page_title: Habitable Exoplanet Imaging Mission
section_title: Preliminary desired specifications
hierarchical_section_title: Habitable Exoplanet Imaging Mission / Preliminary desired specifications
caption_attribution_description: Français&#160;: Starshade Artist's Concept 2 How do we find Earth-like planets outside our solar system? One idea is to send a giant structure that blocks starlight so that astronomers can more easily detect orbiting planets. This artist's rendering shows the proposed starshade concept flying in sync with a space telescope. The giant sunflower-like structure would be used to acquire images of Earth-like rocky planets around nearby stars. The proposed starshade could launch together with a telescope. Once in space, it would separate from the rocket and telescope, unfurl its petals, then move into position to block the light of stars.
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: Based on the science drivers and purpose, the researchers are considering direct imaging and spectroscopy of reflected starlight in the visible spectrum, with potential extensions to the UV and the near infrared parts of the spectrum. The telescope has a primary monolithic mirror that is 4 m (13 ft) in diameter.
  An absolute minimum continuous wavelength range is 0.4 to 1 μm, with possible short wavelength extensions down below 0.3 μm and near infrared extensions to 1.7 μm or even 2.5 μm, depending on the cost and complexity.
  For characterization of extraterrestrial atmospheres, going to longer wavelengths would require a 52 m (171 ft) starshade that would launch separately on a Falcon Heavy, or a larger telescope in order to reduce the amount of background light. An alternative would be to keep the coronagraph small. Characterizing exoplanets at wavelengths shorter than ~350 nm would require a fully UV-sensitive high contrast optical train to preserve throughput, and will make all wavefront requirements more stringent, whether for a starshade or a coronagraph architecture.  Such high spatial resolution, high contrast observations would also open up unique capabilities for studying the formation and evolution of stars and galaxies.
caption: Proposed architecture: starshade with space observatory
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