The hunt for planets beyond the solar system went up a gear today, as NASA launched its Transiting Exoplanet Survey Satellite (TESS) from Cape Canaveral Air Force Station atop a SpaceX Falcon 9 rocket. Successor to the Kepler Space Telescope, TESS will survey more than 200,000 of the brightest stars in the neighborhood of our Sun in search for transiting exoplanets.

Previous to the Kepler mission, exoplanets were extremely rare finds with the first one only confirmed in 1992. Thanks to the unmanned Kepler telescope, over 2,300 have been confirmed with thousands more candidates awaiting study. However, Kepler is now on its last metaphorical legs. After the reaction wheels used to hold it steady began to fail, NASA engineers managed to keep it operating in a reduced capacity for an extended mission, but even that is now coming to a close.

Led by MIT's Kavli Institute for Astrophysics and Space Research, TESS is a much more ambitious two-year mission that will look at a wider variety of brighter stars that are closer to the Earth. During its primary mission, it will look at over 200,000 stars in an area of the sky 400 times greater than that surveyed by Kepler, divided into 26 different sectors each measuring 24° by 96°. According to NASA, the spacecraft's cameras will study each sector for 27 days in divisions of two-minutes of arc, or about 1/15th the diameter of the Moon as seen from Earth.

Once on station, TESS will hunt for exoplanets using the transit method. That is, it will monitor the brightness of stars and measure any dips seen in their light curves. These dips can be due to a dark body like a planet passing in front of the star's disc, and by analyzing the curve scientists can deduce its size, orbit, mass, and composition. These stars will be 30 to 100 times brighter than those seen by the Kepler spacecraft and it is estimated that 300 Earth-like planets will be discovered during the primary mission. In addition, by focusing on closer, brighter stars, it will be much easier for earthbound telescopes to conduct follow-up studies.

Today's launch took place at 6:51 pm EDT under clear skies and went off without any major technical problems. The Falcon 9 reached its point of maximum stress one minute and 16 seconds into the launch with the main engine shutting down at the two-minute-29-second mark. The second stage separated three seconds later and fired two seconds after that. It then made two successful burns that placed TESS in a highly elliptical orbit at about 48 minutes into the flight.

Meanwhile, SpaceX's Falcon 9 first stage executed an autonomous burn and returned to Earth, making a controlled powered landing on the drone seabarge "Of Course I Still Love You" in the Atlantic Ocean. This marks the 24th Falcon 9 landing.

Today's launch was delayed from the initial Monday attempt due to issues with Guidance Navigation and Control systems in the Falcon 9. However, NASA reported that TESS remained in excellent health.

The video below is a recording of the live launch webcast.

Sources: NASA, SpaceX

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