Kepler Spacecraft The Planet Searching Space Telescope
Finding Planets and Solar Systems was Expected, Finding Alien Worlds and Habitable Planets Is Ongoing
Kepler Space Telescope: Project Planet Hunter
Space exploration has been in the doldrums for some time now following several space shuttle accidents costing NASA so much in terms of lost equipment and priceless talent.
Recently, however, unmanned long-range observation projects like the Kepler Space Telescope, have created more than just popular buzz about what's out there in space and the exciting secrets hidden not so far away in the hundreds of planets discovered over the short start of the Planet Detection Project.
Kepler has already discovered gas giants, hot-super-Earths in short period orbits, and ice giants orbiting all sorts of star systems as well as unique phenomenon such as freely-floating planets that aren't orbiting any star at all.
The remaining challenge now is to find the so called Goldilocks Planet ( a rocky planet, one half to twice the size of the Earth), any planet located in the habitable zone of their stars where liquid water and possibly life might exist. More than 10 possible Goldilocks planets have already been singled out and more are still being assessed.
Kepler Mission Scientific Objectives
According to the NASA Kepler website, Kepler Mission is designed to map a fixed part of a star field and by optical survey, mark details of the available planets it finds, how each solar system it maps is structured and the different kinds of planetary systems detected in that sample area.
Determine the abundance of terrestrial and larger planets in or near the habitable zone of a wide variety of stars
Determine the distribution of sizes and shapes of the orbits of these planets
Estimate how many planets there are in multiple-star systems
Determine the variety of orbit sizes and planet reflectivities, sizes, masses and densities of short-period giant planets
Identify additional members of each discovered planetary system using other detection techniques
Determine the properties of those stars that harbor planetary systems.
How does the Kepler Spacecraft Detect Planets?
The Transit Method
When a planet crosses in front of its star as viewed by an observer, the transit causes a slight dimness as the planet blocks the star's light lasting for 1 to 16 hours. This periodic blink will most likely be cause by a planet providing a highly repeatable signal and robust detection method.
Once detected, the planet's orbital size can be calculated from the period (how long it takes the planet to orbit once around the star) and the mass of the star using Kepler's Third Law of planetary motion.
The size of the planet is found from the depth of the transit (how much the brightness of the star dims) and the size of the star. From the orbital size and the temperature of the star, the planet's characteristic temperature can be calculated.
Knowing the temperature of a planet is key to whether or not the planet is habitable (not necessarily inhabited). Only planets with moderate temperatures are habitable for life similar to that found on Earth.
The Kepler instrument is a specially designed 0.95-meter diameter telescope called a photometer or light meter. It has a very large field of view for an astronomical telescope 105 square degrees that is fixed at the same star field in the Cygnus-Lyra region except when it aligns its antenna to earth to send back information.
Kepler monitors 100,000 main-sequence stars for planets and has an expected mission lifetime of 3.5 years that can stretch to at least 6 years at the most. All of its finding are currently recorded in the Extrasolar Planets Encyclopedia, NASA Exoplanet Archive, and New Worlds Atlas.