Imaging Exoplanets: From Adaptive Optics to Starshade In Space

SETI Talks

Tags: Exoplanets, Planetary Exploration, SETI Talks

Time: Wednesday, Jan 15, 2020 -

Location: SRI International Headquarters, 333 Ravenswood Ave., Menlo Park, CA 94025

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Direct imaging of exoplanets – “seeing” the planet as a separate point of light near a star - is extremely difficult, and several decades ago, scientists used to say that it would be impossible to image Earth-like exoplanets. Today this seems possible, using some combination of adaptive optics technology, coronagraphs, or starshades. Adaptive lets telescopes on the ground compensate for the Earth’s atmosphere. Coronagraphs use ultraprecise masks inside telescopes to block the diffracted light from a bright star. Starshades combine a space telescope with a huge flower-shaped spacecraft that flies in formation to block the starlight before it even reaches the telescope.. So what are we waiting for? What are the technological difficulties that make the development of exoplanet-hunting space telescopes so challenging? The future NASA Wide-Field Infrared Survey telescope could test out some of these technologies by studying Jupiter-like planets, and the proposed Habitable Planets Explorer (HabEX) mission could fully integrate them in a search for earthlike planets around dozens of nearby stars.

We invited two experts, astronomers and engineers, to discuss the progress in developing this technology and its future:

  • Jeremy Kasdin, Professor at USF and Princeton University, is the leader of the coronagraph science (the Adjutant Scientist) for NASA's WFIRST mission and has worked extensively on developing the technology for starshades.
  • Bruce Macintosh, Professor at Stanford University, lead an exoplanet Science Investigation Team for the coronagraph instrument on the WFIRST mission and also has proposed mDOT, a microsatellite starshade demonstrator that would use a mini-starshade in low Earth orbit.


Both have been extensively involved in the development of coronagraph technology on Earth and for future space missions. 

Jeremy Kasdin

N. Jeremy Kasdin is a professor at Princeton University in the Mechanical and Aerospace Engineering department with an affiliated appointment in Astrophysics.  Since July 2014 he has been Vice Dean of the School of Engineering and Applied Sciences.  Prof. Kasdin received his BSE from Princeton University in 1985 and his MSE and Ph.D. in 1991 from Stanford University’s department of Aeronautics and Astronautics.  From 1991 to 1998 Prof. Kasdin was a project manager and the chief systems engineer for NASA's Gravity Probe B spacecraft, a satellite test of Einstein's General Theory of Relativity (GP-B was launched in April, 2004).  Prof. Kasdin joined the Princeton faculty in September, 1999, where he researches space systems design, astrodynamics, control and space telescope optics, with a particular focus on exoplanet imaging.

After coming to Princeton, he created the collaborative team investigating high-contrast imaging techniques for detecting and characterizing terrestrial exoplanets.  That group has pioneered the use of pupil-plane coronagraphs and external occulters for space based imaging.  The Princeton team has also developed some of the key techniques for wavefront control with a coronagraph.  Princeton led the astrophysics mission concept study for THEIA, a 4-meter telescope with an external occulter for exoplanet characterization and UV imaging.   Prof. Kasdin has led several Technology Demonstration for Exoplanet Mission studies for NASA analyzing both coronagraphs with wavefront control and external occulters.  He currently sits on the Science Definition Team for the WFIRST-AFTA mission.  Prof. Kasdin is also principal investigator for the CHARIS instrument (Coronagraphic High Angular Resolution Imaging Spectrograph), a high-contrast exoplanet spectrograph to be installed on the Subaru telescope at Mauna Kea in Hawaii in 2016.

Bruce Macintosh

Bruce Macintosh is a professor of physics at the Kavli Foundation of the Stanford University. His  main focus is the direct detection and characterization of extrasolar planets and the use of adaptive optics technology to control light. Bruce is Principal Investigator for the Gemini Planet Imager (GPI) instrument. Bruce led a 600-star survey using GPI that discovered and characterized ten giant planets or brown dwarfs around nearby stars. Bruce is also involved in preparations for the proposed exoplanet coronagraph on the WFIRST-CGI telescope and other approaches to studying extrasolar planets such as the mDOT mission.