ESA Rosetta mission: Philae lander OSIRIS NAC Camera captures landing data

This collection of images was acquired when Rosetta was about 15km above the surface of 67P

High-resolution pictures have now been released of the Philae probe in the act of landing on Comet 67P last Wednesday.

They were acquired by the OSIRIS Narrow Angle Camera (NAC) on the Rosetta satellite, which had dropped the little robot towards the surface of the "ice mountain".

The images are presented as a mosaic covering the half-hour or so around the "first touchdown," the probe then bounced to a stop about 1km away.

Philae lost battery power on Saturday and is no longer talking with Earth.

Scientists still have not located the craft's current resting spot.

But European Space Agency (ESA) controllers have not given up hope of hearing from the plucky robot again, if it can somehow get enough light on to its solar panels to recharge its systems.

Getting a precise fix on its location, to then photograph its present predicament would provide a better idea of whether this is likely to happen.

The new NAC images will certainly help in this respect because they show the direction the lander took as it bounced away.

At the weekend, ESA presented some fascinating views of the first touchdown taken by Rosetta's navigation cameras, but the OSIRIS NAC system has substantially better resolution.

It's a trap
The new mosaic is produced by the Max Planck Institute for Solar System Research, which operates Osiris.

It details Philae's descent, and the impact mark it leaves on 67P's surface. You then see the 100kg probe heading away on its initial bounce.

NB: All times are in GMT on Wednesday. The resolution is 28 cm/pixel.

This rebound reached hundreds of metres above the comet and lasted almost two hours.

When Philae came back down, it made another small leap, which took it into a high-walled trap.

Telemetry and pictures from the robot itself indicate this location is covered in deep shadow for most of 67P's day.

As a consequence, Philae receives insufficient solar power to re-boot and form a radio link to the orbiting Rosetta spacecraft.

ESA cannot be sure the robot will ever come back to life, but even if it does not the agency says it is "hugely happy" with what was achieved in the more than 50 hours following landing.

The probe managed to complete over 80% of its planned primary science campaign on the surface.

MUPUS

'Rock' hard
This data was pulled off the robot just before its sagging energy reserves dropped it into sleep mode.

Little of the results have so far been released by the various instrument teams. The one major exception is MUPUS.

This sensor package from DLR the German space agency's Institute for Planetary Research deployed a thermometer on the end of a hammer.

It retrieved a number of temperature profiles but broke as it tried to burrow its way into the comet's subsurface.

Scientists say this shows the icy material underlying 67P's dust covering to be far harder than anyone anticipated - having the tensile strength of some rocks.

It also helps explain why Philae bounced so high on that first touchdown.

The 4km-wide comet has little gravity, so when key landing systems designed to hold the robot down failed at the crucial moment, the probe would have been relying on thick, soft, compressive layers to absorb its impact.

However much dust it did encounter at that moment, it clearly was not enough to prevent Philae making its giant rebound.

ESA Rosetta mission: Crippled Philae lander endeavours to transmit relevant data

Animator's picture of Philae on the comet 67/P now appears more idealistic and hugely optimistic.

A report on the Philae spacecraft's verified Twitter feed suggests the probe has successfully "hopped" into a new position which may enable its solar panels to work

There was fresh hope for the Rosetta mission after scientists reconnected with the probe which could be holding key information about how life on Earth began.

The 25-year mission was thrown into jeopardy after the Philae craft bounced away from its landing site on the comet 67P/Churyumov-Gerasimenko and became stuck under a cliff.

Scientists had been working on attempts to find and move the probe before it ran out of battery power.

But on Friday those plans were abandoned and instead they began drilling beneath the surface of the comet in an attempt to get some samples on board for analysis.

ESA Philae landers' instruments listed. Consert, Romap, SD2 and Mupus have been initiated but results are unknown.

Contact with the lander was lost before the data could be sent back to Earth, but late last night Philae re-established radio contact with its orbiting Rosetta satellite and is sending data from the surface.

However, less than an hour later scientist confirmed the lander was "getting tired" and the battery voltage was approaching the limit.

Daniel Scuka, Senior Editor for Spacecraft Operations at ESOC, said on the mission blog: "While the search for the final landing site is still on-going, the lander is racing against the clock to meet as many of the core science goals as possible before the primary battery is exhausted.

"Under the low illumination conditions at Philae's location, it is unlikely that the secondary batteries will charge up enough to enable extended surface operations."

They confirmed that they had received data from Philae, and that the drill had moved up and down, but they were unsure what data they had.

A report on the spacecraft's verified Twitter feed, Philae Lander @Philae2014, suggests the craft has successfully "hopped" into a new position, possibly one that will enable more sunlight to shine on its solar panels.

The first of two messages at about 11pm read: "I just started lifting myself up a little and will now rotate and try and optimise the solar power."

This was quickly followed by another which said: "My rotation was successful (35 degrees). Looks like a whole new comet from this angle."

Philae has imaged three different spots on the comet, it was confirmed.

This may be the sum total of knowledge taken out of the Rosetta Philae lander chapter of the mission.

However, in a less optimistic update just before midnight Mr Scuka added: "On board Philae, system voltage has fallen very close to 21.5V; below that, the battery won't last much longer. At this time, there is insufficient sunlight to provide power."

Rosetta The comet is a remnant from the early solar system and may hold clues about how life on Earth began.

Many scientists believe that comets were the driving force, delivering water and amino acids to the planet during the "bombardment phase" about four billion years ago.

If the link with the probe is lost, there is a faint possibility that the solar panels will begin working again when the comet's orbit brings it closer to the Sun.

"We can only hope that as we approach the Sun, maybe in August, if we don't have dust or a huge coma [a dust cloud around the comet] blocking the Sun, then perhaps there would be a chance we could come back and at least see how the lander is doing," said Valentina Lommats, of the German Space Agency.

Crucially, the team had still not located the lander on Friday. On Thursday, team members said they believed Philae had bounced twice before settling in a crater east of the original landing site.

However, scans by the Osiris camera on board the Rosetta mother ship failed to locate the probe.

Rosetta has now started scanning other areas.

An animated gif of the Philae lander departing from Rosetta on its risky but calamitous journey onto the comet 67/P.

However, scientists were confident that they had collected a huge amount of a data, around 90 per cent of what they were hoping for before the solar panels were needed to extend the mission.

Even if Philae's job is finished, the Rosetta mission is to continue.

Rosetta will remain alongside the comet as it moves closer to the Sun.

Instruments on board will analyse the gases of the tail and the comet's interior, measure dust grains and study its atmosphere and gravity.

The comet will reach its closest distance to the Sun on Aug 13 next year, at about 115 million miles, roughly between the orbits of Earth and Mars.

New Horizons: Awaiting New Results on Pluto's Atmosphere

Artist's impression of Pluto, with its wispy atmosphere.

Data from New Horizons' Alice ultraviolet spectrograph will answer a full range of questions about the composition and structure of that atmosphere.

What is Pluto's atmosphere like? It seems like I've been wondering about that for decades!

We've known so little for so long about Pluto's atmosphere, other than it's low-pressure, made mostly of molecular nitrogen (with a little methane and carbon monoxide mixed in) and may be quite extended, it's nice to realise that we'll know a whole lot more after New Horizons visits in summer 2015.

Alice UV spectrograph

My professional interests on New Horizons lie with Pluto's upper atmosphere, what it's made of, how it interacts with space, and how it is processed by sunlight into different gases and aerosols.

A problem in planning atmospheric observations for New Horizons during the flyby is that we really don't know what to expect.

Only a few models have been made that try to predict the composition of Pluto's atmosphere, and they don't agree very much with each other because of the many present uncertainties.

So our plans generally include a lot of survey-type observations, where we try not to assume too much about what we will detect, but are ready for anything.

The best example of this is the Pluto solar occultation observation.

Just Joking!

The Alice ultraviolet spectrograph will watch the Sun set (and then rise again) as New Horizons flies through Pluto's shadow, about an hour after closest approach.

Watching how the different colours of sunlight fade (and then return) as New Horizons enters (and leaves) the shadow will tell us nearly all we could ask for about composition (all gases have unique absorption signatures at the ultraviolet wavelengths covered by Alice) and structure (how those the absorption features vary with altitude will tell us about temperatures, escape rates and possibly about dynamics and clouds).

When the New Horizons data start coming down, these are the data I'll be waiting for the most!

International Global Precipitation Measurement Mission (GPM) Data Goes Public

On March 17, 2014 the Global Precipitation Measurement (GPM) mission's Core Observatory flew over the East coast's last snow storm of the 2013-2014 winter season.

This was also one of the first major snow storms observed by GPM shortly after it was launched on February 27, 2014.

The GPM Core Observatory carries two instruments that show the location and intensity of rain and snow, which defines a crucial part of the storm structure - and how it will behave.

The GPM Microwave Imager sees through the tops of clouds to observe how much and where precipitation occurs, and the Dual-frequency Precipitation Radar observes precise details of precipitation in 3-dimensions.

For forecasters, GPM's microwave and radar data are part of the toolbox of satellite data, including other low Earth orbit and geostationary satellites, that they use to monitor tropical cyclones and hurricanes.

One of the first storms observed by the NASA/JAXA GPM Core Observatory on March 17, 2014, in the eastern United States revealed a full range of precipitation, from rain to snow. 

Image courtesy NASA/JAXA.

The most accurate and comprehensive collection of rain, snowfall and other types of precipitation data ever assembled now is available to the public.

This new resource for climate studies, weather forecasting, and other applications is based on observations by the Global Precipitation Measurement (GPM) Core Observatory, a joint mission of NASA and the Japan Aerospace Exploration Agency (JAXA), with contributions from a constellation of international partner satellites.

The GPM Core Observatory, launched from Japan on Feb. 27, carries two advanced instruments to measure rainfall, snowfall, ice and other precipitation.

The advanced and precise data from the GPM Core Observatory are used to unify and standardize precipitation observations from other constellation satellites to produce the GPM mission data.

These data are freely available through NASA's Precipitation Processing System at Goddard Space Flight Center in Greenbelt, Maryland.

"We are very pleased to make all these data available to scientists and other users within six months of launch," said Ramesh Kakar, GPM program scientist in the Earth Science Division at NASA Headquarters, Washington.

Instruments on the GPM Core Observatory and partner satellites measure energy naturally emitted by liquid and frozen precipitation. Scientists use computer programs to convert these data into estimates of rain and snowfall.

The individual instruments on the partner satellites collect similar data, but the absolute numbers for precipitation observed over the same location may not be exactly the same.

The GPM Core Observatory's data are used as a reference standard to smooth out the individual differences, like a principal violinist tuning the individual instruments in an orchestra.

The result is data that are consistent with each other and can be meaningfully compared. With the higher sensitivity to different types of precipitation made possible by the GPM Core Observatory's Microwave Imager (GMI) and Dual-frequency Precipitation Radar (DPR), scientists can for the first time accurately measure the full range of precipitation from heavy rain to light rain and snow.

The instruments are designed not only to detect rain and snow in the clouds, but to measure the size and distribution of the rain particles and snowflakes.

This information gives scientists a better estimate of water content and a new perspective on winter storms, especially near the poles where the majority of precipitation is snowfall.

"With this GPM mission data, we can now see snow in a way we could not before," said Gail Skofronick-Jackson, GPM project scientist at Goddard Space Flight Center.

"Cloud tops high in the atmosphere have ice in them. If the Earth's surface is above freezing, it melts into rain as it falls. But in some parts of the world, it's cold enough that the ice and snow falls all the way to the ground."

NASA OCO-2: Carbon Counter Reaches Final Orbit, Returns Data

NASA's OCO-2 spacecraft collected "first light” data Aug. 6 over New Guinea. OCO-2’s spectrometers recorded the bar code-like spectra, or chemical signatures, of molecular oxygen or carbon dioxide in the atmosphere. 

The backdrop is a simulation of carbon dioxide created from GEOS-5 model data.

Image Credit: NASA/JPL-Caltech/NASA GSFC

Just over a month after launch, the Orbiting Carbon Observatory-2 (OCO-2), NASA’s first spacecraft dedicated to studying atmospheric carbon dioxide, has maneuvered into its final operating orbit and produced its first science data, confirming the health of its science instrument.

Atmospheric carbon dioxide is the leading human-produced greenhouse gas responsible for warming our world. It is a critical natural component of Earth’s carbon cycle.

OCO-2 will produce the most detailed picture to date of sources of carbon dioxide, as well as their natural “sinks”, places on Earth’s surface where carbon dioxide is removed from the atmosphere.

The observatory will study how these sources and sinks are distributed around the globe and how they change over time.

Artist's rendering of NASA's Orbiting Carbon Observatory (OCO)-2, one of five new NASA Earth science missions set to launch in 2014, and one of three managed by JPL.

Image Credit: NASA/JPL-Caltech

Following launch from California’s Vandenberg Air Force Base on July 2, OCO-2 underwent a series of steps to configure the observatory for in-flight operations.

Mission controllers established two-way communications with the observatory, stabilized its orientation in space and deployed its solar arrays to provide electrical power.

The OCO-2 team then performed a checkout of OCO-2’s systems to ensure they were functioning properly.

Through the month of July, a series of propulsive burns was executed to maneuver the observatory into its final 438-mile (705-kilometer), near-polar orbit at the head of the international Afternoon Constellation, or “A-Train,” of Earth-observing satellites.

It arrived there on Aug. 3. Operations are now being conducted with the observatory in an orbit that crosses the equator at 1:36 p.m. local time.

NASA OCO-2 data to lead scientists forward into the past

Scientists will use measurements from the Orbiting Carbon Observatory-2 to track atmospheric carbon dioxide to sources such as these wildfires in Siberia, whose smoke plumes quickly carry the greenhouse gas worldwide. 

The fires were imaged on May 18 by NASA's Moderate Resolution Imaging Spectrometer instrument on the Terra satellite.

Credit: NASA/LANCE/EOSDIS Rapid Response

NASA's Orbiting Carbon Observatory-2, which launched on July 2, will soon be providing about 100,000 high-quality measurements each day of carbon dioxide concentrations from around the globe.

Atmospheric scientists are excited about that but to understand the processes that control the amount of the greenhouse gas in the atmosphere, they need to know more than just where carbon dioxide is now.

They need to know where it has been. It takes more than great data to figure that out.

"In a sense, you're trying to go backward in time and space," said David Baker, a scientist at Colorado State University in Fort Collins.

"You're reversing the flow of the winds to determine when and where the input of carbon at the Earth's surface had to be to give you the measurements you see now."

Harry Potter used a magical time turner to travel to the past. Atmospheric scientists use a type of computer model called a chemical transport model.

It combines the atmospheric processes found in a climate model with additional information on important chemical compounds, including their reactions, their sources on Earth's surface and the processes that remove them from the air, known as sinks.

Baker used the example of a forest fire to explain how a chemical transport model works. "Where the fire is, at that point in time, you get a pulse of carbon dioxide in the atmosphere from the burning carbon in wood.

The model's winds blow it along, and mixing processes dilute it through the atmosphere. It gradually gets mixed into a wider and wider plume that eventually gets blown around the world."

Some models can be run backward in time, from a point in the plume back to the fire, in other words, to search for the sources of airborne carbon dioxide.

The reactions and processes that must be modeled are so complex that researchers often cycle their chemical transport models backward and forward through the same time period dozens of times, adjusting the model as each set of results reveals new clues.

"You basically start crawling toward a solution," Baker said. "You may not be crawling straight toward the best answer, but you course-correct along the way."

Read the full article here

NASA Cassini Titan flyby: Data collected on mysterious hydrocarbon lakes

Credit: NASA/JPL-Caltech /University of Arizona /University of Idaho

NASA's Cassini mission flew past Titan early Wednesday morning, successfully completing a complex maneuver that will help scientists better understand one of the solar system's most intriguing moons.

Beginning around midnight, a team of scientists and engineers guided the spacecraft into an orbit that allowed them to bounce a radio signal off the surface of Titan toward Earth, where it was received by a land-based telescope array 1 billion miles away.

"We are essentially using Titan as a mirror," said Essam Marouf of San Jose State University, who's a member of the Cassini radio science team. "And the nature of the echo can tell us about the nature of Titan's surface, whether it is liquid or solid, and the physical properties of the material."

Saturn's moon Titan is the second-largest moon in the solar system after Jupiter's moon Ganymede, and in some ways it's one of the most Earth-like bodies we have encountered.

Like Earth, it has a thick atmosphere, and it is the only other world we know of that has a system of liquid lakes and seas on its surface.

However, unlike Earth, its surface is far too cold to sustain liquid water.

Scientists have hypothesized that Titan's famous lakes and seas are made of liquid methane or ethane, but Marouf explains that those inferences are mostly based on the fact that methane and ethane would take on a liquid state in the conditions on Titan, rather than direct observation.

"There is no really direct measurement that tells us what they are exactly," he said.

"If the data from this morning is good enough, it will tell us what these liquids really are."

From 11:30 Tuesday evening to 11 Wednesday morning, Marouf gathered with other members of Cassini's radio science team in a control room at the Jet Propulsion Laboratory in La Canada Flintridge near downtown Los Angeles, watching as the new data were received by a radio telescope array in Australia.

He said they could not analyze the data in real time, but they were able to tell that the signal was clear enough to give them something to work with.

Cassini performed a similar experiment on Saturn's surface on May 17 that was also a success. That time, the researchers were able to collect information from two of the largest bodies of liquid on Titan: Ligea Mare and Kraken Mare.

This time, Cassini bounced its radio signal off an area between the two seas where radar images had found smaller liquid regions similar to rivers, lakes and channels on Earth.

"This kind of experiment takes a meticulous kind of preparation to first know where to look, and then design the maneuvers," Marouf said. "There are many pieces that have to work flawlessly to end up with the data."

He said the team hopes to look over the data this week and share its early results at a Cassini science team meeting next week in the Netherlands.

Astronauts to reveal sobering data on large asteroid impacts

The Sentinel Space Telescope in orbit around the Sun. 

Credit: Ball Aerospace.

This Earth Day, Tuesday, April 22, three former NASA astronauts will present new evidence that our planet has experienced many more large-scale asteroid impacts over the past decade than previously thought; three to ten times more, in fact.

A new visualization of data from a nuclear weapons warning network, to be unveiled by B612 Foundation CEO Ed Lu during the evening event at Seattle's Museum of Flight, shows that "the only thing preventing a catastrophe from a 'city-killer' sized asteroid is blind luck."


Since 2001, 26 atomic-bomb-scale explosions have occurred in remote locations around the world, far from populated areas, made evident by a nuclear weapons test warning network.

In a recent press release B612 Foundation CEO Ed Lu states:

"This network has detected 26 multi-kiloton explosions since 2001, all of which are due to asteroid impacts. It shows that asteroid impacts are NOT rare, but actually 3-10 times more common than we previously thought."

"The fact that none of these asteroid impacts shown in the video was detected in advance is proof that the only thing preventing a catastrophe from a 'city-killer' sized asteroid is blind luck." 

"The goal of the B612 Sentinel mission is to find and track asteroids decades before they hit Earth, allowing us to easily deflect them."

The B612 Foundation is partnered with Ball Aerospace to build the Sentinel Space Telescope Mission.

Once positioned in solar orbit closer to the Sun from Earth, Sentinel will look outwards in infrared to detect hundreds of thousands of as-yet unknown near-Earth objects over 140 meters in size.

The privately-funded spacecraft is slated to launch in 2017-18 aboard a SpaceX Falcon 9 rocket.

In addition to Lu, Space Shuttle astronaut Tom Jones and Apollo 8 astronaut Bill Anders will be speaking at the event, titled "Saving the Earth by Keeping Big Asteroids Away"

The event will be held at 6 p.m. PDT at the Museum of Flight in Seattle, WA.

It is free to the public and the visualization will be made available online on the B612 Foundation website.

FERMI LAT: Data Holds New Clues To Dark Matter

At left is a map of gamma rays with energies between 1 and 3.16 GeV detected in the galactic center by Fermi's LAT; red indicates the greatest number. 

Prominent pulsars are labeled. 

Removing all known gamma-ray sources (right) reveals excess emission that may arise from dark matter annihilations.

Image courtesy T. Linden, Univ. of Chicago.

A new study of gamma-ray light from the center of our galaxy makes the strongest case to date that some of this emission may arise from dark matter, an unknown substance making up most of the material universe.

Using publicly available data from NASA's Fermi Gamma-ray Space Telescope, independent scientists at the Fermi National Accelerator Laboratory (Fermilab), the Harvard-Smithsonian Center for Astrophysics (CfA), the Massachusetts Institute of Technology (MIT) and the University of Chicago have developed new maps showing that the galactic center produces more high-energy gamma rays than can be explained by known sources and that this excess emission is consistent with some forms of dark matter.

Dan Hooper

"The new maps allow us to analyze the excess and test whether more conventional explanations, such as the presence of undiscovered pulsars or cosmic-ray collisions on gas clouds, can account for it," said Dan Hooper, an astrophysicist at Fermilab in Batavia, Ill., and a lead author of the study.

"The signal we find cannot be explained by currently proposed alternatives and is in close agreement with the predictions of very simple dark matter models."

The galactic center teems with gamma-ray sources, from interacting binary systems and isolated pulsars to supernova remnants and particles colliding with interstellar gas.

It's also where astronomers expect to find the galaxy's highest density of dark matter, which only affects normal matter and radiation through its gravity.

Large amounts of dark matter attract normal matter, forming a foundation upon which visible structures, like galaxies, are built.

No one knows the true nature of dark matter, but Weakly Interacting Massive Particles (WIMPs), represent a leading class of candidates.

Theorists have envisioned a wide range of WIMP types, some of which may either mutually annihilate or produce an intermediate, quickly decaying particle when they collide.

Both of these pathways end with the production of gamma rays -- the most energetic form of light -- at energies within the detection range of Fermi's Large Area Telescope (LAT).

When astronomers carefully subtract all known gamma-ray sources from LAT observations of the galactic center, a patch of leftover emission remains.

This excess appears most prominent at energies between 1 and 3 billion electron volts (GeV) -- roughly a billion times greater than that of visible light -- and extends outward at least 5,000 light-years from the galactic center.

Hooper and his colleagues conclude that annihilations of dark matter particles with a mass between 31 and 40 GeV provide a remarkable fit for the excess based on its gamma-ray spectrum, its symmetry around the galactic center, and its overall brightness.

Writing in a paper submitted to the journal Physical Review D, the researchers say that these features are difficult to reconcile with other explanations proposed so far, although they note that plausible alternatives not requiring dark matter may yet materialize.

"Dark matter in this mass range can be probed by direct detection and by the Large Hadron Collider (LHC), so if this is dark matter, we're already learning about its interactions from the lack of detection so far," said co-author Tracy Slatyer, a theoretical physicist at MIT in Cambridge, Mass.

"This is a very exciting signal, and while the case is not yet closed, in the future we might well look back and say this was where we saw dark matter annihilation for the first time."

More Information: "The Characterization of the Gamma-Ray Signal from the Central Milky Way: A Compelling Case for Annihilating Dark Matter" Authors: Tansu Daylan, Douglas P. Finkbeiner, Dan Hooper, Tim Linden, Stephen K. N. Portillo, Nicholas L. Rodd, Tracy R. Slatyer

NIST New measurement technique helps astronomers find habitable planets

A thorium emission lamp’s violet glow, when viewed through a spectroscope (metal tube on right in top image), is split into a spectrum of thousands of bright lines (bottom image). 

New measurements of these lines could help astronomers search for earthlike planets around distant stars. 

Credit: Boutin/NIST

Researchers at the National Institute of Standards and Technology (NIST) have rejuvenated a technique for finding planets near distant stars.

New measurements of light from special lamps could help astronomers find planets hidden in data from more than a decade's worth of extrasolar planet searches, as well as improve telescopes' current capabilities.

Finding extrasolar planets is tricky. Seen through a telescope, planets in the "habitable zone," a region close to a star, where liquid water could exist on a planet's surface, usually get lost in their star's glare.

But as a planet orbits, its gravity makes its parent star wobble a tiny bit, resulting in slight color changes in the star's light due to the Doppler effect.

These changes can only be spotted if the light is first broken into a spectrum of thin lines, which are then compared to an unchanging reference spectrum.

"It's like holding one ruler in front of another and moving the front one to the right and left," says NIST physicist Gillian Nave.

"You can see the front ruler move compared to the one behind it. The star's spectrum is the front ruler, which moves as the planet tugs at it. But the movement is so small that to see it clearly, we need to put a fixed ruler of very high quality behind it. That's where NIST comes in."

The NIST team made extensive new measurements of thorium, a heavy element often used in emission lamps that help provide that fixed ruler.

Scientists have detected more than 400 planets using the Doppler technique but have yet to discover a solar system similar to ours. The new data could help, says Nave.

"Earth causes the Sun to move at a snail's pace," says Nave. "We don't yet have techniques that can find planets of that size, but our new data will get us much closer."

Craig Sansonetti

Stephen Redman, a postdoctoral fellow working at NIST, worked with Nave and physicist Craig Sansonetti to update the most recent thorough measurement of thorium's spectrum, published in 1983.

The more than 8,000 spectral lines it lists are a bit fuzzy by today's standards, good enough to reveal the larger wobble caused by a Jupiter-sized gas giant's gravity, but not the small one an Earth-like world would cause.

Redman spent a year combining observations he made on a spectrometer at NIST with data culled from other researchers' work. The result is a set of nearly 20,000 spectral lines of far greater clarity.

In addition to finding systems similar to our own, the new data should aid the search for planets around dwarf stars.

These have been hard to find using the Doppler method, in part because dwarfs are so faint, but Nave says the new data include good lines in the near infrared, which is the region of the spectrum in which many of these cool stars give off the most light.

"We've already had astronomers from several telescopes ask if they could use the data for planet hunting," Nave says.

"With luck, the measurements will help us search for planets near stars whose wobbling has been hard to detect."

More information: S.L. Redman, G. Nave and C.J. Sansonetti. "The spectrum of thorium from 250 nm to 5500 nm:Ritz wavelengths and optimized energy levels." Astrophysical Journal, DOI: 10.1088/0067-0049/211/1/4, February. 2014.

National Optical Astronomical Observatory (NOAO): App to review Large Synoptic Survey Telescope Data

The Large Magellanic Cloud, an irregular galaxy, is visible in the night sky over the Earth's Southern Hemisphere and may contain hidden astronomical wonders yet to be revealed in the images collected by the Large Synoptic Survey Telescope (LSST). 

Credit: NASA)

University of Arizona computer scientists are teaming up with astronomers at the National Optical Astronomical Observatory (NOAO) to develop a computer program that will sort through the millions of objects detected by the Large Synoptic Survey Telescope (LSST) and create a list of priorities for astronomers to investigate.

The project has recently received a three-year INSPIRE grant, worth more than $700,000, from the National Science Foundation.

"The University of Arizona and NOAO were among the original founding members of the LSST project, making our collaboration to help ensure its success especially appropriate," said Tom Matheson, an associate astronomer at the Tucson-based NOAO.

High in the Andean peaks of Chile, work is underway to build a telescope that will photograph the entire Southern Hemisphere of the sky every three nights for 10 years.

The LSST will create a map of the sky unlike any other, showing changes in astronomical objects almost as they happen over the 10-year period, and opening a floodgate for new astronomical discoveries and research worldwide as new objects are detected each night.

Located in the foothills of the Andes Mountains in Chile, the Large Synoptic Survey Telescope will photograph the entire Southern Hemisphere of the sky every three days for ten years beginning in 2022. 

Credit: Suzanne Jacoby /LSST Project Office

Photographing a portion of the southern sky every 37 seconds each night, the LSST will compile a database of approximately a thousand images per night.

"We can take the picture from one night and subtract it from the picture from three nights before. Everything that has changed will show up in the image, so we can study how the sky varies," Matheson said.

"What we'll get is essentially a movie of the entire southern sky. At the end of the 10 years we can add up all the images and get a really deep picture of objects over the entire southern sky. It's a really fantastic science resource for astronomy," he added.

"It's also a huge amount of data," Matheson said. "In any one of those frames there will be about 10,000 things that change, so that's 10 million objects per night that have changed and we're going to have to figure out what of those is astronomically interesting."

While other astronomy projects are underway around the world to conduct similar surveys, none has ever attempted to map the sky on a scale such as this.

The problem: How to compare between 1 million and 10 million astronomical objects spotted each night by the LSST to the catalog of known objects, prioritize them based upon different factors, and generate a list of most important objects upon which astronomers around the world may train their telescopes.

The team: Matheson, UA associate professor of computer science and member of the UA BIO5 Institute, John Kececioglu, UA professor of computer science, Rick Snodgrass, UA professor of computer science, and NOAO astronomer Abhijit Saha.

NASA Cassini: Data from Titan indicate a rigid, weathered ice shell

A rigid ice shell resists the upward pressure of a buoyant root, whose low density produces a negative gravity anomaly. 

Upward deflection of the ice shell creates positive topography, but surface weathering keeps that topography small. 

Credit: Doug Hemingway

An analysis of gravity and topography data from Saturn's largest moon, Titan, has revealed unexpected features of the moon's outer ice shell.

The best explanation for the findings, the authors said, is that Titan's ice shell is rigid and that relatively small topographic features on the surface are associated with large roots extending into the underlying ocean.

The study is published in the August 29 issue of the journal Nature.

Led by planetary scientists Douglas Hemingway and Francis Nimmo at the University of California, Santa Cruz, the study used new data from NASA's Cassini spacecraft.

The researchers were surprised to find a negative correlation between the gravity and topography signals on Titan.

"Normally, if you fly over a mountain, you expect to see an increase in gravity due to the extra mass of the mountain. On Titan, when you fly over a mountain the gravity gets lower. That's a very odd observation," said Nimmo, a professor of Earth and planetary sciences at UC Santa Cruz.

To explain that observation, the researchers developed a model in which each bump in the topography on the surface of Titan is offset by a deeper "root" big enough to overwhelm the gravitational effect of the bump on the surface.

The root is like an iceberg extending below the ice shell into the ocean underneath it. "Because ice is lower density than water, you get less gravity when you have a big chunk of ice there than when you have water," Nimmo explained.

An iceberg floating in water is in equilibrium, its buoyancy balancing out its weight. In this model of Titan, however, the roots extending below the ice sheet are so much bigger than the bumps on the surface that their buoyancy is pushing them up against the ice sheet.

"It's like a big beach ball under the ice sheet pushing up on it, and the only way to keep it submerged is if the ice sheet is strong," said Hemingway, a doctoral candidate in planetary geophysics at UCSC and lead author of the paper.

"If large roots are the reason for the negative correlation, it means that Titan's ice shell must have a very thick rigid layer."

The researchers calculated that, in this model, Titan's ice shell would have to have a rigid layer at least 40 kilometers thick.

They also found that hundreds of meters of surface erosion and deposition are needed to account for the observed imbalance between the large roots and small surface topography.

The results from their model are similar to estimates obtained by geo-morphologists studying the erosion of impact craters and other features on Titan.

These findings have several implications. For example, a thick rigid ice shell makes it very difficult to produce ice volcanoes, which some have proposed to explain certain features seen on the surface.

More information: Nature paper: dx.doi.org/10.1038/nature12400

NASA MESSENGER Mercury: Data from Third Mercury Solar Day

"Mercury is a planet of many mysteries," adds MESSENGER Principal Investigator Sean Solomon, of Columbia University's Lamont-Doherty Earth Observatory. 

"With each increment of data, we have made discoveries that raised new questions. 

Finding answers to those questions requires further analysis. 

We hope that this latest release of MESSENGER data will induce more of our colleagues from the broader planetary science community to help us unravel the many stories that Mercury has yet to tell."

NASA's Planetary Data System released a new data set collected during MESSENGER's thirteenth through eighteenth month in orbit around Mercury.

With this release, images and measurements are now available to the public for the third full Mercury solar day of MESSENGER orbital operations.

Sean Solomon

NASA requires that all of its planetary missions archive data in the PDS, which makes available well-documented, peer-reviewed data to the research community.

This ninth delivery of MESSENGER measurements includes raw and calibrated data from all seven of the mission's science instruments, plus radio science data from the spacecraft telecommunications system, from March 25 to September 17, 2012.

The team has also provided, for the first time in this release, advanced products created with data collected through March 25, 2012, encompassing the first two full Mercury solar days of MESSENGER orbital operations. Those products include the first global mosaics of Mercury to be delivered to PDS.

"The two advanced image products in this release are an eight-color map and a higher-resolution monochrome map," says Mercury Dual Imaging System (MDIS) Instrument Scientist Nancy Chabot, of the Johns Hopkins University Applied Physics Laboratory (APL).

"They are both the products of thousands of images mosaicked together to reveal Mercury's global geology and color characteristics. These mosaics required considerable effort by many on the MESSENGER team, and we are all very proud to make these global maps available."

Other advanced products include

• summed gamma-ray spectra and background-subtracted, geo-located neutron counts from the Gamma-Ray and Neutron Spectrometer;
• time-averaged magnetic field data from the Magnetometer;
• altimeter profiles, radiometry, and a northern hemisphere digital elevation map produced with data from the Mercury Laser Altimeter (MLA);
• limb tangent height and surface reflectance spectra from the Mercury Atmospheric and Surface Composition Spectrometer;
• pitch-angle and measured-flux distributions and energy spectra from the Energetic Particle and Plasma Spectrometer; and
• occultation data and spherical harmonic gravity and shape models derived from the radio science investigation and the MLA.

"Many in the public have been eagerly awaiting the release of the MESSENGER advanced products, and the MESSENGER team is excited to be able to provide them," says APL's Susan Ensor, MESSENGER's Science Operations Center lead.

"Extra analyses and processing are required to generate these products, which in many cases combine data over time and include maps, topography, and other global data. The team has also worked closely with the PDS in planning and documenting these new products to ensure their long-term usefulness to the science community."

"Mercury is a planet of many mysteries," adds MESSENGER Principal Investigator Sean Solomon, of Columbia University's Lamont-Doherty Earth Observatory.

"With each increment of data, we have made discoveries that raised new questions. Finding answers to those questions requires further analysis. We hope that this latest release of MESSENGER data will induce more of our colleagues from the broader planetary science community to help us unravel the many stories that Mercury has yet to tell."