NASA's Europa Clipper Mission Ultraviolet Spectrograph (Europa-UVS)
Abstract
NASA's Europa multi-flyby mission is designed to provide a diversity of measurements suited to enrich our understanding of the potential habitability of this intriguing ocean world. The Europa Clipper mission's Ultraviolet Spectrograph, Europa-UVS, is largely based on the Juno-UVS instrument, currently in orbit at Jupiter. Its design is even more similar to the Jupiter Icy Moons Explorer UVS (JUICE-UVS), which leads Europa-UVS in its development and delivery schedule by 18 months. The science objectives of Europa-UVS are to: 1) Determine the composition & chemistry, source & sinks, and structure & variability of Europa's atmosphere, from equator to pole; 2) Search for and characterize active plumes in terms of global distribution, structure, composition, and variability; 3) Explore the surface composition & microphysics and their relation to endogenic & exogenic processes; and 4) Investigate how energy and mass flow in the Europa atmosphere, neutral cloud and plasma torus. Europa-UVS observes photons in the 55-210 nm wavelength range, at moderate spectral and spatial resolution along a 7.5° slit. Three distinct apertures send light to the off-axis telescope mirror feeding the long-slit imaging spectrograph: i) a main entrance airglow port is used for most observations (e.g., airglow, aurora, surface mapping, and stellar occultations); ii) a high-spatial-resolution port consists of a small hole in an additional aperture door, and is used for detailed observations of bright targets; and iii) a separate solar port allows for solar occultations, viewing at a 40° offset from the nominal payload boresight. Programmable acquisitions with customized detector array binning and windowing capabilities allow for observational flexibility and optimal science data management. Both photon event time-tagging (pixel list mode) and spectral imaging (histogram mode) acquisition types take advantage of this data volume optimization capability. As on Juno-UVS, the effects of penetrating electron radiation on electronic parts and data quality are mitigated through contiguous shielding, management of high-voltage settings, and careful use of radiation-hardened parts. Additional mitigation of radiation effects on UVS science measurement quality is provided by implementing microchannel plates with ALD coatings (to eliminate gain-sag), borosilicate glass substrates (to decrease sensitivity to energetic particles and secondaries), and large global count rate limits and filtering of pulse height amplitudes (to process noise events). Europa-UVS passed its preliminary design review (PDR) milestone in November 2017. We present the current investigation details regarding the science we plan to address, the salient details of the instrument, and the basic concept of operations.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2828R