Artist's Concept of New Planetary Systems - Credit: NASA
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Eleven ball in the side pocket. Whack! And another 26 planets are discovered! NASA just announced the latest tally and the new discoveries come close to doubling the amount of verified planets and tripling the number of stars which are confirmed to have more than one transiting planet. It’s just another score for understanding how planets came to be… planets which run the gambit from about one and half times the size of Earth up to the size of Jupiter. Of these, fifteen are judged to be between the size of Earth and Neptune – while more observations will reveal their structure. The new bodies orbit the parent star between 6 and 143 days and all are closer than our Sun/Venus distance.
“Prior to the Kepler mission, we knew of perhaps 500 exoplanets across the whole sky,” said Doug Hudgins, Kepler program scientist at NASA Headquarters in Washington. “Now, in just two years staring at a patch of sky not much bigger than your fist, Kepler has discovered more than 60 planets and more than 2,300 planet candidates. This tells us that our galaxy is positively loaded with planets of all sizes and orbits.”
Kepler is a busy-body. It monitors the brightness changes in more than 150,000 stars. Through repeated measurements, it is able to pick out minute magnitude fluctuations which occur as a planet passes between us, Kepler and the parent sun. The newly documented solar systems are host to between two and five closely situated transiting bodies. In such cramped systems, the gravitational interaction between the orbiting members means some are accelerated – and others decelerated – in their tracks. Faster orbital speeds account for changes in orbital periods… Changes that the Kepler mission documents as Transit Timing Variations (TTVs). For planetary systems possessing TTVs, no extreme study with ground-based telescopes is required to verify their existence and the technique allows Kepler to validate the presence of planetary systems around further and fainter stars.
What’s been found? Five of the systems documented as Kepler-25, Kepler-27, Kepler-30, Kepler-31 and Kepler-33, are home to a set of planets whose orbits double each other. The outer body orbits twice for every inner body orbit. Four of the systems, Kepler-23, Kepler-24, Kepler-28 and Kepler-32, are home to a pairing where the outer planet circles the star twice for every three times the inner planet orbits.
“These configurations help to amplify the gravitational interactions between the planets, similar to how my sons kick their legs on a swing at the right time to go higher,” said Jason Steffen, the Brinson postdoctoral fellow at Fermilab Center for Particle Astrophysics in Batavia, Ill., and lead author of a paper confirming four of the systems.
And now for the game ball… Kepler-33 had the most planets of all. With a parent star older and more massive than Sol, the system gives rise to five planets whose sizes run between one and a half to five times the size of Earth. But, this is one crowded grouping. All of the planets orbiting this star are closer than Mercury is to our Sun! Thanks to stellar properties, Kepler is able to distinguish planets like these. The drop in the sun’s brightness and the length of time it takes for the planet to transit all play a role in determining presence. With similar signatures verified around the same star, chances of false readings are unlikely.
“The approach used to verify the Kepler-33 planets shows the overall reliability is quite high,” said Jack Lissauer, planetary scientist at NASA Ames Research Center at Moffett Field, Calif., and lead author of the paper on Kepler-33. “This is a validation by multiplicity.”
A 5-km-wide crater on Vesta displays light and dark material.
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Light and dark material spreads outward from a 5-km-wide crater on Vesta in this image from NASA’s Dawn spacecraft, acquired on October 22, 2011. While craters with differently-toned materials have been previously seen on the asteroid, it is unusual to find one with such a large amount of ejecta of different albedos.
This is a crop of a larger version which was released today on the Dawn website.
This brightness image was taken through the clear filter of Dawn’s framing camera. The distance to the surface of Vesta is 700 kilometers (435 miles) and the image has a resolution of about 70 meters (230 feet) per pixel.
Vesta resides in the main asteroid belt between the orbits of Mars and Jupiter and is thought to be the source of many of the meteorites that fall to Earth. The Dawn spacecraft successfully entered orbit around Vesta on July 16, 2011.
After its investigation of Vesta, Dawn will leave orbit and move on to Ceres. It will become the first spacecraft to orbit two different worlds.
Image Credit: NASA/ JPL-Caltech/ UCLA/ MPS/ DLR/ IDA
The Fomalhaut b photograph. Credit: NASA, ESA, and P. Kalas (University of California, Berkeley, USA)
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When the Hubble Space Telescope photographed the apparent exoplanet Fomalhaut b in 2008, it was regarded as the first visible light image obtained of a planet orbiting another star. The breakthrough was announced by a research team led by Paul Kalas of the University of California, Berkeley. The planet was estimated to be approximately the size of Saturn, but no more than three times Jupiter’s mass, or perhaps smaller than Saturn according to some other studies, and might even have rings. It resides within a debris ring which encircles the star Fomalhaut, about 25 light-years away.
Another team at Princeton, however, has just announced that they believe the original findings are in error, and that the planet is actually a dust cloud, based on new observations by the Spitzer Space Telescope. Their paper has just been accepted by the Astrophysical Journal.
According to the abstract:
The nearby A4-type star Fomalhaut hosts a debris belt in the form of an eccentric ring, which is thought to be caused by dynamical influence from a giant planet companion. In 2008, a detection of a point-source inside the inner edge of the ring was reported and was interpreted as a direct image of the planet, named Fomalhaut b. The detection was made at ~600–800 nm, but no corresponding signatures were found in the near-infrared range, where the bulk emission of such a planet should be expected. Here we present deep observations of Fomalhaut with Spitzer/IRAC at 4.5 µm, using a novel PSF subtraction technique based on ADI and LOCI, in order to substantially improve the Spitzer contrast at small separations. The results provide more than an order of magnitude improvement in the upper flux limit of Fomalhaut b and exclude the possibility that any flux from a giant planet surface contributes to the observed flux at visible wavelengths. This renders any direct connection between the observed light source and the dynamically inferred giant planet highly unlikely. We discuss several possible interpretations of the total body of observations of the Fomalhaut system, and find that the interpretation that best matches the available data for the observed source is scattered light from transient or semi-transient dust cloud.
Kalas has responded to the new study, saying that they considered the dust cloud possibility but ruled it out for various reasons. For one thing, Spitzer lacks the light sensitivity to detect a Saturn-sized planet, and bright rings could also explain the optical characteristics observed. He says, “We welcome the new Spitzer data, but we don’t really agree with this interpretation.”
The Princeton team, interestingly, thinks that there may be a real planet orbiting Fomalhaut, but still hiding from detection. From the paper:
In particular, we find that there is almost certainly no direct flux from a planet contributing to the visible-light signature. This, in combination with the existing body of data for the Fomalhaut system, strongly implies that the dynamically inferred giant planet companion and the visible-light point source are physically unrelated. This in turn implies that the ‘real’ Fomalhaut b still hides in the system. Although we do find a tentative point source in our images that could in principle correspond to this object, its significance is too low to distinguish whether it is real or not at this point.
Of course it will be disappointing if Fomalhaut b does turn out to not be a planet after all, but let’s not forget that thousands of other ones are being discovered and confirmed. There may occasionally be hits-and-misses, but so far the planetary hunt overall has been nothing short of a home run…
Orbital parameters of Asteroid 2012 BX34 from JPL's Small Body Database.
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A small asteroid will pass extremely close to Earth tomorrow (January 27, 2012). Named 2012 BX34, this 11 meter- (36 feet-) wide 8 meter- (26-foot-) space rock (astronomers have updated their estimates of the size) will skim Earth less than 60,000 km (37,000 miles, .0004 AU)>, at around 15:30 UTC, (10:30 am EST) according to the Minor Planet Center. The latest estimates have this small bus-sized asteroid it traveling at about about 8,900 meters/second (about 20,000 miles per hour). 2012 BX34 has been observed by the Catalina Sky Survey and the Mt. Lemmon Survey in Arizona, and the Magdalena Ridge Observatory in New Mexico, so its orbit is well defined and there is no risk of impact to Earth.
Via the @AsteroidWatch Twitter feed, scientists from JPL said “It wouldn’t get through our atmosphere intact even if it dared to try.”
Amateur astronomers in the right place and time could view this object, as it should be about magnitude 14 at the time of closest approach. Click here to see a current orbit diagram, and here to view the ephemeris data. Nick Howes, with the Faulkes Telescope Project said his team is hoping to observe and image the asteroid, — although they aren’t sure if they will be able — but we hope to share their images later.
A rendering of the Cluster satellite, designed to measure electric fields, which Andre and Cully used to detect low-energy ions high above the Earth. (Credit: European Space Agency)
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Thousands of miles above Earth, space weather rules. Here storms of high-energy particles mix the atmosphere, create auroras, challenge satellites and even cause disturbances with electric grids and electronic devices below. It’s a seemingly empty and lonely place – one where a mystery called “cold plasma” has been found in abundance and may well have implications with our connection to the Sun. While it has remained virtually hidden, Swedish researchers have created a new method to measure these cold, charged ions. With evidence of more there than once thought, these new findings may very well give us clues as to what’s happening around other planets and their natural satellites.
“The more you look for low-energy ions, the more you find,” said Mats Andre, a professor of space physics at the Swedish Institute of Space Physics in Uppsala, Sweden, and leader of the research team whose findings have been accepted for publication in Geophysical Research Letters, a journal of the American Geophysical Union. “We didn’t know how much was out there. It’s more than even I thought.”
Where does this enigma originate? The low-energy ions begin in the upper portion of our atmosphere called the ionosphere. Here solar energy can strip electrons from molecules, leaving atoms such as oxygen and hydrogen with a positive charge. However, physically finding these ions has been problematic. While researchers knew they existed at altitudes of about 100 kilometers (60 miles), Andre and colleague Chris Cully set their sites higher – at between 20,000 and 100,000 km (12,400 to 60,000 mi). At the edge, the amount of cold ions varies between 50 to 70%… making up most of the mass of space.
However, that’s not the only place cold plasma has been found. According to the research satellite data and calculations, certain high-altitude zones harbor low-energy ions continuously. As far fetched as it may sound, the team has also detected them at altitudes of 100,000 km! According to Andre, discovering so many relatively cool ions in these regions is surprising because there’s so much energy hitting the Earth’s high altitudes from the solar wind – a hot plasma about 1,000 times hotter than what Andre considers cold. Just how cold? “The low-energy ions have an energy that would correspond to about 500,000 degrees Celsius (about one million degrees Fahrenheit) at typical gas densities found on Earth. But because the density of the ions in space is so low, satellites and spacecraft can orbit without bursting into flames.”
A scientist examines one of the European Space Agency's four Cluster satellites, used in a recent Geophysical Research Letters study to measure low-energy ions. (Credit: European Space Agency)
Pinpointing these low-energy ions and measuring how much material is leaving our atmosphere has been an elusive task. Andre’s workshop is a satellite and one of the four European Space Agency CLUSTER spacecraft. It houses a detector created from a fine wire that measures the electronic field between them during satellite rotation. However, when the data was collected, the researchers found a pair of mysteries – strong electric fields in unexpected areas of space and electric fields that didn’t fluctuate evenly.
“To a scientist, it looked pretty ugly,” Andre said. “We tried to figure out what was wrong with the instrument. Then we realized there’s nothing wrong with the instrument.” What they found opened their eyes. Cold plasma was changing the arrangement of the electrical fields surrounding the satellite. This made them realize they could utilize their field measurements to validate the presence of cold plasma. “It’s a clever way of turning the limitations of a spacecraft-based detector into assets,” said Thomas Moore, senior project scientist for NASA’s Magnetospheric Multiscale mission at the Goddard Space Flight Center in Greenbelt, Maryland. He was not involved in the new research.
Through these new techniques, science can measure and map Earth’s cold plasma envelope – and learn more about how both hot and cold plasma change during extreme space weather conditions. This research points towards a better understanding of atmospheres other than our own, too. Currently the new measurements show about a kilogram (two pounds) of cold plasma escapes from Earth’s atmosphere every second, By having a solid figure as a basis for rate of loss, scientists may be able model what became of Mars’ atmosphere – or explain the atmosphere around other planets and moons. It can also aid in more accurate space weather forecasting – even if it doesn’t directly influence the environment itself. It is a key player, even if it doesn’t cause the damage itself. “You may want to know where the low-pressure area is, to predict a storm,” Andre noted.
Modernizing space weather forecasting to where it is similar to ordinary weather forecasting, was “not even remotely possible if you’re missing most of your plasma,” Moore, with NASA, said. Now, with a way to measure cold plasma, the goal of high-quality forecasts is one step closer. “It is stuff we couldn’t see and couldn’t detect, and then suddenly we could measure it,” Moore said of the low-energy ions. “Now you can actually study it and see if it agrees with the theories.”
The Orion Nebula imaged on January 25, 2012 by Marco T. in Italy.
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This beautiful photo of the Orion Nebula was taken by Marco T. in Italy on January 25, 2012. It was taken with a Canon 500d, and a Skywatcher Black Diamond ED80 Pro
“Sum of 32 shots of 85 seconds at 800 iso and 10 darks,” Marco says. “From Rome so light pollution is high as always, temperature 2 degrees.”
Want to get your astrophoto featured on Universe Today? Join our Flickr group, post in our Forum or send us your images by email (this means you’re giving us permission to post them). Please explain what’s in the picture, when you took it, the equipment you used, etc.
Martian Vista from Opportunity at Endeavour Crater - 8 Years on Mars. NASA’s Opportunity rover celebrated 8 Years on Mars on January 24, 2012. This mosaic shows portions of the segmented rim of Endeavour crater (14 miles, 22 km wide) after the robot arriving at the craters foothills in August 2011. Large ejecta blocks from a smaller nearby crater are visible in the middle. At Endeavour, Opportunity will investigate the oldest minerals deposits she has ever visited from billions of years ago and which may hold clues to environments that were potentially habitable for microbial life. The rover will eventually drive to Cape Tribulation at right after surviving her 5th winter on Mars. Mosaic Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Kenneth Kremer
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Today, the resilient Opportunity robot begins her 9th year roving around beautifully Earth-like Martian terrain where potentially life sustaining liquid water once flowed billions of years ago.
Opportunity celebrates her 8th anniversary on the Red Planet gazing at the foothills of the vast crater named Endeavour, promising a “mother lode” of “watery” science – an unimaginable circumstance since the nail biting landing on the hematite rich plains of Meridiani Planum on 24 January 2004.
“Opportunity is 97 months into the 3 month mission,” team members are proud and universally surprised to say.
“Milestones like 8 years on Mars always make me look forward rather than looking back,” Rover Principal Investigator Prof. Steve Squyres of Cornell University told Universe Today for this article commemorating Opportunity’s landing.
“We’ve still got a lot of exploring to do, but we’re doing it with a vehicle that was designed for a 90-sol mission. That means that every sol is a gift at this point.”
Opportunity has driven more than 21 miles (34 kilometers) across the Red Planet’s surface during what is truly humankind’s first overland expedition on another Planet. See our route map below.
Opportunity Rover Traverse Map at Meridiani Planum on Mars - 2004 to 2012
Traverse map shows the 8 Year Journey of Opportunity from Eagle Crater landing site on Sol 1- Jan. 24, 2004 - to 5th Winter Haven worksite at Greeley Haven at Endeavour Crater rim in January 2012. Opportunity embarked on a crater tour and discovered bountiful evidence for the flow of liquid water on Mars billions of years ago. The robot has shown that ancient ephemeral shallow lakes existed on Mars when the cratered terrain was cut by fluvial channels. Endeavour Crater is 14 miles (22 kilometers) in diameter. Opportunity has so far driven more than 21 miles (34 km) over 8 Years but was only expected to live for 90 Martian days. Credit: NASA/JPL/Cornell/UA/Marco Di Lorenzo/Kenneth Kremer
NASA’s twin rovers Spirit and Opportunity blasted off for Mars atop a pair of Delta II rockets in the summer of 2003 with a mission “warranty” of just 90 Martian days, or Sols.
Today is Sol 2846 of working operations for Opportunity, compared to an anticipated lifetime of only 90 Sols – that amounts to more than 31 times beyond the designer’s expectations.
Indeed, the long lived robot is now enduring her 5th Winter on Mars. And to glimpse the next Martian sunrise, the robo girls manmade components must survive the harsh extremes of frigid Antarctic-like temperatures each and every sol.
“I never thought that we would still be planning sequences for Opportunity today,” Ray Arvidson told Universe Today. Arvidson, of Washington University in St. Louis, is the deputy rover principal investigator.
“I seriously thought both Spirit and Opportunity would be finished by the summer of 2004.”
Opportunity's Eighth Anniversary View From 'Greeley Haven' (False Color). This mosaic of images taken in mid-January 2012 shows the windswept vista northward (left) to northeastward (right) from the location where Opportunity is spending its fifth Martian winter, an outcrop informally named "Greeley Haven. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.
But, Opportunity is the gift to science that keeps on giving.
“I am feeling pretty good as the MER rover anniversaries approach,” Arvidson told me.
“Opportunity has shown that ancient ephemeral shallow lakes existed as Mars moved climatically from an early period when the cratered terrain was cut by fluvial channels to the current dry and cold conditions that dominate.”
“Both rovers have conclusively shown the need for lateral mobility to get to relevant outcrops and back out the secrets associated with past conditions,” Arvidson explained.
Barely a month ago the bountiful harvest from mobility was once again demonstrated when the science team lead by Squyres and Arvidson announced that Opportunity had discovered the most scientifically compelling evidence yet for the flow of liquid water on ancient Mars.
Squyres and Arvidson announced that Opportunity had found a bright vein – named “Homestake” – composed of the mineral gypsum located at the Cape York segment of Endeavour Crater where the intrepid robot is currently spending her 5th Martian Winter.
“This gypsum vein is the single most powerful piece of evidence for liquid water at Mars that has been discovered by the Opportunity rover,” Squyres explained.
Veins are a geologic indication of the past flow of liquid water.
See our mosaic below illustrating the exact location of the “Homestake” vein at Endeavour Crater – also published at Astronomy Picture of the Day; 12 Dec 2011.
Opportunity discovers Water related Mineral Vein at Endeavour Crater - November 2011
Opportunity rover discovered Gypsum at the Homestake mineral vein, while exploring around the base of Cape York ridge at the rim of Endeavour Crater. The vein is composed of calcium sulfate and indicates the ancient flow of liquid water at this spot on Mars. This panoramic mosaic of images was taken on Sol 2761, November 2011, and illustrates the exact spot of the mineral vein discovery.
Credit: NASA/JPL/Cornell/Kenneth Kremer/Marco Di Lorenzo
Published on Astronomy Picture of the Day (APOD): 12 Dec 2011
Opportunity just arrived at the rim of the 14 mile (22 kilometer) wide Endeavour Crater in mid-August 2011 following an epic three year trek across treacherous dune fields from her prior investigative target at the ½ mile wide Victoria Crater.
“It’s like a whole new mission since we arrived at Cape York,” says Squyres.
For the next few months of the bitterly cold Martian winter, Opportunity will conduct a vigorous science campaign while remaining mostly stationary at a spot dubbed “Greeley Haven” in honor of Prof. Ronald Greeley, a team member from Arizona State University who recently passed away.
Opportunity Mars Rover at 5th Winter Worksite at Endeavour Crater
This mosaic shows the view of NASA’s Opportunity rover parked at “Greeley Haven” worksite where the robot will spend her 5th Martian Winter. This mosaic of images shows the Winter Haven view from the Cape York Ridge at the western rim of Endeavour Crater looking south along the crater rim. Tire tracks at right. Credit: NASA/JPL/Cornell/ Marco Di Lorenzo/Kenneth Kremer
At this moment Opportunity is snapping a 360 degree panorama, deploying her robotic arm onto nearby outcrops, collecting microscopic images, making measurements of mineral compositions with the Alpha Particle X-Ray Spectrometer and conducting radio science observations to elucidate the unknown structure of the Martian interior and core.
The rover is covered with a significant coating of dust which limits her ability to generate power from the life sustaining solar arrays. Since Opportunity is traversing just south of the equator, engineers have temporarily parked her on a northerly facing slope to maximize the electric power generation.
“Opportunity is currently sitting on an outcrop of impact breccias at Greeley Haven on Cape York,” said Arvidson.
Opportunity will remain at Greeley Haven until some time after the Winter Solstice of southern Martian winter occurs at the end of March. 'Greeley Haven' Site for Opportunity's Fifth Martian Winter. This mosaic of Greeley Haven was acquired by Opportunity on Sol 2793, Dec. 2, 2011. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.
Then she’ll head south to further explore the veins and eventually drive to deposits of the clay mineral located a few miles (km) away along the craters rim.
“We’ll do good science while we’re at Greeley Haven. But as soon as we catch a wind gust or the seasons change, we’ll be on our way again,” Squyres told me.
The legendary twins Spirit and Opportunity surely rank as one of the greatest triumphs in space exploration.
US Republican presidential candidate Newt Gingrich campaigned in Florida on Wednesday, and made some audacious claims if he would become President of the United States: “By the end of my second term we will have the first permanent base on the Moon and it will be American,” Gingrich said.
He also said that near-Earth space would be busy with launches by that same time frame – with “five or eight” launches a day, for space tourism and manufacturing, and that a new propulsion system would allow astronauts to get to Mars quickly and efficiently. The Space Coast crowd was captivated.
But how Gingrich would convince a future Congress to go along with what certainly would be an expensive proposition? President Obama couldn’t even convince Congress to give NASA an extra $6 billion over five years, and instead NASA’s budget has remained flat, without the big boost in technology development and science the current President was hoping for.
At a later space industry round-table discussion with Gingrich, one person commented that there are “no true space advocates in Congress, just members protecting their NASA centers and space pork.” Gingrich replied: “A good president doesn’t negotiate with Congress. He negotiates with the people, then the people negotiate with Congress.”
Even though Gingrich appears to support NASA, during the earlier rally, he also possibly indicated that he might cut NASA’s budget, saying he thinks NASA should become “lean and aggressive,” and less bureaucratic.
The former Speaker of the House of Representatives said he would support tax-free prizes, devoting 10% of NASA’s budget for entrepreneurial prizes of the kind that spurred Charles Lindbergh’s flight across the Atlantic (even though the current Congress nixed a recent similar proposal for NASA’s Office of Technology), and definitely outlined a nationalistic, US-only vision for space exploration, saying “we clearly have the capacity that Chinese and the Russians will never come anywhere close to us,” and “I accept the charge that I am an American, and Americans are instinctively grandiose, because we believe in a bigger future.”
Gingrich’s biggest Republican opponent at the moment is Mitt Romney, and Romney has ridiculed Gingrich for his Moon base plans. Gingrich even referenced a previous idea he had as “weird.”
“At one point early in my career I introduced the Northwest Ordinance in Space,” Gingrich said, where once there were “13,000 Americans living on the moon, they could petition to become a state.”
Reports from Florida say that Romney will unveil his plans for NASA later this week. The Republican Primary in Florida is on January 31.
With a ‘textbook’ launch, the Progress 46 resupply ship is now on its way to the International Space Station. The Progress launched Wednesday at 11:06 UTC (6:06 p.m. EST, 5:06 a.m. Baikonur time Thursday) from the Baikonur Cosmodrome, Kazakhstan. Inside the vehicle are 2.9 tons of food, fuel and equipment. It will arrive at the ISS and hook up via automated docking with the Pirs docking compartment on 00:08 UTC on Saturday (Friday at 7:08 p.m. EST) Continue reading “New Progress Re-Supply Ship Launches to Space Station”
A 'Blue Marble' image of the Earth taken from the VIIRS instrument aboard NASA's most recently launched Earth-observing satellite - Suomi NPP. This composite image uses a number of swaths of the Earth's surface taken on January 4, 2012. Credit: NASA/NOAA/GSFC/Suomi NPP/VIIRS/Norman Kuring.
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A new high-definition version of the ‘Blue Marble’ has been taken from the newest Earth observation satellite. The just-renamed Suomi NPP satellite took numerous images on January 4, 2012 and this composite image was created from several “swaths” of Earth. It is a stunningly beautiful look at our home planet, with the largest versions of the image showing about 1.6 km (1 mile) per pixel. This Sun-synchronous Earth-orbiting satellite is 824 kilometers (512 miles) above Earth, and it gets a complete view of our planet every day. It is the first of a new generation of satellites that will observe many facets of how our Earth may be changing.
Originally launched as the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP), it was just renamed ‘Suomi NPP’ on to honor a pioneer in the use of satellites, the late Verner E. Suomi.
See below for an image showing these “swaths” from global images taken on November 24, 2011.
The Suomi NPP satellite gets a complete view of our planet every day. This image uses 20 orbital ‘swaths’ from November 24, 2011, and is the first complete global image from the VIIRS instrument. Credit: NASA Earth Observatory.
These images were taken with the The Visible/Infrared Imager Radiometer Suite or VIIRS instrument aboard Suomi NPP.
VIIRS images the surface in long wedges measuring 3,000 kilometers (1,900 miles) across. The swaths from each successive orbit overlap one another, so that at the end of the day, the sensor has a complete view of the globe. The Arctic is missing because it is too dark to view in visible light during the winter.
The NPP satellite was placed in a Sun-synchronous orbit, so its path takes the satellite over the equator at the same local (ground) time in every orbit. This orbit allows the satellite to maintain the same angle between the Earth and the Sun so that all images have similar lighting. This consistent angle is important because it allows scientists to compare images from year to year without worrying about extreme changes in shadows and lighting.
Suomi NPP is carrying five instruments on board, and the biggest and most important instrument is VIIRS.
Unfortunately, an anomaly has been discovered in the instrument. During the checkout phase after it launched in October 2011, engineers detected a larger than expected decrease in sensor sensitivity in four of VIIRS’s near-infrared and visible channels.
An analysis revealed an anomalous material on the surface of the mirror, and further investigation on the ground discovered a non-standard process that occurred during the mirror coating as a potential source of tungsten oxide contamination on the VIIRS mirrors. Tungsten oxides could cause the surface of the mirror to darken.
This evidence suggests that the cause of the contamination is limited to the VIIRS instrument, and is not a concern for other NPP instruments. Officials from NPP said that while this problem is likely irreversible, the darkening of the VIIRS mirror caused by the contamination is expected to reach a plateau and remain at that level for the life of the mission. Although testing on this issue is continuing, NPP mission managers expect this plateau to still provide sufficient margins to allow VIIRS to meet its design requirements.
Still, the images have been spectacular so far from Suomi NPP and we look forward to more high definition views of our Blue Marble.
