page_title: Habitable Exoplanet Imaging Mission
section_title: Overview
hierarchical_section_title: Habitable Exoplanet Imaging Mission / Overview
caption_attribution_description: English: https://blogs.nasa.gov/pluto/2015/08/10/atmospheric-escape-and-flowing-n2-ice-glaciers-what-resupplies-plutos-nitrogen/ IMAGE CAPTION: Backlit by the sun, Pluto’s atmosphere rings its silhouette like a luminous halo in this image taken by NASA’s New Horizons spacecraft. RELATED FILE DESCRIPTION: Pluto - New Horizons Atmospheric Escape and Flowing N2 Ice Glaciers – What Resupplies Pluto’s Nitrogen? Posted on August 10, 2015 at 3:26 pm by ptalbert. IMAGE: =&gt; http://blogs.nasa.gov/pluto/wp-content/uploads/sites/253/2015/08/nh-pluto-atmosphere-300x252.png Backlit by the sun, Pluto’s atmosphere rings its silhouette like a luminous halo in this image taken by NASA’s New Horizons spacecraft. Hi, I’m Kelsi Singer, a postdoctoral researcher at the Southwest Research Institute, working on NASA’s New Horizons mission and specializing in geology and geophysics. One of my areas of expertise is impact cratering. That subject may not seem related to Pluto’s atmosphere or nitrogen at first, but let me tell you about research that New Horizons principal investigator Alan Stern and I conducted and published as a prediction paper before the flyby of Pluto. New Horizons has returned striking images of both Pluto’s surface and its atmosphere. Pluto’s atmosphere is similar to Earth’s in that it is predominantly composed of nitrogen (N). But Pluto’s atmosphere is ~98% N, while Earth’s is only ~78% N. Pluto’s atmosphere is also considerably thinner than Earth’s with ~10,000 times lower pressure at the surface. IMAGE: =&gt; http://blogs.nasa.gov/pluto/wp-content/uploads/sites/253/2015/08/nh-nitrogen-mystery-225x300.jpg Kelsi Singer - SwRI Researcher Kelsi Singer The nitrogen in Pluto’s atmosphere (in the form of N2 gas) is actually flowing away and escaping the planet at an estimated rate of hundreds of tons per hour. We also see what looks like flowing ice on Pluto’s surface in high resolution images made by New Horizons. The water ice (H2O) that we are familiar with on Earth would be completely rigid and stiff at Pluto’s surface temperatures, but ice made out of N2 would be able to flow like a glacier. So where does all of this nitrogen come from? One possibility we tested was that cometary impactors could be delivering the necessary material. We explored several different ways that impacts from comets could bring nitrogen to the surface and atmosphere of Pluto and resupply the escaping nitrogen: IMAGE: =&gt; http://blogs.nasa.gov/pluto/wp-content/uploads/sites/253/2015/08/nh-pluto-terrain-300x177.png 1) Could comets hitting Pluto directly deliver enough N to Pluto’s surface and atmosphere? 2) Could these comets excavate or expose enough N2 ice from the near-surface layers on Pluto by forming impact craters? —&gt; The short answer is that none of these cratering effects seem like they could supply enough nitrogen. In our prediction paper, we suggested the next most likely suspect for supplying this N is heat and geologic activity inside Pluto itself. This activity could process nitrogen out of Pluto’s rocky interior and get it to the surface. We currently have only a tiny fraction of the data back from the New Horizons flyby, but the fact that there are young-looking areas on Pluto hints at relatively recent geologic activity. Stay tuned as we get more data back from the New Horizons spacecraft over the coming months, which will refine our estimates of Pluto’s atmospheric escape and provide more images of Pluto’s surface to assess the types and timing of geologic activity.
context_page_description: The Habitable Exoplanet Imaging Mission is a space telescope concept that would be optimized to search for and image Earth-size habitable exoplanets in the habitable zones of their stars, where liquid water can exist. HabEx would aim to understand how common terrestrial worlds beyond the Solar System may be and the range of their characteristics. It would be an optical, UV and infrared telescope that would also use spectrographs to study planetary atmospheres and eclipse starlight with either an internal coronagraph or an external starshade.
  The proposal, first made in 2016, is for a Flagship NASA mission. If selected in 2021, it will operate at the Lagrangian point L2.
context_section_description: In 2016, NASA began considering four different space telescopes as the next Flagship (Large strategic science missions). They are the Habitable Exoplanet Imaging Mission (HabEx), Large UV Optical Infrared Surveyor (LUVOIR), Origins Space Telescope, and Lynx X-ray Surveyor.  In 2019 the four teams will turn their final reports over to the National Academy of Sciences, whose independent Decadal Survey committee advises NASA on which mission should take top priority. Selection is due to take place in 2021, and if selected, launch would be in approximately 2035.
  The Habitable Exoplanet Imaging Mission (HabEx) is a concept for a mission to directly image planetary systems around Sun-like stars. HabEx will be sensitive to all types of planets; however its main goal is to directly image Earth-size rocky exoplanets, and characterize their atmospheric content. By measuring the spectra of these planets, HabEx will search for signatures of habitability such as water, and be sensitive to gases in the atmosphere potentially indicative of biological activity, such as oxygen or ozone.
caption: Pluto's atmosphere backlit by the Sun
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