While we live our daily lives, NASA’s Transiting Exoplanet Survey Satellite (TESS) scans the skies for planets outside our own solar system. Such planets are called expolanets, and TESS has already discovered 28 of them since April 2018.
This past week, TESS scientists at NASA answered questions on Reddit and provided more information about TESS and it’s discoveries.
Here are a few great questions that were asked and their answers:
What is the difference between TESS and the previous Kepler mission?
TESS is searching for planets around our nearest stellar neighbors, so stars that are bright. When we find planets around bright stars, we can use all of our ground and space-based telescopes to learn more about the planets, like whether they have atmospheres, and what they are made of (are they rocky? Icy? Or some strange water world?) TESS will find many planets that are suitable for the James Webb Space Telescope to observe, and that will be super exciting because Webb will have lots of instruments that can teach us a tremendous amount about the planets’ atmospheres.
What criteria do you use to select a potential system for investigation and where does that data come from?
The team at the TESS Science Office at MIT uses software to pare down the tens of thousands of signals TESS detects as potential planets to a list of a few hundred. We also prioritize planet candidates based on how easy it is for ground-based telescopes to observe them--brighter stars which are relatively calm in their own flaring behavior and in a clear field that has few nearby stars in the way are ideal!
What is the process and timeline of going from raw data to a published planet discovery?
It’s actually relatively quick, only taking a few months for the initial steps! TESS beams data back to Earth, where it’s analyzed by data pipelines at NASA Ames and MIT, and picks out light curves (the change in brightness over time of a star) for the millions of individual stars in the TESS images. Planet search software tools sift out the light curves with patterns that look like a transit of a planet, and vetters identify the best planet candidates by eye. Follow-up observers around the world use telescopes on Earth and in space to study these planet candidates in more detail, and confirm whether they’re actually planets, and if so, what they’re like.
What is the farthest that TESS can see and confidently produce usable data?
TESS has a brightness limit, not a distance limit. People are using TESS to discover supernovae millions of light years away, even though its specific mission is to study stars within 100 light years of us. Lots of people are using TESS to do really cool science on galaxies across the universe!
How much of the sky has TESS covered so far?
TESS just ended the first half of its original 2 year mission, so it has observed about 40% of the sky. This next year will hit another 40%, and then it will move into its first extended mission next year will it will start going back to reobserve some areas and also cover about half of the 20% that it missed the first time around.
Tess was initially planned as a two year mission to last between 2018 and 2020. Recently, the mission was approved for a two year extension which will provide more time for TESS to look for exoplanets.
To learn more about TESS and recently discovered exoplanets visit NASA.