Meet TESS, NASA’s Planet-Hunting Superstar
Just don’t call her four-eyes.
The Transiting Exoplanet Survey Satellite (TESS to her friends) begins collecting data this month. Launched in April, she is equipped with four telescopes, two solar panels, and one mission : find new solar systems. Lots, and lots of new solar systems.
During her 2-year mission, TESS could discover up to 20, 000 new exoplanets around stars all over the sky. That’s only 7 times as many exoplanets as all other telescopes put together. No biggie.
That magical moment of transit: a planet passing in front of its star. (Artist’s view of planets transiting red dwarf star in TRAPPIST-1 system, ESA/Hubble)
To find that many exoplanets, TESS has a few secret weapons. One is her location. In space, you don’t have to worry about clouds, or worse, daylight (ick), hiding that magical moment of transit. That’s when a planet passes in front of its sun, making the star just that teesy-weensy bit dimmer. TESS is also on a unique orbit called P/2 that is ideal for planet hunting. P/2 is a ‘2:1 lunar resonant orbit’ : that means that every time TESS goes around the Earth twice, the Moon has gone around once. That means the moon’s gravity will help keep TESS stable. It is also a very elliptical orbit—a big oval—that lets TESS get close to Earth for fast downloads of its science data, but keeps it out of the Van Allen radiation belts that might damage her sensitive cameras.
Don’t call her four eyes: TESS is the first orbiting observatory to mount four telescopes to find more planets. (Image: NASA)
Those cameras are the real ace up TESS’ sleeve: first of all, there are four of them. The Hubble? Yeah, the Hubble is cool, but it’s only one space telescope. Kepler, NASA’s last planet-hunter, only had one telescope, too. TESS has 4, and together, they cover a huge swath of sky. TESS can monitor one twenty-sixth of the sky at once—four hundred times as much as Kepler did. With that view she will be able to scan the entire sky for exoplanets over the 2 years of her mission. Based on the tiny swath of sky studied by Kepler, astronomers are able to estimate TESS could find up to 20, 000 exoplanets, and that up to 1000 of them could be Earth-sized.
How TESS will scan the sky: each slice of the sky will be observed for 27 days. Only the plane of our solar system is left out (Image: NASA).
A thousand Earth-sized planets would be an amazing discovery, but for all the potential of her secret weapons, TESS almost never got to fly. Scientists at MIT and Google first proposed the mission way back in 2007, but could not raise enough money. In 2008, they went cap-in-hand to NASA, but the space program had other priorities that year. You don’t get to be a scientist at MIT by giving up though—they tried again and again. Finally, in 2013, NASA chose TESS as an ‘explorer class’ mission.
With the bills paid, it was only left to build and launch the telescope. After a few launch-pad hickups and delays, TESS finally lifted off April 18th, 2018 a top a Space X Falcon 9 rocket.
The launch was flawless.
The last few weeks have been spent getting the spacecraft into position in its unique orbit, and making sure everything is working. Now that it’s ready, TESS is ready to get to work.
During the month of June, learn about Exoplanets and TESS in Science North’s Digital Planetarium with “We are Aliens”, showing three times daily on weekends.
