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The selected exoplanet concepts:
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(PLANETQUEST) -- Seven missions designed to hunt for planets orbiting other stars (exoplanets) are among a list of ideas that teams selected by NASA will study for the next generation of astronomy and astrophysics missions.
Jet Propulsion Laboratory, Pasadena, Calif., and Goddard Spaceflight Center, Greenbelt, Md., will manage the studies for the chosen mission concepts.
The final reports will be put up for review in front of the Decadal Survey Committee, which sets the priorities for astronomy and astrophysics studies every 10 years, said Michael Werner, the chief scientist for astronomy and physics at JPL.
"We're delighted at JPL's involvement," said Werner, who is also the project scientist of NASA's Spitzer Space Telescope. "We're looking forward to working with our government, industrial and academic partners to develop really exciting mission concepts."
Planets, planets everywhere
With more than a half-dozen exoplanet mission concepts in the mix, it's clear that the hunt for smaller, Earthlike planets that might harbor life is very much on the minds of NASA and the public.
"The idea has been discussed by thinkers going back to the ancient Greeks, Renaissance thinkers, and all the way up to modern times," said Michael Devirian, manager of the Exoplanet Exploration Program at JPL, which encompasses NASA's planet-finding efforts. "One can imagine primitive man sitting around the campfire, wondering what's outside the circle of light, just as we now conduct our search, outside the circle of light of our sun. The search for other planets touches all of us deep in our psyche, and it's very easy to relate to and imagine what could be out there."
Planet mania is catching the fancy of the younger generation, according to Jakob Van Zyl, who heads JPL's Astronomy and Physics Directorate. "Anytime there's an exoplanet session at a science conference, you have a lot of young people showing up and interested."
The various selections of exoplanet mission concepts span all types of techniques currently being developed to detect planets, according to Devirian. He said NASA plans to issue an announcement of opportunity in 2009 for a moderate-scale exoplanet mission.
"The concepts that we are working on are candidates for this mission," Devirian said. "NASA will wait and see what the Decadal Survey Committee has to say before selecting a mission."
Several planet missions will attempt to zoom in and image giant planets that orbit around some of our neighboring stars. These studies will investigate different types of coronagraphs, mask-like instruments that attach to telescopes to block the harsh, blinding starlight that hides the dimmer planets. By using coronagraphs, scientists can find the comparatively miniscule light from planets orbiting close to these stars. One of these missions combines a coronagraph on the telescope with an external occulter, a starlight blocker flying separately thousands of kilometers away, in order to look very close to a star for planets in orbits similar to the orbit of Earth around our star, the sun.
The remaining two exoplanet missions use interferometers. Interferometers utilize multiple telescopes to simulate an enormous telescope with great resolving power.
One of the missions will test a nulling interferometer to cancel a star's light with the goal of imaging giant planets, and, by seeing light from the ring of dust that marks a planet's orbit, learn about the architectures of planetary systems. The other mission will study a large stellar interferometer - 6 meters, or 20 feet long -- which could be used to find planets by measuring the star's "wiggle," or its reciprocal motion with the planets around it.
"The science of exoplanets is one of the most vibrant and exciting areas to study at this time," Devirian said. "It is also one of the most challenging, so it's very important to conduct these studies to come up with the best approaches for these missions."
The who's who of exoplanet missions
The seven selected science teams and their missions are:
- Access (Actively-Corrected Coronagraphs for Exoplanet System Studies): comparing coronagraphs for exoplanet missions (JPL both manages and is home institution of the principal investigator, John Trauger)
- Davinci (Dilute Aperture Visible Nulling Coronagraph Imager): examining a nulling interferometer (JPL both manages and is home institution for the principal investigator, Michael Shao)
- EPIC (Extrasolar Planetary Imaging Coronagraph): directly imaging exoplanets orbiting nearby stars (Principal investigator Mark Clampin of Goddard Space Flight Center)
- New Worlds Observer: examining a distant external occulter between a telescope and a nearby star (Principal Investigator Webster Cash, University of Colorado)
- PECO (Pupil-mapping Exoplanet Coronagraphic Observer): refining a Phase Induced Amplitude Apodization Coronograph (Principal investigator Olivier Guyon of University of Arizona)
- Planet Hunter: examining a six-meter (26-foot) stellar interferometer (with principal investigator Geoff Marcy of University of California, Berkeley)
- XPC (eXtrasolar Planet Characterizer): examining internal coronagraphs and external occulters (Principal Investigator David Spergel of Princeton University)
