Dean C. Hines[Deputy Principle Investigator]

Exoplanetary Circumstellar Environments and Disk Explorer (EXCEDE):

A new space telescope proposed for NASA’s Explorers program.

Space Science Institute(New Mexico Office)

Glenn Schneider (PI), Olivier Guyon (PS)The University of Arizona

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Terrestrial Planets

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Solar Systems

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Voyager

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Zodiacal Dust

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Zodiacal Dust

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A Vast Zoo of Disk Morphologies

Krist et al. 2007

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Current Status, Limitations, Opportunities

• Current best contrast with HST ~ 10-4

– Ground-based not even close!

• James Webb Space Telescope

– Thermal coronagraphy, but

– Coronagraphic performance similar to HST

• Planet imaging requires 10-9 contrast

– Big apertures needed

– Technology not developed

• EXCEDE –> 10-6–10-7 contrast for terrestrial orbital scales with a sub-meter class space telescope

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Mission Characteristics & Science Payload

• Orbit: Sun-synchronous, 950 km, e = 0, i = 99°, LEO

• Duration: 2 yr after IOC + 1 yr SEOs

• 50-70 cm, unobscured aperture, off-axis telescope

• Passive optics for wavefront error correction

• Phase Induced Aperture Apodization (PIAA) Coronagraph – Suppresses Telescope Diffraction

• Two-band polarimetric imager

– Increased contrast

– Grain characterization

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Mission Characteristics & Science Payload

• Orbit: Sun-synchronous, 950 km, e = 0, i = 99°, LEO

• Duration: 2 yr after IOC + 1 yr SEOs

• 50-70 cm, unobscured aperture, off-axis telescope

• Passive optics for wavefront error correction

• Phase Induced Aperture Apodization (PIAA) Coronagraph – Suppresses Telescope Diffraction

• Two-band polarimetric imager

– Increased contrast

– Grain characterization

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Mission Characteristics & Science Payload

• Orbit: Sun-synchronous, 950 km, e = 0, i = 99°, LEO

• Duration: 2 yr after IOC + 1 yr SEOs

• 50-70 cm, unobscured aperture, off-axis telescope

• Passive optics for wavefront error correction

• Phase Induced Aperture Apodization (PIAA) Coronagraph – Suppresses Telescope Diffraction

• Two-band polarimetric imager

– Increased contrast

– Grain characterization

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Mission Characteristics & Science Payload

• Orbit: Sun-synchronous, 950 km, e = 0, i = 99°, LEO

• Duration: 2 yr after IOC + 1 yr SEOs

• 50-70 cm, unobscured aperture, off-axis telescope

• Passive optics for wavefront error correction

• Phase Induced Aperture Apodization (PIAA) Coronagraph – Suppresses Telescope Diffraction

• Two-band polarimetric imager

– Increased contrast

– Grain characterization

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Why Polarimetry?

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Optics & Science Camera

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Optical Telescope Assembly

Offset PIAA OpticalBench Re-Imaging Optics& Camera

Inside Shroud

Off-Axis SecondaryProvides UnobscuredAperture

Optimized Design Offers Maximum Throughputand No Diffraction Spikes!

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Probing the Habitable Zone

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What We Will See!EXCEDE will image regions inaccessible with current technology. For the 1 Gyr old G2V star HD 107146, EXCEDE will image the inner 60 AU where a giant planet is sculpting the system.

Cen (G2V)HD 82328 (F6IV)

3 AU

EXCEDE will image ≥ 10x Zodi dust clouds orbiting inside the habitable zone for stars within ~10pc of the Earth. Detection would confirm the presence of exo-asteroid belts, with implications for terrestrial planets.

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Placing Our Solar System in Context

• NASA Strategic Plan subgoal 3b: “conduct advanced telescopic searches for Earth-like planets and habitable environments around other stars”

• Science Plan – Strategic Goals and Decadal Outcomes: “understand … the formation of planetary systems” and “create a census of extrasolar planets and measure their properties”

• Science Plan – Targeted Outcomes: “study the birth of … planetary systems,” and “determine what properties of a star… are most strongly correlated with the presence of habitable Earth-like planets”

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Conclusion

• NASA Strategic Plan subgoal 3b: “conduct advanced telescopic searches for Earth-like planets and habitable environments around other stars”

• Science Plan – Strategic Goals and Decadal Outcomes: “understand … the formation of planetary systems” and “create a census of extrasolar planets and measure their properties”

• Science Plan – Targeted Outcomes: “study the birth of … planetary systems,” and “determine what properties of a star… are most strongly correlated with the presence of habitable Earth-like planets

EXCEDE meets these goals for NASA and provides a technology pathfinder for future missions to directly image exo-planets, including those that potentially harbor life!

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Photo Credit: J. McGraw (2008)

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Fin

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