I can show you the worlds - Science in the NewsOutline • Anjali: Robotically Exploring the Solar System • Kirit: Detecting Extrasolar Planets • Sukrit: The Search for Life Beyond

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?


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


EARTH

Sept. 15, 2006

discoveries

Enceladus

has icy jets

Prometheus

perturbs Saturn’s rings


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


originated in the Kuiper beltNASA/ESA/ASI

a view from the infrared - mineral distribution


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


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


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


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 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




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




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

https://www.e-education.psu.edu/astro801/files/astro801/image/Lesson%2012/491px-Habitable_zone-en_svg.png


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


• Substances imprint “fingerprints” on light


• Substances imprint “fingerprints” on lightSpectrum

Wikimedia



Cold gasAbsorption Spectrum

Spectrum

Wikimedia



Hot gas

Cold gasAbsorption Spectrum

Emission Spectrum

Spectrum

Wikimedia


H

Wikimedia


H

He

Wikimedia


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

Documents

I can show you the worlds - Science in the NewsOutline • Anjali: Robotically Exploring the Solar System • Kirit: Detecting Extrasolar Planets • Sukrit: The Search for Life Beyond