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Zareh, Shannon

Publications and source records attributed to Zareh, Shannon.

NASA’s Lunar Trailblazer Mission: A Pioneering Small Satellite for Lunar Water and Lunar Geology

Selected in 2019 as a NASA SIMPLEx mission, Lunar Trailblazer is in implementation for flight system delivery at the end of 2022. The mission’s goal is to understand the form, abundance, and distribution of water on the Moon and the lunar water cycle. Lunar Trailblazer also collects data of candidate landing sites to inform planning for future human and robotic exploration of the Moon and evaluate the potential for in situ resource utilization. Lunar Trailblazer’s two science instruments, the High-resolution Volatiles and Minerals Moon Mapper (HVM3) and the Lunar Thermal Mapper (LTM) provide simultaneous high-resolution spectral imaging data to map OH/water, crustal composition, and thermophysical properties from a 100±30 km lunar polar orbit. The ~210-kg flight system deploys from an ESPA Grande and utilizes a ~1000 m/s ΔV hydrazine chemical propulsion system, similar to that employed by GRAIL. Trailblazing elements include the novel state-of-the-art dataset collected at substantially reduced price point, fully geographically co-registered data products delivered to the Planetary Data System, planetary mission team demographics, Caltech campus mission operations, and student staffing of select mission ops roles. Lunar Trailblazer’s pioneering development is providing key lessons learned for future planetary small spacecraft.

Zareh, Shannon↗

Precise starshade stationkeeping and pointing with a Zernike wavefront sensor

Starshades, large occulters positioned tens of thousands of kilometers in front of space telescopes, o er one of the few paths to imaging and characterizing Earth-like extrasolar planets. However, for the starshade to generate a su ciently dark shadow on the telescope, the two must be coaligned to just 1 meter laterally, even at these large separations. The principal challenge to achieving this level of control is in determining the position of the starshade with respect to the space telescope. In this paper, we present numerical simulations and laboratory results demonstrating that a Zernike wavefront sensor coupled to a WFIRST-type telescope is able to deliver the stationkeeping precision required, by measuring light outside of the science wavelengths. The sensor can determine the starshade lateral position to centimeter level in seconds of open shutter time for stars brighter than eighth magnitude, with a capture range of 10 meters. We discuss the potential for fast (ms) tip/tilt pointing control at the milli-arcsecond level by illuminating the sensor with a laser mounted on the starshade. Finally, we present early laboratory results.

Shaklan, Stuart↗