EXoplanetary Circumstellar Environments and Disk Explorer technology demonstration: Experimental results in air and vacuum
Abstract
Coronagraph technology is advancing and promises to enable space telescopes capable of directly detecting and spatially resolving low surface brightness circumstellar debris disks as well as imaging giant planets as close as in the habitable zones of their host stars. One proposed mission capable of doing this is called EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), which in 2011 was selected by NASA's Explorer program for technology development A (Category Ill). EXCEDE is a 0.7 m space telescope concept designed to achieve raw contrasts of 1e-6 at an inner working angle of 1.2 l/D and 1e-7 at 2 l/D and beyond. In addition to doing fundamental science on debris disks, EXCEDE will also serve as a technological and scientific precursor for an exo-Earth imaging mission. EXCEDE uses a Starlight Suppression System (SSS) based on the PIAA coronagraph, enabling aggressive performance.
In this presentation, we report on our continuing progress of developing the SSS for EXCEDE, and in particular the achievement of the first major milestone in our technology development program (1e-6 median raw contrast between a 1.2 l/D inner working angle and 2 l/D, simultaneously with 1e-7 median raw contrast between 2 l/D and 4 l/D, in monochromatic light and in a controlled and repeatable fashion). In addition, we will describe the upgrades to our system, such as (a) the Low Order Wavefront Sensor (LOWFS) which enabled achieving deep contrasts at aggressive inner working angles; (b) efficient model-based wavefront control algorithms; (c) a reconfiguration of our DM to be upstream of the coronagraph and the addition of the "inverse PIAA" system that enables better outer working angles. Finally, we report on preliminary demonstrations in a vacuum chamber. Even though this technology development is primarily targeted towards EXCEDE, it is also germane to any exoplanet direct imaging spacebased telescopes because of the many challenges common to different coronagraph architectures and mission requirements.- Publication:
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Search for Life Beyond the Solar System. Exoplanets, Biosignatures & Instruments
- Pub Date:
- March 2014
- Bibcode:
- 2014ebi..confP4.72L