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OUT OF THIS WORLD | What's Up In Space - the biggest news coming down to Earth from space

NASA TESS set to reveal thousands of alien worlds around us

Scott Sutherland
Meteorologist/Science Writer

Wednesday, April 18, 2018, 7:57 PM - NASA's newest exoplanet hunter, TESS, is now in space, and set to draw back the veil on our universe, to reveal the thousands of alien worlds that are no doubt surrounding us.

On Wednesday, April 18, at 6:51 p.m. EDT, NASA's newest mission to locate alien worlds - the Transiting Exoplanet Survey Satellite, aka TESS - lifted off from Kennedy Space Center, atop one of SpaceX's Falcon 9 booster rockets.

Just over nine years ago, NASA launched the Kepler Space Telescope, which has found over 2,600 confirmed alien worlds, and an even greater number of 'candidate' worlds, which are simply awaiting confirmation from other sources. Kepler accomplished this by initially fixing its gaze down the local branch of our galactic spiral arm, at one specific batch of around 100,000 stars, watching for what are known as 'transits' (explained below). After three years of operation, the telescope suffered failures of its reaction wheels, which were responsible for keeping its light-collecting instrument steady. Rather than scrapping the mission, the team devised a clever method of continuing, by using the Sun's light to steady the telescope. Under this revised 'K2' mission, Kepler has continued to search for alien worlds, but did so by adjusting its field of view to a different patch of space along the solar system's ecliptic plain, every three months or so. According to NASA, Kepler is now nearing the end of its mission, as its fuel reserves run low.

Now, TESS it will take up the search for exoplanets from Kepler, but rather than looking at only one patch of the sky, this new satellite will scan nearly the entire sky around us, during its first two years in space.

Watch below to see the field of view of TESS, and how it plans to scan space around us.

In order to accomplish its mission, TESS will use a unique orbit around the Earth, unlike anything used before.

TESS's elliptical, highly-inclined orbit around Earth. Credit: NASA's Goddard Space Flight Center

This was the second attempt for NASA and SpaceX to launch TESS. On Monday, April 16, with a little over two hours remaining before the mission's 6:32 p.m. ET liftoff, SpaceX reported that they were standing down for 48 hours, to conduct additional Guidance, Navigation and Control analysis on their Falcon 9 launch vehicle.

How do you find exoplanets?

There are a few ways to tell if there are planets orbiting around a distant star.

You can directly image them, but this is very difficult, and only captures the largest planets, and those in the most distant orbits around their stars. You can watch for a wobble in the star's light, caused as a planet drags the star around in a bit of a stellar dance. Again, this tends to only find the largest planets. You can even use spacetime itself, as a planet's gravity forms a gravitational lens, warping the light from stars directly beyond your star of interest. This, too, only tends to find the largest planets, since they create the largest gravitational lens.

The most successful method at finding planets, and the best at finding smaller, rocky worlds, is the 'transit method'.

Here, you aim a very sensitive, very steady telescope at a distant star, and watch that star, constantly, for as long as possible. If the star's light dims briefly, and does so regularly, by the same amount, it is very likely that you're seeing a planet pass between your telescope and that star. 

Watch below as NASA demonstrates how a 'transiting' exoplanet shows up to a telescope like Kepler or TESS

TESS will use this method as it concentrates on over 200,000 of the brightest stars around us, out to about 300 light years, which will be far brighter than most of the stars studied so far by Kepler. This will provide much more information on these targets, as the spacecraft's cameras spend a total of 27 days on each sector of space. The telescope's cameras will also pick up stars beyond, potentially covering up to hundreds of millions of stars during its mission.

The combined field of view of the four TESS cameras (left), how each of the 26 observation sectors (13 per hemisphere) fit together during the first two years (centre), and the duration of observations for different regions of the celestial sphere, taking into account overlap of TESS's field of view. The dashed black circle around the ecliptic pole is where the James Webb Space Telescope will be able to observe at any time. Credit: NASA GSFC

This schedule will limit TESS's ability to spot repeat transits, except for those planets orbiting closely around red dwarf stars. By scanning nearly all of the space around us, though, the satellite still has a chance to pick up thousands, possibly tens or hundreds of thousands of transiting planets during its initial 2-year scan, simply due to the number of potential planets that are around us, and it may even find things that we can not even anticipate at this time.

"I don’t think we know everything TESS is going to accomplish," Stephen Rinehart, TESS project scientist at NASA’s Goddard Space Flight Center, said in a NASA statement. "To me, the most exciting part of any mission is the unexpected result, the one that nobody saw coming."


Watch Below: New exoplanet-hunting satellite will scan nearly the entire sky for alien worlds

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