The Search for Another Earth Exoplanets and the Kepler Spacecraft

The Search for Another Earth Exoplanet Exploration An exoplanet is a planet outside our Solar System. NASA's Exoplanet Exploration Program science and missions represent a voyage of unprecedented scope, promising insight into humankind's most timeless questions: Where did we come from? Are we alone? The primary goal of these explorations is to discover and characterize planetary systems and Earth-like planets.

The Search for Another Earth The Challenge Exoplanets: - Don't produce any light of their own, except when young. - Are an enormous distance from us. - Are lost in the blinding glare of their parent stars. In addition, there are over 100 billion suns in our own Milky Way galaxy to search.

The Search for Another Earth The Challenge (continued) Advances in data-gathering technology and analysis capabilities now provide scientists with the advanced tools and capabilities to enable this exploration of our galaxy. Observation from highly specialized spacecraft supported by ground-based telescopes has become the primary method used.

The Search for Another Earth The Kepler Spacecraft Carrying a a telescope specifically designed for the search for exoplanets, Kepler has been the workhorse of this effort. Kepler's goal is the creation of a statistical survey that predicts how many Earth-like planets likely exist in our galaxy. The spacecraft was launched into a solar Earth-trailing orbit in March 2009 and is continuing its mission in 2014.

The Search for Another Earth The Kepler Spacecraft Carrying a a telescope specifically designed for the search for exoplanets, Kepler has been the workhorse of this effort. Kepler's goal is the creation of a statistical survey that predicts how many Earth-like planets likely exist in our galaxy. The spacecraft was launched into a solar Earth-trailing orbit in March 2009 and is continuing its mission in Video Clip

The Search for Another Earth What has Kepler been looking at? Kepler has been pointed at a single point in the sky (near the constellation Cygnus) and has been constantly monitoring over 100,000 stars in this region for signs of exoplanets. Staring at these stars, Kepler’s specialized telescope instrument measures the changes in light intensity over time using the “transit method” of detection.

The Search for Another Earth Transit Method of Planetary Detection If a planet passes directly between a star and an observer's line of sight, it blocks out a tiny portion of the star's light, thus reducing its apparent brightness. Sensitive telescope instrumentation can detect this periodic dip in brightness. From the period and depth of the transits, the orbit and size of the star’s planetary companions can be calculated. Video clip

The Search for Another Earth Confirming What Kepler Sees The next step is to confirm the findings. A method often used is measuring the “wobble” of the star as the velocity or change of position of stars tells us the extent of the star's movement induced by a planet's gravitational tug. From that information, scientists can deduce its mass and orbit. This can be done by measuring the “doppler shift” of the star’s light frequencies as it moves slightly with the planet’s orbit.

The Search for Another Earth Other Methods of Detecting Exoplanets Specialized optics and observation methods have made some exoplanet images possible. This photo is from the Palomar Observatory in California. The image shows the HR 8799 planets with star’s light blocked. The star is at the center of the blackened circle in the image. The four spots indicated with the letters “b” through “e” are the planets.

The Search for Another Earth Kepler’s Results This diagram shows Kepler’s search grid after nearly five years of steady, detailed data collection of changes in stars’ light intensities due to the “transit” of exoplanets.

The Search for Another Earth What Have We Found? Over 5500 potential exoplanets as of early March 2014, so far of which approximately 1700 have been confirmed. As shown in the exhibit, of the exoplanets confirmed through Kepler and other studies, about 20, a little over 1%, appear to be potentially habitable. Another 69 potential, but unconfirmed, exoplanets may also be habitable. Why?

The Search for Another Earth The Habitable Zone The exoplanet’s size, its distance from star, and its make-up – gaseous, liquid, or rock – needs to be “just right”. Using what we have found in our existing solar system as a model, scientists have defined a set of parameters and applied them to the data we have observed from deep space. It appears that some of these exoplanets have water present.

The Search for Another Earth What’s Next Spacecraft Operations into the future: --Continued operation of Kepler, Hubble and Spitzer Space Telescopes --New operations by Gaia (ESA); launched in December Launch of CHaracterizing ExOPlanet Satellite (ESA) and Transiting Exoplanet Survey Satellite (NASA) in Launch of James Webb Space Telescope (NASA) in GAIA Spacecraft

The Search for Another Earth Future Work As spacecraft and ground-based observations and data are collected, scientists will continue to refine and improve modeling and analysis techniques to characterize exoplanets. From our world light-years away, scientists from all fields (including geology, biology, and meteorology) develop ideas on how life (plant and animal) may exist on these planet as well as develop a better understanding of Earth and its processes.