This test image from one of the four cameras aboard the Transiting Exoplanet Survey Satellite (TESS) captures a swath of the southern sky along the plane of our galaxy. TESS is expected to cover more than 400 times the amount of sky shown in this image when using all four of its cameras during science operations.
NASA’s newest planet-hunting spacecraft, TESS, just snapped its first test shot — an incredibly clear, star-studded image centered on the Southern constellation of Centaurus. The two-second test exposure using only one of the Transiting Exoplanet Survey Satellite’s (TESS) four cameras reveals more than 200,000 stars .
“We are truly excited about how well the TESS cameras are working,” George Ricker, the TESS mission’s principal investigator and a planetary scientist at MIT, told me. “This beautiful image just popped up on the MIT payload operations display screens right after initial turn-on of the TESS instrument.”
The edge of the Coalsack Nebula is in the right upper corner of the test image, says NASA, and the bright star Beta Centauri is visible at the lower left edge. During its nominal two-year mission, NASA says TESS is expected to cover more than 400 times as much sky as shown in this initial test image. A higher-quality ‘first light’ science image is expected in June .
After successfully passing about 5000 miles from the moon during a May 17 lunar flyby, TESS is now en route to its 13.7-day Earth orbit. Once there by month’s end, TESS will begin its nominal two-year science mission, finding and characterizing extrasolar planets, ranging in size from small rocky planets with masses similar to Earth on up to gas giants.
Four wide-field cameras will give TESS a field-of-view that covers 85 percent of the entire sky. TESS will tile the sky with 26 observation sectors, spending some 27 days focused on each sector and is expected to map the Southern hemisphere in the first year of operations, with a map of the Northern hemisphere coming in the second year.*
TESS will monitor the brightnesses of more than 500,000 stars and is expected to catalog more than 3000 exoplanet candidates, says NASA. Specifically, TESS will look for the periodic brightness dimming of stars caused by the transits of planets passing in of their parent stars. NASA’s Kepler spacecraft used the same method, says NASA, to spot more than 2,600 confirmed exoplanets, most of them orbiting faint stars 300 to 3,000 light-years away.
TESS, in contrast, will target stars less than 300 light-years away, but which are 30 to 100 times brighter than the stars that Kepler targeted.
Because TESS’s stellar targets will be much brighter than Kepler’s, NASA says astronomers will be able to use spectroscopy --- the study of the absorption and emission of light --- to make judgments about a given extrasolar planet’s mass, density, and atmospheric composition.
And the space agency notes that the planets found by TESS should be far easier to characterize with follow-up observations once NASA’S James Webb Space Telescope (JWST) launches in 2020.
* This post has been corrected to note that TESS will survey the Southern hemisphere in its first year; the Northern hemisphere in its second.