufficient to design a system capable of providing 10~(-9) contrast. A coronagraphic system must have sufficient stability that this level of contrast can be maintained over a reasonable observing interval.