Planet-Hunter search for Earth 2.0 NASA’s new mission

What we have found so far ?

Until 25 years ago we didn’t knew any other planets anywhere in the universe. With the help of Kepler Space Telescope, astronomers now know of over 3500 exoplanets between 300 and 3000 light years away. This finding is about to reach 20000 by 2020, thanks to Transiting Exoplanet Survey Satellite (TESS). This satellite is due to launch into space by SpaceX Falcon 9 rocket from Cape Canaveral, Florida on April 16 2018.

TESS by NASA
TESS by NASA [source Astrobiology Magazine]
What could be found ?

TESS is more capable than Kepler and will find exoplanets and other data about them. Based on data by Kepler by going around about 150,000 stars in a very small area of our own Milky Way Galaxy, astronomers estimate that there could be 100 billion exoplanets out there.

TESS Camera
TESS Camera [source NASA ]
It was planned long ago by Massachusetts Institute of Technology (MIT) originally using seed funding from Google. It will be first time that astronomers will be able to get accurate data on sizes, masses and ages of Earth like planets. “We expect TESS will discover a number of planets whose atmospheric compositions hold potential clues to the presence of the life, which could be precisely measured by future observers,” George Ricker, TESS principal investigator at MIR’s Kavli Institute of Astrophysics and Space Research in Cambridge, which is leading the mission.

Kepler vs TESS

Kepler created a huge database long ago which is still used by Google’s AI team to discover new exoplanets, in 2013 its motors got damaged and was no longer to orient itself. Even if it could survived it was due to run-out of fuel this year.

Kepler had a very specific way of looking for exoplanets in its first phase; it started at one small patch of the sky near the constellation of Lyra. Tess has different strategy, its going to study the whole sky.

The location where it will search for exoplanets

TESS will look at stars less than 300 light years away and 30 to 100 times brighter than Kepler’s targets, this is the first two year task of TESS. The light from the exoplanets can help astronomers determine its mass, density and atmospheric composition, and whether there’s any water in its atmosphere.

It will divide the sky into two areas, south for the first year and north for the second year and splice each area into 13 sectors. It will look at each sector in turn, for 27 days each, in the hope of capturing transiting planets. The TESS will study 85% of the sky, which is about 350 times more sky than kepler observed.

The Technology behind TESS

It has incredible cameras, each ultra-wide angle camera has seven lenses to bring the stars into focus, can see a 24 degree-wide square of sky, and has 16.8 megapixel detector behind it.

“CCDs that you can go out and buy are very thin, just two or three microns,” Ricker.” The TESS CCDs are 100 microns thick so they can get near-infrared light and they’re about 100 times better than one in your iPhone.”

It will sit in high-earth, highly elliptical orbit where it will stable for a decade. When TESS swings past Earth every 13.7 days it will begin a three hour downlink of all its data to the NASA Deep Space Network.

How TESS will identify exoplanets ?

The method will be same as of Kepler the transition method, in this method when a planet passes in front of its star, it causes a periodic and regular dip in the star’s brightness, which TESS will detect.

There is one huge limiting factor on what TESS, and any orbiting space telescope, can see is line of sight. In our solar system all planets are generally on the same plane as one another but TESS will only ever find exoplanets whose orbits happen to be perfectly aligned with its point of view.

TESS and JWST will work together

TESS will largely compile an interstellar to-do list for the much more advanced James Webb Space Telescope (JWST). “The JWST is a very large telescope with a set of mirrors 6.5m across, so it’s capable of capturing much more light than TESS,” Paul Hertz, director Astrophysics Division at NASA Headquarters in Washington. “The JWST has spectrometers that can split-up the light and see what kinds of gases are in the atmosphere of planets.”

When the JWST was first conceptualised, not a single exoplanet had been discovered. However this planned event took a knock when JWST had its launch date pushed back from June 2019 to 2020.

Future Planet Seekers

Planetary Transits and Oscillations of Stars (PLATO), an array of 26 small telescope that the European Space Agency plans to launch in 2026. On its four or eight years mission while orbiting 1.5 million km beyond Earth, PLATO will focus on finding Earth-sized planets and super-Earths orbiting Sun-like stars in the habitable zone. It will measure the radii, masses and ages of planets, and even study seismic activity in their host stars.

Exoplanets Missions
Exoplanets Missions [source NASA ]
After PLATO the next generation Wide Field Infrared Survey Telescope (WFIRST) will succeed JWST and tentatively planned to start in the mid 2020. It will have an advanced coronagraph that can study nearby exoplanets.

“There are 100 stars within 20 light years of Earth that likely have planets,” Jeff Volosin, TESS project manager, NASA’s Goddard Space Flight Centre, Greenbelt, Maryland. “If robotic missions could travel at 20% of the speed of light, something that might be possible by the 22nd century, there’s a high probability that many of the stars and planets that will be targeted will be those that TESS is about to find.”

Information source from Techradar

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