NASA's New Planet Hunter Snaps Initial Test Image, Swings by Moon Toward Final Orbit

NASA's next planet hunter, the Transiting Exoplanet Survey Satellite (TESS), is one step closer to searching for new worlds after successfully completing a lunar flyby on May 17. The spacecraft passed about 5,000 miles from the Moon, which provided a gravity assist that helped TESS sail toward its final working orbit.

Above: 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/MIT/TESS)

As part of camera commissioning, the science team snapped a two-second test exposure using one of the four TESS cameras. The image, centered on the southern constellation Centaurus, reveals more than 200,000 stars. The edge of the Coalsack Nebula is in the right upper corner and the bright star Beta Centauri is visible at the lower left edge. TESS is expected to cover more than 400 times as much sky as shown in this image with its four cameras during its initial two-year search for exoplanets. A science-quality image, also referred to as a "first light" image, is expected to be released in June.

TESS will undergo one final thruster burn on May 30 to enter its science orbit around Earth. This highly elliptical orbit will maximize the amount of sky the spacecraft can image, allowing it to continuously monitor large swaths of the sky. TESS is expected to begin science operations in mid-June after reaching this orbit and completing camera calibrations.

Launched from Cape Canaveral Air Force Station in Florida on April 18, TESS is the next step in NASA's search for planets outside our solar system, known as exoplanets. The mission will observe nearly the entire sky to monitor nearby, bright stars in search of transits — periodic dips in a star's brightness caused by a planet passing in front of the star. TESS is expected to find thousands of exoplanets. NASA's upcoming James Webb Space Telescope, scheduled for launch in 2020, will provide important follow-up observations of some of the most promising TESS-discovered exoplanets, allowing scientists to study their atmospheres.

NASA's TESS Shares First Science Image in Hunt to Find New Worlds

NASA's newest planet hunter, the Transiting Exoplanet Survey Satellite (TESS), is now providing valuable data to help scientists discover and study exciting new exoplanets, or planets beyond our solar system. Part of the data from TESS' initial science orbit includes a detailed picture of the southern sky taken with all four of the spacecraft's wide-field cameras. This "first light" science image captures a wealth of stars and other objects, including systems previously known to have exoplanets.

Above: The Transiting Exoplanet Survey Satellite (TESS) took this snapshot of the Large Magellanic Cloud (right) and the bright star R Doradus (left) with just a single detector of one of its cameras on Tuesday, Aug. 7. The frame is part of a swath of the southern sky TESS captured in its "first light" science image as part of its initial round of data collection. (NASA/MIT/TESS)

"In a sea of stars brimming with new worlds, TESS is casting a wide net and will haul in a bounty of promising planets for further study," said Paul Hertz, astrophysics division director at NASA Headquarters in Washington. "This first light science image shows the capabilities of TESS' cameras, and shows that the mission will realize its incredible potential in our search for another Earth."

TESS acquired the image using all four cameras during a 30-minute period on Tuesday, Aug. 7. The black lines in the image are gaps between the camera detectors. The images include parts of a dozen constellations, from Capricornus to Pictor, and both the Large and Small Magellanic Clouds, the galaxies nearest to our own. The small bright dot above the Small Magellanic Cloud is a globular cluster — a spherical collection of hundreds of thousands of stars — called NGC 104, also known as 47 Tucanae because of its location in the southern constellation Toucana, the Toucan. Two stars, Beta Gruis and R Doradus, are so bright they saturate an entire column of pixels on the detectors of TESS's second and fourth cameras, creating long spikes of light.

"This swath of the sky's southern hemisphere includes more than a dozen stars we know have transiting planets based on previous studies from ground observatories," said George Ricker, TESS principal investigator at the Massachusetts Institute of Technology's (MIT) Kavli Institute for Astrophysics and Space Research in Cambridge.

Above: The Transiting Exoplanet Survey Satellite (TESS) captured this strip of stars and galaxies in the southern sky during one 30-minute period on Tuesday, Aug. 7. Created by combining the view from all four of its cameras, this is TESS' "first light," from the first observing sector that will be used for identifying planets around other stars. Notable features in this swath of the southern sky include the Large and Small Magellanic Clouds and a globular cluster called NGC 104, also known as 47 Tucanae. The brightest stars in the image, Beta Gruis and R Doradus, saturated an entire column of camera detector pixels on the satellite's second and fourth cameras. (NASA/MIT/TESS)

TESS's cameras, designed and built by MIT's Lincoln Laboratory in Lexington, Massachusetts, and the MIT Kavli Institute, monitor large swaths of the sky to look for transits. Transits occur when a planet passes in front of its star as viewed from the satellite's perspective, causing a regular dip in the star's brightness.

TESS will spend two years monitoring 26 such sectors for 27 days each, covering 85 percent of the sky. During its first year of operations, the satellite will study the 13 sectors making up the southern sky. Then TESS will turn to the 13 sectors of the northern sky to carry out a second year-long survey.

MIT coordinates with Northrop Grumman in Falls Church, Virginia, to schedule science observations. TESS transmits images every 13.7 days, each time it swings closest to Earth. NASA's Deep Space Network receives and forwards the data to the TESS Payload Operations Center at MIT for initial evaluation and analysis. Full data processing and analysis takes place within the Science Processing and Operations Center pipeline at NASA's Ames Research Center in Silicon Valley, California, which provides calibrated images and refined light curves that scientists can analyze to find promising exoplanet transit candidates.

TESS builds on the legacy of NASA's Kepler spacecraft, which also uses transits to find exoplanets. TESS's target stars are 30 to 300 light-years away and about 30 to 100 times brighter than Kepler's targets, which are 300 to 3,000 light-years away. The brightness of TESS' targets make them ideal candidates for follow-up study with spectroscopy, the study of how matter and light interact.

The James Webb Space Telescope and other space and ground observatories will use spectroscopy to learn more about the planets TESS finds, including their atmospheric compositions, masses and densities.

TESS has also started observations requested through the TESS Guest Investigator Program, which allows the broader scientific community to conduct research using the satellite.

"We were very pleased with the number of guest investigator proposals we received, and we competitively selected programs for a wide range of science investigations, from studying distant active galaxies to asteroids in our own solar system," said Padi Boyd, TESS project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "And of course, lots of exciting exoplanet and star proposals as well. The science community are chomping at the bit to see the amazing data that TESS will produce and the exciting science discoveries for exoplanets and beyond."

TESS Finds Its First Earth-Sized Planet

A nearby system hosts the first Earth-sized planet discovered by NASA's Transiting Exoplanets Survey Satellite, as well as a warm sub-Neptune-sized world, according to a new paper from a team of astronomers that includes Carnegie's Johanna Teske, Paul Butler, Steve Shectman, Jeff Crane, and Sharon Wang.

Their work is published in The Astrophysical Journal Letters.

"It's so exciting that TESS, which launched just about a year ago, is already a game-changer in the planet-hunting business," said Teske, who is second author on the paper. "The spacecraft surveys the sky and we collaborate with the TESS follow-up community to flag potentially interesting targets for additional observations using ground-based telescopes and instruments."

One such tool, the Planet Finder Spectrograph on the Magellan II telescope at Carnegie's Las Campanas Observatory in Chile, was a crucial component of this effort. It helped confirm the planetary nature of the TESS signal, and to measure the mass of the newly discovered sub-Neptune.

The PFS — built by Shectman and Crane using a method pioneered by Butler and his collaborators — works using a technique called the radial velocity method, which is currently the only way for astronomers to measure the masses of individual planets. Without known masses, it is very challenging to determine a planet's density or its general chemical composition.

This method takes advantage of that fact that not only does a star's gravity influence the planet orbiting it, but the planet's gravity also affects the star in turn. The PFS enables astronomers to detect these tiny wobbles that the planet's gravity induces in the star's orbit.

"PFS is one of the only instruments in the Southern Hemisphere that can do these types of measurements," Teske added. "So, it will be a very important part of further characterizing the planets found by the TESS mission."

With an orbit that takes about 36 days to complete, the sub-Neptune, HD 21749b, has the longest period of any of the TESS discoveries published so far. Because of the technique that TESS employs, it is predicted that most of the planets the mission finds will have orbital periods of fewer than 10 days, so HD 21749b is unusual in this regard. In fact, this also made the detection of the planet in the TESS data an extra challenge.

"There was quite some detective work involved, and the right people were there at the right time," said lead author Diana Dragomir of MIT's Kavli Institute for Astrophysics and Space Research. "But we were lucky, and we caught the signals, and they were really clear."

Its host star has about 80 percent of the mass of our Sun and is found about 53 light-years distant from Earth. HD 21749b has about 23 times Earth's mass and a radius of about 2.7 times Earth's. Its density indicates the planet has substantial atmosphere but is not rocky, so it could potentially help astronomers understand the composition and evolution of cooler sub-Neptune planet atmospheres.

Excitingly, the longer period sub-Neptune planet in this system is not alone. It has a sibling planet, HD 21749c, which takes about eight days to orbit the host star and is much smaller — similar in size to Earth.

"Measuring the exact mass and composition of such a small planet will be challenging, but important for comparing HD 21749c to Earth," said Wang. "Carnegie's PFS team is continuing to collect data on this object with this goal in mind."

Thanks to TESS, astronomers will be able to measure the masses, atmospheric compositions, and other properties of many smaller exoplanets for the first time. Although small exoplanets are common in our galaxy, there is still much to learn about their diversity and about how they compare to the planets in our own solar system.

"For stars that are very close by and very bright, we expected to find up to a couple dozen Earth-sized planets," said Dragomir. "And here we are — this would be our first one, and it's a milestone for TESS. It sets the path for finding smaller planets around even smaller stars, and those planets may potentially be habitable."

NASA's Planet Hunter Completes Its Primary Mission

On July 4, NASA's Transiting Exoplanet Survey Satellite (TESS) finished its primary mission, imaging about 75% of the starry sky as part of a two-year-long survey. In capturing this giant mosaic, TESS has found 66 new exoplanets, or worlds beyond our solar system, as well as nearly 2,100 candidates astronomers are working to confirm.

"TESS is producing a torrent of high-quality observations providing valuable data across a wide range of science topics," said Patricia Boyd, the project scientist for TESS at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "As it enters its extended mission, TESS is already a roaring success."

TESS monitors 24-by-96-degree strips of the sky called sectors for about a month using its four cameras. The mission spent its first year observing 13 sectors comprising the southern sky and then spent another year imaging the northern sky.

Now in its extended mission, TESS has turned around to resume surveying the south. In addition, the TESS team has introduced improvements to the way the satellite collects and processes data. Its cameras now capture a full image every 10 minutes, three times faster than during the primary mission. A new fast mode allows the brightness of thousands of stars to be measured every 20 seconds, along with the previous method of collecting these observations from tens of thousands of stars every two minutes. The faster measurements will allow TESS to better resolve brightness changes caused by stellar oscillations and to capture explosive flares from active stars in greater detail.

These changes will remain in place for the duration of the extended mission, which will be completed in September 2022. After spending a year imaging the southern sky, TESS will take another 15 months to collect additional observations in the north and to survey areas along the ecliptic – the plane of Earth's orbit around the Sun – that the satellite has not yet imaged.

TESS looks for transits, the telltale dimming of a star caused when an orbiting planet passes in front of it from our point of view. Among the mission's newest planetary discoveries are its first Earth-size world, named TOI 700 d, which is located in the habitable zone of its star, the range of distances where conditions could be just right to allow liquid water on the surface. TESS revealed a newly minted planet around the young star AU Microscopii and found a Neptune-size world orbiting two suns.

In addition to its planetary discoveries, TESS has observed the outburst of a comet in our solar system, as well as numerous exploding stars. The satellite discovered surprise eclipses in a well-known binary star system, solved a mystery about a class of pulsating stars, and explored a world experiencing star-modulated seasons. Even more remarkable, TESS watched as a black hole in a distant galaxy shredded a Sun-like star.

Missions like TESS help contribute to the field of astrobiology, the interdisciplinary research on the variables and conditions of distant worlds that could harbor life as we know it, and what form that life could take.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

TESS Status Update

NASA's Transiting Exoplanet Survey Satellite (TESS) entered into safe mode on Monday, Oct. 10. The spacecraft is in a stable configuration that suspends science observations. Preliminary investigation revealed that the TESS flight computer experienced a reset.

The TESS operations team reported that science data not yet sent to the ground appears to be safely stored on the satellite. Recovery procedures and investigations are underway to resume normal operations, which could take several days.

TESS launched in April 2018 and has since discovered more than 250 exoplanets – worlds beyond our solar system – and thousands of additional candidates.

TESS Resumes Normal Operations

NASA's Transiting Exoplanet Survey (TESS) began its return to normal operations on Thursday, Oct. 13, at around 6:30 p.m. EDT. Engineers successfully powered up the instrument, and the spacecraft resumed its regular fine-pointing mode. The team expects that TESS will resume science observations later on Friday, and all science data stored on the spacecraft will be downlinked at the next opportunity.

TESS entered into safe mode on Oct. 10 following a reset of its flight computer. The team will spend the next several days analyzing data to determine the cause.