Technology demonstration of starshade manufacturing for NASA's Exoplanet mission program

Abstract

It is likely that the coming decade will see the development of a large visible light telescope with enabling technology for imaging exosolar Earthlike planets in the habitable zone of nearby stars. One such technology utilizes an external occulter, a satellite flying far from the telescope and employing a large screen, or starshade, to suppress the incoming starlight sufficiently for detecting and characterizing exoplanets. This trades the added complexity of building the precisely shaped starshade and flying it in formation against simplifications in the telescope since extremely precise wavefront control is no longer necessary. In this paper we present the results of our project to design, manufacture, and measure a prototype occulter petal as part of NASA's first Technology Development for Exoplanet Missions program. We describe the mechanical design of the starshade and petal, the precision manufacturing tolerances, and the metrology approach. We demonstrate that the prototype petal meets the requirements and is consistent with a full-size occulter achieving better than 10 −10 contrast.

Achieving high-contrast ratios with a 60-cm starshade

“…Starshades have been developed from the concept stage to an accepted, mid-TRL architecture in less than a decade [4,3,5] however, additional development is needed before the mission will be ready to fly. We have separated the critical technologies for the starshade into four development areas (Figure 2) in which current work is proceeding [6,7] . Figure 2: The testing program described here directly addresses the "Performance Verification and Modeling" critical technology areas of the starshade development Since the optical performance of the full-scale starshade system cannot be tested from the ground, numerical modeling, validated by sub-scale tests, will be critical to the mission success.…”

Galactic planetary science

“…Direct imaging from space is the expected next step to be taken in space after transit. Space telescopes with various types of coronagraphs are being studied in the US, Europe and Japan (Clampin & Lyon, 2010;Cash & New Worlds Study Team, 2010;Kasdin et al, 2012;Guyon et al, 2013;Serabyn et al, 2013;Boccaletti et al, 2013;Enya et al, 2011). A mission for direct imaging, would be technically more challenging than a transit one and certainly more expensive -the telescope cannot be a light bucket, to start with.…”

Planet formation imager (PFI): introduction and technical considerations

“…Space occulter. Advances in starshade technology in the context of exoplanet discovery 16 suggest new possibilities for space-based imaging systems. Angular resolution can be obtained through occultations of astronomical bodies by large shades in a way similar to classic lunar occultation work.…”