generalspeaking

Friday, April 13, 2018

Reaching For The Stars To Discover Planets

"We learned from Kepler [NASA's planet-hunting space telescope] that there are more planets than stars in our sky, and now TESS will open our eyes to the variety of planets around some of the closest stars."
"TESS will cast a wider net than ever before for enigmatic worlds."
Paul Hertz, director, NASA's astrophysics division

"There are 20 million stars we can look at. Galaxies, stars, active galactic nuclei."
"TESS [transiting exoplanet survey satellite] looks like a little toy inside the Falcon 9."
George Ricker, M.I.T. researcher, leader, TESS team

tess transiting exoplanet survey satellite ccd sensor nasa

George Ricker, the principal investigator of TESS, holds up a spare silicon wafer of camera sensors that will be used in the spacecraft. Bill Ingalls/NASA

"Most of the stars with planets are far away. Tess will fill in planets around nearby stars."
"This is the era of the M dwarf. Personally, I will always hold out for the true Earth twin, one we feel a kinship with."
Sara Seager, planetary scientist, Massachusetts Institute of Technology

TESS, transiting exoplanet survey satellite telescope illustration NASA

In several days' time TESS will leave Earth's orbit with its multiplicityof cameras, ascending on a SpaceX Falcon 9 rocket to become a temporary fixture between Earth and its moon. For the following two years it will be deployed, scanning the sky for the presence of those elusive, alien worlds as the latest effort mounted to see if the questions that have intrigued us for millennia dominating astronomy can be answered.

Are we alone in the Universe as sentient creatures manipulating our environment and looking for answers to creation? Are there other habitable planets like our own? It wasn't all that long ago when it wasn't known by astronomers that planets existed outside our solar systems. Until 1994 when a planet circling a sunlike star, 51 Pegasi, was discovered, and science felt assured that answers were waiting to be found.

Kepler, launched by NASA in 2009, informed astronomers of the presence of four thousand possible planets in one limited area of the Milky Way alone. Now, astronomers are convinced that billions of potentially habitable planets exist in our galaxy. Close, but not too close, estimated at ten to fifteen light-years' distance from Earth.

tess transiting exoplanet survey satellite coverage zone zone night sky vs kepler nasa

The TESS exoplanet search zone compared to that of the Kepler Mission. Zach Berta-Thompson/NASA

TESS is being dispatched to take over from Kepler, to find those planets that will be close enough to examine with telescopes, even for an interstellar robot to make an exploratory visit. Leader of the TESS team, M.I.T. researcher George Ricker feels that the presence of at least 500 Earth-sized planets will be found within 300 light-years of our globe. TESS will be capable of precise brightness measurements.

It is anticipated that most exoplanets will be represented by orbiting stars called red dwarfs, smaller and cooler than our sun, making up the greater majority of stars in the universe, and there most of the planets may be discovered, in our own neighbourhood of outer space. Those planets will be monitored by TESS using the light from stars, detecting slight light blips meaning a planet passes in front of its star.

Planners of this mission expect to catalog 20,000 new exoplanet candidates in various shapes and sizes, anticipating they will succeed in identifying the masses and orbits of 50 new planets less than four times Earth's dimensions. That would be a reflection of most planets in the universe but no examples have been discovered in our solar system so "we don't know anything about them", noted Dr. Seager.

NASA has contracted with SpaceX for the first time for one of its science missions. The four small cameras meant to stare at sections of sky for 27 days at a time mounted on TESS have a formidable task ahead of them. In year one researchers plan to survey the southern hemisphere of the sky and in year two the northern sky. An extended mission will result in a repeat.

200,000 nearby stars will have their brightness measured every two minutes with images of the entire 24-degree swaths of sky recorded every half-hour, perfect for finding and studying favourites in the race to locate habitable exoplanets -- M dwarfs, in the language of astronomy.