Wednesday, May 30, 2007

Tuesday, May 22, 2007

Saturn's Clumpy Rings

Contact: Carolina Martinez 818-354-9382Jet Propulsion Laboratory, Pasadena, Calif.

Zenaida Gonzalez Kotala 407-823-6120University of Central Florida, Orlando News Release: 2007-062 May 22, 2007

Cassini 'Cat Scan' Maps Clumps In Saturn's Rings

Saturn's largest and most densely packed ring is composed of tightly packed clumps of particles separated by nearly empty gaps, according to new findings from NASA's Cassini spacecraft.

These clumps in Saturn's B ring are neatly organized and constantly colliding, which surprised scientists.

"The rings are different from the picture we had in our minds. We originally thought we would see a uniform cloud of particles. Instead we find that the particles are clumped together with empty spaces in between," said Larry Esposito, principal investigator for the Cassini ultraviolet imaging spectrograph at the University of Colorado, Boulder. "If you were flying under Saturn's rings in an airplane, you would see these flashes of sunlight come through the gaps, followed by dark and so forth. This is different from flying under a uniform cloud of particles."

Because previous interpretations assumed the ring particles were distributed uniformly, scientists underestimated the total mass of Saturn's rings. The mass may actually be two or more times previous estimates.

"These results will help us understand the overall question of the age and hence the origin of Saturn's rings," said Josh Colwell, assistant professor of physics at the University of Central Florida, Orlando, and a team member of the Cassini ultraviolet imaging spectrograph. A paper with these results appears in the journal Icarus.
Scientists observed the brightness of a star as the rings passed in front of the star on multiple occasions. This provided a measurement of the amount of ring material between the spacecraft and the star.

"Combining many of these occultations at different viewing geometries is like doing a CAT scan of the rings," said Colwell. "By studying the brightness of stars as the rings pass in front of them, we are able to map the ring structure in 3-D and learn more about the shape, spacing and orientation of clusters of particles."

The observations confirm that the gravitational attraction of ring particles to each other creates clumps, or "self-gravity wakes." If the clumps were farther from Saturn, they might continue to grow into a moon. But because these clumps are so close to Saturn, their different speeds around the planet counteract this gravitational attraction so that the clumps get stretched like taffy and pulled apart. The clumps are constantly forming and coming apart once they reach about 30 to 50 meters (about 100 to 160 feet) across.
"At any given time, most particles are going to be in one of the clumps, but the particles keep moving from clump to clump as clumps are destroyed and new ones are formed," added Colwell.

In the dense B ring, the classical cloud model of the rings predicted that particles collide about twice per hour on average. "Our results show that the particles in the B ring spend most of their time in almost continuous contact with other particles," said Colwell. These clumps may act like super-sized particles, changing the way the rings spread due to collisions.

The clumps are seen in all regions of the B ring that are not opaque. One surprising aspect of the measurements is that the clumps in the B ring are broad and very flat, like big sheets of particles. They are roughly 10 to 50 times wider than they are thick. Scientists are also surprised that the B ring clumps are flatter and have smaller spaces between them than those found in the neighboring A ring.

A picture of the rings based on these results is available at:, and .

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter was designed, developed and assembled at JPL. The ultraviolet imaging spectrograph was built at, and the team is based at the University of Colorado, Boulder.

- end -

How not to run out of toilet paper on the Moon

Monday, May 21, 2007

Join the Moon-Mars Blitz!

Spirit gets into the act

Natalie Godwin/Guy Webster 818-354-0850/6278
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown/Tabatha Thompson 202-358-1726/3895
NASA Headquarters, Washington

NEWS RELEASE: 2007-061 May 21, 2007

Mars Rover Spirit Unearths Surprise Evidence of Wetter Past

PASADENA, Calif. - A patch of Martian soil analyzed by NASA's rover Spirit is so rich in silica that it may provide some of the strongest evidence yet that ancient Mars was much wetter than it is now. The processes that could have produced such a concentrated deposit of silica require the presence of water.

Members of the rover science team heard from a colleague during a recent teleconference that the alpha particle X-ray spectrometer, a chemical analyzer at the end of Spirit's arm, had measured a composition of about 90 percent pure silica for this soil.

"You could hear people gasp in astonishment," said Steve Squyres of Cornell University, Ithaca, N.Y., principal investigator for the Mars rovers' science instruments. "This is a remarkable discovery. And the fact that we found something this new and different after nearly 1,200 days on Mars makes it even more remarkable. It makes you wonder what else is still out there."

Spirit's miniature thermal emission spectrometer observed the patch, and Steve Ruff of Arizona State University, Tempe, noticed that its spectrum showed a high silica content. The team has laid out plans for further study of the soil patch and surrounding deposits.

Exploring a low range of hills inside a Connecticut-sized basin named Gusev Crater, Spirit had previously found other indicators of long-ago water at the site, such as patches of water-bearing, sulfur-rich soil; alteration of minerals; and evidence of explosive volcanism.

"This is some of the best evidence Spirit has found for water at Gusev," said Albert Yen, a geochemist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. One possible origin for the silica could have been interaction of soil with acid vapors produced by volcanic activity in the presence of water. Another could have been from water in a hot spring environment. The latest discovery adds compelling new evidence for ancient conditions that might have been favorable for life, according to members of the rover science team.

David Des Marais, an astrobiologist at NASA's Ames Research Center, Moffett Field, Calif., said, "What's so exciting is that this could tell us about environments that have similarities to places on Earth that are clement for organisms."

Spirit and its twin rover, Opportunity, completed their original three-month prime missions in April 2004. Both are still operating, though showing signs of age. One of Spirit's six wheels no longer rotates, so it leaves a deep track as it drags through soil. That churning has exposed several patches of bright soil, leading to some of Spirit's biggest discoveries at Gusev, including this recent discovery.

Doug McCuistion, director of NASA's Mars Exploration Program, said, "This unexpected new discovery is a reminder that Spirit and Opportunity are still doing cutting-edge exploration more than three years into their extended missions. It also reinforces the fact that significant amounts of water were present in Mars' past, which continues to spur the hope that we can show that Mars was once habitable and possibly supported life."

The newly discovered patch of soil has been given the informal name "Gertrude Weise," after a player in the All-American Girls Professional Baseball League, according to Ray Arvidson of Washington University in St. Louis, deputy principal investigator for the rovers.

"We've looked at dozens of disturbed soil targets in the rover tracks, and this is the first one that shows a high silica signature," said Ruff, who last month proposed using Spirit's miniature thermal emission spectrometer to observe this soil. That instrument provides mineral composition information about targets viewed from a distance. The indications it found for silica in the overturned soil prompted a decision this month to drive Spirit close enough to touch the soil with the alpha particle X-ray spectrometer. Silica commonly occurs on Earth as the crystalline mineral quartz and is the main ingredient in window glass. The Martian silica at the Gertrude Weise patch is non-crystalline, with no detectable quartz.

Spirit worked within about 50 yards or meters of the Gertrude Weise area for more than 18 months before the discovery was made. "This discovery has driven home to me the value of in-depth, careful exploration," Squyres said. "This is a target-rich environment, and it is a good thing we didn't go hurrying through it."

Meanwhile, on the other side of the planet, Opportunity has been exploring Victoria Crater for about eight months. "Opportunity has completed the initial survey of the crater's rim and is now headed back to the area called Duck Bay, which may provide a safe path down into the crater," said John Callas, project manager for the rovers at JPL.

JPL, a division of the California Institute of Technology, Pasadena, manages the Mars Exploration Rover project for NASA's Science Mission Directorate. For images and information about the rovers, visit .

- end -

Thursday, May 17, 2007

James Webb Space Telescope Description,_better_with_new_space_telescope.htm

Water Plumes on Enceladus Explained

Carolina Martinez 818-354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Tim Stephens 831-459-2495
University of Santa Cruz, Calif.

News Release: 2007-060 May 16, 2007

Frictional Heating Explains Plumes on Enceladus
Pasadena, Calif.--Rubbing your hands together on a cold day generates a bit of heat, and the same process of frictional heating may be what powers the geysers jetting out from the surface of Saturn's moon Enceladus.

Tidal forces acting on fault lines in the moon's icy shell cause the sides of the faults to rub back and forth against each other, producing enough heat to transform some of the ice into plumes of water vapor and ice crystals, according to a new study published in the May 17 issue of the journal Nature.Francis Nimmo, assistant professor of Earth and planetary sciences at the University of California, Santa Cruz, and his co-authors calculated the amount of heat that could be generated by this mechanism and concluded that it is the most likely explanation for the plumes and other features observed in the south polar region of Enceladus. This region is warmer than the rest of the frozen surface of Enceladus and has features called "tiger stripes" that look like tectonic fault lines."We think the tiger stripes are the source of the plumes, and we made predictions of where the tiger stripes should be hottest that can be tested by future measurements," Nimmo said.Driving the whole process is the moon's eccentric orbit, which brings it close to Saturn and then farther away, so that the gravitational attraction it feels changes over time."It's getting squeezed and stretched as it goes around Saturn, and those tidal forces cause the faults to move back and forth," Nimmo said.Unlike some other proposals for the origin of the plumes, this mechanism does not require the presence of liquid water near the surface of Enceladus, noted co-author Robert Pappalardo of NASA's Jet Propulsion Laboratory in Pasadena, Calif."The heat is sufficient to cause ice to sublimate, like in a comet -- the ice evaporates into vapor, and the escaping vapor drags particles off into space," Pappalardo said.The study does suggest, however, that Enceladus has a liquid ocean lying deep beneath the ice. That allows the ice shell to deform enough to produce the necessary movement in the faults. If the ice shell sat directly on top of the moon's rocky interior, tidal forces would not produce enough movement in the faults to generate heat, Nimmo said.

The frictional, or "shear heating," mechanism is consistent with an earlier study by Nimmo and Pappalardo which proposed that Enceladus reoriented itself to position its hot spot at the south pole (see earlier press release at In that study, the researchers described how the reorientation of Enceladus would result from a lower density of the thick ice shell in this region.
In the new paper, the researchers estimated the thickness of the ice shell to be at least 5 kilometers (3 miles) and probably several tens of kilometers or miles. They also estimated that the movement along the fault lines is about half a meter over the course of a tidal period.

In addition to Nimmo and Pappalardo, the co-authors of the paper include John Spencer of the Southwest Research Institute in Boulder, Colo., and McCall Mullen of the University of Colorado, Boulder. This study was funded by NASA's Planetary Geology and Geophysics and Outer Planets research programs.

Enceladus has sparked great interest among scientists, particularly since the discovery more than a year ago by NASA's Cassini spacecraft of the geysers shooting off its surface. This is one of two papers about Enceladus appearing in the May 17 issue of Nature. In the other paper, scientists explain how cracks in the icy surface of Enceladus open and close under Saturn's pull. Saturn's tides could control the timing of the geyser's eruptions, researchers suggest.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA’s Jet Propulsion Laboratory, a division of Caltech, manages the Cassini-Huygens mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.

More information on the Cassini mission is available at and .


Mars Rover Update

Spirit is still examining silica rich material at Home Plate.

Nothing new for Opportunity

Monday, May 14, 2007

Debunking the Early Women Astronauts Contraversy

It is an overhyped story designed to sell books:

Test Pilots were uniquely qualified to be astronauts because they were used to handling crises while piloting. For historical reasons, women weren't being used as test pilots at that time.

Digging Lunar Dirt

is harder than it looks:

Thursday, May 10, 2007

Mars Rover Update

Status (Spirit: Driving around and exploring the Home Plate area; Opportunity: Opportunity tested new hazard avoidance software and got its solar panels cleaned by a dust devil or the wind)

Spirit Pictures (Nodule-rich rock):

A Great Place to Spend Mother's Day

on Mars!

Hot Planet Found

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

Grey Hautaluoma 202-358-0668
NASA Headquarters, Washington

NEWS RELEASE: 2007-055 May 9, 2007

NASA Finds Extremely Hot Planet, Makes First Exoplanet Weather Map

Pasadena, Calif. – Researchers using NASA's Spitzer Space Telescope have learned what the weather is like on two distant, exotic worlds. One team of astronomers used the infrared telescope to map temperature variations over the surface of a giant, gas planet, HD 189733b, revealing it likely is whipped by roaring winds. Another team determined that the gas planet HD 149026b is the hottest yet discovered. Both findings appear May 9 in Nature.

"We have mapped the temperature variations across the entire surface of a planet that is so far away, its light takes 60 years to reach us," said Heather Knutson of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., lead author of the paper describing HD 189733b.

The two planets are "hot Jupiters" - sizzling, gas giant planets that zip closely around their stars. Roughly 50 of the more than 200 known planets outside our solar system, called exoplanets, are hot Jupiters. Visible-light telescopes can detect these strange worlds and determine certain characteristics, such as their sizes and orbits, but not much is known about their atmospheres or what they look like.

Since 2005, Spitzer has been revolutionizing the study of exoplanets' atmospheres by examining their infrared light, or heat. In one of the new studies, Spitzer set its infrared eyes on HD 189733b, located 60 light-years away in the constellation Vulpecula. HD 189733b is the closest known transiting planet, which means that it crosses in front and behind its star when viewed from Earth. It races around its star every 2.2 days.

Spitzer measured the infrared light coming from the planet as it circled around its star, revealing its different faces. These infrared measurements, comprising about a quarter of a million data points, were then assembled into pole-to-pole strips, and, ultimately, used to map the temperature of the entire surface of the cloudy, giant planet.

The observations reveal that temperatures on this balmy world are fairly even, ranging from 650 degrees Celsius (1,200 Fahrenheit) on the dark side to 930 degrees Celsius (1,700 Fahrenheit) on the sunlit side. HD 189733b, and all other hot Jupiters, are believed to be tidally locked like our moon, so one side of the planet always faces the star. Since the planet's overall temperature variation is mild, scientists believe winds must be spreading the heat from its permanently sunlit side around to its dark side. Such winds might rage across the surface at up to 9600 kilometers per hour (6,000 miles per hour). The jet streams on Earth travel at 322 kilometers per hour (200 miles per hour).

"These hot Jupiter exoplanets are blasted by 20,000 times more energy per second than Jupiter," said co-author David Charbonneau, also of the Harvard-Smithsonian Center for Astrophysics. "Now we can see how these planets deal with all that energy."

Also, HD 189733b has a warm spot 30 degrees east of "high noon," or the point directly below the star. In other words, if the high-noon point were in Seattle, the warm spot would be in Chicago. Assuming the planet is tidally locked to its parent star, this implies that fierce winds are blowing eastward.

In the second Spitzer study, astronomers led by Joseph Harrington of the University of Central Florida in Orlando discovered that HD 149026b is a scorching 2,038 degrees Celsius (3,700 Fahrenheit), even hotter than some low-mass stars. Spitzer was able to calculate the temperature of this transiting planet by observing the drop in infrared light that occurs as it dips behind its star.

"This planet is like a chunk of hot coal in space," said Harrington. "Because this planet is so hot, we believe its heat is not being spread around. The day side is very hot, and the night side is probably much colder."

HD 149026b is located 279 light-years away in the constellation Hercules. It is the smallest and densest known transiting planet, with a size similar to Saturn's and a core suspected to be 70 to 90 times the mass of Earth. It speeds around its star every 2.9 days.

According to Harrington and his team, the oddball planet probably reflects almost no starlight, instead absorbing all of the heat into its fiery body. That means HD 149026b might be the blackest planet known, in addition to the hottest.

"This planet is off the temperature scale that we expect for planets," said Drake Deming, a co-author of the paper, from NASA's Goddard Space Flight Center, Greenbelt, Md.

NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena.

For more information about the Spitzer Space Telescope, visit or


Tuesday, May 08, 2007

Phoenix Mars Lander on its way to Florida

NEWS RELEASE: 2007-054 May 8, 2007

NASA'S Next Mars Spacecraft Crosses the Mississippi

A U.S. Air Force C-17 cargo aircraft carried NASA's Phoenix Mars Lander spacecraft Monday, May 7, from Colorado to Florida, where Phoenix will start a much longer trip in August.

After launch, Phoenix will land on a Martian arctic plain next spring. It will use a robotic digging arm and other instruments to determine whether the soil environment just beneath the surface could have been a favorable habitat for microbial life. Studies from orbit suggest that within arm's reach of the surface, the soil holds frozen water.

"This is a critical milestone for our mission," said Peter Smith of the University of Arizona, Tucson, principal investigator for Phoenix. "Our expert engineering team has completed assembly and testing of the spacecraft. The testing shows our instruments are capable of meeting the high-level requirements for the mission."

Workers have been assembling and testing the spacecraft for more than a year in Denver. "We're excited to be going back to Mars," said Ed Sedivy, Phoenix program manager at Lockheed Martin Space Systems Co., Denver. "Assembly, integration and testing of the spacecraft have gone very well. We delivered Phoenix stowed inside its back shell and it will stay in that configuration until it lands softly on Mars."

A Delta II launch vehicle will start Phoenix on its longer trip from Cape Canaveral Air Force Station, Fla. The earliest possible launch time will be Aug. 3, at 5:35 a.m. EDT. Opportunities for energy-efficient launches to Mars come about every two years. Orbital geometries of Mars and Earth make this year particularly favorable for sending a lander to far-northern Mars to arrive when sunshine is at a maximum there.

"The arctic plains are the right place for the next step in Mars exploration, and this is the right time to go there," said Leslie Tamppari, Phoenix project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "We expect to touch Martian ice for the first time, a real leap in NASA's follow-the-water strategy. The lander needs solar energy, and we will arrive for a three-month prime mission right at the end of northern Mars' spring."

Phoenix will be prepared for launch in a payload processing facility at NASA's Kennedy Space Center, Florida. The first checkout activity will be a spin-balance test May 10 and 11. This will be followed on May 15 by installation of the heat shield and then a separation test. The next major milestones, during the third week of May, will be a landing radar integration test and launch system verification test. The last week of May will include an entry, descent and landing system verification test, followed by a guidance navigation and control test.

The rocket that will launch Phoenix is a Delta II 7925, manufactured by United Launch Alliance, Denver. The first stage is scheduled to be hoisted into the launcher of Pad 17-A at Cape Canaveral Air Force Station the third week of June. Nine strap-on solid rocket boosters will then be raised and attached. The second stage, which burns hypergolic propellants, will be hoisted atop the first stage the first week of July. The fairing, which surrounds the spacecraft, will then be hoisted into the clean room of the mobile service tower.

Next, engineers will perform several tests of the Delta II. In mid-July, as a leak check, the first stage will be loaded with liquid oxygen during a simulated countdown. The next day, a simulated flight test will be performed, simulating the vehicle’s post-liftoff flight events without fuel aboard. The electrical and mechanical systems of the entire Delta II will be exercised during this test. Once the Phoenix payload is placed atop the launch vehicle in the third week of July, a major test will be conducted: an integrated test of the Delta II and Phoenix working together. This will be a combined minus count and plus count, simulating all events as they will take place on launch day, but without propellants aboard the vehicle. Finally, one week before launch, the Delta II payload fairing will be installed around the Phoenix lander.

The NASA Launch Services Program at the Kennedy Space Center and the United Launch Alliance are responsible for the launch of the Delta II.

Phoenix is the first mission of NASA's Mars Scout Program of competitively proposed, relatively low-cost missions to Mars. Selected in 2003, Phoenix saves expense by using a lander structure and some other components originally built for a 2001 mission that was canceled while in development. Smith of the University of Arizona leads the Phoenix mission, with project management at JPL and development partnership at Lockheed Martin. International contributions are provided by the Canadian Space Agency, the University of Neuchatel (Switzerland), the University of Copenhagen (Denmark), the Max Planck Institute (Germany) and the Finnish Meteorological institute. JPL is a division of the California Institute of Technology in Pasadena. Additional information about Phoenix is available online at .

Space Week

Check it out on the Science Channel:

Mars is coming back

Get your telescopes ready for December!

Stick to your budget or step aside

Thursday, May 03, 2007

Ancient Volcanic Explosion on Mars

This supported by the pictures taken recently by Spirit.

Contact: Guy Webster/Natalie Godwin 818-354-6278/0850
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown 202-358-1726
NASA Headquarters, Washington

News Release: 2007-051 May 3, 2007

NASA's Mars Rover Finds Evidence of Ancient Volcanic Explosion

NASA's Mars Exploration Rover Spirit has discovered evidence of an ancient volcanic explosion at "Home Plate," a plateau of layered bedrock approximately 2 meters (6 feet) high within the "Inner Basin" of Columbia Hills, at the rover's landing site in Gusev Crater. This is the first explosive volcanic deposit identified with a high degree of confidence by Spirit or its twin, Opportunity.

There is strong evidence that those layers are from a volcanic explosion, said Steve Squyres of Cornell University, Ithaca, N.Y. Squyres is principal investigator for the rovers' science instruments. The findings about volcanic activity are reported in a paper published in the May 4 issue of the journal Science.

Evidence shows the area near Home Plate is dominated by basaltic rocks. "When basalt erupts, it often does so as very fluid lava, rather than erupting explosively," Squyres said. "One way for basaltic lava to cause an explosion is for it to come into contact with water – it's the pressure from the steam that causes it to go boom."

Scientists suspect that the explosion that formed Home Plate may have been caused by an interaction of basaltic lava and water. "When you look at composition of the rocks in detail, there are hints that water may have been involved," Squyres said. One example is the high chlorine content of the rocks, which might indicate that basalt had come into contact with a brine.

One of the strongest pieces of evidence for an explosive origin for Home Plate is a "bomb sag" preserved in layered rocks on the lower slopes of the plateau. Bomb sags form in volcanic explosions on Earth when rocks ejected skyward by the explosion fall into soft deposits, deforming them as they land.

Spirit arrived at Home Plate in February 2006 and spent several months exploring it in detail before driving to "Low Ridge" to pass the Martian winter. Spirit has now returned to Home Plate to continue exploration there. "We decided to go back to Home Plate, once the Martian winter ended, because it is one of the most interesting places that we've found on Gusev Crater," Squyres said. "Last year we primarily explored the northern and eastern sides of it. This time we're hoping to get to the southern and western sides." Spirit's continued exploration of Home Plate will focus largely on testing the idea that water was involved in its formation process.

Spirit and Opportunity are in their fourth year of exploring Mars. They successfully completed their three-month prime missions in April 2004, and the missions have been extended four times. As of April 26, Spirit had spent 1,177 sols, or Martian days, on the surface of Mars and had driven 7,095 meters (4.4 miles), and Opportunity had spent 1,157 sols and driven 10,509 meters (6.5 miles).

"Considering their age, both rovers are in good health. All science instruments are functioning and continuing to return superb science data," said John Callas, project manager of the Mars Exploration Rover mission at NASA's Jet Propulsion Laboratory, Pasadena, Calif.

JPL manages the Mars Exploration Rover project for NASA's Science Mission Directorate. JPL is a division of the California Institute of Technology in Pasadena.

For images and information about the rovers and their discoveries on the Web, visit: or

For information about NASA and agency programs on the Internet, visit: .

Mercury has a Liquid Core

I thought as much since it has a small magnetic field.

Here is an aritcle:

The full NASA press release follows

Contact: DC Agle/Carolina Martinez 818-393-9011/354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Dwayne Brown/Tabatha Thompson 202-358-1726/3895
NASA Headquarters, Washington

News Release: 2007-050 May 3, 2007

NASA Antenna Cuts Mercury to Core, Solves 30 Year Mystery

Researchers working with high-precision planetary radars, including the Goldstone Solar System Radar of NASA's Jet Propulsion Laboratory, Pasadena, Calif., have discovered strong evidence that the planet Mercury has a molten core. The finding explains a more than three-decade old planetary mystery that began with the flight of JPL's Mariner 10 spacecraft. The research appears in this week's issue of the journal Science.

Launched in Nov. 1973, Mariner 10 made three close approaches to Mercury in 1974 and 75. Among its discoveries was that Mercury had its own weak magnetic field – about one percent as strong as that found on Earth.

"Scientists had not expected to find a magnetic field at Mercury," said Professor Jean-Luc Margot of Cornell University, Ithaca, N.Y., leader of the research team. "Planetary magnetic fields are associated with molten cores, and the prevailing theory was the planet was too small to have a molten core."

Scientists theorized that Mercury consisted of a silicate mantle surrounding a solid iron core. This iron was considered solid -- or so the theory went – because small planets like Mercury cool off rapidly after their formation. If Mercury followed this pattern, then its core should have frozen long ago.

Many believed the Mercury mystery would only be resolved if and when a spacecraft landed on its aggressively toasty surface. Then, in 2002, scientists began pointing some of the most powerful antennas on our planet at Mercury in an attempt to find the answer.

"On 18 separate occasions over the past five years, we used JPL's Goldstone 70-meter [230-foot] antenna to fire a strong radar signal at Mercury," said Planetary Radar Group Supervisor Martin Slade of JPL, a co-author of the paper. "Each time, the radar echoes from the planet were received about 10 minutes later at Goldstone and another antenna in West Virginia."

Measuring the echo of particular surface patterns from the surface of Mercury and how long they took to reproduce at both Goldstone and the Robert C. Byrd Green Bank Telescope in West Virginia allowed scientists to calculate Mercury's spin rate to an accuracy of one-thousandth of a percent. The effect was also verified with three more independent radar observations of Mercury transmitted from the National Science Foundation's Arecibo Observatory in Puerto Rico.

With these data the science team was able to detect tiny twists in Mercury's spin as it orbited the sun. These small variations were double what would be expected for a completely solid body. This finding ruled out a solid core, so the only logical explanation remaining was that the core – or at the very least the outer core -- is molten and not forced to rotate along with its shell.

Maintaining a molten core over billions of years requires that it also contain a lighter element, such as sulfur, to lower the melting temperature of the core material. The presence of sulfur supports the idea that radial mixing, or the combining of elements both close to the sun and farther away, was involved in Mercury's formation process.

"The chemical composition of Mercury's core can provide important clues about the processes involved in planet formation," said Margot. "It is fundamental to our understanding of how habitable worlds -- planets like our own -- form and evolve."

Mercury still has its share of mysteries. Some may be solved with the NASA spacecraft Messenger, launched in 2004 and expected to make its first Mercury flyby in 2008. The spacecraft will then begin orbiting the planet in 2011. "It is our hope that Messenger will address the remaining questions that we cannot address from the ground," said Margot.

The study's other co-authors include Stan Peale of the University of Santa Barbara in California; Raymond Jurgens, a JPL engineer, and Igor Holin of the Space Research Institute in Moscow, Russia.

The Goldstone antenna is part of NASA's Deep Space Network Goldstone station in Southern California's Mojave Desert. Goldstone's 70-meter diameter antenna is capable of tracking a spacecraft traveling more than 16 billion kilometers (10 billion miles) from Earth. The surface of the 70-meter reflector must remain accurate within a fraction of the signal wavelength, meaning that the precision across the 3,850-square-meter (41,400-square-foot) surface is maintained within one centimeter (0.4 inch).

For more information about NASA and agency programs on the Internet, visit:

Mars Rover Update

Status (Nothing new for Spirit, Opportunity's scientists and engineers are still deciding on when and if Opportunity will enter "Victoria Crater." Meanwhile it is driving back to its starting place on the rim.):

Spirit Pictures (3 new ones):

No new Opportunity pictures

Patchy Ice on Mars

Contact:Guy Webster 818-354-6278Jet Propulsion Laboratory, Pasadena, Calif.
Robert Burnham 480-458-8207
Arizona State University, Tempe

News Release: 2007-049 May 2, 2007
Sharp Views Show Ground Ice on Mars is Patchy and Variable
Using observations by NASA's Mars Odyssey orbiter, scientists have discovered that water ice lies at variable depths over small-scale patches on Mars.
The findings draw a much more detailed picture of underground ice on Mars than was previously available. They suggest that when NASA's next Mars mission, the Phoenix Mars Lander, starts digging to icy soil on an arctic plain in 2008, it might find the depth to the ice differs in trenches just a few feet apart. The new results appear in the May 3, 2007, issue of the journal Nature.
"We find the top layer of soil has a huge effect on the water ice in the ground," said Joshua Bandfield, a research specialist at Arizona State University, Tempe, and author of the paper. His findings come from data sent back to Earth by the Thermal Emission Imaging System camera on Mars Odyssey. The instrument takes images in five visual bands and 10 heat-sensing (infrared) ones.
The new results were made using infrared images of sites on far-northern and far-southern Mars, where buried water ice within an arm's length of the surface was found five years ago by the Gamma Ray Spectrometer suite of instruments on Mars Odyssey. The smallest patches detectable by those instruments are several hundred times larger than details detectable by the new method of mapping depth-to-ice, which sees differences over scales of a few hundred yards or meters.
The new approach uses thermal imaging as a thermometer to measure how fast the ground changes temperature during local spring, summer and fall. The dense, icy layer retains heat better than the looser soil above it, so where the icy layer is closer to the surface, the surface temperature changes more slowly than where the icy layer is buried deeper.
The resulting maps show that the nature of the surface soil makes a difference in how close to the surface the ice lies. Areas with many rocks at the surface, Bandfield explained, "pump a lot of heat into the ground and increase the depth where you'll find stable ice." In contrast, dusty areas tend to insulate the ice, allowing it to survive closer to the surface. "These two surface materials -- rock and dust -- vary widely across the ground, giving underground ice a patchy distribution," he said.
Computer models helped him interpret the temperature observations, he said. "They show areas where water ice would be only an inch or so under the soil, while in other areas ice could lie many feet below the surface."
The results fit long-term climatic models for Mars. These show the planet has been both warmer and colder in the past, similar to glacial cycles on Earth. Bandfield said, "The fact that ice is present near the depth of stability in the current Martian climate shows that the ground ice is responding to climate cycles." In turn, he added, this implies that water ice in the ground can swap places with water vapor in the atmosphere as the climate changes.
Philip Christensen of Arizona State University, Tempe, principal investigator for the Thermal Emission Imaging System, said, "Scientists have known for more than a decade that water is on Mars, mostly in the form of ice. What's exciting is finding out where the ice is in detail and how it got there. We've reached the next level of sophistication in our questions."
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, Calif., manages Mars Odyssey for NASA's Science Mission Directorate. Odyssey's Thermal Emission Imaging System is operated by Arizona State University. For additional information about Odyssey and the new findings, visit and .

New Space Telescope Info

Thumbs up again!

Astronaut Glove Challenge

Thumbs Up!

Tuesday, May 01, 2007

Virgin Galactic Update

6 g's for 200 g's.

6 g's is a lot, I doubt Hawking can handle it. He'll have to go through centrifuge training first so they'll know for sure.