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Meet TESS, seeker of alien worlds





  • NEW YORK TIMES

    Workers attach a shield at the base of the Transit Exoplanet Survey Satellite, TESS, at Kennedy Space Center, Cape Canaveral, Florida, on February 15. The new NASA spacecraft will be launched in April. will give the scientists a much clearer view of the planets orbiting stars around us.


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KENNEDY SPACE CENTER, Fla. >> The search for cosmic real estate is nearing the beginning.

Earliest at 18:32. On April 16th, in NASA's Broken Language, a small spacecraft known as the Transit Exoplanet Survey Satellite, or TESS, bursting with cameras and ambition, will rise on a SpaceX Falcon 9 rocket in a blaze of smoke and fire and one take a long residence between the moon and the earth.

There it will spend at least the next two years, searching the sky for foreign worlds.

TESS is the last effort to try to answer questions that have fascinated and dominated humans for millennia Astronomy for the last three decades: Are we alone? Are there other earths? The detection of even a single microbe anywhere else in the galaxy would shake science.

Not so long ago, astronomers did not know if there were planets outside our solar system, or if there were any, if they could ever be found. But with the discovery of a planet circling the sun-like star 51 Pegasi, there was a revolution:

NASA's Kepler spacecraft discovered some 4,000 possible planets in 2009 in a small part of the Milky Way near the constellation Cygnus. Kepler went on to examine other star fields only briefly after his pointer system was broken. After nine years in space, he runs out of fuel.

Thanks to efforts like Kepler's, astronomers now believe there are billions of potentially habitable planets in our galaxy, meaning that the next one could be near 10 to 15 light-years away. Years from here.

And so the torch happened. Now it is TESS's job to find those nearby planets close enough to telescope them or even visit an interstellar robot.

"Most stars with planets are far away," said Sara Seager, a planetary scientist at the Massachusetts Institute of Technology and member of the TESS team, regarding Kepler's bounty. "TESS will fill planets around stars nearby."

George Ricker, an MIT researcher and leader of the TESS team, expects to find some 500 planets on Earth within 300 light years, close enough for a coming generation of telescopes on the ground and in space Habitability – or maybe even according to inhabitants.

But according to TESS, there will be more than planets in the universe.

"TESS will be a lot of fun," said Ricker. "There are 20 million stars we can look at." The spacecraft will be able to make accurate brightness measurements of every glint in the sky, he said. "Galaxies, stars, active galactic nuclei," his voice stops.

Most exoplanets will orbit stars called Red Dwarfs, much smaller and cooler than the Sun. They represent the vast majority of stars in our neighborhood (and in the universe) and probably occupy most of the planets.

Like Kepler, TESS will hunt these planets by monitoring the light of stars and briefly detecting light intrusions. Fading indicates that a planet has passed in front of its star.

The mission's planners say they are finally expecting to catalog 20,000 new exoplanet candidates of all shapes and sizes. In particular, they have promised to develop the masses and orbits of 50 new planets less than four times the size of Earth.

Most of the planets in the universe are in this area – between Earth and Neptune. But since there are no examples in our own solar system, as Seager notes, "we know nothing about them."

Are these so-called super-earths, mostly rocks with a touch of atmosphere, right? Mini Neptune with small cores buried deep in sprawling gas balls?

Data from Kepler and astronomers suggest that the difference is mass: fertile rocks are often less than 1 1/2 times the size of the Earth, while barren ice clouds are often larger. Where the line is real and how many planets fall on one side or the other could determine how many worlds out there are bullets of freezing steam or potential gardens.

"We need to make accurate mass measurements," said David Latham of the Harvard-Smithsonian Center for Astrophysics, which is responsible for organizing astronomers to track TESS observations.

To this end, the team has 80 nights of observation time each year for the next five years on a spectrograph called Harps North, which is on an Italian telescope on the island of La Palma in the Canary Islands, part of Spain off the coast of Africa, resides

HARPS – For High Accuracy Radial Speed ​​Planet Searcher – can measure the mass of a planet by how much it wobbles its home star when it's in orbit. Such measurements, if accurate enough, could help distinguish the composition and structure of these bodies.

TESS is one of NASA's smaller missions with a budget of $ 200 million; In comparison, Kepler had a budget of 650 million dollars.

The key to this work is to get very stable and sensitive detectors – the imaging chips that are the elite relatives of the sensors in your smartphone – so they can reliably absorb changes in brightness, just a few Parts per million that signal a planet passing its star.

Ricker said he and his colleagues started "noodling" in 2006 in a planet finding mission. The scientists resumed their competition in 2010 for the NASA's "Small Explorers" program, which involves less expensive missions participate in a competition for a larger mission.

They had made great efforts to develop a compact spacecraft for NASA. NASA chose SpaceX's Falcon 9, which can carry a much larger payload to launch the TESS mission.

This is the first time NASA has bought a ride from SpaceX, the Rock, and a company run by Elon Musk for one of their science missions. All eyes will be on the Launchpad, given that SpaceX occasionally delivers unfortunate, if spectacular, missions.

On top of the spaceship are four small cameras, each with a 24 degree field of view, a piece of sky about the size of the Orion constellation.

The cameras will each stare at neighboring sky areas for 27 days and then go to the next point. During the first year, researchers will study the entire southern hemisphere of the sky; in the second year, they will sew together the northern sky. If the mission lasts more than two years, they will repeat themselves.

Ricker and his colleagues have compiled a list of 200,000 nearby stars whose brightness is measured and reported every two minutes in a so-called spacecraft stamp mode. Meanwhile, images of the entire 24-degree stripe of the sky are recorded every half hour.

This cadence is perfect for finding and exploring current favorites in the quest to find habitable exoplanets, the ubiquitous red dwarf stars. or M dwarfs, in astronomical jargon. "This is the era of the dwarf M," Seager said.

Because they are so much cooler and less bright than the Sun, their "Goldilocks" zones – where in principle liquid water is possible – are only a few million miles from each star, instead of the 90 million miles of which the earth is the Sun encircled.

At the shorter distance, one year in the life of a red dwarf planet is only 10 to 30 days. When TESS watches this part of the sky for 27 days, it can detect three differences in brightness due to transit, enough to authenticate the planet as a true candidate and examine its reality.

To begin his excellent adventure, TESS is placed in an unusually eccentric orbit, bringing the satellite to the Moon at its furthest point. Gravity interaction with the Moon will then keep TESS in a stable 13.7-day orbit for as long as 1,000 years, Ricker said.

The Great Apogee, the farthest distance from Earth, will minimize obstruction and interference from our planet. The spacecraft will send its data upwards at approximately 67,000 miles on each orbit when it is closest to Earth.

Latham called it "a smooth orbit". But it will take almost two months and many rocket burns to get there and start doing science. If all goes well, it would be mid-June.

At some point during this process, Ricker said, the team will direct the spacecraft's cameras to Earth for a final look back home.

When asked if he was ready Mr. Exoplanet, Ricker flinched. "What I'm looking forward to," he said, "gets to see some data."


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