Our latest space telescope, Transiting Exoplanet Survey Satellite (TESS), launched in April. This
week, planet hunters worldwide received all the data from the first two months
of its planet search. This view, from four cameras on TESS, shows just one
region of Earth’s southern sky.
The Transiting Exoplanet Survey Satellite (TESS) captured
this strip of stars and galaxies in the southern sky during one 30-minute
period in August. Created by combining the view from all four of its cameras, TESS
images will be used to discover new exoplanets. Notable features in this swath
include the Large and Small Magellanic Clouds and a globular cluster called NGC
104. The brightest stars, Beta Gruis and R Doradus, saturated an entire column
of camera detector pixels on the satellite’s second and fourth cameras.
The data in the images from TESS will soon lead to discoveries of
planets beyond our solar system – exoplanets. (We’re at 3,848 so far!)
But first, all that data (about 27 gigabytes a day) needs to be
processed. And where do space telescopes like TESS get their data cleaned up?
At the Star Wash, of course!
TESS sends about 10 billion pixels of data to Earth
at a time. A supercomputer at NASA Ames in Silicon Valley processes the raw
data, turning those pixels into measures of a star’s brightness.
And that brightness? THAT’S HOW WE FIND PLANETS! A dip in a star’s
brightness can reveal an orbiting exoplanet in transit.
TESS will spend a year studying our southern sky, then will turn
and survey our northern sky for another year. Eventually, the space telescope
will observe 85 percent of Earth’s sky, including 200,000 of the brightest and
closest stars to Earth.
Once it launches, TESS will look for new planets that orbit bright stars relatively close to Earth. We’re expecting to find giant planets, like Jupiter, but we’re also predicting we’ll find Earth-sized planets. Most of those planets will be within 300 light-years of Earth, which will make follow-up studies easier for other observatories.
TESS will find these new exoplanets by looking for their transits. A transit is a temporary dip in a star’s brightness that happens with predictable timing when a planet crosses between us and the star. The information we get from transits can tell us about the size of the planet relative to the size of its star. We’ve found nearly 3,000 planets using the transit method, many with our Kepler space telescope. That’s over 75% of all the exoplanets we’ve found so far!
TESS will look at nearly the entire sky (about 85%) over two years. The mission divides the sky into 26 sectors. TESS will look at 13 of them in the southern sky during its first year before scanning the northern sky the year after.
What makes TESS different from the other planet-hunting missions that have come before it? The Kepler mission (yellow) looked continually at one small patch of sky, spotting dim stars and their planets that are between 300 and 3,000 light-years away. TESS (blue) will look at almost the whole sky in sections, finding bright stars and their planets that are between 30 and 300 light-years away.
TESS will also have a brand new kind of orbit (visualized below). Once it reaches its final trajectory, TESS will finish one pass around Earth every 13.7 days (blue), which is half the time it takes for the Moon (gray) to orbit. This position maximizes the amount of time TESS can stare at each sector, and the satellite will transmit its data back to us each time its orbit takes it closest to Earth (orange).
Kepler’s goal was to figure out how common Earth-size planets might be. TESS’s mission is to find exoplanets around bright, nearby stars so future missions, like our James Webb Space Telescope, and ground-based observatories can learn what they’re made of and potentially even study their atmospheres. TESS will provide a catalog of thousands of new subjects for us to learn about and explore.
Sunday, April 15 11 a.m. EDT – NASA Social Mission Overview
Join mission experts to learn more about TESS, how it will search for worlds beyond our solar system and what scientists hope to find! Have questions? Use #askNASA to have them answered live during the broadcast.
Today (4/06), we celebrate the special radio frequency transmitted by emergency beacons to the international search and rescue network.
This 406 MHz frequency, used only for search and rescue, can be “heard” by satellites hundreds of miles above the ground! The satellites then “forward” the location of the beacon back to Earth, helping first responders locate people in distress worldwide, whether from a plane crash, a boating accident or other emergencies.
Our Search and Rescue office, based out of our Goddard Space Flight Center, researches and develops emergency beacon technology, passing the technology to companies who manufacture the beacons, making them available to the public at retail stores. The beacons are designed for personal, maritime and aviation use.
The search and rescue network, Cospas-Sarsat, is an international program that ensures the compatibility of distress alert services with the needs of users. Its current space segment relies on instruments onboard low-Earth and geosynchronous orbiting satellites, hundreds to thousands of miles above us.
Space instruments forward distress signals to the search and rescue ground segment, which is operated by partner organizations around the world! They manage specific regions of the ground network. For example, the National Oceanic and Atmospheric Administration (NOAA) operates the region containing the United States, which reaches across the Atlantic and Pacific Oceans as well as parts of Central and South America.
NOAA notifies organizations that coordinate search and rescue efforts of a 406 MHz distress beacon’s activation and location. Within the U.S., the U.S. Air Force responds to land-based emergencies and the U.S. Coast Guard responds to water-based emergencies. Local public service organizations like police and fire departments, as well as civilian volunteers, serve as first responders.
Here at NASA, we research, design and test search and rescue instruments and beacons to refine the existing network. Aeronautical beacon tests took place at our Langley Research Center in 2015. Using a 240-foot-high structure originally used to test Apollo spacecraft, our Search and Rescue team crashed three planes to test the survivability of these beacons, developing guidelines for manufacturers and installation into aircraft.
In the future, first responders will rely on a new constellation of search and rescue instruments on GPS systems on satellites in medium-Earth orbit, not hundreds, but THOUSANDS of miles overhead. These new instruments will enable the search and rescue network to locate a distress signal more quickly than the current system and achieve accuracy an order of magnitude better, from a half mile to approximately 300 feet. Our Search and Rescue office is developing second-generation 406 MHz beacons that make full use of this new system.
We will also incorporate these second-generation beacons into the Orion Crew Survival System. The Advanced Next-Generation Emergency Locator (ANGEL) beacons will be attached to astronaut life preservers. After splashdown, if the Orion crew exits the capsule due to an emergency, these beacons will make sure we know the exact location of floating astronauts! Our Johnson Space Center is testing this technology for used in future human spaceflight and exploration missions.
If you’re the owner of an emergency beacon, remember that beacon registration is free, easy and required by law.
Our Transiting Exoplanet Survey Satellite (TESS), which will scan the skies to look for planets beyond our solar system—known as exoplanets—is now in Florida to begin preparations for launch in April. Below, 10 Things to know about the many, many unknown planets out there awaiting our discovery.
We call planets in our solar system, well, planets, but the many planets we’re starting to discover outside of our solar system are called exoplanets. Basically, they’re planets that orbit another star.
2—All eyes on TRAPPIST-1.
Remember the major 2016 announcement that we had discovered seven planets 40 light-years away, orbiting a star called TRAPPIST-1? Those are all exoplanets. (Here’s a refresher.)
3—Add 95 new ones to that.
Just last month, our Kepler telescope discovered 95 new exoplanets beyond our solar system (on top of the thousands of exoplanets Kepler has discovered so far). The total known planet count beyond our solar system is now more than 3,700. The planets range in size from mostly rocky super-Earths and fluffy mini-Neptunes, to Jupiter-like giants. They include a new planet orbiting a very bright star—the brightest star ever discovered by Kepler to have a transiting planet.
4—Here comes TESS.
How many more exoplanets are out there waiting to be discovered? TESS will 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—and is expected to find thousands of exoplanets.
5—With a sidekick, too.
Ourupcoming James Webb Space Telescope, will provide important follow-up observations of some of the most promising TESS-discovered exoplanets. It will also allow scientists to study their atmospheres and, in some special cases, search for signs that these planets could support life.
6—Prepped for launch.
TESS is scheduled to launch on a SpaceX Falcon 9 rocket from Cape Canaveral Air Force Station nearby our Kennedy Space Center in Florida, no earlier than April 16, pending range approval.
7—A groundbreaking find.
In 1995, 51 Pegasi b (also called “Dimidium”) was the first exoplanet discovered orbiting a star like our Sun. This find confirmed that planets like the ones in our solar system could exist elsewhere in the universe.
A recent statistical estimate places, on average, at least one planet around every star in the galaxy. That means there could be a trillion planets in our galaxy alone, many of them in the range of Earth’s size.
9—Signs of life.
Of course, our ultimate science goal is to find unmistakable signs of current life. How soon can that happen? It depends on two unknowns: the prevalence of life in the galaxy and a bit of luck. Read more about the search for life.
We’re always making amazing discoveries about the farthest reaches of our universe, but there’s also plenty of unexplored territory much closer to home.
Our “Backyard Worlds: Planet 9” is a citizen science project that asks curious people like you — yes, you there! — to help us spot objects in the area around our own solar system like brown dwarfs. You could even help us figure out if our solar system hosts a mysterious Planet 9!
You’ll figure out how to tell the difference between real objects, like planets and stars, and artifacts. Artifacts are blurry blobs of light that got scattered around in WISE’s instruments while it was looking at the sky. These “optical ghosts” sometimes look like real objects.
Why can’t we use computers to do this, you ask? Well, computers are good at lots of things, like crunching numbers. But when it comes to recognizing when something’s a ghostly artifact and when it’s a real object, humans beat software all the time. After some practice, you’ll be able to recognize which objects are real and which aren’t just by watching them move!
One of the things our citizen scientists look for are brown dwarfs, which are balls of gas too big to be planets and too small to be stars. These objects are some of our nearest neighbors, and scientists think there’s probably a bunch of them floating around nearby, we just haven’t been able to find all of them yet.
Image Credit: Ryan Trainor, Franklin and Marshall College
How do we know for sure that we’ve spotted actual, bona fide, authentic brown dwarfs? Well, like with any discovery in science, we followed up with more observation. Our team gets time on ground-based observatories like the InfraRed Telescope Facility in Hawaii, the Magellan Telescope in Chile (pictured above) and the Apache Point Observatory in New Mexico and takes a closer look at our candidates. And sure enough, our participants found 17 brown dwarfs!
But we’re not done! There’s still lots of data to go through. In particular, we want your help looking for a potential addition to our solar system’s census: Planet 9. Some scientists think it’s circling somewhere out there past Pluto. No one has seen anything yet, but it could be you! Or drop by and contribute to our other citizen science projects like Disk Detective.
Congratulations to the citizen scientists who spotted these 17 brown dwarfs: Dan Caselden, Rosa Castro, Guillaume Colin, Sam Deen, Bob Fletcher, Sam Goodman, Les Hamlet, Khasan Mokaev, Jörg Schümann and Tamara Stajic.
There’s never been a better time to ponder this age-old question. We now know of thousands of exoplanets – planets that orbit stars elsewhere in the universe.
So just how many of these planets could support life?
Scientists from a variety of fields — including astrophysics, Earth science, heliophysics and planetary science — are working on this question. Here are a few of the strategies they’re using to learn more about the habitability of exoplanets.
Squinting at Earth
Even our best telescopic images of exoplanets are still only a few pixels in size. Just how much information can we extract from such limited data? That’s what Earth scientists have been trying to figure out.
One group of scientists has been taking high-resolution images of Earth from our Earth Polychromatic Imaging Camera and ‘degrading’ them in order to match the resolution of our pixelated exoplanet images. From there, they set about a grand process of reverse-engineering: They try to extract as much accurate information as they can from what seems — at first glance — to be a fairly uninformative image.
So far, by looking at how Earth’s brightness changes when land versus water is in view, scientists have been able to reverse-engineer Earth’s albedo (the proportion of solar radiation it reflects), its obliquity (the tilt of its axis relative to its orbital plane), its rate of rotation, and even differences between the seasons. All of these factors could potentially influence a planet’s ability to support life.
Avoiding the “Venus Zone”
In life as in science, even bad examples can be instructive. When it comes to habitability, Venus is a bad example indeed: With an average surface temperature of 850 degrees Fahrenheit, an atmosphere filled with sulfuric acid, and surface pressure 90 times stronger than Earth’s, Venus is far from friendly to life as we know it.
The surface of Venus, imaged by Soviet spacecraft Venera 13 in March 1982
Since Earth and Venus are so close in size and yet so different in habitability, scientists are studying the signatures that distinguish Earth from Venus as a tool for differentiating habitable planets from their unfriendly look-alikes.
Using data from our Kepler Space Telescope, scientists are working to define the “Venus Zone,” an area where planetary insolation – the amount of light a given planet receives from its host star – plays a key role in atmospheric erosion and greenhouse gas cycles.
Planets that appear similar to Earth, but are in the Venus Zone of their star, are, we think, unlikely to be able to support life.
Modeling Star-Planet Interactions
When you don’t know one variable in an equation, it can help to plug in a reasonable guess and see how things work out. Scientists used this process to study Proxima b, our closest exoplanet neighbor. We don’t yet know whether Proxima b, which orbits the red dwarf star Proxima Centauri four light-years away, has an atmosphere or a magnetic field like Earth’s. However, we can estimate what would happen if it did.
The scientists started by calculating the radiation emitted by Proxima Centauri based on observations from our Chandra X-ray Observatory. Given that amount of radiation, they estimated how much atmosphere Proxima b would be likely to lose due to ionospheric escape — a process in which the constant outpouring of charged stellar material strips away atmospheric gases.
With the extreme conditions likely to exist at Proxima b, the planet could lose the equivalent of Earth’s entire atmosphere in 100 million years — just a fraction of Proxima b’s 4-billion-year lifetime. Even in the best-case scenario, that much atmospheric mass escapes over 2 billion years. In other words, even if Proxima b did at one point have an atmosphere like Earth, it would likely be long gone by now.
Imagining Mars with a Different Star
We think Mars was once habitable, supporting water and an atmosphere like Earth’s. But over time, it gradually lost its atmosphere – in part because Mars, unlike Earth, doesn’t have a protective magnetic field, so Mars is exposed to much harsher radiation from the Sun’s solar wind.
But as another rocky planet at the edge of our solar system’s habitable zone, Mars provides a useful model for a potentially habitable planet. Data from our Mars Atmosphere and Volatile Evolution, or MAVEN, mission is helping scientists answer the question: How would Mars have evolved if it were orbiting a different kind of star?
Scientists used computer simulations with data from MAVEN to model a Mars-like planet orbiting a hypothetical M-type red dwarf star. The habitable zone of such a star is much closer than the one around our Sun.
Being in the habitable zone that much closer to a star has repercussions. In this imaginary situation, the planet would receive about 5 to 10 times more ultraviolet radiation than the real Mars does, speeding up atmospheric escape to much higher rates and shortening the habitable period for the planet by a factor of about 5 to 20.
These results make clear just how delicate a balance needs to exist for life to flourish. But each of these methods provides a valuable new tool in the multi-faceted search for exoplanet life. Armed with these tools, and bringing to bear a diversity of scientific perspectives, we are better positioned than ever to ask: are we alone?