Jan. 11, 2012: Astronomers using data from NASA's Kepler mission have discovered the three smallest planets yet detected orbiting a star beyond our sun.
The planets orbit a single star, called KOI-961, and are 0.78, 0.73 and 0.57 times the radius of Earth. The smallest is about the size of Mars.
"This is the tiniest solar system found so far," said John Johnson, the principal investigator of the research from NASA's Exoplanet Science Institute at the California Institute of Technology in Pasadena. "It's actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy."
This artist's concept depicts an itsy bitsy planetary system -- so compact, in fact, that it's more like Jupiter and its moons than a star and its planets. Astronomers using data from NASA's Kepler mission and ground-based telescopes recently confirmed that the system, called KOI-961, hosts the three smallest exoplanets known so far to orbit a star other than our sun. [more]
All three planets are thought to be rocky like Earth, but orbit close to their star. That makes them too hot to be in the habitable zone, which is the region where liquid water could exist. Of the more than 700 planets confirmed to orbit other stars -- called exoplanets -- only a handful are known to be rocky.
"Astronomers are just beginning to confirm thousands of planet candidates uncovered by Kepler so far," said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington." Finding one as small as Mars is amazing, and hints that there may be a bounty of rocky planets all around us."
Kepler searches for planets by continuously monitoring more than
150,000 stars, looking for telltale dips in their brightness caused by
crossing, or transiting, planets. At least three transits are required
to verify a signal as a planet. Follow-up observations from ground-based
telescopes also are needed to confirm the discoveries.
'Honey I Shrunk the Planetary System': This artist's concept compares the KOI-961 planetary system to Jupiter and the largest four of its many moons. Image credit: NASA/JPL-Caltech [more]
Red dwarfs are the most common kind of star in our Milky Way
galaxy. The discovery of three rocky planets around one red dwarf
suggests that the galaxy could be teeming with similar rocky planets.
Production Editor: Dr. Tony Phillips | Credit: Science@NASA
Dec 5, 2011:
NASA's Kepler mission has confirmed its first planet in the "habitable zone" of a distant sun-like star.
This artist's conception illustrates Kepler-22b, a planet known to comfortably circle in the habitable zone of a sun-like star. [larger image]
The newly confirmed planet, Kepler-22b, is about 2.4 times the radius of Earth. Scientists don't yet know if Kepler-22b has a predominantly rocky, gaseous or liquid composition, but its discovery is a step closer to finding Earth-like planets1.
The "habitable zone" of a planetary system refers to the band of
orbits where liquid water could exist on a planet’s surface. Kepler has
recently discovered more than 1,000 new planet candidates. Ten of these
candidates are near-Earth-size and orbit in the habitable zone of their
host star. Candidates require follow-up observations to verify they are
Kepler-22b is located 600 light-years away. While the planet is larger than Earth, its orbit of 290 days around a sun-like star resembles that of our world. The planet's host star belongs to the same class as our sun, called G-type, although it is slightly smaller and cooler.
Kepler discovers planets and planet candidates by measuring dips
in the brightness of more than 150,000 stars to search for planets that
cross in front, or "transit," the stars. Kepler requires at least three
transits to verify a signal as a planet.
This diagram compares our own solar system to Kepler-22, a star system containing the first "habitable zone" planet discovered by NASA's Kepler mission.
The habitable zone is the sweet spot around a star where temperatures are right for water to exist in its liquid form. Liquid water is essential for life on Earth.
The Kepler science team uses ground-based telescopes and the
Spitzer Space Telescope to review observations on planet candidates the
spacecraft finds. The star field that Kepler observes in the
constellations Cygnus and Lyra can only be seen from ground-based
observatories in spring through early fall. The data from these other
observations help determine which candidates can be validated as
The findings, based on observations conducted May 2009 to September 2010, show a dramatic increase in the numbers of smaller-size planet candidates. Earth-size and super Earth-size candidates have increased in number by more than 200 and 140 percent since February, respectively. These new data suggest that planets one to four times the size of Earth may be abundant in the galaxy.
So far, there are 48 planet candidates in their star's habitable
zone. While this is a decrease from the 54 reported in February, the
Kepler team has applied a stricter definition of what constitutes a
habitable zone in the new catalog, to account for the warming effect of
atmospheres, which would move the zone away from the star, out to longer
Production Editor: Dr. Tony Phillips | Credit: Science@NASA
by Tammy Plotner on December 1, 2011 from UniverseToday.com
The Kepler field as seen in the sky over Kitt Peak National Observatory. The approximate position of HD 179070 is indicated by the circle (sky imaged using a diffraction grating to show spectra of brighter stars, credit J. Glaspey; telescopes imaged separately and combined, credit P. Marenfeld)
Are you ready to add another planet to the growing list of discoveries? Thanks to work done by Steve Howell of the NASA Ames Research Center and his research team, the Kepler Mission has scored another. Cataloged as 21-b, this “new” planet measures about one and half times the Earth’s radius and no more than 10 times the mass… but its “year” is only 2.8 days long!
With such a speedy orbit around its parent star, this little planet quickly drew attention to itself. Kepler 21-b’s sun is much like our own and one of the brightest in the Kepler field. Given its unique set of circumstances, it required a team of over 65 astronomers (that included David Silva, Ken Mighell and Mark Everett of NOAO) and cooperation with several ground-based telescopes including the 4 meter Mayall telescope and the WIYN telescope at Kitt Peak National Observatory to confirm its existence.
At this point, observations place this hot little planet at about 6 million kilometers away from the parent star, where it has estimated temperatures of about 1900 K, or 2960 F. While this isn’t even anywhere near a life-supporting type of planet, Kepler 21-b remains of interest because of its size. The parent star, HD 179070, is just slightly larger than the Sun and about half its age. Regardless, it can still be seen with optical aid and it is only about 352 light years away from Earth.
Kepler light curve of HD 179070 showing the eclipse of Kepler-21b. The data cover 15 months. The figure shows the binned, and phase folded-data based on 164 individual transits over-plotted by the model fit (Purple line).
Why are findings like these exciting? Probably because a large amount of stars show short period brightness oscillations – which means it’s difficult to detect a planetary passage from a normal light curve. In this case, it took 15 long months to build up enough information – including spectroscopic and imaging data from a number of ground based telescopes – to make a confident call on the planet’s presence.
It ain’t easy being a little planet… But they can be found!
Original Story Source: NOAO News Release.
Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
2011 February 2
NASA FINDS EARTH-SIZE PLANET CANDIDATES IN HABITABLE ZONE, SIX PLANET SYSTEM
MOFFETT FIELD, Calif. -- NASA's Kepler mission has discovered its first Earth-size planet candidates and its first candidates in the habitable zone, a region where liquid water could exist on a planet's surface. Five of the potential planets are near Earth-size and orbit in the habitable zone of smaller, cooler stars than our sun.
Candidates require follow-up observations to verify they are actual planets. Kepler also found six confirmed planets orbiting a sun-like star, Kepler-11. This is the largest group of transiting planets orbiting a single star yet discovered outside our solar system.
"In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today's reality," said NASA Administrator Charles Bolden. "These discoveries underscore the importance of NASA's science missions, which consistently increase understanding of our place in the cosmos."The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter. Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size -- up to twice the size of Earth -- to larger than Jupiter.
"The fact that we've found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting sun-like stars in our galaxy," said William Borucki of NASA's Ames Research Center in Moffett Field, Calif., the mission's science principal investigator. "We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone, some of which could have moons with liquid water."
Among the stars with planetary candidates, 170 show evidence of multiple planetary candidates. Kepler-11, located approximately 2,000 light years from Earth, is the most tightly packed planetary system yet discovered. All six of its confirmed planets have orbits smaller than Venus, and five of the six have orbits smaller than Mercury's. The only other star with more than one confirmed transiting planet is Kepler-9, which has three. The Kepler-11 findings will be published in the Feb. 3 issue of the journal Nature.
Kepler-11 is a star in the Kepler spacecraft field of observations and is roughly 2000 light years away from our Solar System. The star is notable because of the detection of multiple transiting planets around it, and because the star is similar to our Sun in mass and size. Based on the observations by the Kepler spacecraft as well as the Keck telescopes, the star is believed to have 6 planets orbiting it, several of which are close to Earth in terms of mass and size. 
"Kepler-11 is a remarkable system whose architecture and dynamics provide clues about its formation," said Jack Lissauer, a planetary scientist and Kepler science team member at Ames. "These six planets are mixtures of rock and gases, possibly including water. The rocky material accounts for most of the planets' mass, while the gas takes up most of their volume. By measuring the sizes and masses of the five inner planets, we determined they are among the lowest mass confirmed planets beyond our solar system."
All of the planets orbiting Kepler-11 are larger than Earth, with the largest ones being comparable in size to Uranus and Neptune. The innermost planet, Kepler-11b, is ten times closer to its star than Earth is to the sun. Moving outward, the other planets are Kepler-11c, Kepler-11d, Kepler-11e, Kepler-11f, and the outermost planet, Kepler-11g, which is half as far from its star as Earth is from the sun.
The planets Kepler-11d, Kepler-11e and Kepler-11f have a significant amount of light gas, which indicates that they formed within a few million years of the system's formation.
"The historic milestones Kepler makes with each new discovery will determine the course of every exoplanet mission to follow," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.
Kepler, a space telescope, looks for planet signatures by measuring
tiny decreases in the brightness of stars caused by planets crossing in
front of them. This is known as a transit.
August 26, 2010 from UniverseToday.com
Relative sizes and orbital periods of the newly discovered planets and the super-Earth candidate as they cross their host star, Kepler-9. Image courtesy of NASA/Kepler/Darin Ragozzine
The Kepler mission has discovered a system of two Saturn size planets with perhaps a third planet that is only 1.5 times the radius of Earth. While the news of this discovery is tempered somewhat with the announcement by a team from the European Southern Observatory of a system with five confirmed Neptune-sized planets and perhaps two additional smaller planets, both discoveries highlight that the spacecraft and techniques astronomers are using to find exoplanets are getting the desired results, and excitingly exoplanet reseach now includes the study of multiplanet systems. This discovery is the first time multiple planets were found by looking at transit time variations, which can provide more information about planets, such as their masses.
“What is particularly special
about this system, is that the variations in transit times are large
enough, that we can use these transit timing to detect the masses of
these bodies” said Matthew Holman, Kepler team lead for the study of star Kepler-9, speaking on the AAAS Science
podcast. Additionally, these findings should provide the tools
astronomers need to determine even more physical conditions of these
planets — and others — in the future.
The team analyzed seven months of data from the orbiting Kepler telescope, and the two large confirmed planets—Kepler-9b and Kepler-9c— are transiting the parent star at unstable rates. The planets’ 19.2- and 38.9-day transition periods are increasing and decreasing at average, respective rates of four and 39 minutes per orbit.
“One thing that caught our attention right off, is when we do preliminary estimates at the time of the transit, we saw large variations in this particular system. Not only did we see more than one planet transiting, but one planet seemed to be speeding up and one slowing down," Holman said.
Because period one is roughly twice the other, they have a signature of what is called a 2:1 orbital resonance, where astronomers expect to see large timing variation, due to the orbital gravitational push and pull the systems has on all the objects.
"The variation in transit times depend upon the masses of the planets," Holman told reporters in a news conference announcing the findings. "The larger the mass the larger the variations. These variations allows us to determine the mass of the objects and we can confirm that they are planets."
The team also confirmed the objects were planets with radial velocity observations with the Keck I telescope.
The third planet, with a mass several times that of the Earth, is transiting the star in a more interior orbit, but further analysis will be necessary to confirm that this signature is actually a planet.
“We are being very careful at this point to only call it a planet candidate, rather than a confirmed planet,” Holman said. “If it is confirmed it would only have a radius of about 1.5 that of Earth’s. It has a much shorter orbital period of 1.6 days, so it is very close to its host star, so we should be able to see evidence of many transits.”
Holman added that this discovery — regardless of whether they are able to confirm that this is a planet or not — highlights the sensitivity of Kepler to very small signatures.
Holman said the planets have probably migrated to be closer to the star from where they started out when they formed. “Likely they formed with the star, but likely they formed farther out at the “snow line” several times farther away from the star than the Earth is, and by a dynamical process move in closer," he said in the Science podcast.
The resonance is a signature that some kind of migration had occurred, called convergent migration, where planets are moving towards the star and also coming closer to each other.
From all the transit timing information that has been gathered so far, astronomers are piecing together the migration history of this planetary system. "The whole history of that system may be encoded in the information we have," said Alycia Weinberger, from the Department of Terrestrial Magnetism at the Carnegie Institution. "Isn't it cool that what the planetary system looks like today has much to tell us about its history?".
Kepler looks for the signatures of planets by measuring tiny decreases in the brightness of stars when planets cross in front of, or transit them. The size of the planet can be derived from the change in the star's brightness. In June, mission scientists announced the mission has identified more than 700 planet candidates, including five systems with more than one planet candidate. This is the first of those systems to be confirmed.
Kepler principal investigator William Borucki said the team is working hard to get these candidates "turned into confirmed planets."
Asked about why the public seems to be so interested in the Kepler mission, Borucki said, "We addressing a very important question, which is, are there other earths out there and are they frequent? Any answer is important. If we get zero that might mean there is very little life out there in the universe."
June 15th, 2010 from UniverseToday.com
Written by Nancy Atkinson
The Kepler spacecraft has found over 750 candidates for extrasolar planets, and that is just from data collected in the first 43 days of the spacecraft's observations. "This is the biggest release of candidate planets
that has ever happened," said William Borucki, Kepler's lead scientist. "The number of candidate planets is actually greater than all the planets that have been discovered in the last 15 years."
This is an astounding amount of potential exoplanets from data taken during such a short period of time, however Borucki added that they expect only about 50% of these candidates to actually turn out to be planets,
as some may be
eclipsing binary stars or other
artifacts in the data. But still, even half would be the biggest group
discovery of exoplanets ever.
The Kepler team has found so many candidates, they are sharing. They will keep the top 400 candidates to verify and confirm with observations using other telescopes – with observations done by Kepler team members. And today they have released the other 350 candidates, including five potential multiple planet systems.
However, some astronomers are upset about this and think the Kepler team should release all of their findings from the first year, as is typically done with NASA data.
Kepler launched on March 6, 2009, and has been on the hunt for exoplanets. Of course, the holy grail is finding an Earth-like or Earth-sized planet, especially those in the habitable zone of stars where liquid water
and possibly life might exist. In the spring of 2009 the Kepler Mission conducted high precision photometry on nearly 156,000 stars to detect the frequency and characteristics of small exoplanets. Kepler studied an area in the constellation Cygnus, looking for the small changes in light that would signal a planet passing in front of its star.
But it takes time to verify candidates and find out if they are actually exoplanets. Usually, confirming the transit of an exoplanet requires observations of three different transits. While NASA’s policy requires astronomers to release their data from NASA instruments in a year, the Kepler team has worked out an agreement with the space agency so they can keep a certain portion of their data until they actually have time to verify this huge amount of exoplanet data. Between launch delays of other telescopes, cloudy nights for Earth based telescopes, and viewing a part of the sky that is only visible from the ground from April until September, they haven't had the observing time they needed to check out all their planet candidates. The extension of the deadline gives the Kepler team the time to make sure they have gone through and found all the false positives and other potential misinterpretations of the Kepler data.
Dennis Overbye in the New York Times has written an article that delves more deeply into this little controversy. What is propriety data, and what is public? It's a tough argument either way: scientists who have put years of their life into building a spacecraft should have the time they need to verify their data. But others feel the science should be open and available, and a policy is a policy: the deadline for releasing the data is here.
Whatever your feelings on open or closed data (and the Kepler team is only getting an extra six months on just part of their data, by the way), you have to be impressed with the quantity of potential exoplanet finds. And Kepler still has at least two years left of observations.
Papers of interest:
The First Five EXOPLANET
NASA's Kepler space telescope, designed to find Earth-size planets in the habitable zone of sun-like stars, has discovered its first five new exoplanets, or planets beyond our solar system.
Kepler's high sensitivity to both small and large planets enabled the discovery of the exoplanets, named Kepler 4b, 5b, 6b, 7b and 8b. The discoveries were announced Monday, Jan. 4,
by the members of the Kepler science team during a news briefing at the American Astronomical Society meeting in Washington.
"These observations contribute to our understanding of how planetary systems form and evolve from the gas and dust disks that give rise to both the stars and their planets," said William Borucki
of NASA's Ames Research Center in Moffett Field, Calif. Borucki is the mission's science principal investigator. "The discoveries also show that our science instrument is working well.
Indications are that Kepler will meet all its science goals."
Known as "hot Jupiters" because of their high masses and extreme temperatures, the new exoplanets range in size from similar to Neptune to larger than Jupiter. They have orbits ranging
from 3.3 to 4.9 days. Estimated temperatures of the planets range from 2,200 to 3,000 degrees Fahrenheit, hotter than molten lava and much too hot for life as we know it. All five of the exoplanets
orbit stars hotter and larger than Earth's sun.
"It's gratifying to see the first Kepler discoveries rolling off the assembly line," said Jon Morse, director of the Astrophysics Division at NASA Headquarters in Washington. "We expected Jupiter-size planets in short orbits to be the first planets Kepler could detect. It's only a matter of time before more Kepler observations lead to smaller planets with longer period orbits, coming closer
and closer to the discovery of the first Earth analog."
Launched on March 6, 2009, from Cape Canaveral Air Force Station in Florida, the Kepler mission continuously and simultaneously observes more than 150,000 stars. Kepler's science
instrument, or photometer, already has measured hundreds of possible planet signatures that are being analyzed.
While many of these signatures are likely to be something other than a planet, such as small stars orbiting larger stars, ground-based observatories have confirmed the existence of the
five exoplanets. The discoveries are based on approximately six weeks' worth of data collected since science operations began on May 12, 2009.
Kepler looks for the signatures of planets by measuring dips in the brightness of stars. When planets cross in front of, or transit, their stars as seen from Earth, they periodically block the starlight.
The size of the planet can be derived from the size of the dip. The temperature can be estimated from the characteristics of the star it orbits and the planet's orbital period.
Kepler will continue science operations until at least November 2012. It will search for planets as small as Earth, including those that orbit stars in a warm habitable zone where liquid water could
exist on the surface of the planet. Since transits of planets in the habitable zone of solar-like stars occur about once a year and require three transits for verification, it is expected to take at
least three years to locate and verify an Earth-size planet.
According to Borucki, Kepler's continuous and long-duration search should greatly improve scientists' ability to determine the distributions of planet size and orbital period in the future. "Today's discoveries are a significant contribution to that goal," Borucki said. "The Kepler observations will tell us whether there are many stars with planets that could harbor life, or whether we might
be alone in our galaxy."
Kepler is NASA's 10th Discovery mission. Ames is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory in Pasadena, Calif., managed the Kepler mission development. Ball Aerospace & Technologies Corp. of Boulder, Colo., was responsible for developing the Kepler flight system. Ball and the Laboratory for Atmospheric and Space Physics at the University of Colorado in Boulder are supporting mission operations.
Ground observations necessary to confirm the discoveries were
conducted with ground-based telescopes the Keck I in Hawaii;
Hobby-Ebberly and Harlan J. Smith 2.7m in Texas; Hale and
Shane in California ; WIYN, MMT and Tillinghast in Arizona; and Nordic Optical in the Canary Islands, Spain.
[Bill Borucki's Press Conference slides 2010 Jan 4 (Power Point, 31.36 MB) (30 Mb)]
[Bill Borucki's Plenary Talk at AAS 2010 Jan 4 (Power Point, 16.54 MB) (17 Mb)]
Image above: Liftoff of the Delta II rocket carrying NASA's Kepler spacecraft. Image credit: NASA/Jack Pfaller
› Larger Image
The Delta II rocket carrying the Kepler planet-hunting spacecraft lifted off on time at 10:49 p.m. EST from Launch Complex 17-B at Cape Canaveral Air Force Station in Florida. The spectacular nighttime launch followed a smooth countdown free of technical issues or weather concerns.
Kepler's mission: to peer closely at a patch of space for at least three-and-a-half years, looking for rocky planets similar our own. The spacecraft will target an area rich with stars like our sun, watching for a slight dimming in the starlight as planets slip through the space between.
"Kepler is a critical component in NASA's broader efforts to ultimately find and study planets where Earth-like conditions may be present," said Jon Morse, the Astrophysics Division director at NASA Headquarters in Washington. "The planetary census Kepler takes will be very important for understanding the frequency of Earth-size planets in our galaxy and planning future missions that directly detect and characterize such worlds around nearby stars."
› Multimedia for Feb. 19 Press conference
› Launch Processing Images
KEPLER JUST BEFORE LAUNCH
AFTER LAUNCH UPDATE:
Engineers acquired a signal from Kepler at 12:11 a.m. Saturday March 7, after it separated from its spent third-stage rocket and entered its final sun-centered orbit, trailing 950 miles behind Earth. The spacecraft is generating its own power from its solar panels.
"Kepler now has the perfect place to watch more than 100,000 stars for signs of planets," said William Borucki, the mission's science principal investigator at NASA's Ames Research Center at Moffett Field, Calif. Borucki has worked on the mission for 17 years. "Everyone is very excited as our dream becomes a reality. We are on the verge of learning if other Earths are ubiquitous in the galaxy."
The first planets to roll out on the Kepler "assembly line" are expected to be the portly "hot Jupiters" -- gas giants that circle close and fast around their stars. NASA's Hubble and Spitzer space telescopes will be able to follow up with these planets and learn more about their atmospheres. Neptune-size planets will most likely be found next, followed by rocky ones as small as Earth. The true Earth analogs -- Earth-sized planets orbiting stars like our sun at distances where surface water, and possibly life, could exist -- would take at least three years to discover and confirm. Ground-based telescopes also will contribute to the mission by verifying some of the finds.
In the end, Kepler will give us our first look at the frequency of Earth-size planets in our Milky Way galaxy, as well as the frequency of Earth-size planets that could theoretically be habitable.
"Even if we find no planets like Earth, that by itself would be profound. It would indicate that we are probably alone in the galaxy," said Borucki.
2009 MAY 15th UPDATE:
Written by Nancy Atkinson
The checkout and calibration phase for the Kepler spacecraft has been completed, and now the telescope will begin one of the longest and most important stare-downs ever attempted. Kepler will spend the next three-and-a-half years staring at more than 100,000 stars searching for telltale signs of planets. Kepler should have the ability to find planets as small as Earth that orbit sun-like stars at distances where temperatures are right for possible lakes and oceans. “Now the fun begins,” said William Borucki, Kepler science principal investigator for the mission. “We are all really excited to start sorting through the data and discovering the planets.”
During the checkout phase scientists have collected data to characterize the imaging performance as well as the noise level in the measurement electronics. The scientists have constructed the list of targets for the start of the planet search, and this information has been loaded onto the spacecraft.
“If Kepler got into a staring contest, it would win,” said James Fanson, Kepler project manager at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. “The spacecraft is ready to stare intently at the same stars for several years so that it can precisely measure the slightest changes in their brightness caused by planets.” Kepler will hunt for planets by looking for periodic dips in the brightness of stars — events that occur when orbiting planets cross in front of their stars and partially block the light.
The mission’s first finds are expected to be large, gas planets situated close to their stars. Such discoveries could be announced as early as next year (2010).
We’ll be eagerly awaiting!
Filed under: Extrasolar Planets
MORE AT KEPLER'S WEBSITE at: http://kepler.nasa.gov/
Ames Research Center, Moffett Field, Calif.
George H. Diller
Kennedy Space Center, Fla.
Jet Propulsion Laboratory, Pasadena, Calif.
Feb. 26, 2009
Kepler is a spaceborne telescope designed to search the nearby region of our galaxy for Earth-size planets orbiting in the habitable zone of stars like our sun. The habitable zone is the region around a star where temperatures permit water to be liquid on a planet's surface.
Liquid water is considered essential for the existence of life as we know it. The vast majority of the approximately 300 planets known to orbit other stars are much larger than Earth, and none is believed to be habitable. The challenge for Kepler is to look at a large number of stars in order to statistically estimate the total number of Earth-size planets orbiting sun-like stars in the habitable zone. Kepler will survey more than 100,000 stars in our galaxy.
Engineers are reviewing all common hardware between the Delta II rocket carrying the Kepler telescope and the Taurus XL launch vehicle. On Tuesday, a Taurus carrying NASA's Orbiting Carbon Observatory failed to reach orbit. Managers want to confirm there will not be similar issues with Kepler's Delta II.
Kepler's original March 5 target launch date was moved one day later to accommodate the additional time for analysis. The March 6 target date still must be confirmed by the U.S Air Force, which manages the eastern launch range. Kepler's Flight Readiness Review is on Monday, March 2.
NASA's Launch Services Program at NASA's Kennedy Space Center, Fla., is responsible for the launch of Kepler aboard a Delta II 7925-10L rocket. United Launch Alliance is conducting the launch for NASA. NASA's Ames Research Center, Moffett Field, Calif., is the home organization of the principal science investigator and is responsible for the ground system development, mission operations and science data analysis. NASA's Jet Propulsion Laboratory, Pasadena, Calif., is responsible for the spacecraft and the Kepler mission development. Ball Aerospace & Technologies Corporation of Boulder, Colo., is responsible for developing and building the Kepler spacecraft and supporting mission operations.
Accreditation and Media Access Badges for Kennedy and Cape Canaveral Air Force Station
All news media, including those who are permanently badged at Kennedy, must complete the accreditation process for activities associated with the Kepler launch. Accreditation requests for Kepler at Kennedy Space Center and Cape Canaveral Air Force Station must be received by the close of business Tuesday, March 3. The media accreditation process is online at:
On Thursday, March 5, media without permanent credentials may obtain NASA access badges at the Kennedy Space Center Badging Office between 6 a.m. and 4 p.m. This facility is located on State Road 405 just east of the Kennedy Space Center Visitor Complex. Two forms of government-issued identification are required, including at least one with a picture. For further information about media accreditation, contact Laurel Lichtenberger in the news media accreditation office at 321-867-4036.
Prelaunch News Conference
Thursday, March 5: A prelaunch press conference will be held at the Kennedy Space Center news center at 1 p.m. Participants will be:
- Ed Weiler, associate administrator, Science Mission Directorate, NASA Headquarters, Washington
- Omar Baez, NASA launch director and launch manager, Kennedy Space Center
- Vernon Thorp, program manager, NASA Missions, United Launch Alliance
- Jim Fanson, Kepler project manager, Jet Propulsion Laboratory
- John Troeltzsch, Kepler program manager, Ball Aerospace Corporation
- Joel Tumbiolo, U.S. Air Force Delta II launch weather officer, 45th Weather Squadron, Cape Canaveral Air Force Station
Mission Science Briefing
Immediately following the prelaunch news conference, a Kepler mission science briefing will be held. Participants will be:
- Ed Weiler, associate administrator, Science Mission Directorate, NASA Headquarters
- Bill Borucki, science principal investigator, Ames Research Center
- Natalie Batalha, co-investigator, San Jose State University
- Gibor Basri, co-investigator, University of California at Berkeley
Tower Rollback Photo Opportunity and Remote Camera Placements
Thursday, March 5: Photographers who wish to cover the rollback of the mobile service tower from around the Delta II or to set up remote cameras at Pad 17-B will be escorted by NASA and United Launch Alliance representatives to the launch complex. Departure by vehicle convoy will be at 11:30 a.m. from the Space Florida parking lot located on Poseidon Avenue, adjacent to Gate 1 of Cape Canaveral Air Force Station.
Launch Day Press Site Access to Cape Canaveral Air Force Station
Friday, March 6: Verification of pre-issued press credentials and sign-in will begin at 9:30 p.m. at the Space Florida parking lot.
News media representatives covering the launch will be required to show their permanent Kennedy credentials or temporary Kennedy machine badge before being allowed to participate in the caravan traveling to the media viewing site. Following the launch, media will be escorted by caravan back to Gate 1. Those media requiring access to the Kennedy news center after launch must proceed through Gate 2 on State Road 3. Media requiring remote camera retrieval will remain at Press Site 1 until escorted to the launch pad. Following camera retrieval, participating media will be escorted back to Gate 1.
To reach the Space Florida parking lot, after passing the Pass and Identification Building outside Gate 1 of Cape Canaveral Air Force Station, turn right at the traffic light at the intersection of SR 401 and Poseidon Avenue. Make an immediate left turn at the Navaho display.
No post-launch news conference is planned. A post-launch news release will be issued after contact has been made with Kepler and the state of health of the spacecraft has been determined. This should occur within one hour of the spacecraft's separation from the Delta II. Official spokespersons will be available at the Kennedy news center for interviews at that time.
News Center Hours for Launch
The Kennedy news center will be open for Kepler news operations beginning on Tuesday, March 3, from 8 a.m. to 4:30 p.m. and continuing through launch day. Starting March 3, status reports on the launch of Kepler and any updates to the media advisory will be recorded on the Kennedy news media update phone line at 321-867-2525.
NASA Television Coverage
NASA Television coverage of the Kepler prelaunch press conference and of the launch will be carried on the NASA TV Public Channel (Channel 101).
NASA Television coverage of the Kepler prelaunch news conference and mission science briefing at Kennedy will begin at 1 p.m. on Thursday, March 5. Two-way question and answer capability will be available from other participating NASA centers. On Friday, March 6, NASA Television coverage of the launch will begin at 9 p.m. and conclude after spacecraft separation from the Delta II rocket 62 minutes after launch.
Audio of the prelaunch news conference will be carried on the NASA "V" circuits. The briefings begin at 1 p.m. on Thursday, March 5 and may be accessed by dialing 321-867-1220, 1240, 1260 or 7135. On launch day, Friday, March 6, "Mission Audio" countdown activities without NASA launch commentary will be carried on 321-867-7135 beginning at 8 p.m. Audio of the NASA launch commentary will begin at 9 p.m. and be available on 321-867-1220, 1240 or 1260. It also will be available on amateur radio frequency 146.940 Mhz (VHF), heard within Brevard County. For information about receiving NASA Television, go to:
NASA Web Prelaunch and Launch Coverage
NASA's home on the Internet, http://www.nasa.gov, will provide extensive prelaunch and launch day coverage of the Kepler mission.
Kepler's prelaunch webcast, featuring Kepler's Deputy Principal Investigator Dr. David Koch and Kennedy Mission Manager Armando Piloto, will be streamed on the Web and broadcast on NASA TV on Thursday, March 5, at 11:30 a.m.
Live countdown coverage through NASA's launch blog begins at 9 p.m. Friday, March 6. Coverage features real-time updates as countdown milestones occur as well as streaming video clips highlighting launch preparations and liftoff. For questions, contact Jeanne Ryba at 321-867-7824.
To view the webcast or blog or to learn more about the Kepler mission, visit:
The Kepler Mission is a NASA space observatory designed to discover Earth-like planets orbiting other stars. The spacecraft was launched on March 7, 2009.Johannes Kepler. With a planned mission lifetime of at least 3.5 years, Kepler uses a photometer developed by NASA to continuously monitor the brightness of over 145,000 main sequence stars in a fixed field of view. The data collected from these observations will be analyzed to detect periodic fluctuations that indicate the presence of extrasolar planets (planets outside our solar system) that are in the process of crossing the faceDiscovery Program of low-cost, focused science missions. NASA's Ames Research Center is the home organization of the science principal investigator and is responsible for the ground system development, mission operations and science data analysis. Kepler mission development was managed by NASA's Jet Propulsion Laboratory until December 2009 but was then transferred to NASA Ames Research Center. Ball Aerospace & Technologies Corp. was responsible for developing the Kepler flight system. The mission is named in honor of German astronomer of other stars. Kepler is a mission under NASA's
The Kepler Mission is currently in active operation, with the first main results announced on 4 January 2010. As expected, the initial discoveries were all short-period planets, with longer period planets expected later. The first six weeks of data revealed five previously unknown planets, all very close to their stars. Among the notable results are one of the least dense planets yet found, and two low-mass white dwarf stars that were initially reported as being members of a new class of stellar objects.
Most of the extrasolar planets detected so far by other projects are giant planets, mostly the size of Jupiter and bigger. Kepler is designed to look for planets 30 to 600 times less massive, closer to the order of Earth's mass (Jupiter is 318 times more massive than Earth). The method used, the transit method, involves observing repeated transit of planets in front of their stars, which causes a slight reduction in the star's apparent magnitude, on the order of 0.01% for an Earth-sized planet. The degree of this reduction in brightness can be used to deduce the diameter of the planet, and the interval between transits can be used to deduce the planet's orbital period, from which estimates of its orbital semi-major axis (using Kepler's laws) and its temperature (using models of stellar radiation) can be calculated.
The probability of a random planetary orbit being along the line-of-sight to a star is the diameter of the star divided by the diameter of the orbit. For an Earth-like planet at 1 AU transiting a Sol-like star the probability is 0.465%, or about 1 in 215. At 0.72 AU (the orbital distance of Venus) the probability is slightly larger, at 0.65%; such planets could be Earth-like if the host star is a late G-type star such as Tau Ceti. In addition, because planets in a given system tend to orbit in similar planes, the possibility of multiple detections around a single star is actually rather high. For instance, if an alien Kepler-like mission observed Earth transiting the Sun, there is a 12% chance of also seeing Venus transit.
The Kepler Mission has a much higher probability of detecting Earth-like planets than the Hubble Space Telescope, since it has a much larger field of view (approximately 10 degrees square), and is dedicated to detecting planetary transits. The Hubble Space Telescope, in contrast, is used to address a wide range of questions and rarely looks continuously at just one starfield. Of the approximately half million stars in Kepler's field of view, around 150,000 stars were selected for observation and they are observed simultaneously, measuring variations in their brightness every 30 minutes. This provides a better chance for seeing a transit. In addition, the 1-in-215 probability means that if 100% of stars observed had the same diameter as the Sun, and each had one Earth-like terrestrial planet in an orbit identical to that of the Earth, Kepler would find about 465; but if only 10% of stars observed were such, then it would find about 46. The mission is well suited to determine the frequency of Earth-like planets orbiting other stars.
Since Kepler must see at least three transits to be sure the dimming was caused by a planet, and since larger planets give a signal that is easier to check, scientists expect the first reported results will be larger Jupiter sized planets in tight orbits. The first of these were reported after only a few months of operation. Smaller planets, and planets further from their sun will take longer, and discovering planets comparable to Earth is expected to take three years or longer.
In January 2006, the project was delayed eight months because of budget cuts and consolidation at NASA. It was delayed again by four months in March 2006 due to fiscal problems. At this time the high-gain antenna was changed from a gimballed design to one fixed to the frame of the spacecraft to reduce cost and complexity, at the cost of one observation day per month.
The observatory was launched on March 7, 2009 at 03:49:57 UTC (March 6, 10:49:57 p.m. EST) aboard a Delta II rocket from Cape Canaveral Air Force Station, Florida. The launch was a complete success and all three stages were completed by 04:55 UTC. The cover of the telescope was jettisoned on April 7, 2009 and the first light images were taken on the next day.
On April 20, 2009 it was announced that the Kepler science team had concluded that further refinement of the focus would dramatically increase the scientific return. On April 23, 2009 it was announced that the focus had been successfully optimized by moving the primary mirror 40 micrometers (1.6 thousandths of an inch) towards the focal plane and tilting the primary mirror 0.0072 degree. On May 12, 2009 at 5:01 p.m. Pacific Time (17:01 UTC-8) Kepler successfully completed its commissioning phase and began its search for planets around other stars.
On June 19, 2009, the spacecraft successfully sent its first science data to Earth. It was discovered that Kepler had entered safe mode on June 15. A second safe mode event occurred on July 2. In both cases the event was triggered by a processor reset. The spacecraft resumed normal operation on July 3 and the science data collected since June 19 was downlinked that day. On October 14, 2009, the cause of these safing events was determined to be a low voltage power supply which provides power to the RAD750 processor. On January 12, 2010, one portion of the focal plane transmitted anomalous data, suggesting a problem with focal plane MOD-3 module, covering 2 out of Kepler's 42 CCDs. As of Feb. 18, 2010, MOD-3 remains offline.
Once Kepler has detected a transit-like signature, it is necessary to rule out false positives with follow-up tests such as doppler spectroscopy. Although Kepler was designed for photometry it turns out that it is capable of astrometry and such measurements can help confirm or rule out planet candidates.
NASA held a press conference to discuss early science results of the Kepler Mission on August 6, 2009. At this press conference, it was revealed that Kepler has confirmed the existence of the previously-known transiting exoplanet HAT-P-7b, and is functioning well enough to discover Earth-size planets.
Since Kepler's detection of planets depends on seeing very small changes in brightness, stars that vary in brightness all by themselves (variable stars) are not useful in this search. From the first few months of data, Kepler scientists have determined that about 7500 stars from the initial target list are such variable stars. These were dropped from the target list, and will be replaced by new candidates. On November 4, 2009, the Kepler project publicly released the light curves of the dropped stars.
Ground-based follow-up studies of the first six weeks of data, reveal five previously unknown planets, all very close to their stars, one (Kepler-4b) slightly larger than Neptune and four (Kepler-5b, 6b, 7b, and 8b) larger than Jupiter, including one (Kepler-7b), that is one of the least dense planets found yet. Another discovery, not yet understood, are at least two objects that are the size of planets, but hotter than their stars. One analysis suggests these objects are white dwarfs.
From the paper "Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority are Found to be Neptune-Size and Smaller": "On 15 June 2010 the Kepler Mission released data on all but 400 of the ~156,000 planetary target stars to the public. At the time of this publication, 706 targets from this first data set have viable exoplanet candidates with sizes as small as that of the Earth to larger than that of Jupiter. Here we give the identity and characteristics of 306 of the 706 targets. The released targets include 5 candidate multi-planet systems. Data for the remaining 400 targets with planetary candidates will be released in February 2011. The Kepler results based on the candidates in the released list imply that most candidate planets have radii less than half that of Jupiter", "The Kepler results imply that small candidate planets with periods less than 30 days are much more common than large candidate planets with periods less than 30 days and that the ground-based discoveries are sampling the large-size tail of the size distribution." This contradicts older theories which had suggested small and Earth-like planets would be relatively infrequent. Based on Kepler data, an estimate of around 100 million habitable planets in our galaxy may be realistic. However, some media reports of the TED talk have led to misunderstandings, apparently partly due to confusion concerning the term "Earth-like". By way of clarification, a letter to the Director of the NASA Ames Research Center, for the Kepler Science Council dated August 2, 2010 states, "Analysis of the current Kepler data does not support the assertion that Kepler has found any Earth-like planets." "
Paper on multi-planet system candidates: "Five Kepler target stars that show multiple transiting exoplanet candidates"
Also published was:"Kepler Eclipsing Binary Stars. I. Catalog and Principal Characterization of 1832 Eclipsing Binaries in the First Data Release"
Celestial north is towards the lower left corner.
Kepler is not in an Earth orbit but in an Earth-trailing solar orbit so that Earth does not occlude the stars which are observed continuously and the photometer is not influenced by stray light from Earth. This orbit avoids gravitational perturbations and torques inherent in an Earth orbit, allowing for a more stable viewing platform. The photometer points to a field in the northern constellations of Cygnus, Lyra and Draco, which is well out of the ecliptic plane, so that sunlight never enters the photometer as the spacecraft orbits the Sun. Cygnus is also a good choice to observe because it will never be obscured by Kuiper belt objects or the asteroid belt.
An additional benefit of that choice is that Kepler is pointing in the direction of the Solar System's motion around the center of the galaxy. Thus, the stars which are observed by Kepler are roughly the same distance from the galaxy center as the Solar System, and also close to the galactic plane. This fact is important if position in the galaxy is related to habitability, as suggested by the Rare Earth hypothesis.
The spacecraft has a mass of 1,039 kilograms (2,290 lb), has a 0.95-meter (37.4 in) aperture, and a 1.4-meter (55 in) primary mirror (the largest on any telescope outside of Earth orbit). The spacecraft has a 105 deg² (about 12 degree diameter) field of view (FOV), roughly equivalent to the size of one's fist held at arm's length. The photometer has a soft focus to provide excellent photometry, rather than sharp images. The combined differential photometric precision (CDPP) for a m(V)=12 solar-like star for a 6.5 hour integration will be 20 ppm, including an expected stellar variability of 10 ppm. An Earth-like transit produces a brightness change of 84 ppm and lasts for 13 hours when it crosses the center of the star. The focal plane is made up of 42 CCDs at 2200 × 1024 pixels which makes it the largest camera launched into space with a resolution of 95 megapixels. The array is cooled by heat pipes connected to an external radiator. The CCDs are read out every six seconds (to limit saturation) and co-added on board for 30 minutes. However, even though at launch Kepler had the highest data rate of any NASA mission, the 30 minute sums of all 95 million pixels are more data than can be stored and sent back to Earth. Therefore the science team has pre-selected the relevant pixels associated with each star of interest, amounting to about 5 percent of the pixels. The data from these pixels is then requantized, compressed and stored, along with other auxiliary data, in the on-board 16 gigabyte solid-state recorder. Data that is stored and downlinked includes science stars, p-mode stars, smear, black level, background and full field-of-view images.
The mission's life-cycle cost is estimated at US$600 million, including funding for 3.5 years of operation.
The Kepler mission is operated out of Boulder, Colorado, by the Laboratory for Atmospheric and Space Physics (LASP). The solar array will be rotated to face the Sun at the solstices and equinoxes. These rotations will be used to optimize the amount of sunlight falling on the solar array and to keep the heat radiator pointing towards deep space. Together, LASP and Ball Aerospace & Technologies Corp. (who are responsible for building the spacecraft and instrument) control the spacecraft from the mission operations center located on the research campus of the University of Colorado. LASP performs essential mission planning and the initial collection and distribution of the science data.
NASA contacts the spacecraft using the X band communication link twice a week for command and status updates. Scientific data are downloaded once a month using the Ka band link at a maximum data transfer rate of 4.33 Mb/s. The Kepler spacecraft conducts its own partial analysis on board and only transmits scientific data deemed necessary to the mission in order to conserve bandwidth.
Science data telemetry collected during mission operations at LASP is
sent on for processing at the Kepler Data Management Center (DMC),
located at the Space Telescope Science
Institute on the campus of The Johns
Hopkins University in Baltimore, Maryland.
The science data telemetry is decoded and processed into uncalibrated FITS-format
science data products by the DMC, which are then passed along to the
Science Operations Center (SOC) at NASA Ames Research Center, for
calibration and final processing. The SOC at NASA Ames Research Center
(ARC) develops and operates the tools needed to process scientific data
for use by the Kepler Science Office (SO). Accordingly, the SOC develops
the pipeline data processing software based on scientific algorithms
developed by the SO. During operations, the SOC (1) receives calibrated
pixel data from the DMC, (2) applies the analysis algorithms to produce
light curves for each star, (3) performs transit searches for detection
of planets (threshold-crossing events, or TCEs) and (4) performs data
validation of candidate planets by evaluating various data products for
consistency as a way to eliminate false positive detections. The SOC
also evaluates the photometric performance on an on-going basis and
provides the performance metrics to the SO and Mission Management
Office. Finally, the SOC develops and maintains the project’s scientific
databases, including catalogs and processed data. The SOC finally
returns calibrated data products and scientific results back to the DMC
for long-term archiving, and distribution to astronomers around the
world through the Multimission Archive at STScI (MAST).
Celestial north is towards the lower left corner.
The image, shown to the right, is magnified detail from the full field of view image shown above. This image also identifies the TrES-2b system and clearly shows the parent binary star, GSC 03549-02811, in the constellation Draco.
Kepler has a fixed field of view (FOV) against the sky. The diagram to the left shows the celestial coordinates and where the detector fields are located, along with the locations of a few bright stars with celestial north at the top left corner. Click on the diagram to see a detailed view.
The mission website has a calculator that will determine if a given object falls in the FOV and if so where it will appear in the photo detector output data stream.
Below is a table of known extrasolar planetary systems from the list of extrasolar planets that fall within the FOV of Kepler.
Kepler has also identified two systems containing objects which are smaller and hotter than their parent stars: KOI-74 and KOI-81. These objects are probably low-mass white dwarf stars produced by previous episodes of mass transfer in their systems.
In 2010, the Kepler team released a paper which had data for 312 extrasolar planet candidates from an observation period of only 33.5 days. NASA also announced that there were 400 candidates that needed further research because of the low radii. The data for these candidates is planned to be released in February 2011.
Retrieved from "http://en.wikipedia.org/wiki/Kepler_Mission"
Categories: Artificial satellites orbiting Sun | Discovery program | Space telescopes | Johannes Kepler | 2009 in spaceflight | Exoplanetology | Spaceflights
Astronomer discover a Super-Neptune
BY DR EMILY BALDWIN
FROM ASTRONOMY NOW
Posted: 2009 January 22
Astronomers at the Harvard-Smithsonian Center for Astrophysics have discovered a planet 4.7 times the size of Earth and
25 times more massive, earning it the nickname of a “super-Neptune”. HAT-P-11b was discovered via the transit method, whereby a planet passes in front of its parent star, thus temporarily, but periodically reducing its brightness as seen by an observer in the same line of sight. In the case of HAT-P-11b, the periodic dimming, which reduced the stars luminosity by around 0.4 percent, was detected by a network of small, automated telescopes known as HATNet, which is operated by the Harvard-Smithsonian Center for Astrophysics in Arizona and Hawaii.
This artist's conception reveals the newly discovered super-Neptune planet orbiting a star 120 light years away from Earth. Normally blue in colour, its red hue is caused by the illumination from the nearby red dwarf star. Image: David A. Aguilar (CfA).
HAT-P-11b is the 11th extrasolar planet found by HATNet, and an important addition to the inventory of exoplanets since it is one of the smallest yet discovered by any of the several transit search projects underway around the world. Compared with our own Solar System’s planet Neptune, which has a diameter 3.8 times that of Earth and a mass 17 times Earth's, the new world is 4.7 times the size of Earth and has 25 Earth masses, placing it into the category of super-Neptunes.
Furthermore, the newfound world orbits very close to its star at a rate of one revolution every 4.88 days. As a result, it is baked to a temperature of around 600 degrees Celsius. The host star, HAT-P-11 is roughly three-quarters the size of our own Sun and somewhat cooler.
The astronomers who made the discovery say that there are indications of a second planet in the HAT-P-11 system, but more radial velocity data are needed to confirm this, and to subsequently determine its properties. The radial velocity technique allows a planet to be inferred by looking at the ‘wobble’ induced on its host star.
A separate team has already located another transiting super-Neptune, known as GJ436b, around a different star, which was discovered by a radial velocity search and later found to have transits. "Having two such objects to compare helps astronomers to test theories of planetary structure and formation," says Harvard astronomer Gaspar Bakos.
The HAT-P-11 system will come under further scrutiny once the forthcoming Kepler mission begins operations. Located in the constellation Cygnus, HAT-P-11 is favourably situated for Kepler to provide the finer details, and maybe even uncover more planets, in this extrasolar planetary system. "We expect Kepler to measure the detailed properties of HAT-P-11 with the extraordinary precision possible only from space," says Robert Noyes, another member of the super-Neptune discovery team.
Kepler is currently scheduled to launch on March 5 this year, and will seek out extrasolar planets using the transit technique. A lot of hopes are riding on this mission, for it has the potential to detect the first Earthlike world orbiting a distant star.