Kepler mission

The start of NASA s Kepler mission is planned for February 2009 and has goals similar to those of the COROT project, though rather more ambitiousiit is intended to determine the percentage of terrestrial and larger planets there are in or near the habitable zone of a wide variety of stars, and also to determine the distribution of sizes and shapes of the orbits of these planets. 

The Kepler mission also supports the objectives of the future NASA Origins missions Space Interferometry Mission (SIM) and Terrestrial Planet Finder (TPF). 

Kepler Space Telescope a NASA-built optical space telescope that monitors 170000 stars continuously for four years to search for transiting exoplanets. The goal of the Kepler mission is to determine the frequency of Earth-sized planets around other stars. 

RV searches and space based transit missions like ESA s Corot initially, and now NASA s Kepler mission, provide statistics of the occurrence of planets around Sun-like stars. NASA s Kepler telescope that mOTiitors stars for planetary transits was launched in 2009 and is observing one distant stellar field monitoring about 150,000 stars continuously for 5 years with sensitivity for detecting transits down to Earth-size planets around Sun-analogue stars. Several Kepler transit planet candidates from the first data release in February 2011 [9] and about 50 planets from the February 2012 data release [10], with radii consistent with rocky planet models, orbit their host stars in the so called Habitable Zone (see discussion below), providing first statistics of the number of planets and Earth-like planets (etaEarth) in the HZ (see e.g. [11]). 

On March 6, 2009 the Kepler mission was launched (Fig. 6.4). It will sample stars in the solar neighborhood in the Orionarm of our spiral Galaxy. Transits will be observed. Such transits of exoplanets last typically between 2 and 6 hours, the amplitude of brightness variation is on the order of several 100 ppm. The diameter of the telescope used is 0.95 m. A large field of view on the sky will be observed... 

Fig. 6.4 The Kepler telescope which is mtiinly used as a photometer to observe simultaneously the brightness of 100000 stars using 42 CCD ctimeras. Credit NASA, Kepler mission...

Basri, G., Ramos-Stierle, R, Soto, K., Lewis, T, Reiners, A., Borucki, W., Koch, D. The Kepler mission terrestrial extrasolar planets and stellttr activity. In van Belle, G. (ed.) 14th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun. Astronomical Society of the Pacific Conference Series, vol. 384, p. 281 (2008)... 

Now consider the hypothetical problem of trying to teach the physics of space flight during the period in time between the formulation of Kepler s laws and the publication of Newton s laws. Such a course would introduce Kepler s laws to explain why all spacecraft proceed on elliptical orbits around a nearby heavenly body with the center of mass of that heavenly body in one of the focal points. It would further introduce a second principle to describe course corrections, and define the orbital jump to go from one ellipse to another. It would present a table for each type of known spacecraft with the bum time for its rockets to go from one tabulated course to another reachable tabulated course. Students completing this course could run mission control, but they would be confused about what is going on during the orbital jump and how it follows from Kepler s laws. 

Recent discoveries by ground based observations, as well as the Corot and Kepler space-missions, found planets with masses below 10 MEarth and densities akin to Neptune as well as Earth, suggesting that there is not one cut-off mass above which a planet is like Neptune and below which it is rocky like Earth or Venus. Note that the term Mini-Neptune is used for small extrasolar giant planets, not mini-Uranus, even though Uranus is the less massive planet (17.1 and 14.5 Earth masses. 

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