Transcript How to Become a Planet Hunter-Careers in

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NASA: How to Become a Planet Hunter:
Careers in Space Science
Presented by: Dr. Stephen Edberg
May 24, 2012
Exoplanet Discovery and
Exploration: Expanding
Geography Outside Our Solar
System
Stephen J. Edberg
Exoplanet Exploration Directorate
NASA Jet Propulsion Laboratory
California Institute of Technology
There are 200 billion stars in our galaxy…
…one of them is our Sun.
The Sun has eight (or nine) planets…
…we know of one that has life.
What about elsewhere?
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
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artists
educators
public affairs officers
business managers
and others
Stars are a billion
times brighter…
…than the planet
…hidden
in the glare.
Like this firefly.
Planet Discovery Methods
• Direct Imaging (Vis & IR)
• Radial Velocity
• Transits
• Gravitational Microlensing
• Astrometry
• Pulsar Timing
Planets by Direct Imaging
Radial Velocity - 1
NO
Radial Velocity - 2
BLUE
Radial Velocity - 3
RED
Radial Velocity - 4
Single Line “Binary” - Planet
Planets by Radial Velocity:
Actual Observation Method
Star Spectrum
Iodine Spectrum
540-775 nm
Single Line “Binary” - Planet
Planets by
Radial Velocity
Without Iodine Cell
Planets by Transit - 1
Planets by Transit - 2
Kepler Spacecraft
Transit Geometry
Starlight passing
through the planet’s
atmosphere.
z
T( z, )
By observing the
spectrum of the star +
planet as the planet
transits, we can
determine the height of
the atmosphere where it
becomes opaque and
determine its chemical
composition.
Traub
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Transit/Occultation Weather Map
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
educators
public affairs officers
business managers
and others
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Gene Serabyn
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
educators
public affairs officers
business managers
and others
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Diana Blaney
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
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physicists
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mathematicians
computer scientists
engineers
artists
educators
public affairs officers
business managers
and others
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Ara Chutjian
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
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mathematicians
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computer scientists
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engineers
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artists
educators
public affairs officers
business managers
and others
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Jan & Paul Chodas
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
educators
public affairs officers
business managers
and others
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Jeanne M Holm
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
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artists
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educators
public affairs officers
business managers
and others
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Sanjoy S Moorthy
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
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educators
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public affairs officers
business managers
and others
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Leslie L Lowes
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
educators
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public affairs officers
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business managers
and others
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Carolina Carnalla-Martinez
There is a role for everyone who wants
to be a part of this great exploration.
Contributors include:
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astronomers
planetary scientists
physicists
mathematicians
computer scientists
engineers
artists
educators
public affairs officers
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business managers
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and others
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Joanne Kennedy
What We Know
What We Want to Know
• About Planets
• About Planetary Systems
Knowledge and Ignorance of Extrasolar Planets
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What we do know
– Giant planet occurrence is high: ~7%
– Mass distribution extends to near Earth’s mass
– Eccentric orbits are common: scattering?
– Many multiple systems of giant planets are known
What we don’t know
– Existence of terrestrial planets
 Are there low-mass planets in the ‘habitable
zone’? Super-Earths certainly.
– Mass distribution of planets is incomplete and has
strong selection effects
 What about spectral type?
 Stellar age?
 Evolutionary state?
Planetary Systems: Questions
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Statistics of planetary
systems
– How common are
planetary systems?
– Are certain star types
favored?
– What is the distribution of
planetary systems in the
Galaxy?
Characterizing planetary
systems
– What are the orbit radii?
– Are the orbits circular or
eccentric?
– Are multiple-planet
systems common?
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For multiple planet systems
– What is the typical mass
distribution of planets in a
system?
– What is the typical radius
distribution?
– Are the orbits co-planar?
 Must have astrometry
to answer this
– Are the planets’ orbits
stable?
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What We Want to Know
• About Planets
• About Planetary Systems
How do we find out?
You can help us!
Planets by Stellar Wobble
Small planet
Massive planet
Principle of Astrometric Planet
Detection
How Much Wobble?
It can be measured with an accuracy
of about 1 μas (quite a bit thinner
than the line plotted here).
“The wobble effect”: our
Solar System as seen at 10 pc distance
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1 tick mark = 200 µas
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Sun-Jupiter wobble = 500 µas
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Sun-Earth wobble = 0.3 µas
Ordinary Telescope – Optical, IR, Radio
An ordinary telescope collects electromagnetic
radiation, forms an image which is then analyzed to
determine the nature/position of the object in the field
of view.
Telescope
Telescope
Resolution Sensitivity
 /D
detector
 = wavelength
diameter (D)
Airy Disk
D
Michelson Stellar Interferometry
An interferometer combines the light from two or
more small telescopes (Mersenne) to yield the
angular resolution of a much larger telescope.
Interferometer Resolution
Interferometer
 /B
 = wavelength
Telescope (d)
Combiner & Telescope (d)
detector
baseline (B)
Fringe
Pattern
Sensitivity
 (2*d*B)
SIM Lite could have made
measurements precise enough to
find Earths orbiting other stars.
But What Is a Habitable Planet?
A good planet is:
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Not too
big
Not too small
Not too hot or too cold
New spacecraft will be able to find planets similar in mass to
Earth, at the “right distance” from their host stars. We can
study them with advanced telescopes like...
Terrestrial Planet Finder – Interferometer
(TPF-I)
International TPF-I / Darwin:
Emma X-Array
Terrestrial Planet Finder – Coronagraph
(TPF-C)
Jupiter
Earth
Images from
3 Types of Coronagraph
Terrestrial Planet Finder – Occulter
(TPF-O)
Planet
Target Star
NWD Starshade
JWST
• Big telescope (planet is faint!)
• Big occultor (few times size of
telescope)
• Big separation (to see close to star)
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Color Gives a First Impression of a Planet
Solar system planets
have colors that label
them by type.
Planet spectra
Blue (0.4-0.6 m),
Green (0.6-0.8 m),
Red (0.8-1.0 m)
Vegetation as a Surface Biosignature
Visible photo
Near-infrared photo
S. Seager
TPF Investigations
The TPFs can distinguish
between planets...
Searching for Other Earths
You can search for other Earths if you
• Want to explore new worlds.
• Read and learn as much as you can in the subject that
interests you.
• Learn to share your ideas clearly in writing.
Searching for Other Earths
http://planetquest.jpl.nasa.gov/
and, for my Aliens vs. Editor blog,
http://planetquest.jpl.nasa.gov/ave
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