Download Kepler, a Planet Hunting Mission

Kepler, a Planet Hunting Mission
Riley Duren
Kepler Chief Engineer
Jet Propulsion Laboratory,
California Institute of Technology
with thanks to Jim Fanson (Kepler Project Manager)
for slide contributions
Kepler is
NASA’s first mission
capable of finding Earthsize planets orbiting in the
habitable zone of other stars
Speculation on the existence of
other habitable worlds is age-old
[T]here are infinite worlds both like
and unlike this world of ours ... we
must believe that in all worlds
there are living creatures and
plants and other things we see in
this world....
Epicurus (341-270 BC)
Habitable planets must orbit in the
“habitable zone” of their parent star
Habitable Zone ⇒ water can exist in liquid state
Terrestrial Planets
(rocky bodies)
Gas Giant Planets
Trans Neptunian
Objects
Habitable planets should have mass
between about 0.5 Me and 10 Me
< 0.5 Me can’t hold on to a life sustaining atmosphere
> 10 Me holds on to H & He and becomes a gas giant
Mercury
Venus
Earth
Mars
Orbit “within” the Habitable Zone of the Sun
Kepler will discover planets by
observing transits
• A transit occurs when a planet
passes in front of its star and
blocks part of the star’s light.
• Earth-size planets produce
very small reductions in the
star’s brightness (we need to
go to space to detect them).
– Jupiter would block 1% of the
sun’s disk
– Earth (or Venus) would block
only 0.008% of the sun’s disk
Transit of Venus across the Sun
The Kepler Spacecraft
Photometer
Solar Array
Spacecraft
Bus
The Photometer is a wide-angle
“Schmidt camera” telescope
0.95 m dia Schmidt Corrector Lens
95 megapixel Camera
Sunshade
Metering Structure
1.4 m dia Primary Mirror
Kepler 95 Megapixel Focal Plane
Kepler will monitor 100,000 stars
across >100 deg2 of sky
Kepler field of view projected
onto the sky
Kepler’s field of view is
>35,000 times larger than the
Hubble’s
Art copyright Jon Lomberg www.jonlomberg.com
Earth-trailing solar orbit provides stable
thermal environment and continuous viewing
Kepler Ground Segment Elements
STScI
DSN Madrid
ATCA
DSN Goldstone
DSN Canberra
Kepler Launched on a Delta-II Rocket
Kepler Launched March 6, 2009
©2009 Ben Cooper
http://www.launchphotography.com
Kepler departed the vicinity of the Earth-Moon
system within a few days
“First Light” Image from Kepler
The field of view contains 4.5 million stars
NGC 6791 is an open star cluster
13,000 light years from Earth
TrES-2 is one of three known Hot Jupiters
orbiting stars in the Kepler field of view
MOON
Kepler’s results will be profound
• Kepler will complete a statistically significant census of
planets around 100,000 sun-like stars
– If such planets are common, Kepler will detect about a hundred
– If Kepler detects none, then Earth-like planets are very rare...and we
may be alone in the galaxy
Sun-like
POTENTIALLY HABITABLE PLANETS
EARTH-SIZE PLANETS NOT IN THE HZ
The planet hunt is on!
•
•
10 days of calibration data produced first new science result in light
curve of known hot Jupiter exoplanet HAT-P7b
Planet is so hot (2,650K) it glows like a hot ember
Transit signature of planet
passing in front of star
Sinusoidal light curve due to
“phases” of the planet as it
orbits star
Eclipse of planet passing
behind star. This is similar in
depth to an Earth-size planet
transit.
Kepler’s optical phase curve of the exoplanet HAT-P-7b, W.J. Borucki, et al, Science, Vol 325, 7 Aug 2009
Stay Tuned…
Kepler Mission Website
http://kepler.nasa.gov
backup
Mission is named in honor of
Johannes Kepler (1571-1630)
• German mathematician &
astronomer
• Best known for “Kepler’s
laws of planetary motion”
1.
2.
3.
Kepler's elliptical orbit law: The planets
orbit the sun in elliptical orbits with the
sun at one focus.
Kepler's equal-area law: The line
connecting a planet to the sun sweeps
out equal areas in equal amounts of time.
Kepler's law of periods: The time
required for a planet to orbit the sun,
called its period, is proportional to the
long axis of the ellipse raised to the 3/2
power.
• Successfully predicted the
1631 transits of Mercury &
Venus
Kepler Project Organization
Laboratory for Astronomy & Solar Physics (LASP)
-Mission Operations Center
Space Telescope Science Institute (STScI)
-Data Management Center
Ball Aerospace & Technology Corp (BATC)
-Spacecraft Prime Contractor
NASA Ames Research Center (ARC)
-Science Principal Investigator
-Science Operations Center
ATCA
Jet Propulsion Laboratory (JPL)
-Project Management
-Systems Engineering
-Deep Space Network
DSN Goldstone
DSN Canberra
Selection of the Kepler field
• Rich in stars but not too crowded (near galactic plane)
• Continuous viewing zone (away from ecliptic plane)
• Ground based follow-up (Northern hemisphere)
Ground-based methods can’t find Earthlike planets orbiting Sun-like stars
• About 350 planets are
known to orbit other stars.
– Most found by the radial
velocity method; about a
dozen have been found by
the transit method
– All but a few are gas giants
– Most have very short
period orbits (“roasters”)
– None are “habitable”
• Kepler is optimized to find
Earth-size (and smaller)
planets orbiting in the
habitable zone of sun-like
stars.
http://planetquest1.jpl.nasa.gov/atlas/atlas_index.cfm
Kepler in checkout at the Cape
Commissioning was accomplished in
approximately two months