Background
SwRI’s UVS/Alice family of ultraviolet imaging spectrographs have played a key role in flagship planetary science missions from ESA’s Rosetta mission (launched March 2004) to NASA’s Europa Clipper (launched October 2024). While the impressive capabilities of these instruments have continued to improve, they have also become more resource intensive, limiting their scope for inclusion on smaller, lower-cost missions. The goal of this project is to design an alternative, more compact UV instrument concept that will complement the heritage design and allow us to perform equally compelling science from smaller spacecraft.
Approach
We aim to develop a compact UV imager design that uses Fabry-Pérot optics and new UV-optimized CMOS detectors. The key element in a Fabry-Pérot design is a pair of parallel mirrors that are separated by a distance optimized so that light at the target wavelength experiences constructive interference. This allows for an instrument with higher spectral resolution and sensitivity than a conventional spectrograph of a similar size, but with a smaller bandpass. The optical design developed during this project will therefore be useful for specific science goals, such as measuring the shapes of specific emission lines to determine atmospheric temperatures and velocities, providing complementary information to the heritage UVS design with its broader applications.
In addition to producing a new optical design, we will validate the performance of UV-optimized CMOS detectors and determine if they are a feasible alternative to the microchannel plate (MCP) detectors used in the UVS/Alice instruments. The use of a CMOS detector would allow us to avoid the higher power consumption and more complex readout electronics associated with MCP detectors, potentially facilitating a more compact, less resource intensive instrument.
Accomplishments
We started by defining key performance requirements including spectral resolution, bandpass, and spatial coverage for an imager targeting ionospheric oxygen emissions from low Earth orbit. These requirements were then used to develop an initial optical design, which will be continue to be refined for the remainder of the project period. In parallel to the optical design work, we have been preparing to test three CMOS detectors at far-UV and mid-UV wavelengths, but have not yet been able to begin testing due to extended use of the test equipment by another project. Once completed, the detector tests will allow us to validate the sensitivity of our instrument design and potentially to miniaturize it further.