NASA’s Transiting Exoplanet Survey Satellite Arrives at Kennedy Space Center for Launch
NASA’s next planet-hunting mission has arrived in Florida to begin preparations for launch. The Transiting Exoplanet Survey Satellite (TESS) is scheduled to launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station nearby NASA’s Kennedy Space Center in Florida no earlier than April 16, pending range approval. TESS was delivered Feb. 12 aboard a truck from Orbital ATK in Dulles, Virginia, where it spent 2017 being assembled and tested. Over the next month, the spacecraft will be prepped for launch at Kennedy’s Payload Hazardous Servicing Facility (PHSF).
TESS is the next step in NASA’s search for planets outside our solar system, known as exoplanets. The mission will scan nearly the entire sky to monitor more than 200,000 of the nearest and brightest stars in search of transit events — periodic dips in a star’s brightness caused by planets passing in front of their stars. TESS is expected to find thousands of exoplanets. The upcoming James Webb Space Telescope, scheduled for launch in 2019, will provide important follow-up observations of some of the most promising TESS-discovered exoplanets, allowing scientists to study their atmospheres and, in some special cases, to search for signs that these planets could support life.
TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA’s Goddard Space Flight Center in Greenbelt, Maryland. Dr. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission. Additional partners include Orbital ATK, NASA’s Ames Research Center in California’s Silicon Valley, the Harvard-Smithsonian Center for Astrophysics and the Space Telescope Science Institute. More than a dozen universities, research institutes and observatories worldwide are participants in the mission. NASA’s Launch Services Program is responsible for launch management. SpaceX of Hawthorne, California, is the provider of the Falcon 9 launch service.
Banner image: NASA's Transiting Exoplanet Survey Satellite (TESS), shown here in a conceptual illustration, will identify exoplanets orbiting the brightest stars just outside our solar system. Credit: NASA's Goddard Space Flight Center
The Transiting Exoplanet Survey Satellite arrives at NASA’s Kennedy Space Center, where it will undergo final preparations for launch. Launch is scheduled for no earlier than April 16, pending range approval.
Meet TESS, NASA’s Next Step in the Quest for Alien Earths
Launching in April on a two-year primary mission, the observatory could ultimately discover 20,000 planets—some of which could be much like our own
In a clean room inside a clean room at NASA’s Kennedy Space Center, a petite telescope is perched on a stand for a final series of checkouts prior to launch. The extra fastidiousness is because the observatory’s four cameras will fly without protective covers—one of several simplifying design decisions made to help ensure the Transiting Exoplanet Survey Satellite, or TESS, will meet its goal of measuring the masses of at least 50 small, rocky and potentially Earth-like worlds as part of the first all-sky, exoplanet survey.
TESS was proposed even before NASA’s planet-hunting Kepler space telescope, launched in 2009, demonstrated the viability of a space-based exoplanet survey. Both telescopes use the so-called “transit” method (as opposed to these techniques) to find planets, looking for worlds in silhouette as they pass in front of their parent stars relative to the telescopes’ lines of sight. Kepler not only established transits as the dominant planet-hunting technique, it also stunningly revealed our galaxy brims with planets, particularly worlds two to four times the size of Earth.
During its initial mission, Kepler scouted stars more than a thousand light-years away in a patch of sky within the constellations Cygnus, Lyra and Draco. So far, scientists have confirmed 2,341 exoplanets circling stars in Kepler’s original pool of some 170,000 targets. Another 4,496 candidate planets are pending, but many may never be confirmed because their stellar hosts are too dim to be easily observed by ground-based telescopes for necessary follow-up studies.
The TESS team took the opposite approach, starting with what ground observations would be needed to follow-up and confirm candidate transiting Earth-like planets, and then deciding on specific targets for the telescope. They selected about 200,000 stars for study during TESS’s two-year primary mission. Each of those target stars already has been plotted in detail by the European Space Agency’s ongoing Gaia space telescope, which is creating the best-yet all-sky catalogue of stellar positions and distances.
Most of TESS’s targets are within 300 light-years from Earth, significantly closer and up to a hundred times brighter than most of the stars studied by Kepler. “On TESS, we will be able to do ground-based follow-up on all of them. It will just be a matter of priorities, not abilities,” says project scientist Stephen Rinehart, with NASA’s Goddard Space Flight Center.
The transit technique pioneered by Kepler and planned for TESS reveals the size of a planet relative to its host star. If several transits can be observed, scientists also can determine how far from the star a planet orbits—information that can then be used to estimate its temperature and whether it could support liquid water on its surface, a key consideration for habitability.
But to assess a planet’s mass—which is needed to determine whether it is dense with metal and rock like Earth or instead composed of ice or gas—astronomers usually turn to ground-based telescopes. Often only a relatively modest observatory, it turns out, is needed to look for wobbles in a star’s spin caused by the slight but regular gravitational tugging of its orbiting planetary brood. The TESS project is enlisting dozens of astronomers and reserving time on several ground-based telescopes for such studies.
THE HUNT IS ON
The hunt for neighboring Earth-like planets begins about two months after TESS’s launch, which is currently slated for mid-April. That’s when the telescope should arrive in an unusual operational orbit that loops high around Earth, passing only as close as about 67,300 miles before zooming out to nearly the orbit of the moon some 234,000 miles away. When TESS is at the highest point of its orbit with respect to Earth, the moon will be 90 degrees to the left or right, serving as an orbital ballast that will keep the telescope gravitationally steady for decades without the use of steering thrusters.
This eccentric orbit allows TESS to spend most of its time in deep, dark space, with minimal interference from sunshine and the light reflecting off Earth and the moon. The spacecraft will swing around the planet every 13.7 days, orbiting exactly twice as fast as the moon. When TESS is closest to Earth it will suspend observations for 10 hours to transmit stored science data to one of NASA’s three Deep Space Network ground stations. Those transmissions will occur on high-rate, Ka-band frequencies—a first for the network that will pave the way for other data-intensive future space missions, including the James Webb Space Telescope.
TESS’s data will not only include measurements of each target star’s brightness taken every two minutes, but also a full-sky image taken every half-hour capturing more than 20 million stars and 10 million galaxies. “It’s just going to be this treasure trove of data. We expect that that archive will be mined for years,” says NASA astronomer Patricia Boyd, who leads Goddard’s TESS Guest Investigator Program.
The telescope is outfitted with four cameras positioned to cover a wedge of sky 24 degrees across and 96 degrees long, the equivalent of about 10,000 full moons. Shifting its field of view every two orbits, TESS will cover the sky’s entire southern hemisphere during the first year of operation and then flip to cover its northern hemisphere in the second year. In all, TESS will cover 90 percent of the sky, an area about 400 times larger than what Kepler observed.
Of key interest are the stars around the ecliptic poles, which will be included in each slice of the sky covered by TESS. These are the stars directly above and below the ecliptic plane, in which the planets move around the sun. Worlds in these regions will become primary targets for follow-up studies by the James Webb Space Telescope, which, among its many other tasks, will attempt to ferret out the atmospheric chemistry for some transiting exoplanets. Webb is slated to launch in 2019. “In that role TESS serves as a finder scope for Webb. We’re finding the particular star that actually potentially hosts an exoplanet around it,” says TESS lead scientist George Ricker, with Massachusetts Institute of Technology.
Ricker adds that “it shouldn’t be hard” to meet the TESS mission goal to measure the mass of 50 small planets. Simulations forecast that by the end of the initial three-year ground observation program, the team should have verified more like 500 small planets, not 50, he says.
Ultimately, TESS could contribute as many as 20,000 new planets to the exoplanet catalogue, most of which will be circling M-dwarf stars that are one quarter to one half the diameter of the sun and much dimmer and cooler. M-dwarfs, which comprise about 70 percent of stars in the Milky Way, are TESS’s primary targets.
“To me the most exciting thing about any new mission is the thing you don’t expect,” says Rinehart, the project scientist. “I really hope that somewhere along the line we find something bizarre, something that we can’t explain that requires us to really think hard about what it is we’re seeing. I think we will, but I have no idea what it will be.”
Quelle: Scientific American
TESS – the latest exoplanet finder – in final preparations for launch
Next month, SpaceX is set to launch the Transiting Exoplanet Survey Satellite, or TESS, is the next step in humanity’s ongoing effort to discover and characterize exoplanets, including planets that might host life. The spacecraft is currently scheduled to launch on a Falcon 9 on April 16 from SLC-40 at Cape Canaveral.
The TESS project has its origins in a concept study at MIT in the mid-2000’s and was submitted as an Astrophysics Explorer mission finalist in 2012, as a successor program to Kepler, which was at the time in its primary mission.
In April 2013, TESS was selected as a new Explorer mission, following in the footsteps of Explorer 1, America’s first successful orbiting satellite, the mission that discovered the Van Allen radiation belts around Earth, and missions like COBE (Cosmic Background Explorer) which made groundbreaking discoveries about the Big Bang and resulted in a Nobel Prize.
Regarding where TESS fits in the astrophysics and exoplanet program, Dr. Ricker states, “The role that TESS actually has, when it launches, is basically to be a bridge between Kepler and follow-on missions. In particular Webb, and future missions that we’re anticipating will come online in the next 40 or 50 years.”
The 362 kg. (798 lb)., $243 million TESS spacecraft consists of an Orbital ATK LEOStar-2 bus containing four hydrazine thrusters and associated fuel tanks, 2 solar panels delivering 433 W of power, four gyroscopes, a high gain Ka-band antenna and 2 S-band antennae, science and flight computers, and a sunshade to keep spacecraft and instrument temperatures stable.
The sunshade is necessary for high-quality observations of the stars TESS would be tasked to observe. Finally and most importantly, TESS features four MIT Lincoln Labs-made CCD cameras as the science payload.
These cameras are extremely sophisticated and are among the most sensitive astronomical instruments ever produced. The CCD wafers are 100 microns thick and are very sensitive to cool M-class red dwarf stars, which make up the majority of stars in the sky, and were custom made at MIT.
The cameras each have an athermal design, a 24×24 degree field of view, and each camera features seven lens elements plus a 100 mm effective pupil diameter. Each camera has a 16.8 Megapixel resolution for a total of over 64 Megapixels and has a band pass from 600 to 1000 nm (the red and near-infrared side of the electromagnetic spectrum). The cameras also have lens hoods to keep out stray light that could interfere with their observations.
These cameras are mounted on an optical plate which Orbital ATK spacecraft program director Robert Lockwood describes as “a very rigid, low thermal expansion type of structure, so that the cameras stay very fixed all the time, relative to each other.”
An issue with the cameras’ focus was found during assembly of the spacecraft, but after analysis is not expected to impact the mission or science goals. After launch, the spacecraft will cool to its ultimate operating temperature and the camera focus will drift during this time (about one week) but the drift will stop once TESS is at its operating temperature.
TESS is currently scheduled for launch on April 16, 2018 from Cape Canaveral Air Force Station, Florida, from Launch Complex 40, aboard a Falcon 9.
After launch, the F9’s second stage and then the spacecraft thrusters will send TESS into an elliptical high Earth orbit with a 2:1 resonance with the Moon using a lunar flyby as part of the process.
TESS will begin a 60 day commissioning process to activate its scientific payload and to move to a 17 earth radii (108,307 km/67,298 mi) by 59 earth radii (375,889 km/233,566 mi) science orbit. Once TESS is in its proper orbit it will start a two year primary mission to find exoplanets transiting bright stars, covering 85% of the sky, as opposed to Kepler, which viewed a very narrow slice of sky in the constellations Lyra and Cygnus during its primary mission.
The TESS spacecraft will scan the sky in the Southern Hemisphere for the first year, and the northern hemisphere the second year. TESS, using four gyroscopes, will point its cameras at a 24 x 96 degree sector of the sky and cover it from the ecliptic to the celestial pole for 27 days, then move on to the next sector and so on.
There are 13 sectors per hemisphere, and each sector overlaps near the celestial pole for continuous coverage and the ability to observe long period planet transits (similar to Earth orbiting the Sun) in that area, along with shorter period transits around stars nearer to the ecliptic.
TESS will orbit the Earth once every 13.7 days and will transmit data at 100 mb/s to the Deep Space Network and the Orbital ATK Mission Operations Center for spacecraft data and to the MIT Payload Operations Center for science data.
The data will be processed and sent to the Science Processing & Operations Center (SPOC) for further handling including the creation of light curves and detection of transit signatures, and after this processing the data will be sent to the TESS Science Office (TSO) which will identify objects of interest for follow-up observations. The data will also be archived at the Mikulski Archive for Space Telescopes (MAST) and the data will be available for public use.
The 100 mb/s data rate is much higher than Kepler and other beyond low earth orbit science missions have used to date, and a portion of the Ka-band will be used due to ITU regulations.
Orbital ATK’s Robert Lockwood stated regarding what the Deep Space Network calls the Ka2 band, “26 GHz, is really the band that is allocated for those missions that are not deep space. And so that was available and really, that’ll be the second time using that band. But it’s available and we’ve tested it out fully with DSN and it works very well.”
When TESS reaches its orbital perigee every 13.7 days the craft will transmit its data to Earth, then continue observing its designated sector of space.
TESS is set to observe approximately 200,000 dwarf stars, ranging from F5 stars larger and hotter than the Sun to G and K Sun-like stars to M5 red dwarf stars, within 100 parsecs (300 light years) of the Sun. These stars, ranging from naked-eye brightness to magnitude 13, are much brighter than the stars studied during the Kepler mission and will be far better candidates for follow-up studies than the stars in Kepler’s field of view, most of which are too dim and far away for good follow-up studies from JWST or ground-based observatories.
As Dr. Ricker put it, “These are the ones that are close to the solar neighborhood that TESS is really going to focus on. And the reason that we’re focusing on the solar neighborhood is that the host stars are going to be bright. You’re going to have a lot of photons for follow-up work, which involves spectroscopy or polarimetry or a lot of other techniques that both ground-based and space-based astronomers are going to use.”
Approximately 20,000 exoplanets, including 300 “super-earths” or lesser-sized planets, are expected to be found by TESS during its primary mission (compared to 3000+ exoplanets discovered to date by Kepler and other observatories), which will greatly expand humanity’s burgeoning catalog of exoplanets.
The planets TESS finds will be extensively studied by JWST and other observatories in space and on the ground, and their masses would be obtained by means of radial velocity observations (TESS would only be able to get the sizes of the planets and not their masses).
Once the masses and sizes of the planets are found their densities can be calculated and they can be characterized as rocky planets, water worlds, or “mini-Neptune” ice giants or gas giants like Jupiter. Future observatories like JWST and the budget-threatened WFIRST, as well as large ground-based telescopes like E-ELT, can also obtain the spectra of these worlds and find out if they have atmospheres and what those atmospheres are made of
The TESS mission’s “full frame” images (covering up to the equivalent of 10,000 Moons in one frame, with a very wide field) will be able to cover up to 20 million stars and it is expected that TESS results will not be limited to exoplanets but will also deliver insights on colliding neutron stars (and resulting gravitational waves), type 1a supernovae, and other space phenomena.
Although TESS is nominally projected for a two year primary mission, it has been designed so that it can last much longer, and its high Earth orbit is designed so that TESS does not have to use much hydrazine fuel to maintain operations, and radiation hazards and stray light are minimized. Temperatures are very stable in the chosen orbit, and the orbit itself will stay stable for decades, so extended missions are possible up to 20 years into the future. These extended missions can extend the TESS exoplanet catalog and confirm planets that may otherwise be missed during the primary mission.
Regarding the mission’s legacy, Dr. Ricker states, regarding the stars TESS will observe, “And once we’ve found the planets associated with them, those are going to be the primary candidates that everyone, all astronomers for centuries to come, are going to focus on these objects. And that’s the excitement that we have about this mission, is this is really a mission for the ages.”
The TESS mission is expected to be a discovery machine, as Dr. Ricker put it, “There are a lot of things when you have an instrument that has this large of a field of view looking at the sky in an uninterrupted way, there’s just an incredible amount of science that will come out that we’re not even anticipating from TESS.“
Media Invited to Upcoming Launch of NASA’s Newest Planet-Hunting Spacecraft
NASA’s Transiting Exoplanet Survey Satellite is targeted to launch no earlier than April 16, 2018, on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station in Florida. The satellite will find planets outside the solar system that periodically block part of the light from their host stars as they pass by, or transit.
Credits: Goddard Space Flight Center/Chris Meaney
Media accreditation now is open for the launch of a NASA spacecraft that will search for planets outside of our solar system with a field of view almost 400 times larger than that of the agency’s Kepler mission.
NASA’s Transiting Exoplanet Survey Satellite (TESS) is targeted to launch no earlier than 6:32 p.m. EDT April 16 on a SpaceX Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Air Force Station (CCAFS) in Florida. The mission will find planets outside our solar system, known as exoplanets, that periodically block part of the light from their host stars as they pass by, or transit.
Media prelaunch and launch activities will take place at CCAFS and NASA’s neighboring Kennedy Space Center. Credentialing deadlines are as follows:
International media without U.S. citizenship must apply by 4:30 p.m. Thursday, March 15, for access to CCAFS, or by 4:30 p.m. Thursday, March 29, for Kennedy media activities only.
U.S. media must apply by 4:30 p.m. Friday, April 6.
All media accreditation requests should be submitted online at:
For questions about accreditation, please email firstname.lastname@example.org. For other questions, or additional information, contact Kennedy’s newsroom at 321-867-2468.
TESS will search for thousands of exoplanets in orbit around the brightest and nearest stars outside our solar system during a two-year period of surveying our solar neighborhood. In its mission to identify new worlds, the spacecraft will monitor more than 200,000 stars, looking for a telltale sign: a decrease in a star’s brightness that occurs when an orbiting planet transits between its star and an observing spacecraft, temporarily blocking the star’s light.
TESS is a NASA Astrophysics Explorer mission led and operated by the Massachusetts Institute of Technology (MIT) and managed by NASA’s Goddard Space Flight Center. George Ricker of MIT’s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission.
Additional partners include Orbital ATK, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics and the Space Telescope Science Institute. More than a dozen universities, research institutes and observatories worldwide are participating in the mission.
NASA to Discuss Upcoming Launch of Next Planet Hunter
The Transiting Exoplanet Survey Satellite (TESS) is a NASA Explorer mission launching in 2018 to study exoplanets, or planets orbiting stars outside our solar system. TESS will discover thousands of exoplanets in orbit around the brightest stars in the sky.
Credits: NASA GSFC
Join NASA at 1 p.m. EDT Wednesday, March 28, as astrophysics experts discuss the upcoming launch of NASA’s next planet hunter, the Transiting Exoplanet Survey Satellite (TESS). Reporters can attend the event in person at the James Webb Auditorium at NASA Headquarters in Washington or participate by phone.
The briefing will be broadcast live on NASA Television and the agency’s website.
Scheduled to launch April 16, TESS is expected to find thousands of planets outside our solar system, known as exoplanets, orbiting the nearest and brightest stars in our cosmic neighborhood. Powerful telescopes like NASA’s upcoming James Webb Space Telescope can then further study these exoplanets to search for important characteristics, like their atmospheric composition and whether they could support life.
Credits: NASA GSFC
The news briefing participants will be:
Paul Hertz, director, Astrophysics Division at NASA Headquarters in Washington
George Ricker, TESS principal investigator, Massachusetts Institute of Technology Kavli Institute for Astrophysics and Space Research, Cambridge, Massachusetts
Sara Seager, TESS deputy director of science, Massachusetts Institute of Technology, Cambridge, Massachusetts
Jeff Volosin, TESS project manager, NASA’s Goddard Space Flight Center, Greenbelt, Maryland
A question-and-answer session will take place during the event with reporters on-site and by phone. Members of the public can also ask questions during the briefing by participating in person, or using #AskNASA.
TESS, the Transiting Exoplanet Survey Satellite, is the next step in the search for planets outside of our solar system, including those that could support life. The mission will find exoplanets that periodically block part of the light from their host stars, events called transits. TESS will survey 200,000 of the brightest stars near the sun to search for transiting exoplanets. In this image, technicians help prepare the spacecraft for its mission.
Currently scheduled to launch on April 16, 2018, TESS will survey the entire sky over the course of two years by breaking it up into 26 different sectors, each 24 degrees by 96 degrees across. The powerful cameras on the spacecraft will stare at each sector for at least 27 days, looking at the brightest stars at a two-minute cadence. From Earth, the Moon occupies half a degree, which is less than 1/9,000th the size of the TESS tiles.The stars TESS will study are 30 to 100 times brighter than those the Kepler mission and K2 follow-up surveyed, which will enable far easier follow-up observations with both ground-based and space-based telescopes. TESS will also cover a sky area 400 times larger than that monitored by Kepler.
NASA’s next planet hunter is ready to find undiscovered worlds
Illustration of the Transiting Exoplanet Survey Satellite (TESS) in front of a lava planet orbiting its host star. TESS will identify thousands of potential new planets for further study and observation. (Credits: NASA/GSFC)
The search for extraterrestrial life is about to get serious, as the U.S. space agency announced in a statement this week. NASA’s Transiting Exoplanet Survey Satellite (TESS) has completed all certifications and is currently undergoing final preparations for an April 16 launch aboard a SpaceX Falcon 9 rocket from Cape Canaveral, Florida.
Initially slated for a two-year mission, TESS will ascend to an elliptical 13.7-day orbit around the Earth. It’s a unique and extreme orbit that’s never been used before, varying as close as 67,000 miles and as far away as 232,000 miles from its home planet. According to Space.com, the stable orbit will allow TESS to stay in space for decades without any need for course corrections.
Outfitted with four wide-angle cameras, TESS will be able to observe 85 percent of the surrounding sky as it looks for exoplanets. The instruments on the spacecraft will map 26 different “sectors” of the sky over a two-year period.
Specifically, TESS will be looking for a phenomenon called a “transit,” which is when a planet passes in front of its star. The resulting decrease in brightness can be observed and measured with spectroscopy, giving astronomers a better idea of the size and composition of the planet.
“TESS is opening a door for a whole new kind of study,” said Stephen Rinehart at Goddard Space Flight Center. “We’re going to be able study individual planets and start talking about the differences between planets. The targets TESS finds are going to be fantastic subjects for research for decades to come.
TESS is replacing the aging Kepler telescope, which is running on fumes and will soon be unable to maneuver. Unlike TESS, Kepler is in a solar orbit and can only make observations in one direction. “TESS will cast a wider net than ever before for enigmatic worlds whose properties can be probed by NASA’s upcoming James Webb Space Telescope and other missions,” said Paul Hertz of NASA.
Kepler used the same methods to discover more than 2,600 exoplanets, but it was always observing the same area of space and most of the planets were more than a thousand light-years away. TESS will set its sights on more nearby stars that are within 300 light-years of Earth.
The discoveries made by TESS may invite further study with the upcoming $8.8 billion James Webb Telescope planned for launch in 2020. “With those larger telescopes, we’ll be able to look for telltale signs in the atmospheres of those planets that might tell us what the planets are made of, and perhaps even whether they have the kinds of gases in their atmospheres that, on Earth, are an indication of life,” Hertz said at a news conference.
TESS may even moonlight at times to investigate other cosmic phenomenon it encounters besides exoplanets. Researchers will be invited to use the spacecraft as part of a “guest investigator” program, NASA said.
“I don’t think we know everything TESS is going to accomplish,” Rinehart added. “To me, the most exciting part of any mission is the unexpected result, the one that nobody saw coming.”
Quelle: FOX NEWS
TESS’s planet hunt begins
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NASA’s newest observatory in space has started its search for planets around other stars, officials said Friday, as astronomers zero in on worlds that are ripe for research by follow-up missions like the James Webb Space Telescope.
The Transiting Exoplanet Survey Satellite officially began a two-year science mission Wednesday, around three months after its blastoff from Cape Canaveral aboard a SpaceX Falcon 9 rocket.
“I’m thrilled that our new planet hunter mission is ready to start scouring our solar system’s neighborhood for new worlds,” said Paul Hertz, NASA’s astrophysics division director. “Now that we know there are more planets than stars in our universe, I look forward to the strange, fantastic worlds we’re bound to discover.”
Equipped with four 16.8-megapixel science cameras, TESS will look for blinks in light coming from relatively bright, nearby stars caused when planets pass in front of them. From those observations, astronomers can determine the size of each newly-discovered planet, then use other techniques such as radial velocity measurements to derive their masses.
TESS is a follow-up to NASA’s Kepler mission, which is nearing the end of its mission searching for planets around other stars. Kepler — NASA’s first mission dedicated to an exoplanet search — generally looked for worlds around more distant stars, resulting in 2,650 new confirmed planets beyond our solar system to date.
The TESS mission is geared to observe stars closer to the sun. In addition, Kepler has only pointed at certain parts of the sky, while TESS will take a broader look.
George Ricker, who leads the TESS science team at MIT’s Kavli Institute for Astrophysics and Space Research, said the exoplanet surveyor is a “finder scope” for the Webb telescope and huge ground-based observatories.
“You can go out on a dark night, and you can see 6,000 stars or so in the sky with your naked eye,” Ricker said. “We’re going to look at every single one of those stars.”
Approximately 20 million stars will be visible by TESS’s light-sensitive cameras, including targets up to a million times fainter than observable with the naked eye, Ricker said. Around 200,000 of those stars are “pre-selected” by the TESS science team for special emphasis because of their proximity and brightness.
Each of TESS’s cameras house four custom-built red-sensitive CCD detectors designed and developed by MIT’s Lincoln Laboratory.
“TESS is a survey machine, and it’s going to find the very best planets for us to follow-up, and among that category are these small rocky planets, transiting small red dwarf stars,” said Sara Seager, deputy science director on the TESS mission at MIT, in an interview before the mission’s launch.
Ricker said he expects TESS to find between 500 and 1,000 planets that are between one and three times the size of Earth. Up to 20,000 planets the size of Neptune or Jupiter could be discovered by TESS, he said.
That would grow the number of known planets beyond our solar system by factor of five or more, but it’s not all about expanding the exoplanet catalog.
“The focus that TESS has on finding systems associated with bright stars means that they will be much easier to follow-up,” Ricker said in an interview with Spaceflight Now. “Once you find that a transiting system exists, it’s something that you’ll want to come back to and study more and more as improved instruments, satellites and telescopes become available because this is going to be the benchmark for future research.”
That’s where the James Webb Space Telescope becomes a crucial tool for astronomers seeking to learn more about the nature of faraway exoplanets. Scheduled for launch in early 2021, the oft-delayed Webb telescope will be able to probe the atmospheres of some of these worlds, learning about their chemical make-up and searching for evidence that the planets might be habitable.
Once launched, the huge, expandable observatory “will be able to look for characteristic signatures of materials in the atmospheres of those planets … and something that’s potentially a biogenic signature,” Ricker told Spaceflight Now. “Of course, that takes a lot of care and a lot of work. TESS can only point the way to these are the best targets that you should be focusing on with Webb.”
TESS will scan around 85 percent of the sky during its two-year prime mission, beginning with stars in the southern sky. In 2019, the observatory will shift its aim to the northern sky.
The mission will primarily look at M-dwarf stars, which are smaller and cooler than the sun, and make up the majority of the stars in the Milky Way galaxy. Also called red dwarfs, the stars that are TESS’s focus have not been thoroughly investigated to determine whether they harbor their own solar systems.
Since its April 18 launch, TESS has maneuvered into a unique orbit in gravitational resonance with the moon that takes the spacecraft between distances of 67,000 miles (108,000 kilometers) and 233,000 miles (376,000 kilometers) from Earth. In that orbit, TESS makes one loop around Earth about every two weeks.
NASA released the first test image from one of TESS’s four cameras in May, showing roughly 200,000 stars along the plane of our Milky Way galaxy.
The first set of science data from TESS will be downlinked to Earth in August, and NASA said astronomers will immediately begin analyzing the imagery. Software will help scientists cull the data and detect transit signals from exoplanets.
Built by Northrop Grumman Innovation Systems — formerly known as Orbital ATK — TESS fired its thrusters multiple times, and used a gravity assist flyby of the moon May 17, to reach the $337 million mission’s final orbit, a stable perch that requires no further rocket burns and which passes close enough to Earth to transmit full frame images from the craft’s science cameras through a high-speed Ka-band downlink. The orbit also keeps TESS away from the damaging influence of the Van Allen radiation belts.
The spacecraft, which weighed less than a half-ton at launch, carries enough fuel to continue operating up to 20 or 30 years, Ricker said in an interview before TESS’s launch. That assumes NASA funding and spacecraft parts remain robust.