NASA's Dawn spacecraft is preparing to observe Ceres on April 29 from an "opposition" position, directly between the dwarf planet's mysterious Occator Crater and the sun. This unique geometry may yield new insights about the bright material in the center of the crater.
While preparing for this observation, one of Dawn's two remaining reaction wheels stopped functioning on April 23. By electrically changing the speed at which these gyroscope-like devices spin, Dawn controls its orientation in the zero-gravity, frictionless conditions of space.
The team discovered the situation during a scheduled communications session on April 24, diagnosed the problem, and returned the spacecraft to its standard flight configuration, still with hydrazine control, on April 25. The failure occurred after Dawn completed its five-hour segment of ion thrusting on April 22 to adjust its orbit, but before the shorter maneuver scheduled for April 23-24. The orbit will still allow Dawn to perform its opposition measurements. The reaction wheel's malfunctioning will not significantly impact the rest of the extended mission at Ceres.
Dawn completed its prime mission in June 2016, and is now in an extended mission. It has been studying Ceres for more than two years, and before that, the spacecraft orbited giant asteroid Vesta, sending back valuable data and images. Dawn launched in 2007.
The Dawn operations team has been well prepared to deal with the loss of the reaction wheel. The spacecraft is outfitted with four reaction wheels. It experienced failures of one of the wheels in 2010, a year before it entered orbit around Vesta, and another in 2012, as it was completing its exploration of that fascinating world. (See issues with these devices). When a third reaction wheel stopped working this week, the spacecraft correctly responded by entering one of its safe modes and assigning control of its orientation to its hydrazine thrusters.
Today, Dawn's elliptical orbit will bring it from an altitude of 18,800 miles (30,300 kilometers) to 17,300 miles (27,900 kilometers) above Ceres.
The Dawn mission is managed by NASA's Jet Propulsion Laboratory in Pasadena, California, for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit: http://ift.tt/2oWML7n
More information about Dawn is available at the following sites:
› Conventional theory holds that vertical seafloor movement creates nearly all of the energy that generates tsunamis.
› A new study shows that horizontal seafloor movement also creates energy for tsunamis.
› The finding further validates a GPS-based approach for detecting a tsunami's size and strength for early warnings.
A new NASA study is challenging a long-held theory that tsunamis form and acquire their energy mostly from vertical movement of the seafloor.
An undisputed fact was that most tsunamis result from a massive shifting of the seafloor -- usually from the subduction, or sliding, of one tectonic plate under another during an earthquake. Experiments conducted in wave tanks in the 1970s demonstrated that vertical uplift of the tank bottom could generate tsunami-like waves. In the following decade, Japanese scientists simulated horizontal seafloor displacements in a wave tank and observed that the resulting energy was negligible. This led to the current widely held view that vertical movement of the seafloor is the primary factor in tsunami generation.
In 2007, Tony Song, an oceanographer at NASA's Jet Propulsion Laboratory in Pasadena, California, cast doubt on that theory after analyzing the powerful 2004 Sumatra earthquake in the Indian Ocean. Seismograph and GPS data showed that the vertical uplift of the seafloor did not produce enough energy to create a tsunami that powerful. But formulations by Song and his colleagues showed that once energy from the horizontal movement of the seafloor was factored in, all of the tsunami's energy was accounted for. Those results matched tsunami data collected from a trio of satellites -the NASA/Centre National d'Etudes Spatiales (CNES) Jason, the U.S. Navy's Geosat Follow-on and the European Space Agency's Environmental Satellite.
Further research by Song on the 2004 Sumatra earthquake, using satellite data from the NASA/German Aerospace Center Gravity Recovery and Climate Experiment (GRACE) mission, also backed up his claim that the amount of energy created by the vertical uplift of the seafloor alone was insufficient for a tsunami of that size.
"I had all this evidence that contradicted the conventional theory, but I needed more proof," Song said.
His search for more proof rested on physics -- namely, the fact that horizontal seafloor movement creates kinetic energy, which is proportional to the depth of the ocean and the speed of the seafloor's movement. After critically evaluating the wave tank experiments of the 1980s, Song found that the tanks used did not accurately represent either of these two variables. They were too shallow to reproduce the actual ratio between ocean depth and seafloor movement that exists in a tsunami, and the wall in the tank that simulated the horizontal seafloor movement moved too slowly to replicate the actual speed at which a tectonic plate moves during an earthquake.
"I began to consider that those two misrepresentations were responsible for the long-accepted but misleading conclusion that horizontal movement produces only a small amount of kinetic energy," Song said.
Building a Better Wave Tank
To put his theory to the test, Song and researchers from Oregon State University in Corvallis simulated the 2004 Sumatra and 2011 Tohoku earthquakes at the university's Wave Research Laboratory by using both directly measured and satellite observations as reference. Like the experiments of the 1980s, they mimicked horizontal land displacement in two different tanks by moving a vertical wall in the tank against water, but they used a piston-powered wave maker capable of generating faster speeds. They also better accounted for the ratio of how deep the water is to the amount of horizontal displacement in actual tsunamis.
The new experiments illustrated that horizontal seafloor displacement contributed more than half the energy that generated the 2004 and 2011 tsunamis.
"From this study, we've demonstrated that we need to look at not only the vertical but also the horizontal movement of the seafloor to derive the total energy transferred to the ocean and predict a tsunami," said Solomon Yim, a professor of civil and construction engineering at Oregon State University and a co-author on the study.
The finding further validates an approach developed by Song and his colleagues that uses GPS technology to detect a tsunami's size and strength for early warnings.
The JPL-managed Global Differential Global Positioning System (GDGPS) is a very accurate real-time GPS processing system that can measure seafloor movement during an earthquake. As the land shifts, ground receiver stations nearer to the epicenter also shift. The stations can detect their movement every second through real-time communication with a constellation of satellites to estimate the amount and direction of horizontal and vertical land displacement that took place in the ocean. They developed computer models to incorporate that data with ocean floor topography and other information to calculate the size and direction of a tsunami.
"By identifying the important role of the horizontal motion of the seafloor, our GPS approach directly estimates the energy transferred by an earthquake to the ocean," Song said. "Our goal is to detect a tsunami's size before it even forms, for early warnings."
The study is published in Journal of Geophysical Research -- Oceans.
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NASA's digital communications team will be honored at the 21st Annual Webby Awards on May 16 in New York. For the first time, NASA's social media presence has been recognized by the Webby Awards, winning in corporate communications and being honored with the People's Voice Award.
NASA's Cassini project was recognized with its second Webby for science websites. NASA.gov, the agency's primary website, received its ninth People's Voice Award in the Government & Civil Innovation category. The agency's Jet Propulsion Laboratory social media team in Pasadena, California, was nominated in the Education & Discovery category, and the Cassini social media team was nominated for the Best Overall Social Presence category.
"First and foremost, a sincere 'thank you' to our NASA friends and fans for their support," said NASA's Associate Administrator for Communications Jen Rae Wang. "We value their interest and support of exploration and discovery. We're very happy to see NASA's digital communications efforts honored with Webby Awards. As our NASA fan community turn more to the web and social media for news, they will find NASA there for them."
Established in 1996 by the International Academy of Digital Arts and Sciences, the Webby Awards honor excellence on the internet, including websites, advertising and media, online film and video, mobile sites, apps and social media.
NASA's Office of Communications has managed NASA.gov, the agency's primary home on the web since 1994, setting a high standard for government online communications. The site won Webby awards in 2003, 2012 and 2014, and visitors to NASA.gov have voted it the winner of the People's Voice award eight times since 2002, most recently in 2016. The site receives an average of more than 300,000 visits a day, and surges with major announcements, such as the discovery of the first known system of seven Earth-size planets around a single star, which brought in 6.7 million visits in a week.
The Cassini mission site also has been honored in past years, with a nomination for best science website in 2005 and a win for best science website in 2009.
NASA's social media presence comprises more than 525 social media accounts on 18 platforms. Through this presence, NASA seeks to not just share new discoveries and stories about space exploration on social media, but to do so in a way that is understandable and engages the public to interact with our content. The agency's flagship Twitter account now has more than 22 million followers, the most of any federal government agency, and is in the top 100 overall accounts on the platform. NASA's flagship Instagram account has more than 20 million followers and is in the top 100 accounts on the platform, in addition to NASA being the largest federal government agency on Facebook and Google+. NASA maintains a robust presence sharing behind-the-scenes stories on Snapchat and curates highlights from around the agency on Tumblr, Pinterest and GIPHY. All told, NASA's social media presence reaches more than 130 million followers across all agency accounts. Thanks in large part to social media, more people are now connecting and engaging with NASA and learning about its missions.
To view all of NASA's social media accounts, visit:
Scientists have discovered a new planet with the mass of Earth, orbiting its star at the same distance that we orbit our sun. The planet is likely far too cold to be habitable for life as we know it, however, because its star is so faint. But the discovery adds to scientists' understanding of the types of planetary systems that exist beyond our own.
"This 'iceball' planet is the lowest-mass planet ever found through microlensing," said Yossi Shvartzvald, a NASA postdoctoral fellow based at NASA's Jet Propulsion Laboratory, Pasadena, California, and lead author of a study published in the Astrophysical Journal Letters.
Microlensing is a technique that facilitates the discovery of distant objects by using background stars as flashlights. When a star crosses precisely in front of a bright star in the background, the gravity of the foreground star focuses the light of the background star, making it appear brighter. A planet orbiting the foreground object may cause an additional blip in the star's brightness. In this case, the blip only lasted a few hours. This technique has found the most distant known exoplanets from Earth, and can detect low-mass planets that are substantially farther from their stars than Earth is from our sun.
The newly discovered planet, called OGLE-2016-BLG-1195Lb, aids scientists in their quest to figure out the distribution of planets in our galaxy. An open question is whether there is a difference in the frequency of planets in the Milky Way's central bulge compared to its disk, the pancake-like region surrounding the bulge. OGLE-2016-BLG-1195Lb is located in the disk, as are two planets previously detected through microlensing by NASA's Spitzer Space Telescope.
"Although we only have a handful of planetary systems with well-determined distances that are this far outside our solar system, the lack of Spitzer detections in the bulge suggests that planets may be less common toward the center of our galaxy than in the disk," said Geoff Bryden, astronomer at JPL and co-author of the study.
For the new study, researchers were alerted to the initial microlensing event by the ground-based Optical Gravitational Lensing Experiment (OGLE) survey, managed by the University of Warsaw in Poland. Study authors used the Korea Microlensing Telescope Network (KMTNet), operated by the Korea Astronomy and Space Science Institute, and Spitzer, to track the event from Earth and space.
KMTNet consists of three wide-field telescopes: one in Chile, one in Australia, and one in South Africa. When scientists from the Spitzer team received the OGLE alert, they realized the potential for a planetary discovery. The microlensing event alert was only a couple of hours before Spitzer's targets for the week were to be finalized, but it made the cut.
With both KMTNet and Spitzer observing the event, scientists had two vantage points from which to study the objects involved, as though two eyes separated by a great distance were viewing it. Having data from these two perspectives allowed them to detect the planet with KMTNet and calculate the mass of the star and the planet using Spitzer data.
"We are able to know details about this planet because of the synergy between KMTNet and Spitzer," said Andrew Gould, professor emeritus of astronomy at Ohio State University, Columbus, and study co-author.
Although OGLE-2016-BLG-1195Lb is about the same mass as Earth, and the same distance from its host star as our planet is from our sun, the similarities may end there.
OGLE-2016-BLG-1195Lb is nearly 13,000 light-years away and orbits a star so small, scientists aren't sure if it's a star at all. It could be a brown dwarf, a star-like object whose core is not hot enough to generate energy through nuclear fusion. This particular star is only 7.8 percent the mass of our sun, right on the border between being a star and not.
Alternatively, it could be an ultra-cool dwarf star much like TRAPPIST-1, which Spitzer and ground-based telescopes recently revealed to host seven Earth-size planets. Those seven planets all huddle closely around TRAPPIST-1, even closer than Mercury orbits our sun, and they all have potential for liquid water. But OGLE-2016-BLG-1195Lb, at the sun-Earth distance from a very faint star, would be extremely cold -- likely even colder than Pluto is in our own solar system, such that any surface water would be frozen. A planet would need to orbit much closer to the tiny, faint star to receive enough light to maintain liquid water on its surface.
Ground-based telescopes available today are not able to find smaller planets than this one using the microlensing method. A highly sensitive space telescope would be needed to spot smaller bodies in microlensing events. NASA's upcoming Wide Field Infrared Survey Telescope (WFIRST), planned for launch in the mid-2020s, will have this capability.
"One of the problems with estimating how many planets like this are out there is that we have reached the lower limit of planet masses that we can currently detect with microlensing," Shvartzvald said. "WFIRST will be able to change that."
JPL manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena, California. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit:
NASA's Cassini spacecraft is set to make its first dive through the narrow gap between Saturn and its rings on April 26, 2017. Because that gap is a region no spacecraft has ever explored, Cassini will use its dish-shaped high-gain antenna (13 feet or 4 meters across) as a protective shield while passing through the ring plane. No particles larger than smoke particles are expected, but the precautionary measure is being taken on the first dive. The Cassini team will use data collected by one of the spacecraft's science instruments (the Radio and Plasma Wave Subsystem, or RPWS) to ascertain the size and density of ring particles in the gap in advance of future dives. As a result of its antenna-forward orientation, the spacecraft will be out of contact with Earth during the dive.
Below is a list of milestones expected to occur during the event, if all goes as planned:
-- 5 p.m. PDT (8 p.m. EDT) on April 25: Cassini is approaching Saturn over the planet's northern hemisphere in advance of its first of 22 planned dives through the gap between the planet and its rings.
-- 1:34 a.m. PDT (4:34 a.m. EDT) on April 26: As it passes from north to south over Saturn, Cassini begins a 14-minute turn to point its high-gain antenna into the direction of oncoming ring particles. In this orientation, the antenna acts as a protective shield for Cassini's instruments and engineering systems.
-- 2 a.m. PDT (5 a.m. EDT) on April 26: Cassini crosses the ring plane during its dive between the rings and Saturn. The spacecraft's science instruments are collecting data, but Cassini is not in contact with Earth at this time.
-- No earlier than 11:50 p.m. PDT on April 26 (2:50 a.m. EDT on April 27): Earth has its first opportunity to regain contact with Cassini as the giant, 230-foot (70-meter) Deep Space Network antenna at Goldstone, California, listens for the spacecraft's radio signal.
-- Likely no earlier than 12:30 a.m. PDT (3:30 a.m. EDT) on April 27: Images are scheduled to become available from the spacecraft.
As Cassini engineers monitor the status of the spacecraft, updates to these milestones will be added at:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, California, manages the mission for NASA's Science Mission Directorate. JPL designed, developed and assembled the Cassini orbiter.
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NASA's digital communications team will be honored at the 21st Annual Webby Awards on May 16 in New York. For the first time, NASA’s social media presence has been recognized by the Webby Awards, winning in corporate communications and being honored with the People's Voice Award.
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NASA's Cassini spacecraft has had its last close brush with Saturn's hazy moon Titan and is now beginning its final set of 22 orbits around the ringed planet.
The spacecraft made its 127th and final close approach to Titan on April 21 at 11:08 p.m. PDT (2:08 a.m. EDT on April 22), passing at an altitude of about 608 miles (979 kilometers) above the moon's surface.
Cassini transmitted its images and other data to Earth following the encounter. Scientists with Cassini's radar investigation will be looking this week at their final set of new radar images of the hydrocarbon seas and lakes that spread across Titan's north polar region. The planned imaging coverage includes a region previously seen by Cassini's imaging cameras, but not by radar. The radar team also plans to use the new data to probe the depths and compositions of some of Titan's small lakes for the first (and last) time, and look for further evidence of the evolving feature researchers have dubbed the "magic island."
"Cassini's up-close exploration of Titan is now behind us, but the rich volume of data the spacecraft has collected will fuel scientific study for decades to come," said Linda Spilker, the mission's project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.
Gateway to the Grand Finale
The flyby also put Cassini on course for its dramatic last act, known as the Grand Finale. As the spacecraft passed over Titan, the moon's gravity bent its path, reshaping the robotic probe's orbit slightly so that instead of passing just outside Saturn's main rings, Cassini will begin a series of 22 dives between the rings and the planet on April 26. The mission will conclude with a science-rich plunge into Saturn's atmosphere on Sept. 15.
"With this flyby we're committed to the Grand Finale," said Earl Maize, Cassini project manager at JPL. "The spacecraft is now on a ballistic path, so that even if we were to forgo future small course adjustments using thrusters, we would still enter Saturn's atmosphere on Sept. 15 no matter what."
Cassini received a large increase in velocity of approximately 1,925 mph (precisely 860.5 meters per second) with respect to Saturn from the close encounter with Titan.
After buzzing Titan, Cassini coasted onward, reaching the farthest point in its orbital path around Saturn at 8:46 p.m. PDT (11:46 p.m. EDT) on April 22. This point, called apoapse, is where each new Cassini lap around Saturn begins. Technically, Cassini began its Grand Finale orbits at this time, but since the excitement of the finale begins in earnest on April 26 with the first ultra-close dive past Saturn, the mission is celebrating the latter milestone as the formal beginning of the finale.
The spacecraft's first finale dive will take place on April 26 at 2 a.m. PDT (5 a.m. EDT). The spacecraft will be out of contact during the dive and for about a day afterward while it makes science observations from close to the planet. The earliest time Cassini is scheduled to make radio contact with Earth is 12:05 a.m. PDT (3:05 a.m. EDT) on April 27. Images and other data are expected to begin flowing in shortly after communication is established.
A new narrated, 360-degree animated video gives viewers a sense of what it might be like to fly alongside Cassini as it makes one of its Grand Finale dives.
More information about Cassini's Grand Finale, including image and video resources, is available at:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.
NASA astronaut Peggy Whitson, currently living and working aboard the International Space Station, broke the record Monday for cumulative time spent in space by a U.S. astronaut – an occasion that was celebrated with a phone call from President Donald Trump, First Daughter Ivanka Trump, and fellow astronaut Kate Rubins.
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President Donald Trump, First Daughter Ivanka Trump, and NASA astronaut Kate Rubins will make a special 20-minute, Earth-to-space call at 10 a.m. EDT Monday, April 24, to personally congratulate NASA astronaut Peggy Whitson for her record-breaking stay aboard the International Space Station.
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A new observation from NASA's Mars Reconnaissance Orbiter (MRO) captures the landing platform that the rover Opportunity left behind in Eagle Crater more than 13 years and 27 miles (or 44 kilometers) ago.
A series of bounces and tumbles after initial touchdown plunked the airbag-cushioned lander into the crater, a mere 72 feet (22 meters) across, on Jan. 25, 2004, Universal Time (Jan. 24, PST).
The scene includes Eagle Crater and Opportunity's nearby parachute and backshell, from the April 10, 2017, observation by MRO's High Resolution Imaging Science Experiment (HiRISE) camera.
This is the first view from HiRISE of the Eagle Crater scene. Mars Reconnaissance Orbiter began orbiting Mars more than two years after Opportunity's landing.One of the first images from HiRISEin 2006 showed Opportunity at the rim of a much larger crater, Victoria, nearly 4 miles (about 6 kilometers) south of the landing site.
Eagle Crater is at the upper right of the new image. The lander platform's job was finished once the rover rolled off it. The parachute and backshell are at the lower left.
The smattering of small craters on a broad plain is a reminder of the amazement expressed in 2004 about Opportunity achieving a "hole-in-one" landing. When the lander's petals opened and Opportunity sent home itsfirst lookat its surroundings, it provided the first-ever close-by view of sedimentary rocks on Mars, in Eagle's rim.
After leaving the lander and exporing Eagle Crater, the rover recorded alook-back viewbefore departing the scene. Opportunity remains active more than 13 years later.
HiRISE, the most powerful telescope ever sent to Mars, is operated by the University of Arizona, Tucson, and was built by Ball Aerospace & Technologies Corp. of Boulder, Colorado. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the MRO Project and Mars Exploration Rover Project for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, built the orbiter and collaborates with JPL to operate it. JPL built the rover. For additional information about MRO visit:
A new image from NASA's Cassini spacecraft shows planet Earth as a point of light between the icy rings of Saturn.
The spacecraft captured the view on April 12, 2017, at 10:41 p.m. PDT (1:41 a.m. EDT on April 13). Cassini was 870 million miles (1.4 billion kilometers) away from Earth when the image was taken. Although far too small to be visible in the image, the part of Earth facing Cassini at the time was the southern Atlantic Ocean.
Earth's moon is also visible nearby in a cropped, zoomed-in version of the image.
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.
Few places are as hostile to life as Chile's Atacama Desert. It's the driest place on Earth, and only the hardiest microbes survive there. Its rocky landscape has lain undisturbed for eons, exposed to extreme temperatures and radiation from the sun.
If you can find life here, you might be able to find it in an even harsher environment -- like the surface of Mars. That's why a team of researchers from NASA and several universities visited the Atacama in February. They spent 10 days testing devices that could one day be used to search for signs of life on other worlds. That group included a team from NASA's Jet Propulsion Laboratory in Pasadena, California, working on a portable chemistry lab called the Chemical Laptop.
With just a small water sample, the Laptop can check for amino acids, the organic molecules that are widespread in our solar system and considered the building blocks of all life as we know it. Liquid-based analysis techniques have been shown to be orders of magnitude more sensitive than gas-based methods for the same kinds of samples. But when you scoop up a sample from Mars, the amino acids you're looking for will be trapped inside of or chemically bonded to minerals.
To break down those bonds, JPL has designed another piece of technology, a subcritical water extractor that would act as the "front end" for the Laptop. This extractor uses water to release the amino acids from a soil sample, leaving them ready to be analyzed by the Chemical Laptop.
"These two pieces of technology work together so that we can search for biosignatures in solid samples on rocky or icy worlds," said Peter Willis of JPL, the project's principal investigator. "The Atacama served as a proving ground to see how this technology would work on an arid planet like Mars."
To find life, just add water
Willis' team revisited an Atacama site he first went to in 2005. At that time, the extractor he used was manually operated; in February, the team used an automated extractor designed by Florian Kehl, a postdoctoral researcher at JPL.
The extractor ingests soil and regolith samples and mixes them with water. Then, it subjects the samples to high pressure and temperature to get the organics out.
"At high temperatures, water has the ability to dissolve the organic compounds from the soil," Kehl said. "Think of a tea bag: in cold water, not much happens. But when you add hot water, the tea releases an entire bouquet of molecules that gives the water a particular flavor, color and smell."
To remove the amino acids from those minerals, the water has to get much hotter than your ordinary cup of tea: Kehl said the extractor is currently able to reach temperatures as high as 392 degrees Fahrenheit (200 degrees Celsius).
Liquid samples would be more readily available on ocean worlds like Jupiter's moon Europa, Kehl said. There, the extractor might still be necessary, as amino acids could be bonded to minerals mixed into the ice. They also may be present as part of larger molecules, which the extractor could break into smaller building blocks before analyzing them with the Chemical Laptop. Once the extractor has prepared its samples, the Laptop can do its work.
NASA's own tricorder
The Chemical Laptop checks liquid samples for a set of 17 amino acids -- what the team refers to as "the Signature 17." By looking at the types, amounts and geometries of these amino acids in a sample, it's possible to infer the presence of life.
"All these molecules 'like' being in water," said Fernanda Mora of JPL, the Chemical Laptop's lead scientist. "They dissolve in water and they don't evaporate easily, so they're much easier to detect in water."
The Laptop mixes liquid samples with a fluorescent dye, which attaches to amino acids and makes it possible to detect them when illuminated by a laser.
Then, the sample is injected onto a separation microchip. A voltage is applied between the two ends of the chip; each amino acid responds to that voltage at a different speed, allowing them to be identified by how quickly they move. A laser shining at the end of the chip's channel allows the Laptop to detect light emitted from the dye as the molecules move.
"The idea is to automate and miniaturize all the steps you would do manually in a chemistry lab on Earth," Mora said. "That way, we can do the same analyses on another world simply by sending commands with a computer."
The near-term goal is to integrate the extractor and Chemical Laptop into a single, automated device. It would be tested during future field campaigns to the Atacama Desert with a team of researchers led by Brian Glass of NASA's Ames Research Center in Mountain View, California.
"These are some of the hardest samples to analyze you can get on the planet," Mora said of the team's work in the Atacama. She added that in the future, the team wants to test this technology in icy environments like Antarctica. Those could serve as analogs to Europa and other ocean worlds, where liquid samples would be more readily plentiful.
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After a six-hour flight, NASA astronaut Jack Fischer and cosmonaut Fyodor Yurchikhin of the Russian space agency Roscosmos arrived at the International Space Station at 9:23 a.m. EDT Thursday where they will continue important scientific research.
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As NASA's Dawn spacecraft continues exploring Ceres, evidence mounts that the enigmatic dwarf planet retains a significant amount of water ice. A new study in the journal Nature Geoscience adds to this picture, showing how ice may have shaped the variety of landslides seen on Ceres today.
"Images from Dawn show that landslides, many of which are similar to those seen on Earth, are very common on Ceres, and further the case that Ceres has a lot of water ice involved in its structure," said Britney Schmidt, who led the study. She is an associate of the Dawn science team and assistant professor at Georgia Institute of Technology in Atlanta.
Types of Landslides
Schmidt and colleagues identified three types of landslides. Type I, which are relatively round and large, have thick "toes" at their ends. They look similar to rock glaciers and icy landslides on Earth. Type I landslides are mostly found at high latitudes on Ceres, which is also where the most ice is thought to reside just beneath the surface, suggesting they involve the most ice of any of the flow features. Three small Type 1 flows are found in Oxo Crater, a tiny bright crater in the northern hemisphere that hosts an ice deposit at the surface.
Type II features are often thinner and longer than Type I, and are the most common type of landslide on Ceres. The landslide deposits appear similar to those left behind by avalanches seen on Earth.
Ceres' Type III features may involve a brief melting of some of the ice within the soil-like regolith, causing the material to flow like mud before refreezing. These landslides are always associated with large impact craters, and may have formed when an impact event melts subsurface ice on Ceres. These features have similar appearances to ejected material from craters in the icy regions of Mars and on Jupiter's moon Ganymede.
"The locations of these different types of features reinforces the idea that the shallow subsurface of Ceres is a mixture of ice and rock, and that ice is most plentiful near the surface at the poles," Schmidt said.
Scientists were also surprised at just how many landslides have occurred on Ceres in general. About 20 to 30 percent of craters greater than 6 miles (10 kilometers) wide have some type of landslide associated with them. Such widespread "ground ice" features, which formed from of a mixture of rock and ice, had only been observed before on Earth and Mars.
Implications and Future Observations
Based on the shape and distribution of landslides on Ceres, study authors estimate that the ice in the upper few tens of meters of Ceres may range from 10 percent to 50 percent by volume.
"These kinds of flows are not seen on bodies such as Vesta, which Dawn studied from 2011 to 2012, because the regolith is devoid of water," said Carol Raymond, deputy principal investigator for the Dawn mission, based at NASA's Jet Propulsion Laboratory, Pasadena, California.
Now in its extended mission phase, Dawn is using its ion engine to swivel the plane of its orbit around Ceres to prepare for observations from a new orbit and orientation. At the end of April, the spacecraft will be directly between the sun and the mysterious Occator Crater. In this geometry, Dawn may deliver new insights about the reflective material of Ceres' most famous "bright spot," the highly reflective center of Occator that has been named Cerealia Facula.
The Dawn mission is managed by JPL for NASA's Science Mission Directorate in Washington. Dawn is a project of the directorate's Discovery Program, managed by NASA's Marshall Space Flight Center in Huntsville, Alabama. UCLA is responsible for overall Dawn mission science. Orbital ATK Inc., in Dulles, Virginia, designed and built the spacecraft. The German Aerospace Center, Max Planck Institute for Solar System Research, Italian Space Agency and Italian National Astrophysical Institute are international partners on the mission team. For a complete list of mission participants, visit:
NASA has selected 399 research and technology proposals from 277 American small businesses and 44 research institutions that will enable NASA's future missions into deep space, and advancements in aviation and science, while also benefiting the U.S. economy.
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NASA's senior Mars rover, Opportunity, is departing "Cape Tribulation," a crater-rim segment it has explored since late 2014, southbound for its next destination, "Perseverance Valley."
The rover team plans observations in the valley to determine what type of fluid activity carved it billions of years ago: water, wind, or flowing debris lubricated by water.
A color panorama of a ridge called "Rocheport" provides both a parting souvenir of Cape Tribulation and also possible help for understanding the valley ahead. The view was assembled from multiple images taken by Opportunity's panoramic camera.
"The degree of erosion at Rocheport is fascinating," said Opportunity Deputy Principal Investigator Ray Arvidson, of Washington University in St. Louis. "Grooves run perpendicular to the crest line. They may have been carved by water or ice or wind. We want to see as many features like this on the way to Perseverance Valley as we can, for comparison with what we find there."
Perseverance Valley is about two football fields long. It cuts downward west to east across the western rim of Endeavour Crater. The crater is about 14 miles (22 kilometers) in diameter, with a segmented rim that exposes the oldest rocks ever investigated in place on Mars. Opportunity has less than four football fields' distance of driving to reach the top of the valley after departing Cape Tribulation, a raised segment about 3 miles (5 kilometers) long on the crater's western rim.
In 68 months since reaching Endeavour Crater, Opportunity has explored "Cape York," "Solander Point" and "Murray Ridge" before reaching Cape Tribulation about 30 months ago. "Cape Byron," the next raised segment to the south, contains Perseverance Valley and is separated from Tribulation by a gap of flatter ground.
Five drives totaling about 320 feet (98 meters) since the beginning of April have brought Opportunity to a boundary area where Cape Tribulation meets the plain surrounding the crater.
Cape Tribulation has been the site of significant events in the mission. There, in 2015, Opportunity surpassed a marathon-race distance of total driving since its 2004 landing on Mars. It climbed to the highest-elevation viewpoint it has reached on Endeavour's rim. In a region of Tribulation called "Marathon Valley," it investigated outcrops containing clay minerals that had been detected from orbit. There were some name-appropriate Tribulation experiences, as well. The rover team has coped with loss of reliability in Opportunity's non-volatile "flash" memory since 2015. With flash memory unavailable, each day's observations are lost if not radioed homeward the same day.
"From the Cape Tribulation departure point, we'll make a beeline to the head of Perseverance Valley, then turn left and drive down the full length of the valley, if we can," Arvidson said. "It's what you would do if you were an astronaut arriving at a feature like this: Start at the top, looking at the source material, then proceed down the valley, looking at deposits along the way and at the bottom."
Clues to how the valley was carved could come from the arrangement of different sizes of rocks and gravel in the deposits.
He said, "If it was a debris flow, initiated by a little water, with lots of rocks moving downhill, it should be a jumbled mess. If it was a river cutting a channel, we may see gravel bars, crossbedding, and what's called a 'fining upward' pattern of sediments, with coarsest rocks at the bottom." Another pattern that could be evidence of flowing water would be if elongated pieces of gravel in a deposited bed tend to be stacked leaning in the same direction, providing a record of the downstream flow direction.
Now more than 13 years into a mission originally scheduled to last three months on Mars, Opportunity remains unexpectedly capable of continued exploration. It has driven about four-tenths of a mile (two-thirds of a kilometer) since the start of 2017, bringing the total traverse so far to 27.6 miles (44.4 kilometers). The current season on Mars is past the period when global dust storms might arise and curtail Opportunity's solar power.
Opportunity and the next-generation Mars rover, Curiosity, as well as three active NASA Mars orbiters, and surface missions to launch in 2018 and 2020 are all part of a legacy of robotic exploration which is helping to lay the groundwork for sending humans there in the 2030s. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, built Opportunity and manages the mission for NASA's Science Mission Directorate, Washington. For more information about Opportunity, visit:
NASA's Cassini spacecraft will make its final close flyby of Saturn's haze-enshrouded moon Titan this weekend. The flyby marks the mission's final opportunity for up-close observations of the lakes and seas of liquid hydrocarbons that spread across the moon's northern polar region, and the last chance to use its powerful radar to pierce the haze and make detailed images of the surface.
Closest approach to Titan is planned for 11:08 p.m. PDT on April 21 (2:08 a.m. EDT April 22). During the encounter, Cassini will pass as close as 608 miles (979 kilometers) above Titan's surface at a speed of about 13,000 mph (21,000 kph).
The flyby is also the gateway to Cassini's Grand Finale -- a final set of 22 orbits that pass between the planet and its rings, ending with a plunge into Saturn on Sept. 15 that will end the mission. During the close pass on April 21, Titan's gravity will bend Cassini's orbit around Saturn, shrinking it slightly, so that instead of passing just outside the rings, the spacecraft will begin its finale dives which pass just inside the rings.
The flyby is Cassini's 127th targeted encounter with Titan. A targeted flyby is one for which the spacecraft uses its rocket engine or thrusters to accurately aim toward the encounter.
Cassini's radar instrument will look for changes in Titan's methane lakes and seas, and attempt for the first (and last) time to study the depth and composition of Titan's smaller lakes. The radar instrument will also search a final time for Titan's "magic island," a mysterious feature in one of the moon's seas that changed in appearance over the course of several flybys. Scientists hope to gain additional insights to help them determine whether the feature is waves, bubbles, floating debris, or something else entirely.
More information about Cassini's final Titan flyby is available at:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.
President Donald Trump, First Daughter Ivanka Trump, and NASA astronaut Kate Rubins will make a special Earth-to-space call Monday, April 24, from the Oval Office to personally congratulate NASA astronaut Peggy Whitson for her record-breaking stay aboard the International Space Station.
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NASA scientists from across the agency will present their latest findings and perspectives on topics ranging from the origins and evolution of life on Earth to the search for habitable environments and life in our solar system and beyond during the 2017 Astrobiology Science Conference, April 24-28 in Mesa, Arizona.
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Radar images of asteroid 2014 JO25 were obtained in the early morning hours on Tuesday, with NASA's 70-meter (230-foot) antenna at the Goldstone Deep Space Communications Complex in California. The images reveal a peanut-shaped asteroid that rotates about once every five hours. The images have resolutions as fine as 25 feet (7.5 meters) per pixel.
Asteroid 2014 JO25 was discovered in May 2014 by astronomers at the Catalina Sky Survey near Tucson, Arizona -- a project of NASA's Near-Earth Objects Observations Program in collaboration with the University of Arizona. The asteroid will fly safely past Earth on Wednesday at a distance of about 1.1 million miles (1.8 million kilometers), or about 4.6 times the distance from Earth to the moon. The encounter is the closest the object will have come to Earth in 400 years and will be its closest approach for at least the next 500 years.
"The asteroid has a contact binary structure - two lobes connected by a neck-like region," said Shantanu Naidu, a scientist from NASA's Jet Propulsion Laboratory in Pasadena, California, who led the Goldstone observations. "The images show flat facets, concavities and angular topography."
The largest of the asteroid's two lobes is estimated to be 2,000 feet (620 meters) across.
Radar observations of the asteroid also have been conducted at the National Science Foundation's Arecibo Observatory in Puerto Rico. Additional radar observations are being conducted at both Goldstone and Arecibo on April 19 20, and 21, and could provide images with even higher resolution.
Radar has been used to observe hundreds of asteroids. When these small, natural remnants of the formation of the solar system pass relatively close to Earth, deep space radar is a powerful technique for studying their sizes, shapes, rotation, surface features, and roughness, and for more precise determination of their orbital path.
NASA's Jet Propulsion Laboratory, Pasadena, California, manages and operates NASA's Deep Space Network, including the Goldstone Solar System Radar, and hosts the Center for Near-Earth Object Studies for NASA's Near-Earth Object Observations Program within the agency's Science Mission Directorate.
More information about asteroids and near-Earth objects can be found at:
Raul Polit-Casillas grew up around fabrics. His mother is a fashion designer in Spain, and, at a young age, he was intrigued by how materials are used for design.
Now, as a systems engineer at NASA's Jet Propulsion Laboratory in Pasadena, California, he is still very much in the world of textiles. He and his colleagues are designing advanced woven metal fabrics for use in space.
These fabrics could potentially be useful for large antennas and other deployable devices, because the material is foldable and its shape can change quickly. The fabrics could also eventually be used to shield a spacecraft from meteorites, for astronaut spacesuits, or for capturing objects on the surface of another planet. One potential use might be for an icy moon like Jupiter's Europa, where these fabrics could insulate the spacecraft. At the same time, this flexible material could fold over uneven terrain, creating "feet" that won't melt the ice under them.
The prototypes that Polit-Casillas and colleagues have created look like chain mail, with small silver squares strung together. But these fabrics were not sewn by hand; instead, they were "printed," created in one piece with advanced technologies.
A technique called additive manufacturing, otherwise known as 3-D printing on an industrial scale, is necessary to make such fabrics. Unlike traditional manufacturing techniques, in which parts are welded together, additive manufacturing deposits material in layers to build up the desired object. This reduces the cost and increases the ability to create unique materials.
"We call it '4-D printing' because we can print both the geometry and the function of these materials," said Polit-Casillas. "If 20th Century manufacturing was driven by mass production, then this is the mass production of functions."
Fabricating spacecraft designs can be complex and costly, said Andrew Shapiro-Scharlotta of JPL, whose office funds research for early-stage technologies like the space fabric. He said that adding multiple functions to a material at different stages of development could make the whole process cheaper. It could also open the door to new designs.
"We are just scratching the surface of what's possible," Shapiro-Scharlotta said. "The use of organic and non-linear shapes at no additional costs to fabrication will lead to more efficient mechanical designs."
The space fabrics have four essential functions: reflectivity, passive heat management, foldability and tensile strength. One side of the fabric reflects light, while the other absorbs it, acting as a means of thermal control. It can fold in many different ways and adapt to shapes while still being able to sustain the force of pulling on it.
The JPL team not only wants to try out these fabrics in space someday, they want to be able to manufacture them in space, too.
Separate from his space fabric research, Polit-Casillas co-founded JPL's Atelier, a workshop that does rapid prototyping of advanced concepts and systems. They use additive manufacturing to mix metals and polymers, creating composites with a range of functionality.
In the distant future, Polit-Casillas said, astronauts might be able to print materials as they're needed -- and even recycle old materials, breaking them down and reusing them. Conservation is critical when you're trapped in space with just the resources you take with you.
But it would also be critical to think about new forms. Print a single plate of aluminum, and it has limited functionality. Print the same plate using a heat-radiating design, and suddenly it's more useful. Spacecraft housing could have different functionality on its outsides and insides, becoming more than just structural.
"I can program new functions into the material I'm printing," Polit-Casillas said. "That also reduces the amount of time spent on integration and testing. You can print, test and destroy material as many times as you want."
This kind of design-based thinking could revolutionize the way spacecraft are engineered. Instead of having to assemble something with dozens of parts, all of which create potential points of failure, the spacecraft of the future could be created "whole cloth" -- and with added function, as well.
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Jet Propulsion Laboratory, Pasadena, Calif.
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2017-110
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New NASA data show that snowpack in the Tuolumne River Basin in California's Sierra Nevada -- a major source of water for San Francisco and California's Central Valley -- is currently larger than the four previous years of snowpack combined. NASA's Airborne Snow Observatory (ASO) measured the Tuolumne Basin snowpack on April 1, a critical annual measurement of snow for states and their inhabitants, at 1.2 million acre-feet (1.5 cubic kilometers). That's enough snow to fill the Rose Bowl in Pasadena, California, nearly 1,600 times.
The Airborne Snow Observatory is the only program that measures snow depth, snow water equivalent (the water contained in snow), and how much sunlight snow reflects over an entire basin, using two scientific instruments (a scanning lidar and an imaging spectrometer) on a King Air aircraft. All other snow-monitoring programs sample only a few locations on the ground or give an average over a broad area. The Airborne Snow Observatory flies in California, Colorado, Oregon, Nevada and Idaho, and is flying a research version in the Swiss Alps.
Frank Gehrke, chief of the California Cooperative Snow Surveys of California's Department of Water Resources, said, "In such a huge snow season, the data available from ASO will provide critical guidance for water managers as we enter into the peak melt season later this spring."
Principal Investigator Tom Painter of NASA's Jet Propulsion Laboratory in Pasadena, California, explained, "Before ASO, water managers had intense stress worrying about how much potential runoff was stored in the mountain snowpack, with little historical information about snowpack years as large as this to guide reservoir management and allocation decisions. With ASO, we will be precisely quantifying this volume and how it changes through the spring." Before 2013, when the ASO program began, errors in forecasting the total Sierra Nevada snowmelt-season runoff were frequently greater than 20 percent and occasionally greater than 40 percent. Now, errors in forecasting runoff from basins that ASO monitors have dropped to less than 2 percent.
The 2017 California snowpack is close to the largest on the record, which consists of decades' worth of snow measurements made at ground level. ASO mapping showed that Tuolumne Basin's snowpack is twice the volume of last year's snowpack and 21 times larger than the snowpack of 2015, the lowest on record. The combined April 1 snow water equivalent of 2013 through 2016 -- years when California was in an intense drought -- added up to only 92 percent of this year's April 1 measurement. In much of the Central Sierra, snow lies 25 feet deep (8 meters). In some high mountain basins, it's deeper than 80 feet (24 meters). And since April 1, it has continued to snow.
This year, the program began mapping the San Joaquin River Basin in California's Central Valley, with funding from the Friant Water Authority in Friant, California, and NASA's Western Water Applications Office. In that basin, this year's April 1 snow water equivalent was about 2.9 million acre-feet (3.6 cubic kilometers). Jeff Payne, water resources director for Friant, said, "This is a critical path to better water management for the San Joaquin River and Friant Dam, particularly in a year like this one, where annual inflow from snowmelt might be 10 times the operating capacity of our reservoir. A lot of the snow in our basin accumulates in protected wilderness areas where conventional monitoring is restricted or prohibited. ASO is leading us to earlier and better water management decisions."
With the addition of the San Joaquin Basin, the Airborne Snow Observatory now maps the snowpack of the entire Central Sierra Nevada range from Kings River in the south to the Tuolumne River in the north, a milestone in a planned expansion of the program to cover the entire Sierra Nevada and other key regions in the West.
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Alan Buis
Jet Propulsion Laboratory, Pasadena, California
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Written by Carol Rasmussen
NASA's Earth Science News Team
2017-109
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The International Space Station will be capable of dozens of new scientific investigations from NASA and around the world when Orbital ATK's Cygnus spacecraft delivers more than 7,600 pounds of cargo Saturday, April 22.
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This year, NASA will celebrate Earth Day, April 22, with a variety of live and online activities Thursday and Friday, April 20-21, to engage the public in the agency’s mission to better understand and protect our home planet.
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A new NASA- and Department of Energy-funded study finds that recent increases in global methane levels observed since 2007 are not necessarily due to increasing emissions, but instead may be due to changes in how long methane remains in the atmosphere after it is emitted.
The second most important human-produced greenhouse gas after carbon dioxide, methane is colorless, odorless and can be hard to track. The gas has a wide range of sources, from decomposing biological material to leaks in natural gas pipelines. In the early 2000s, atmospheric scientists studying methane found that its global concentration -- which had increased for decades, driven by methane emissions from fossil fuels and agriculture -- leveled off as the sources of methane reached a balance with its destruction mechanisms. The methane levels remained stable for a few years, then unexpectedly started rising again in 2007, a trend that is still continuing.
Previous studies of the renewed increase have focused on high-latitude wetlands or fossil fuels, Asian agricultural growth, or tropical wetlands as potential sources of the increased emissions. But in a study published today in the early online edition of the Proceedings of the National Academy of Sciences, researchers at Harvard University in Cambridge, Massachusetts; Caltech in Pasadena, California; and NASA's Jet Propulsion Laboratory, also in Pasadena, suggest that methane emissions might not have increased dramatically in 2007 after all.
The researchers used long-term measurements of methane, its isotopes and methylchloroform (1,1,1,-trichloroethane, a chemical compound that serves as a proxy for estimating how long methane remains in the atmosphere) from numerous global ground stations. From these data, the scientists were able to determine sources of methane and how quickly it is destroyed in Earth's atmosphere. They found that the most likely explanation for the recent increase has less to do with methane emissions than previously thought and more to do with changes in the availability of the hydroxyl radical (OH), which breaks down methane in the atmosphere. As such, the amount of hydroxyl in the atmosphere has an impact on global methane concentrations. If global levels of hydroxyl decrease, global methane concentrations will increase -- even if methane emissions remain constant.
"Think of the atmosphere like a kitchen sink with the faucet running," said co-corresponding author Christian Frankenberg, an associate professor of environmental science and engineering at Caltech and a JPL research scientist. "When the water level inside the sink rises, that can mean that you've opened up the faucet more. Or it can mean that the drain is blocking up. You have to look at both."
In this analogy, the hydroxyl radical represents the draining mechanism in the sink. It is highly reactive and acts like a detergent in the atmosphere, triggering a series of chemical reactions that culminate in the formation of carbon dioxide and water vapor.
In tracking the observed changes in methane and the inferred changes in hydroxyl, Frankenberg and his colleagues noted that fluctuations in hydroxyl concentrations can explain some of the recent methane trends. However, the authors cannot explain the causes for the global changes in hydroxyl concentrations seen in the past decade. They say future independent studies are needed to quantify year-to-year variations in the hydroxyl radical and their potential drivers. They would also like to see the trends they detected verified with more detailed studies of the sources and the destruction mechanisms of methane, particularly in the tropics.
"The tropics are the tricky part," Frankenberg said. "They're very complex in terms of methane emissions and destruction." Methane has the shortest lifetime in the tropics due to the large amounts of water vapor and radiation there. But because tropical areas are often remote and cloud-covered (thwarting satellite observation), they remain understudied, he said.
The study is titled "Ambiguity in the causes for decadal trends in atmospheric methane and hydroxyl." Frankenberg's collaborators on the paper are lead author and Harvard graduate student Alexander Turner, Daniel Jacob of Harvard, and Paul Wennberg of Caltech. A NASA Carbon Monitoring System grant co-funded the study.
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Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
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Robert Perkins
Caltech, Pasadena, Calif.
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rperkins@caltech.edu
2017-108
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These raw, unprocessed images of Saturn's moon, Atlas, were taken on April 12, 2017, by NASA's Cassini spacecraft. The flyby had a close-approach distance of about 7,000 miles (11,000 kilometers).
These images are the closest ever taken of Atlas and will help to characterize its shape and geology. Atlas (19 miles, or 30 kilometers across) orbits Saturn just outside the A ring -- the outermost of the planet's bright, main rings.
Additional raw images from Cassini are available at:
The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory in Pasadena, California, manages the mission for the agency's Science Mission Directorate in Washington. The Cassini imaging operations center is based at the Space Science Institute in Boulder, Colorado. Caltech in Pasadena manages JPL for NASA.
NASA has selected Astrotech Space Operations, LLC, of Titusville, Florida, to provide commercial payload processing services for agency missions launching from NASA’s Kennedy Space Center and Cape Canaveral Air Force Station in Florida.
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Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other "ocean worlds" in our solar system and beyond. The findings are presented in papers published Thursday by researchers with NASA's Cassini mission to Saturn and Hubble Space Telescope.
In the papers, Cassini scientists announce that a form of chemical energy that life can feed on appears to exist on Saturn's moon Enceladus, and Hubble researchers report additional evidence of plumes erupting from Jupiter's moon Europa.
"This is the closest we've come, so far, to identifying a place with some of the ingredients needed for a habitable environment," said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate at Headquarters in Washington. "These results demonstrate the interconnected nature of NASA's science missions that are getting us closer to answering whether we are indeed alone or not."
The paper from researchers with the Cassini mission, published in the journal Science, indicates hydrogen gas, which could potentially provide a chemical energy source for life, is pouring into the subsurface ocean of Enceladus from hydrothermal activity on the seafloor.
The presence of ample hydrogen in the moon's ocean means that microbes - if any exist there - could use it to obtain energy by combining the hydrogen with carbon dioxide dissolved in the water. This chemical reaction, known as "methanogenesis" because it produces methane as a byproduct, is at the root of the tree of life on Earth, and could even have been critical to the origin of life on our planet.
Life as we know it requires three primary ingredients: liquid water; a source of energy for metabolism; and the right chemical ingredients, primarily carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. With this finding, Cassini has shown that Enceladus - a small, icy moon a billion miles farther from the sun than Earth - has nearly all of these ingredients for habitability. Cassini has not yet shown phosphorus and sulfur are present in the ocean, but scientists suspect them to be, since the rocky core of Enceladus is thought to be chemically similar to meteorites that contain the two elements.
"Confirmation that the chemical energy for life exists within the ocean of a small moon of Saturn is an important milestone in our search for habitable worlds beyond Earth," said Linda Spilker, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, California.
This graphic illustrates how Cassini scientists think water interacts with rock at the bottom of the ocean of Saturn's icy moon Enceladus, producing hydrogen gas. Credit: NASA/JPL-Caltech/Southwest Research Institute › Larger image
The Cassini spacecraft detected the hydrogen in the plume of gas and icy material spraying from Enceladus during its last, and deepest, dive through the plume on Oct. 28, 2015. Cassini also sampled the plume's composition during flybys earlier in the mission. From these observations scientists have determined that nearly 98 percent of the gas in the plume is water, about 1 percent is hydrogen and the rest is a mixture of other molecules including carbon dioxide, methane and ammonia.
The measurement was made using Cassini's Ion and Neutral Mass Spectrometer (INMS) instrument, which sniffs gases to determine their composition. INMS was designed to sample the upper atmosphere of Saturn's moon Titan. After Cassini's surprising discovery of a towering plume of icy spray in 2005, emanating from hot cracks near the south pole, scientists turned its detectors toward the small moon.
Cassini wasn't designed to detect signs of life in the Enceladus plume - indeed, scientists didn't know the plume existed until after the spacecraft arrived at Saturn.
"Although we can't detect life, we've found that there's a food source there for it. It would be like a candy store for microbes," said Hunter Waite, lead author of the Cassini study.
The new findings are an independent line of evidence that hydrothermal activity is taking place in the Enceladus ocean. Previous results, published in March 2015, suggested hot water is interacting with rock beneath the sea; the new findings support that conclusion and add that the rock appears to be reacting chemically to produce the hydrogen.
The paper detailing new Hubble Space Telescope findings, published in The Astrophysical Journal Letters, reports on observations of Europa from 2016 in which a probable plume of material was seen erupting from the moon's surface at the same location where Hubble saw evidence of a plume in 2014. These images bolster evidence that the Europa plumes could be a real phenomenon, flaring up intermittently in the same region on the moon's surface.
The newly imaged plume rises about 62 miles (100 kilometers) above Europa's surface, while the one observed in 2014 was estimated to be about 30 miles (50 kilometers) high. Both correspond to the location of an unusually warm region that contains features that appear to be cracks in the moon's icy crust, seen in the late 1990s by NASA's Galileo spacecraft. Researchers speculate that, like Enceladus, this could be evidence of water erupting from the moon's interior.
"The plumes on Enceladus are associated with hotter regions, so after Hubble imaged this new plume-like feature on Europa, we looked at that location on the Galileo thermal map. We discovered that Europa's plume candidate is sitting right on the thermal anomaly," said William Sparks of the Space Telescope Science Institute in Baltimore. Sparks led the Hubble plume studies in both 2014 and 2016.
The researchers say if the plumes and the warm spot are linked, it could mean water being vented from beneath the moon's icy crust is warming the surrounding surface. Another idea is that water ejected by the plume falls onto the surface as a fine mist, changing the structure of the surface grains and allowing them to retain heat longer than the surrounding landscape.
For both the 2014 and 2016 observations, the team used Hubble's Space Telescope Imaging Spectrograph (STIS) to spot the plumes in ultraviolet light. As Europa passes in front of Jupiter, any atmospheric features around the edge of the moon block some of Jupiter's light, allowing STIS to see the features in silhouette. Sparks and his team are continuing to use Hubble to monitor Europa for additional examples of plume candidates and hope to determine the frequency with which they appear.
NASA's future exploration of ocean worlds is enabled by Hubble's monitoring of Europa's putative plume activity and Cassini's long-term investigation of the Enceladus plume. In particular, both investigations are laying the groundwork for NASA's Europa Clipper mission, which is planned for launch in the 2020s.
"If there are plumes on Europa, as we now strongly suspect, with the Europa Clipper we will be ready for them," said Jim Green, Director of Planetary Science, at NASA Headquarters.
Hubble's identification of a site which appears to have persistent, intermittent plume activity provides a tempting target for the Europa mission to investigate with its powerful suite of science instruments. In addition, some of Sparks' co-authors on the Hubble Europa studies are preparing a powerful ultraviolet camera to fly on Europa Clipper that will make similar measurements to Hubble's, but from thousands of times closer. And several members of the Cassini INMS team are developing an exquisitely sensitive, next-generation version of their instrument for flight on Europa Clipper.
For more information on ocean worlds in our solar system and beyond, visit:
Two veteran NASA missions are providing new details about icy, ocean-bearing moons of Jupiter and Saturn, further heightening the scientific interest of these and other "ocean worlds" in our solar system and beyond. The findings are presented in papers published Thursday by researchers with NASA’s Cassini mission to Saturn and Hubble Space Telescop
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With two suns in its sky, Luke Skywalker's home planet Tatooine in "Star Wars" looks like a parched, sandy desert world. In real life, thanks to observatories such as NASA's Kepler space telescope, we know that two-star systems can indeed support planets, although planets discovered so far around double-star systems are large and gaseous. Scientists wondered: If an Earth-size planet were orbiting two suns, could it support life?
It turns out, such a planet could be quite hospitable if located at the right distance from its two stars, and wouldn't necessarily even have deserts. In a particular range of distances from two sun-like host stars, a planet covered in water would remain habitable and retain its water for a long time, according to a new study in the journal Nature Communications.
"This means that double-star systems of the type studied here are excellent candidates to host habitable planets, despite the large variations in the amount of starlight hypothetical planets in such a system would receive," said Max Popp, associate research scholar at Princeton University in New Jersey, and the Max Planck Institute of Meteorology in Hamburg, Germany.
Popp and Siegfried Eggl, a Caltech postdoctoral scholar at NASA's Jet Propulsion Laboratory, Pasadena, California, created a model for a planet in the Kepler 35 system. In reality, the stellar pair Kepler 35A and B host a planet called Kepler 35b, a giant planet about eight times the size of Earth, with an orbit of 131.5 Earth days. For their study, researchers neglected the gravitational influence of this planet and added a hypothetical water-covered, Earth-size planet around the Kepler 35 AB stars. They examined how this planet's climate would behave as it orbited the host stars with periods between 341 and 380 days.
"Our research is motivated by the fact that searching for potentially habitable planets requires a lot of effort, so it is good to know in advance where to look," Eggl said. "We show that it's worth targeting double-star systems."
In exoplanet research, scientists speak of a region called the "habitable zone," the range of distances around a star where a terrestrial planet is most likely to have liquid water on its surface. In this case, because two stars are orbiting each other, the habitable zone depends on the distance from the center of mass that both stars are orbiting. To make things even more complicated, a planet around two stars would not travel in a circle; instead, its orbit would wobble through the gravitational interaction with the two stars.
Popp and Eggl found that on the far edge of the habitable zone in the Kepler 35 double-star system, the hypothetical water-covered planet would have a lot of variation in its surface temperatures. Because such a cold planet would have only a small amount of water vapor in its atmosphere, global average surface temperatures would swing up and down by as much as 3.6 degrees Fahrenheit (2 degrees Celsius) in the course of a year.
"This is analogous to how, on Earth, in arid climates like deserts, we experience huge temperature variations from day to night," Eggl said. "The amount of water in the air makes a big difference."
But, closer to the stars, near the inner edge of the habitable zone, the global average surface temperatures on the same planet stay almost constant. That is because more water vapor would be able to persist in the atmosphere of the hypothetical planet and act as a buffer to keep surface conditions comfortable.
As with single-star systems, a planet beyond the outer edge of the habitable zone of its two suns would eventually end up in a so-called "snowball" state, completely covered with ice. Closer than the inner edge of the habitable zone, an atmosphere would insulate the planet too much, creating a runaway greenhouse effect and turning the planet into a Venus-like world inhospitable to life as we know it.
Another feature of the study's climate model is that, compared to Earth, a water-covered planet around two stars would have less cloud coverage. That would mean clearer skies for viewing double sunsets on these exotic worlds.
NASA's planet-hunting Kepler telescope is managed by NASA's Ames Research Center in Silicon Valley. JPL, a divison of Caltech, managed Kepler mission development.
Decades of overpumping groundwater have irreversibly altered layers of clay beneath California's Central Valley, permanently reducing the aquifer's ability to store water, finds a new satellite remote sensing study by scientists at Stanford University, Stanford, California; and NASA's Jet Propulsion Laboratory in Pasadena, California.
The study, published online in the journal Water Resources Research, reveals that overpumping caused land in the state's San Joaquin Valley to sink almost 3 feet (85 centimeters) during a recent drought from 2007 to 2010. As a result, the aquifer permanently lost between 336,000 and 606,000 acre-feet of natural water storage capacity. An acre-foot is equal to 326,000 gallons. In comparison, the Hetch Hetchy Reservoir that stores the primary water supply for the San Francisco Bay area has a capacity of about 360,000 acre-feet.
The San Joaquin Valley is one of the largest U.S. agricultural hubs, producing an estimated $17 billion of crops a year. The new findings come just as the state is experiencing its wettest season in years following an extended, record-setting drought.
"California is getting all of this rain, but in the Central Valley, there has been a loss of space to store it," said study coauthor Rosemary Knight, George L. Harrington professor at Stanford's School of Earth, Energy & Environmental Sciences.
Knight and her colleagues used data acquired with a satellite technology called Interferometric Synthetic Aperture Radar (InSAR) collected by the Phased-Array L-band Synthetic Aperture Radar (PALSAR) instrument on the Japan Aerospace Exploration Agency's Advanced Land Observing Satellite to measure centimeter-scale changes in elevation in the San Joaquin Valley between 2007 and 2010. The scientists compared multiple satellite InSAR images of Earth's surface to calculate how much the land subsided (sank).
"Our work is a good example of the use of Earth-observing satellites to answer down-to-Earth questions about the sustainability of water resources," said JPL research scientist and study coauthor Tom Farr.
Subsidence happens when the water pressure in the subsurface dips below a critical level when too much groundwater is removed, causing the sediments to compact. "As you pump groundwater out of an aquifer, the water pressure in the tiny pores of the sediment drops," said study first author Ryan Smith, a doctoral candidate in Knight's lab. "That reduces the ability of the aquifer to hold up the ground above it and causes it to collapse. That collapse is manifested at the surface as subsidence."
If too much water is extracted, particularly from clay layers, the compaction becomes irreversible, and the soil's ability to retain water is permanently diminished. "When too much water is taken out of clay, its structure is rearranged at the microscopic level and it settles into a new configuration that has less storage space," said Knight, who is also affiliated with the Stanford Woods Institute for the Environment.
This not only makes it more difficult to store water in the future, but also makes it harder to draw any existing water out of the ground today. "It's like trying to suck water from a really thin straw," Knight said. "The pressure that needs to be exerted to pull the water out gets greater and greater as the clay structure collapses."
The scientists only examined InSAR data collected during the drought period between 2007 and 2010. Since then, California has experienced a more severe drought, from 2012 to 2016. "Although our paper didn't deal with the most recent drought, I think it's safe to say that the latest drought may have caused at least as much, or even more, subsidence and permanent compaction in the region than the last one," Smith said. "This is because the rate of water decline increased during that period, causing the groundwater to drop to historically low levels. Recent InSAR studies by JPL, not included in this study, also demonstrate that subsidence continued at a similar, and in some cases even greater, rate compared with what we saw from 2007 to 2010."
One way farmers in the region could alleviate the problem, Knight said, is to avoid drawing water from clay layers and instead pump groundwater from more shallow sand and gravel layers, which are more easily recharged and are less susceptible to permanent compaction.
Until recently, however, distinguishing clay layers from sand and gravel from the surface required drilling expensive wells. But Knight's group is testing a novel geophysical electromagnetic method that involves flying a helicopter equipped with instruments capable of imaging the subsurface from the air to create a three-dimensional map of clay, sand and gravel deposits.
"With the right geophysical tool," Knight said, "we can not only better understand the composition of the subsurface, but also help guide pumping and groundwater recharge efforts."
Other study coauthors include Howard Zebker, Jessica Reeves and Jingyi Chen from Stanford University and Zhen Liu at JPL. Funding for the study was provided by the S.D. Bechtel Jr. Foundation, NASA's Terrestrial Hydrology Program and the National Science Foundation.
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Alan Buis
Jet Propulsion Laboratory, Pasadena, Calif.
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Ker Than
Stanford University, Palo Alto, Calif.
650-723-9820
kerthan@stanford.edu
2017-104
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NASA astronaut Jack Fischer is poised for a journey of exploration and research on the International Space Station. Extensive coverage of upcoming prelaunch activities, launch and arrival will air on NASA Television and streamed on the agency’s website.
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NASA commercial cargo provider Orbital ATK is targeting its seventh commercial resupply services mission to the International Space Station for 11:11 a.m. EDT Tuesday, April 18. Coverage of the launch begins at 10 a.m. on NASA Television and the agency’s website.
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NASA astronaut and Expedition 51 commander Peggy Whitson will take viewers 250 miles off the Earth to the International Space Station in the highest resolution video ever broadcast live from space at 1:30 p.m. EDT on Wednesday, April 26.
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New research on solar storms finds that they not only can cause regions of excessive electrical charge in the upper atmosphere above Earth's poles, they also can do the exact opposite: cause regions that are nearly depleted of electrically charged particles. The finding adds to our knowledge of how solar storms affect Earth and could possibly lead to improved radio communication and navigation systems for the Arctic.
A team of researchers from Denmark, the United States and Canada made the discovery while studying a solar storm that reached Earth on Feb. 19, 2014. The storm was observed to affect the ionosphere in all of Earth's northern latitudes. Its effects on Greenland were documented by a network of global navigation satellite system, or GNSS, stations as well as geomagnetic observatories and other resources. Attila Komjathy of NASA's Jet Propulsion Laboratory, Pasadena, California, developed software to process the GNSS data and helped with the data processing. The results were published in the journal Radio Science.
Solar storms often include an eruption on the sun called a coronal mass ejection, or CME. This is a vast cloud of electrically charged particles hurled into space that disturbs the interplanetary magnetic field in our solar system. When these particles and the magnetic disturbances encounter Earth's magnetic field, they interact in a series of complex physical processes, and trigger perturbations in the Earth's magnetic field. Those perturbations are called geomagnetic storms. The interactions may cause unstable patches of excess electrons in the ionosphere, an atmospheric region starting about 50 miles (80 kilometers) above Earth's surface that already contains ions and electrons.
The 2014 geomagnetic storm was a result of two powerful Earth-directed CMEs. The storm initially produced patches of extra electrons in the ionosphere over northern Greenland, as usual. But just south of these patches, the scientists were surprised to find broad areas extending 300 to 600 miles (500 to 1,000 kilometers) where the electrons were "almost vacuumed out," in the words of Per Hoeg of the National Space Research Institute at the Technical University of Denmark, Lyngby. These areas remained depleted of electrons for several days.
The electrons in the ionosphere normally reflect radio waves back to ground level, enabling long-distance radio communications. Both electron depletion and electron increases in this layer can possibly cause radio communications to fail, reduce the accuracy of GPS systems, damage satellites and harm electrical grids.
"We don't know exactly what causes the depletion," Komjathy said. "One possible explanation is that electrons are recombining with positively charged ions until there are no excess electrons. There could also be redistribution -- electrons being displaced and pushed away from the region, not only horizontally but vertically."
The paper is titled "Multiinstrument observations of a geomagnetic storm and its effects on the Arctic ionosphere: A case study of the 19 February 2014 storm." Lead author Tibor Durgonics is a doctoral student at the Technical University of Denmark. Richard Langley (University of New Brunswick, Canada) provided data sets and interpretation.
JPL is a division of Caltech in Pasadena, California.
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Jet Propulsion Laboratory, Pasadena, California
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Written by Carol Rasmussen
NASA's Earth Science News Team
2017-103
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