Science Overview

FINESSE is the first mission dedicated to the spectral characterization of the rapidly growing number of newly discovered worlds. It will revolutionize our understanding of exoplanet atmospheres by spectroscopically surveying 500 planets outside of our Solar System, ranging from terrestrials with extended atmospheres to sub-Neptunes to gas giants. FINESSE's broad, instantaneous spectral coverage and survey capability enable exploration of TESS discoveries and will provide a framework for interpreting detailed JWST observations. The FINESSE survey will yield transformative knowledge about the extended planet family by discovering what these alien worlds are like, determining what makes them they way they are, and allowing this knowledge to be applied in the broader planetary context, including the search for life outside of our Solar System.

Science Objectives

FINESSE directly addresses NASA's science objective to "Generate a census of extra-solar planets and measure their properties." FINESSE will:
  • Determine key aspects of the planet formation process. FINESSE will obtain the atmospheric composition measurements of metallicity and carbon-to-oxygen ratio that are needed to address all future efforts to understand planet origins. Through these measurements we will discover whether our Solar System formation was typical or exceptional.
  • Reveal the crucial factors that establish planetary climate. FINESSE measurements will determine planetary energy budgets, the role of aerosols (cloudsand hazes) in establishing the atmospheric radiation balance and the processes that control heat redistribution from the dayside to the nightside.

Measurement Technique

During a transit, light from the parent star filters through the planet's atmosphere, encoding molecular features. FINESSE obtains a spectrum by measuring how light at each wavelength changes during a transit. This proven technique is extended to measure light curve changes during the planet's orbit using observations spaced between transit and eclipse; this approach maps emission as a function of longitude on the exoplanet.

Science Team

Mark Swain (PI-JPL)
Jacob Bean (Science Team Lead-U of Chicago), Geoffrey Bryden (JPL), John Chapman (JPL), Nicolas Cowan (McGill), Jonathan Fortney (UC Santa Cruz), Robert Green (Instrument Scientist-JPL), Caitlin Griffith (U of Arizona-LPL), Tiffany Kataria (JPL), Eliza Kempton (Grinnell), Laura Kreidberg (Harvard), David Latham (Harvard-Smithsonian/CfA), Michael Line (ASU), Suvrath Mahadevan (Penn State), Jorge Melendez (U of Sao Paulo), Julianne Moses (SSI), Vivien Parmentier (AMU/CNRS/LAM), Gael Roudier (JPL), Evgenya Shkolnik (ASU), Adam Showman (U of Arizona-LPL), Kevin Stevenson (STScI), Gautam Vasisht (JPL), Edward Wright (UCLA), Yuk Yung (Caltech), Robert Zellem (JPL)

Mission Events

Earth-Sun L2 (Heliocentric) orbit
2016 MIDEX Standard LV compatible
Near-unrestricted launch period (better than 95% launch availability)
DSN stations for downlink (one eight-hour pass/week during Science Operations)
Two-year Baseline Science Mission duration
Full-sky coverage every four months

Scientific Instrument(s)

- Spectrometer, 0.5-5.0 μm, ~
λ/Δλ = 80 @ 1.2μm, 300 @ 3 μm
75 cm diameter primary mirror