Areas of Ames Ingenuity: Exoplanets
Our view of the universe has been profoundly – and forever – changed by the recent discovery of worlds beyond our solar system. Nearly a thousand extrasolar (beyond our solar system) planets – often referred to as “exoplanets” – have been confirmed since the first was discovered in 1995.
The vast majority of these exoplanets have been found without being able to see them directly. This exoplanet census will impact fields ranging from science to philosophy, and help frame the ongoing pursuit of one of humanity’s most fundamental questions: Are we alone?
Ames is providing scientific and management leadership of Kepler, NASA’s first mission to discover exoplanets around stars beyond our sun. Launched in 2009, Kepler has already transformed humanity’s perception of the cosmos, having discovered thousands of planetary candidates in orbit around distant stars. By the end of its mission, Kepler will determine the frequency of Earth-size and rocky planets in our home Galaxy. The most important of those planets will be found within the habitable zone of their parent star, where temperatures are conducive to the existence of liquid water. Most research suggests that the presence of liquid water and an energy source, such as heat from a star, are necessary ingredients for creating life – as we know it.
Knowing that exoplanets exist, the ultimate goal will be to directly image and characterize them, in order to assess their ability to host life. Ames is part of a consortium developing the technologies needed to directly image exoplanets with an innovative coronagraph. A coronagraph is a telescope that masks the bright disk of a star, so that faint objects near the star can be detected. This is a monumental challenge, given that the faint planets are always located extremely close to much brighter stars. Ames is an important partner in a consortium pursuing technology development for one of the most promising architectures for imaging exoplanets called Phase Induced Amplitude Apodization (PIAA).
Before directly imaging planets, the PIAA architecture may be tested in space on the EXoplanetary Circumstellar Environments and Disk Explorer (EXCEDE) mission. Ames is teamed with the University of Arizona and Lockheed Martin on this Explorer-class mission designed to image the circumstellar disks of dust around other stars. It is these disks that provide the raw ingredients for future planet formation, while also serving as a source of noise when attempting to directly image faint planets already formed.
Featured example: Kepler - The search for potentially habitable worlds
How are we discovering hundreds of planets while trying to determine the frequency of rocky and Earth-like planets in our Milky Way Galaxy?
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Kepler uses transit photometry to measure tiny and periodic dips in the light received from other stars as unseen planets pass in front of their host star. Sensitive to light dips much smaller than one percent, Kepler will have discovered thousands of new worlds by the end of its mission. It will produce the first estimate of the number of terrestrial, or rocky Earth-like, planets in our Galaxy.
The Kepler concept was formulated and refined at Ames, and the center is responsible for managing the mission, and for science operations and data analysis. Now in an extended mission phase, Ames is committed to making the Kepler data available to the worldwide community as soon as it is downlinked from the spacecraft and calibrated.
Featured example: Ames Coronagraph Experiment
What research and testing is Ames doing that will enable NASA to directly image extrasolar planets in the future?
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The Ames Coronagraph Experiment (ACE) is a laboratory testbed for testing and refining the optical performance of a promising architecture that may enable NASA to directly image extrasolar planets in the future. Based on an innovative design concept, ACE is a high performance prototype developed in collaboration with JPL, the University of Arizona, and the National Astronomical Observatory of Japan.
The PIAA coronagraph uses innovative techniques and deformable mirrors to mask the light of a bright star, taper the optical light beam, and detect dim planets at small distances from their parent star. This approach makes it possible to detect and image Earth-sized planets with compact telescopes as small as 1.4 meters in diameter, reducing the mass – and cost – of previous concepts now deemed unaffordable.This work may allow NASA to build a planet-imaging telescope as soon as the 2020s.
Featured example: EXCEDE
How is a small 0.5-meter diameter telescope being used to directly image and characterize the remnants of dusty debris disks from which planets formed around nearby stars?
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Ames is teamed with the University of Arizona on EXCEDE, an Explorer-class mission concept. EXCEDE will use the innovative PIAA architecture and a small 0.5-meter diameter telescope to directly image and characterize the remnants of dusty debris disks from which planets presumably formed around nearby stars. This will not only provide an important flight demonstration of the PIAA technologies, but will provide critical information on the “exozodiacal” scattered light originating from dust in the circumstellar environment.
These measurements will dramatically impact the design of future exoplanet imaging telescopes, since the reflected light tends to mask the faint planets we are trying to see. The ACE testbed at Ames will be used to improve the technological performance of the PIAA coronagraph, and enhance the possibility that this mission could fly by the end of the decade.