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I can show you the worldsThe Science of Planetary Exploration
Anjali TripathiKirit KarkareSukrit Ranjan
Earth
PlanetsStar
Planets
Solar SystemSun
Outline
• Anjali: Robotically Exploring the Solar System
• Kirit: Detecting Extrasolar Planets
• Sukrit: The Search for Life Beyond Earth
I can show you the worldsHow can we learn about the planets?
Anjali TripathiKirit KarkareSukrit Ranjan
The Naked Eye
Tunc Tenzel (TWAN/The World at Night)
NASA/JPL
Wellcome Library
Telescopes
NASA/JPL
Wellcome Library
Telescopes
AIP
NASA/JPL9
Spacecraft!Spacecraft!
Unmanned, or robotic missions
NASA//ESA/ASI
NASA/JPL
• Allow us to get a closer view
• Get measurements in place
SENSES in space
Orbiter
Flyby
Lander
Voyager I & IIFlying by the Outer Solar
System
12
Voyager I & II
Imaging (WA/NA)
Spectrometers (UV/IR)
Photopolarimeter
PlasmaCosmic Ray
Radio/Plasma Wave Antenna
Magnetometers
Science Instruments
NASA/JPL
Golden Record
Flying by the Gas Giants
Flying by the Gas GiantsVoyager I & II
NASA/JPL
Visited Jupiter, Saturn, Uranus & Neptune
Voyager I & II
Sept ‘77 Aug ‘77
Mar ‘79
July ‘79
Nov ‘80
Aug ‘81
Jan ‘86
Aug ‘89
VOYAGER 1 VOYAGER 2
VOYAGER 1
VOYAGER 2
jupiter has rings
discovery:
NASA/JPL
discoveries:
more moons
3 - jupiter3 - saturn
10 - uranus 6 - neptune
proteus
(neptune)
storms on neptune
NASA/JPL
4,000,000,000 miles awayFebruary 14, 1990
NASA/JPL
4,000,000,000 miles awayFebruary 14, 1990
Not fare well,But fare forward, Voyagers.-- T. S. Eliot, The Dry Salvages
NASA/JPL
10,000,000,000 miles awayToday - Still going!
Orbiting Saturn, Landing on TitanCassini-Huygens
NASA/ESA/ASI
Orbiting Saturn, Landing on TitanCassini-Huygens
NASA/ESA/ASI
NASA/JPL
Cassini-HuygensOrbiting Saturn
NASA/JPL/Space Science Institute
Sept. 15, 2006
You are here
NASA/JPL/Space Science Institute
EARTH
Sept. 15, 2006
discoveries
Enceladus
has icy jets
Prometheus
perturbs Saturn’s rings
NASA/JPL/Space Science Institute
about Saturn’s moons:
Voyager IISept. 4, 1981
1.3 million miles away
Phoebe
CassiniJune 11, 2004
1200 miles away
NASA/ESA/ASI
water frost
NASA/ESA/ASI
a view from the ultraviolet
Phoebe Saturn’s Moon
made of loose dust and ice particles
a view from the infrared - temperature
NASA/ESA/ASI
0
0.46 hours
0.91 hours
2.75 hours
3.16 hours
Time
day-night variation
Phoebe Saturn’s Moon
originated in the Kuiper beltNASA/ESA/ASI
a view from the infrared - mineral distribution
Phoebe Saturn’s Moon
HuygensLanding on Titan
• Imager
• Measure winds using radio
• Analyze the atmosphere
• Measure Titan’s surface
NASA/ESA/ASI
Cassini-
Titan’s wind - the furthest sounds in the Solar System
descent unto Titan
NASA/ESA/ASI
drainage channels
Titan has rain & flows
pebbles
hills
ESA/NASA/JPL/University of Arizona
lakes
of liquid methane
NASA/JPL29
NASA/JPL29
Gas giants
NASA/JPL29
Rocky planets
Spirit!
Opportunity!
NASA
Mars
Mars Exploration RoversRemote Sensing Package Pancam
In-Situ Package Microscopic Imager
Rock Abrasion Tool
Magnetic properties experiment
NASA/JPL
Roving a Rocky World
In-Situ Package Microscopic Imager Alpha Particle X-Ray Spectrometer Mössbauer Spectrometer Rock Abrasion Tool
Remote Sensing Package Pancam Mini-TES
RAT hole water?
NASA/JPL/Cornell/USGS/U. MainzSpirit
water?
different, rippled layers
blueberries
sulphates and standing water
flows
NASA/JPL/Cornell/MPI/U. Mainz
Meridiani Rock and Soil Sample
need water to form
Opportunity
coming soon...
sample return
NASA/JPL/Texas A&M/Cornell
worlds like our own and wildly different worlds.
Spacecraft help us sense
Sunset on MarsSpirit Rover
May 19, 2005
Voyager
Cassini Mars RoversHuygens
I can show you the worldsDetecting Extrasolar Planets
Anjali TripathiKirit KarkareSukrit Ranjan
Outline
• Why is exoplanet detection hard?• How do we detect exoplanets?• What have we found?
NASA/JPL-Caltech/T. Pyle
I want to see an Exoplanet ...
Harvard-Smithsonian CfA, Rob Ratkowski
Can I just point a telescope at a nearby star?
Jupiter and its Moons
Wikimedia
Seeing Exoplanets is HARD!
• Other stars are far away• Planets are faint compared to stars
Alpha Centauri
ESO
How can we see a planet?
John Johnson (Caltech)
Look for two effects on starlight:
Stellar wobbleTransit
Wikimedia
Effect 1: TransitsA planet crossing a star dims the total light
Just like the transit of Venus
Wikimedia
NASA, ESA, and G. Bacon (STSci)
Transits
Transit Light Curve
Charbonneau et al. 2010
Charbonneau et al. 2010 Leger et al 2009
Transit Light Curve
Here at Harvard: MEarth
Zachory Berta (Harvard-Smithsonian CfA)
The Kepler Mission
NASA
Effect 2: Stellar Wobble
John Johnson (Caltech)
The Doppler Effect
As the star moves back and forth, the colors of light change
Wikimedia
The Nature of Light
Wikimedia
• Starlight is a mixture of colors
• Separate the colors with a prism
How a Telescope Separates Colors
Steve Vogt (UCSC)
Spectral Line
John Johnson (Caltech)
Mass
Orbital period
Stellar Wobble Curve
Stellar Wobble Curve
Keck Telescopes
W. M. Keck Observatory
Direct Imaging
NASA
• Block out the
starlight with a coronagraph
• Just like the sun
• Very recent advance
HR 8799, Beta Pictoris
Wikimedia, ESO/A.-M. Lagrange et al.
What Have We Found?
• 700+ planets!
• Strange properties
David Aguilar (Harvard-Smithsonian CfA)
!"#$%#&'()*#+,-./)0,11,23)0,1"(
45)6"7)+'()*#+,-4)0,11,23)0,1"(
51 Peg b
David Aguilar (Harvard-Smithsonian CfA) Seth Shostak (SETI)
GJ 1214 b
NASA/Kepler mission/Wendy Stenzel
I can show you the worldsAstrobiology: The Search for Extraterrestrial Life
Anjali TripathiKirit Karkare
Sukrit Ranjan
Overview
• What is life? What are we looking for?
• Looking for life in our solar system
• Looking for life beyond our solar system (extrasolar planets)
Overview
• What is life? What are we looking for?
• Looking for life in our solar system
• Looking for life beyond our solar system (extrasolar planets)
What Do We Mean By Life?
• Metabolism– Consumes
nutrients, releases wastes
• Earthlike life– Fewer assumptions Wikimedia
What is Earthlike Life?
• Liquid water • Carbon-based
Wikimedia
Overview
• What is life? What are we looking for?
• Looking for life in our solar system
• Looking for life beyond our solar system (extrasolar planets)
Life in Our Solar System? Mars
NASA
Life in Our Solar System? Mars
NASA
Wikimedia
Life in Our Solar System? Europa
Wikimedia
Life in Our Solar System? Europa
NASA/JPL
Life in Our Solar System? Ganymede
Wikimedia
Life in Our Solar System? Ganymede
NASA Wikimedia
Overview
• What is life? What are we looking for?
• Looking for life in our solar system
• Looking for life beyond our solar system (extrasolar planets)
Life in Other Solar Systems
NASA
The Habitable Zone
• Habitable zone: distance from star where liquid water can exist– too close:
water boils– too far:
water freezes Wikimedia via PSU
The Habitable Zone
• “Goldilocks Zone”• Depends on
brightness of star– Brighter stars:
further out– Dimmer stars:
closer inWikimedia via PSU
How Do We Look For Life Lightyears Away?
• Life modifies its environment– “Biosignatures”
• Carl Sagan: Galileo Experiment
NASA/JPL/JHU
Galileo Spacecraft
Galileo’s View of Earth
Biosignatures
• Most detectable feature in Earth’s atmosphere: methane
• Methane in the presence of oxygen is unstable
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
• White light is made up of light of many different wavelengths (colors)
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
• Substances imprint “fingerprints” on light
Spectroscopy: Identifying Chemicals From Afar
• Substances imprint “fingerprints” on lightSpectrum
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
• Substances imprint “fingerprints” on light
Cold gasAbsorption Spectrum
Spectrum
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
• Substances imprint “fingerprints” on light
Hot gas
Cold gasAbsorption Spectrum
Emission Spectrum
Spectrum
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
H
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
H
He
Wikimedia
Spectroscopy: Identifying Chemicals From Afar
H
He
Fe
Wikimedia
Transmission Spectroscopy
Wikimedia/A Feild, STSci & NASA
absorption line spectrumStarlight filters through the planet’s
sodium rich atmosphere.
Transmission Spectroscopy
• Many substances detected for big planets– Water, methane,
sodium...
• Race on to find and study small planets
NASA, ESA, and G. Bacon (STSci)
Towards Earthlike Worlds: The MEarth Project
GJ1214B - steam planetSTSci
Tagxedo.comI can show you the worlds
wobble
Thank you!SITN would like to acknowledge the following
organizations for their generous support.
Harvard Medical SchoolOffice of Communications and External Relations
Division of Medical Sciences
The Harvard Graduate School of Arts and Sciences (GSAS)
The Harvard GSAS Graduate Student Council (GSC)
The Harvard Biomedical Graduate Students Organization (BGSO)
The Harvard/MIT COOP
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