{"id":14982,"date":"2018-04-13T05:34:19","date_gmt":"2018-04-13T05:34:19","guid":{"rendered":"https:\/\/www.revoscience.com\/en\/?p=14982"},"modified":"2020-05-27T06:00:23","modified_gmt":"2020-05-27T06:00:23","slug":"tess-readies-for-takeoff","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/tess-readies-for-takeoff\/","title":{"rendered":"TESS readies for takeoff"},"content":{"rendered":"

Satellite developed by MIT aims to discover thousands of nearby exoplanets, including at least 50 Earth-sized ones.<\/strong><\/em><\/span><\/p>\n

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A set of flight camera electronics on one of the TESS cameras, developed by the MIT Kavli Institute for Astrophysics and Space Research (MKI), will transmit exoplanet data from the camera to a computer aboard the spacecraft that will process it before transmitting it back to scientists on Earth.
Image: MIT Kavli Institute<\/figcaption><\/figure>\n

(Cambridge, MA) — There are potentially thousands of planets that lie just outside our solar system \u2014 galactic neighbors that could be rocky worlds or more tenuous collections of gas and dust. Where are these closest exoplanets located? And which of them might we be able to probe for clues to their composition and even habitability? The Transiting Exoplanet Survey Satellite (TESS) will be the first to seek out these nearby worlds.<\/span><\/p>\n

The NASA-funded spacecraft, not much larger than a refrigerator, carries four cameras that were conceived, designed, and built at MIT, with one wide-eyed vision: to survey the nearest, brightest stars in the sky for signs of passing planets.<\/span><\/p>\n

Now, more than a decade since MIT scientists first proposed the mission, TESS is about to get off the ground. The spacecraft is scheduled to launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station in Florida, no earlier than\u00a0April 16, at 6:32 p.m. EDT<\/span><\/span>.<\/span><\/p>\n

TESS will spend two years scanning nearly the entire sky \u2014 a field of view that can encompass more than 20 million stars. Scientists expect that thousands of these stars will host transiting planets, which they hope to detect through images taken with TESS\u2019s cameras.<\/span><\/p>\n

Amid this extrasolar bounty, the TESS science team at MIT aims to measure the masses of at least 50 small planets whose radii are less than four times that of Earth. Many of TESS\u2019s planets should be close enough to our own that, once they are identified by TESS, scientists can zoom in on them using other telescopes, to detect atmospheres, characterize atmospheric conditions, and even look for signs of habitability.<\/span><\/p>\n

\u201cTESS is kind of like a scout,\u201d says Natalia Guerrero, deputy manager of TESS Objects of Interest, an MIT-led effort that will catalog objects captured in TESS data that may be potential exoplanets.<\/span><\/p>\n

\u201cWe\u2019re on this scenic tour of the whole sky, and in some ways we have no idea what we will see,\u201d Guerrero says. \u201cIt\u2019s like we\u2019re making a treasure map: Here are all these cool things. Now, go after them.\u201d<\/span><\/p>\n

A seed, planted in space<\/strong><\/span><\/p>\n

TESS\u2019s origins arose from an even smaller satellite that was designed and built by MIT and launched into space by NASA on Oct. 9, 2000. The High Energy Transient Explorer 2, or HETE-2, orbited Earth for seven years, on a mission to detect and localize gamma-ray bursts \u2014 high-energy explosions that emit massive, fleeting bursts of gamma and X-rays.<\/span><\/p>\n

To detect such extreme, short-lived phenomena, scientists at MIT, led by principal investigator George Ricker, integrated into the satellite a suite of optical and X-ray\u00a0 cameras outfitted with CCDs, or charge-coupled devices, designed to record intensities and positions of light in an electronic format.<\/span><\/p>\n

\u201cWith the advent of CCDs in the 1970s, you had this fantastic device \u2026 which made a lot of things easier for astronomers,\u201d says HETE-2 team member Joel Villasenor, who is now also instrument scientist for TESS. \u201cYou just sum up all the pixels on a CCD, which gives you the intensity, or magnitude, of light. So CCDs really broke things open for astronomy.\u201d<\/span><\/p>\n

In 2004, Ricker and the HETE-2 team wondered whether the satellite\u2019s optical cameras could pick out other objects in the sky that had begun to attract the astronomy community: exoplanets. Around this time, only a handful of planets outside our solar system had been discovered. These were found with a technique known as the transit method, which involves looking for periodic dips in the light from certain stars, which may signal a planet passing in front of the star.<\/span><\/p>\n

\u201cWe were thinking, was the photometry of HETE-2\u2019s cameras sufficient so that we could point to a part of the sky and detect one of these dips? Needless to say, it didn\u2019t exactly work,\u201d Villasenor recalls. \u201cBut that was sort of the seed that started us thinking, maybe we should try to fly CCDs with a camera to try and detect these things.\u201d<\/span><\/p>\n

A path, cleared<\/strong><\/span><\/p>\n

In 2006, Ricker and his team at MIT proposed a small, low cost satellite (HETE-S) to NASA as a Discovery class mission, and later on as a privately funded mission for $20 million. But as the cost of, and interest in, an all-sky exoplanet survey grew, they decided instead to seek NASA funding, at a higher level of $120 million. In 2008, they submitted a proposal for a NASA Small Explorer (SMEX) Class Mission with the new name \u2014 TESS.<\/span><\/p>\n

At this time, the satellite design included six CCD cameras, and the team proposed that the spacecraft fly in a low-Earth orbit, similar to that of HETE-2. Such an orbit, they reasoned, should keep observing efficiency relatively high, as they already had erected data-receiving ground stations for HETE-2 that could also be put to use for TESS.<\/span><\/p>\n

But they soon realized that a low-Earth orbit would have a negative impact on TESS\u2019s much more sensitive cameras. The spacecraft\u2019s reaction to the Earth\u2019s magnetic field, for example, could lead to significant \u201cspacecraft jitter,\u201d producing noise that hides an exoplanet\u2019s telltale dip in starlight.<\/span><\/p>\n

NASA bypassed this first proposal, and the team went back to the drawing board, this time emerging with a new plan that hinged on a completely novel orbit. With the help of engineers from NASA\u2019s Goddard Space Flight Center and the Aerospace Corporation, the team identified a never-before-used \u201clunar-resonant\u201d orbit that would keep the spacecraft extremely stable, while giving it a full-sky view.<\/span><\/p>\n

Once TESS reaches this orbit, it will slingshot between the Earth and the moon on a highly elliptical path that could keep TESS orbiting for decades, shepherded by the moon\u2019s gravitational pull.<\/span><\/p>\n

\u201cThe moon and the satellite are in a sort of dance,\u201d Villasenor says. \u201cThe moon pulls the satellite on one side, and by the time TESS completes one orbit, the moon is on the other side tugging in the opposite direction. The overall effect is the moon\u2019s pull is evened out, and it\u2019s a very stable configuration over many years. Nobody\u2019s done this before, and I suspect other programs will try to use this orbit later on.\u201d<\/span><\/p>\n

In its current planned trajectory, TESS will swing out toward the moon for less than two weeks, gathering data, then swing back toward the Earth where, on its closest approach, it will transmit the data back to ground stations from 67,000 miles above the surface before swinging back out. Ultimately, this orbit will save TESS a huge amount of fuel, as it won\u2019t need to burn its thrusters on a regular basis to keep on its path.<\/span><\/p>\n

With this revamped orbit, the TESS team submitted a second proposal in 2010, this time as an Explorer class mission, which NASA approved in 2013. It was around this time that the Kepler Space Telescope ended its original survey for exoplanets. The observatory, which was launched in 2009, stared at one specific patch of the sky for four years, to monitor the light from distant stars for signs of transiting planets.<\/span><\/p>\n

By 2013, two of Kepler\u2019s four reaction wheels had worn out, preventing the spacecraft from continuing its original survey. At this point, the telescope\u2019s measurements had enabled the discovery of nearly 1,000 confirmed exoplanets. Kepler, designed to study far-off stars, paved the way for TESS, a mission with a much wider view, to scan the nearest stars to Earth.<\/span><\/p>\n

\u201cKepler went up, and was this huge success, and researchers said, \u2018We can do this kind of science, and there are planets everywhere,\u201d says TESS member Jennifer Burt, an MIT-Kavli postdoc. \u201cAnd I think that was really the scientific check box that we needed for NASA to say, \u2018Okay, TESS makes a lot of sense now.\u2019 It\u2019ll enable not just detecting planets, but finding planets that we can thoroughly characterize after the fact.\u201d<\/span><\/p>\n

Stripes in the sky<\/strong><\/span><\/p>\n

With the selection by NASA, the TESS team set up facilities on campus and in MIT\u2019s Lincoln Laboratory to build and test the spacecraft\u2019s cameras. The engineers designed \u201cdeep depletion\u201d CCDs specifically for TESS, meaning that the cameras can detect light over a wide range of wavelengths up to the near infrared. This is important, as many of the nearby stars TESS will monitor are red-dwarfs \u2014 small, cool stars that emit less brightly than the sun and in the infrared part of the electromagnetic spectrum.<\/span><\/p>\n

If scientists can detect periodic dips in the light from such stars, this may signal the presence of planets with significantly tighter orbits than that of Earth. Nevertheless, there is a chance that some of these planets may be within the \u201chabitable zone,\u201d as they would circle much cooler stars, compared with the sun. Since these stars are relatively close by, scientists can do follow-up observations with ground-based telescopes to help identify whether conditions might indeed be suitable for life.\u00a0<\/span><\/p>\n

TESS\u2019s cameras are mounted on the top of the satellite and surrounded by a protective cone to shield them from other forms of electromagnetic radiation. Each camera has a 24 by 24 degree view of the sky, large enough to encompass the Orion constellation. The satellite will start its observations in the Southern Hemisphere and will divide the sky into 13 stripes, monitoring each segment for 27 days before pivoting to the next. TESS should be able to observe nearly the entire sky in the Southern Hemisphere in its first year, before moving on to the Northern Hemisphere in its second year.<\/span><\/p>\n

While TESS points at one stripe of the sky, its cameras will take pictures of the stars in that portion. Ricker and his colleagues have made a list of 200,000 nearby, bright stars that they would particularly want to observe. The satellite\u2019s cameras will create \u201cpostage stamp\u201d images that include pixels around each of these stars. These images will be taken every two minutes, in order to maximize the chance of catching the moment that a planet crosses in front of its star. The cameras will also take full-frame images of all the stars in a particular stripe of the sky, every 30 minutes.\u00a0<\/span><\/p>\n

\u201cWith the two-minute pictures, you can get a movie-like image of what the starlight is doing as the planet is crossing in front of its host star,\u201d Guerrero says. \u201cFor the 30-minute images, people are excited about maybe seeing supernovae, asteroids, or counterparts to gravitational waves. We have no idea what we\u2019re going to see at that timescale.\u201d<\/span><\/p>\n

Are we alone?<\/strong><\/span><\/p>\n

After TESS launches, the team expects that the satellite will reestablish contact within the first week, during which it will turn on all its instruments and cameras. Then, there will be a 60-day commissioning phase, as engineers at NASA and MIT calibrate the instruments and monitor the satellite\u2019s trajectory and performance. After that, TESS will begin to collect and downlink images of the sky. Scientists at MIT and NASA will take the raw data and convert it into light curves that indicate the changing brightness of a star over time.<\/span><\/p>\n

From there, the TESS Science Team, including Sara Seager, the Class of 1941 Professor of Earth, Atmospheric and Planetary Sciences, and deputy director of science for TESS, will look through thousands of light curves, for at least two similar dips in starlight, indicating that a planet may have passed twice in front of its star. Seager and her colleagues will then employ a battery of methods to determine the mass of a potential planet.<\/span><\/p>\n

\u201cMass is a defining planetary characteristic,\u201d Seager says. \u201cIf you just know that a planet is twice the size of Earth, it could be a lot of things: a rocky world with a thin atmosphere, or what we call a \u201cmini-Neptune\u201d \u2014 a rocky world with a giant gas envelope, where it would be a huge greenhouse blanket, and there would be no life on the surface. So mass and size together give us an average planet density, which tells us a huge amount about what the planet is.\u201d<\/span><\/p>\n

During TESS\u2019s two-year mission, Seager and her colleagues aim to measure the masses of 50 planets with radii less than four times that of Earth \u2014 dimensions that could signal further observations for signs of habitability. Meanwhile, the whole scientific community and public will get a chance to search through TESS data for their own exoplanets. Once the data are calibrated, the team will make them publicly available. Anyone will be able to download the data and draw their own interpretations, including high school students, armchair astronomers, and other research institutions.<\/span><\/p>\n

With so many eyes on TESS\u2019S data, Seager says there\u2019s a chance that, some day, a nearby planet discovered by TESS might be found to have signs of life.<\/span><\/p>\n

\u201cThere\u2019s no science that will tell us life is out there right now, except that small rocky planets appear to be incredibly common,\u201d Seager says. \u201cThey appear to be everywhere we look. So it\u2019s got to be there somewhere.\u201d<\/span><\/p>\n

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA\u2019s Goddard Space Flight Center in Greenbelt, Maryland. George Ricker of MIT\u2019s Kavli Institute for Astrophysics and Space Research serves as principal investigator for the mission.\u00a0Additional partners include Orbital ATK, NASA\u2019s 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 participants in the mission.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Satellite developed by MIT aims to discover thousands of nearby exoplanets, including at least 50 Earth-sized ones. (Cambridge, MA) — There are potentially thousands of planets that lie just outside our solar system \u2014 galactic neighbors that could be rocky worlds or more tenuous collections of gas and dust. Where are these closest exoplanets located? […]<\/p>\n","protected":false},"author":6,"featured_media":14983,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[17,20],"tags":[],"class_list":["post-14982","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-research","category-space-news"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0-300x200.jpg",300,200,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",600,400,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",600,400,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",540,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",95,63,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",639,426,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2018\/04\/MIT-TESS-Mission-01_0.jpg",150,100,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Research<\/a> Space\/ AstroPhysics<\/a>","tag_info":"Space\/ AstroPhysics","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/14982","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=14982"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/14982\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/14983"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=14982"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=14982"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=14982"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}