We propose to build and fly a VUV sounding rocket spectrometer, furst: the full-sun ultraviolet rocket spectrograph, to obtain the first high resolution, high quality VUV spectrum of the…

Montana State University was awarded a $2.53 million research grant on June 13, 2018, to develop and deploy FURST (Full-Sun Ultraviolet Rocket Spectrograph), a vacuum ultraviolet (VUV) sounding rocket spectrometer designed to obtain the first high-resolution, high-quality VUV spectrum of the Sun as a star. The instrument will operate across the 112-200 nanometer wavelength range with a spectral resolution exceeding R>20,000, with absolute radiometric and wavelength calibration conducted prior to launch. The project addresses a critical gap in heliophysics research: while high-resolution VUV spectra exist for sun-like stars observed by the Hubble Space Telescope, no comparable high-resolution solar irradiance spectrum currently exists for our own Sun, limiting understanding of solar radiation's influence on the heliosphere and planetary atmospheres.

The research will enable analysis of chromospheric and coronal heating processes, center-to-limb brightness variations, and spectral line profiles, generating a fully calibrated UV spectrum for distribution to the scientific community. This award supports cross-disciplinary collaboration between heliophysics and astrophysics communities while advancing understanding of planetary atmosphere aeronomy, including exoplanetary systems. The project is funded through a civilian federal agency with a completion date of June 11, 2026, and will be performed at Montana State University's Bozeman, Montana campus. No set-aside designation was applied to this grant award.

We propose to build and fly a VUV sounding rocket spectrometer, furst: the full-sun ultraviolet rocket spectrograph, to obtain the first high resolution, high quality VUV spectrum of the sun-as-a-star. Our proposed spectrometer covers the 112-200 NM wavelength range with a spectral resolution r>20,000, and will undergo absolute radiometric and wavelength calibration prior to launch. Our team's extensive combined experience has been brought to bear to produce an elegant and robust payload design that simplifies calibration as well as deployment and operation in space. A defining goal of heliophysics is to understand the influence of solar radiation, plasma and magnetic field with interplanetary space , with the planets and smaller solar system bodies. Strikingly, no high resolution spectrum of solar irradiance exists, and construction of such a spectrum from existing data and models is fraught with difficulties. In contrast, hubble space telescope (HST) data of objects including sun-like STARS such as alpha CEN a are of far higher quality than solar data. Thus we are facing the peculiar fact that we know the inputs of VUV radiation to the heliosphere of a planet surrounding alpha CEN a far more precisely than we can for our own heliosphere! Critically, a resolution of>10,000 (10,000 on the sun. The unknown center-to-limb variations of brightness with wavelengths across line profiles presents a fundamental challenge for which data simply do not exist. Our aim will be to deliver a fully calibrated UV spectrum to the community at the earliest opportunity. This will foster cross-community collaborations across helio- and astro- physics, including some needs for aeronomy of planetary atmospheres including those outside of the solar system. The analysis of furst data will shed light on the fundamental processes of chromospheric and coronal heating, by focusing upon sometimes subtle, yet very significant differences in high quality UV spectra of the sun and the STARS. HST data exist for a dozen or so sun-like STARS of a quality already beyond our ability to construct a comparable sun-as-a-star UV spectrum. The new solar spectra will enable US to understand the nature of magnetic energy dissipation as a sun-like star evolves, and the dependence of magnetic activity on stellar mass and metallicity. This proposed research addresses three of the four main goals of heliophysics, as articulated by the decadal panel: 1. Determine the origins of the sun's activity and predict the variations in the space environment form nress-300 version 3.0 APR 09 3. Determine the interaction of the sun with the solar system and the interstellar medium. 4. Discover and characterize fundamental processes that occur both within the heliosphere and throughout the universe.