Kepler Mission: The Search Earth-like Planets By Kurt Wiehenstroer May 9, 2007

Planet Finding History Mercury 3000 BC Venus, Mars, Jupiter, Saturn Wondering stars 1610 Galileo - telescopic Jupiter Uranus, William Herschel March 13, 1781 Neptune was first observed by Galle and d'Arrest on Sept 23, 1846 Dwarf Planet Pluto was discovered in 1930 by a fortunate accident. Clyde W. Tombaugh. Around PSR B Aleksander Wolszczan

Doppler Shift due to Stellar Wobble Most successful Method larger the planet - more the wobble closer to the star - more the wobble The larger color shift in the spectrum of starlight.

Its light is red shifted Light is blue shifted Longer wavelength Shorter wavelength

Toward us - blue-shifted Away - red-shifted Radial Velocity

Best spectroscopes detect motions of about 15 meters/sec Earth only forces the Sun to move at 0.1 meters/sec orbit and mass Radial velocity 51 Pegasi

Astrometric Method Slight side to side motion of the star caused by the orbiting planet (RA & DEC). Peter van de Kampf tried to confirm exoplanets orbiting Barnard's star using this method in NASA's SIM PlanetQuest mission and the Keck Interferometer I & II (Hawaii) will use this strategy. Sun due to Jupiter at 33 light years

Transit Technique First demonstrated in 1999 on an extrasolar planet An Eclipse: A distant planet moves between us and its star slight decrease in brightness. Kepler mission launch 2008

Secondary Eclipse Technique Star 10,000 or more x brighter than the planet - visible Planets give off infrared = heat Star only 100s x brighter in infrared Star + Planet = Infrared Planet goes behind star, IR of star only Subtract the two = IR of planet

Light rays become bent when passing through space that is warped by the presence of a massive object such as a star. Gravitational microlensing find objects that emit no light or are otherwise undetectable.

Direct imaging Detect the planets themselves. Block out some of the light from the star Take direct photos Technique - starlight nulling. 173 light years, 5J mass, orbit 1700 years around brown dwarf, constellation Hydra

Other methods Polarimetry - polarizied light Star light 'unpolarised', planet light 'polarised' Polarimeters detect polarised light Nulling Interferometry - Pulsar Timing lighthouse light pulses timing altered

Nulling Interferometry The light from individual telescopes can be combined to simulate collection by a much larger telescope. This technique is called interferometry and was pioneered using radio telescopes. It is now being applied to optical and infrared telescopes. This method relies on the wave nature of light. A wave has peaks and troughs. Usually when combining light in an interferometer, the peaks are lined up with one another, boosting the signal. In nulling interferometry, however, the peaks are lined up with the troughs so they cancel each other out and the star disappears. Planets in orbit around the star show up, however, because they are offset from the central star and their light takes different paths through the telescope system. Within five years, a team of astronomers from ESA and ESO will be using a nulling interferometer. The team will use the four 8-metre telescopes of ESO's Very Large Telescope and will combine the beams with GENIE (Ground-based European Nulling Interferometer Experiment). GENIE may be able to take pictures of 'hot' Jupiters but will be hampered by our planet's atmosphere. The Keck Interferometer, for example, will use nulling techniques

Polarimetry Astronomical devices known as polarimeters are capable of detecting just polarized light and rejecting the unpolarized beams. Pulsar timing The main drawback of the pulsar-timing method is that pulsars are relatively rare, so it is unlikely planets will be found this way. Also, life unlikely because of high- energy radiation. In 1992, Aleksander Wolszczan used this method to discover planets around the pulsar PSR

Johannes Kepler German mathematician Astronomer and astrologer Key figure in the 17th century astronomical revolution. Most known for three laws of planetary motion still used today (December 27, 1571 – November 15, 1630) 1. Elliptical orbits 2. Law of Equal Areas - change velocity 3. Time of orbit & distance from Sun

Kepler Mission A NASA Discovery mission selected in 2001 Spaceborne telescope - survey distant stars Determine the prevalence of Earthlike planets. Detect planets indirectly, uses the "transit" method.

Kepler Telescope

37 mirror

FAQs Why can't Earth-size planetary transits be observed from the ground? The atmosphere Don't the stars vary more than the change caused by a transit? The transit will cause more change than the stars like our sun change. Why not use the Hubble Space Telescope? The field of view (FOV) of the HST is too small to observe a large number of bright stars. Are there other photometry missions? MOST and COROT.

Kepler Telescope layout

Visible Stars with Planets 0. Pollux Gemini day

Visible Starts with Planets

Canada's First space Telescope MOST ~ Microvariabilite & Oscillations Stellaires June 30, 2003 low-Earth Polar orbit 820 km high/ 100 mins Suitcase-sized microsatellite (65 x 65 x 30 cm; 60kg) Optical mirror - 15 cm CCD (1024 by 1024 pixels) Photometry Method

COROT (French) COnvection ROtation and planetary Transits. Polar orbit, 827km high, December 27, 2006 Launch vehicle: Soyuz 2.1b 630kg Mirror: 27cm afocal, 2½ year mission Detectors: 4 CCD's 2048 x 2048 wide

COROT finds May 2007 COROT first planet, COROT-Exo-1b, Very hot gas giant, with a radius = 1.78 x Jupiter. Orbits a yellow dwarf star similar to Sun, period of about 1.5 days light years from us, in the direction of the constellation Unicorn (Monoceros). Coordinated spectroscopic observations from the ground equivalent to about 1.3 of Jupiter.

If approved and built, launch in 2014 or later. Infra-red telescope absorption lines water, carbon dioxide and ozone Infra-Red Space Interferometer ESAs Darwin Mission

SIM PlanetQuest SIM PlanetQuest launch in 2015 JPL Positions and distances of stars several hundred times more accurate than any previous program. Optical interferometry - light from two or more telescopes combined to = single, gigantic telescope mirror

Terrestrial Planet Finder (TPF) Two complementary observatories ~visible, infrared Size, temperature, and placement of planets Earth-sized in the habitable zones of distant solar systems. Spectroscopy - life gases like carbon dioxide, water vapor, ozone and methane VisibleInfrared

The James Webb Space Telescope The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope, scheduled for launch in JWST's instruments will be designed to work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range. JWST will have a large mirror, 6.5 meters (21.3 feet) in diameter and a sunshield the size of a tennis court. JWST will reside in an orbit about 1.5 million km (1 million miles) from the Earth.

James Webb Space Telescope Northrop Grumman Space Technology

Gliese 581 c April 2007 Mass(m)> 5.03 ME Radius(r)~1.5 RE Density(ρ)> kg/m3 Temperature(T)~290 K 26.6 F Age ~ 4.3 Billion years Orbital period(P) d Found using radial velocity technique

4/26/2007 Gliese 581 system as rendered in CelestiaCelestia

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