A CubeSat to study an analog of exoplanets with interferometric observations in the ultraviolet
Résumé
Exoplanet instrumentation and methods have improved to the point where we can start to probe the atmospheres of planets several parsecs away. Our efforts are pushing down to ever smaller and more Earth-like planets. In the quest to find and understand Earth-like systems, Venus is often used as a local analog to the distant planets we are finding.
Unfortunately, because of its angular proximity to the Sun, Venus is not as well studied by the modern suite of infrared and ultraviolet telescopes as the other solar system planets. This is putting us in the uncomfortable position of using an analog to exoplanets with significant gaps in our understanding of the very processes we'd like to study in those more distant exoplanets.
We present the design of a CubeSat to measure ultraviolet line profiles of Venus in order to better understand its relationship both to Earth and to analogous exoplanets. By using a CubeSat we can baffle and optimize the instrument to observe near to the Sun. The single target CubeSat allows us to achieve the long integrations needed to achieve the high signal to noise measurements needed for high resolution spectroscopy despite the modest aperture of the CubeSat.
The design achieves its high resolution by using a spatially heterodyned spectrometer in the SCARI configuration. In order to meet the stringent stability and size constraints intrinsic to the CubeSat environment the spectrometer is implemented as a monolith, similar to the SHIMMER construction. The high etendue of the spectrometer allows for such high resolutions even with the relatively poor point spread function expected from a CubeSat class telescope.