Posted on by Nancy Atkinson

Mitigating Asteroid Threats Will Take Global Action

Computer generated simulation of an asteroid strike on the Earth. Credit: Don Davis/AFP/Getty Images

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During the past 24 hours, the Earth has been hit by about a million small meteoroids – most of which burned up in the atmosphere as shooting stars. This happens every day. And occasionally – once every 10,000 years or so — a really big asteroid (1 km in diameter or larger) comes along and smacks Earth with an extinction-level impact. That idea might cause some of us to lose some sleep. But in between are other asteroid hits that occur every 200-300 years where a medium-sized chunk of space rock intersects with Earth’s orbit, producing a Tunguska-like event, or worse.

“Those are the objects we are concerned with,” said former Apollo astronaut Rusty Schweickart, speaking at a 3-day workshop in Darmstadt, Germany which focused on plans and recommendations for global coordination and response to an asteroid threat. “We need to take action now to bring the world together and recognize this as a global threat so that we can make a cooperative international decision to act to extend the survival of life on Earth.”

There are likely about one million Near Earth Objects out there that could do substantial damage if one hit the Earth. This isn’t anything new – Earth has been in this same environment for billions years.

“What’s new is that we have now opened our eyes via telescopes and are seeing something flying by our heads, so to speak,” said Schweickart during a media event at the workshop. “When you see something flying by your head, you duck. It turns out we have the capability of ducking and causing these objects to miss us. Because we now know about this threat and because we can in fact prevent an impact, we then have a moral obligation to do so.”

Former astronaut Tom Jones, who also attended the workshop, told Universe Today that NASA hopes to find all the 500 meter objects within a few decades, “and thus through action be able to prevent an impact from that large an object, removing it from the overall asteroid hazard. Smaller objects are much more numerous (the approximately million NEOs mentioned above) and can cause city-size damage. We’ll have to search diligently for those in the coming decade and it’ll be several decades before we find those hundreds of thousands of 30-meter sized -subTunguskas.”

Schweickart discussed in a recent Universe Today article that we do possess the technology to move asteroids or change their orbits, and that this technology does need to be tested, and tested soon. But since an impact event could affect the entire world, the decisions on policies and international agreements about asteroid mitigation could actually pose a bigger challenge in dealing with an asteroid threat than putting the technology together.

“Bureaucracy is the most likely reason we will be hit with an asteroid in the future, not the technology,” said Schweickart. “That is an audacious statement to make, but if we can get past that and do our jobs right we should never be hit in the future by an asteroid that could threaten life on Earth. And it’s going to be a heck of a challenge.”

The Mission Planning and Operations Group (MPOG) workshop included astronauts and space scientists and was the latest in a series of workshop designed to offer suggestions to the UN Committee on the Peaceful Uses of Outer Space. Included were representatives from NASA, ESA, the Secure World Foundation and the Association of Space Explorers. They are working on defining future planning tasks and studies for the Group that will later be merged with findings of other experts to create a final report to the UN committee. This report will recommend how to react to an impact threat.

But there are issues such as, how changing an asteroid’s orbit could make it miss one area on Earth and instead hit another area.

“The issue of NEOs is an issue that the United nations has been considering for 10 years or so,” said Sergio Camacho, representing the UN Committee. “The reason it has to go through the UN is that when we make a decision, whatever action is taken might affect others and put them at risk where they are not at risk at the beginning. That can’t be a unilateral decision, and we need to pool the resources of space agencies in order to address the problem. It will be within the framework of the UN that we will be able to master this cooperation.”

Schweickart and the Association of Space Explorers, have been working on this issue for over 9 years and are just now beginning to see a little headway in the bureaucratic process. Everyone at the workshop agreed that political decisions and political awareness is something that has to be taken seriously.

“Two weeks ago a small object passed in between the Earth and the Moon,” said Schweickart,“ and on Halloween an object half a kilometer in diameter Is going to pass within five lunar distances of Earth — in terms of astronomical distances, that is very close. These things are happening, but I hope we areable to act soon and act responsibly without having to have a reminder” – meaning the wake-up call of an actual impact and not being prepared for it.

For more information:

The MPOG workshop (where you can watch the press conference)

Association of Space Explorers,

Posted on by Jon Voisey

A Comet that Gives Twice?

A green and red Orionid meteor striking the sky below Milky Way and to the right of Venus. Zodiacal light is also seen at the image The trail appears slightly curved due to edge distortion in the lens. Taken by Mila Zinkova
A green and red Orionid meteor striking the sky below Milky Way and to the right of Venus. Zodiacal light is also seen at the image The trail appears slightly curved due to edge distortion in the lens. Taken by Mila Zinkova

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While historically, meteor showers were portents of ill omens, we know today that they are the remnants of ejecta from comets entering our atmosphere. Many showers have had their parent comets identified. But a new study is suggesting that two meteor showers, the December Monocerotids and the November Orionids, may share the same parent.


The possibility of a single comet providing multiple showers isn’t too difficult to imagine. Since comets orbit the Sun in elliptical paths there are two potential points the path can intersect Earth’s orbit: Once on the way in and once on the way out. The trouble is that comets don’t tend to orbit directly in the ecliptic plane (defined by the plane on which the Earth orbits the Sun). Thus, comets only puncture through this plane at points known as “nodes”. As a body passes from the upper half to the lower (where upper and lower are the halves defined by Earth’s north and south poles respectively) this point of intersection of the orbit with the ecliptic plane is known as the descending node. When it heads back up, this is the ascending node. If both nodes happen to lie near enough to Earth’s orbital path, the potential for two meteor showers exists. Another possibility is that orbital evolution cause the nodes to change their position and, over time, crossed Earth’s orbit at two different points.

In principle, identifying a parent comet for two showers is much simpler with the first method. In that instance, the comet still orbits in the same path (or near enough) to be conclusively identified as the progenitor. If such an instance were to arise due to orbital evolution, the case must be much more indirect since interactions with planets, even at fairly large distances, can induce large uncertainties in the orbital history.

The December Monocerotids have been associated with a comet known as C/1917 F1 Mellish. Unfortunately for the researchers, the current orbital characteristics of the comet did not feature nodes in Earth’s orbit and did not match the November Orionids. Thus, to establish a connection between the two meteor streams, the team of astronomers from Comenius University in Slovakia, looked at the characteristics of the showers. In order to track these characteristics, the team utilized a publicly available database of meteor recordings from SonotaCo which uses webcams to capture video of meteors and then compute the orbital characteristics of the debris. However, the two showers did share suspiciously similar distributions of sizes (and thus brightnesses) of meteors as well as the velocity and less so, but still notable, the eccentricity.

This led the team to suspect that the node had evolved across Earth’s orbit sweeping by once in the past to create the stream of debris that forms the November shower, and more recently, crossed our orbit to create the December shower. If this hypothesis were correct, the team expected to also find subtle differences hinting that the November shower was older. Sure enough, the November Orionids show a larger dispersion of velocities than that of the December shower.

In the future, the team plans to revise the orbital characteristics of the parent comet. While they were able to show that the precession of the orbit would allow for the situation described, it was only one of a number of possible solutions. Thus, refining the knowledge of the orbit, perhaps from archival photographic plates, would allow the team to better constrain the path and determine the orbital history sufficiently to reinforce or refute their scenario.

Posted on by Nancy Atkinson

Carbon Dioxide — Not Water — Creating Gullies on Mars, New Study Says

Gullies on a Martian sand dune in this trio of images from NASA's Mars Reconnaissance Orbiter deceptively resemble features on Earth that are carved by streams of water. However, these gullies likely owe their existence to entirely different geological processes apparently related to the winter buildup of carbon-dioxide frost. Image Credit: NASA/JPL-Caltech/University of Arizona

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Intriguing images of brand new, fresh gullies on Mars has most of us thinking of one thing: water. But at least for one type of Mars gully, carbon dioxide frost is the impetus behind fresh flows showing up on images from orbiting spacecraft.

“Gullies that look like this on Earth are caused by flowing water, but Mars is a different planet with its own mysteries,” said Serina Diniega, author of a new paper published in the journal Geology. “The timing we see points to carbon dioxide, and if the mechanism is linked to carbon-dioxide frost at these dune gullies, the same could be true for other gullies on Mars.”

Scientists have seen evidence of fresh gullies on Mars, beginning 2000 with images from the Mars Global Surveyor. Different mechanisms were proposed including water and carbon dioxide, as well as other forces.

On the HiRISE website, searching for “gullies” provides a bounty of images. Some fresh gullies are on sand dunes, commonly starting at a crest. Others are on rockier slopes, such as the inner walls of craters, sometimes starting partway down the slope.

Active Dune Gullies in Kaiser Crater (ESP_018186_1330) Active Dune Gullies in Kaiser Crater. Credit: NASA/JPL/University of Arizona

While a graduate student at the University of Arizona, Tucson, Diniega tracked changes in gullies on faces of sand dunes in seven locations on southern Mars. In looking at before-and-after images, in all cases, the gullies appeared after the known winter build-up of carbon-dioxide frost on the dunes. Before-and-after images that looked at periods in spring, summer and autumn showed no new activity.

Because new flows in these gullies apparently occured in winter, rather than at a time when any frozen water might be most likely to melt, Diniega and co-authors at the University of Arizona and Johns Hopkins University Applied Physics Laboratory believe they found evidence that carbon dioxide, rather than water, were responsible for the flows. Some carbon dioxide from the Martian atmosphere freezes on the ground during winter and sublimates back to gaseous form as spring approaches.

A series of images from HiRISE taken from 2008 to 2010 showing changes in a gully. Credit: NASA/JPL/University of Arizona

“One possibility is that a pile of carbon-dioxide frost accumulating on a dune gets thick enough to avalanche down and drag other material with it,” Diniega said. Other suggested mechanisms are that gas from sublimating frost could lubricate a flow of dry sand or erupt in puffs energetic enough to trigger slides.

The team focused their study on dune gullies that are shaped like rockier slope gullies, with an alcove at the top, a channel or multiple channels in the middle, and an apron at the bottom. The 18 dune gullies in which the researchers observed new activity range in size from about 50 meters or yards long to more than 3 kilometers (2 miles) long.

Source: JPL

Posted on by Nancy Atkinson

Shuttle Launch Delayed at Least One Day

Space Vehicle
Space Shuttle Discovery

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Second Update (10/30): Launch of space shuttle Discovery is now targeted for Wednesday, Nov. 3 at 3:52p EDT. Technicians are still working to make repairs on the OMS engine.

The launch of space shuttle Discovery for the STS-133 mission has been pushed back at least one day due to the discovery of leaks in the right hand Orbital Maneuvering System Pod. Therefore, the launch will occur no sooner than Tuesday, Nov. 2 (and that has now been pushed to Nov. 3) . Managers, engineers and technicians are evaluating helium and nitrogen leaks in the pressurization portion of the OMS pod. The leaks must be fixed before launch and the decision was made to delay at least a day. Countdown had been scheduled to begin at 3 p.m. EDT today (Friday) but could begin on Saturday at 2 p.m. if the leak situation is resolved soon. The launch window on Tuesday, November 2 would open at 4:17 p.m. Wednesday, Nov. 3 at 3:52p EDT. NASA will be holding a press conference at 10 am EDT (watch on NASA TV), and we’ll provide an update after the conference. (See update below)

These leaking helium and nitrogen seals are unrelated to the fuel leak that was repaired last week, also related to Discovery’s right OMS pod.

In other shuttle news, there are some political rumblings that the additional shuttle mission — among other things — that was part of the newly signed outline for NASA’s budget could be under threat of being cut. Some politicians are looking at cutting NASA’s budget in order to save money, and the $300 million uptick for NASA is one target. For more information, check out this article in the Orlando Sentinel.

UPDATE: During the press conference Friday morning, launch test director Jeff Spaulding said this type of repair has been done several times previously on the launch pad, so they are not very worried about this causing a big delay. They do have to re-pressurize the various tanks, which require a pad clear (getting all personnel away from the launch pad), so that causes some delay in that they can’t proceed with the normal countdown activities.

As of right now, they are assuming they can launch on Tuesday because it is a rather routine repair. The teams did work overnight on removing the seals where the leak was found. “The standard process is to remove and inspect both sides of the connector to look at the problem of what caused the leak,” Spaulding said. “Sometimes the seals reseat themselves just by taking them apart and putting it back together, but the team did see contamination — a seal was in the wrong place. They did get it to lock up when they reconnected it, but they weren’t really comfortable with it knowing there was possibly some contamination.”
So today, the teams will likely replace the connectors.

STS-133 is an 11 day mission to the ISS, which is bringing up supplies, and the new permanent logistics module (basically a store room) and the humanoid robot Robonaut 2. (R2).

NASA is expect a huge crowd for the launch, as this is Discovery’s final mission. There’s also an air show in the area this weekend, so many people are planning to attend both the show and the launch. But that is not a factor in making the decision to launch, Spaulding said. “We are happy to have the teams that handle these kinds of repairs, and we will fly this vehicle only when it is ready to go.”

Another item of note is that Nov. 2 is Election Day here in the US, so NASA has encouraged their employees to do early voting in case the launch is on Tuesday and employees would then likely not have the time to vote.

As far as weather, Weather Director Kathy Winters said on Tussday there is a small concern about some rain coming into the area, and right now there would be a 30% chance of weather prohibiting launch on Tuesday.

Posted on by Nancy Atkinson

Kepler Spacecraft Can “Hear” a Red Giant Concerto in Space

The stars and their light variation studied by Kepler.

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Not only is the Kepler spacecraft hunting down extrasolar planets, but it also provides the ability to study stars in unprecedented detail. “We knew that if Kepler had the sensitivity of detecting Earth-size planets, that it would have capability to transform our knowledge of stars themselves,” said Natalie Batalha of San Jose State University in California, a co-investigator on the Kepler Astroseismic Science Consortium. This international partnership of over 400 astronomers uses the Kepler spacecraft to “listen” to tiny oscillations, or “star quakes,” in red giant stars, allowing scientists to do groundbreaking work in deducing the fundamental properties of stars.

In just the first year of Kepler’s operation, the team has been able to study thousands of stars using astroseismology, while previously only a few dozen of stars had been “listened to” using this technique.
“We can say Kepler is listening to thousands of musicians in the sky,” said Daniel Huber, a graduate student at the University of Sydney, during a webcast of a press conference about the new findings.

“From first year of the Kepler mission we moved from having a couple of dozen of stars with a couple of weeks of data,” said Travis Metcalfe, scientist at The National Center for Atmospheric Research, responding to a question posed by Universe today “to having one month to study each of a several thousands of stars. This is an enormous expansion of our capability to study this type of star and what the oscillations tells us.”
Similar to how seismologists study earthquakes to probe the Earth’s interior, astroseismology measures the natural pulse of light waves from stars to gain new insights into stellar structure and evolution.

The variations in brightness can be interpreted as vibrations, or oscillations within the stars, using a technique called asteroseismology. The oscillations reveal information about the internal structure of the stars, in much the same way that seismologists use earthquakes to probe the Earth's interior. Credit: Kepler Astroseismology team.

“Kepler allows us to study the periods of stellar oscillations, and we use them to study the cores of stars — in a way to touch the stars — and get the most accurate measurements of stars we have ever made,” said Hans Kjeldsen, associate professor, KASC, Aarhus University in Denmark.

They can measure size and age with extreme precision and they have now characterized the structure and life cycle of over 1,000 red giants. What they have found so far confirms the current principals of stellar evolution and allows for better predictions of what might happen to our Sun in several billion years.

Kjeldsen said they are getting data of amazing quality. “We can now actually study stars of all phases and evolutionary stages, of different mass, and all different types. This is the amazing thing for me. Instead of looking one star for awhile and then moving on to next star, we now have access to thousands of stars at once. And having said that, there are still thousands and thousands of stars we still need to study.”

Metcalfe said astroseismology listens to the oscillations of the star, and can hear a tone so low that even a whale would have a hard time hearing it. Kepler can see even tiny oscillations as a flickering in the star.
“Sound waves travel into the star and bring information up to the surface, which Kepler can see as a tiny flickering in brightness of the star,” said astronomer Travis Metcalfe of The National Center for Atmospheric Research.

That flickering has a tone like the notes of a musical instrument. “We essentially measure the tone of these musical notes from the star,” he said. “Larger stars flicker in lower tones while smaller stars in higher tones.”

Listen to Daniel Huber's Red Giant Oscillation Symphony

One star that Metcalfe has been focusing on is a red giant, that measured twice the size of the Sun. KIC 11026764 now has the most accurately known properties of any star in the Kepler field. In fact, few stars in the universe are known to similar accuracy, the team said. The oscillations reveal that this star is 5.94 billion years old and is powered by hydrogen fusion in a thin shell around a helium-rich core.

In this consortium, no dollars are actually exchanged between nations. The US provides the Kepler instrument and software pipeline, while the international partners are supplying human resources of ingenuity and scientific expertise.

“We’re not just getting a great legacy of scientific results, but also a valuable symbiosis and partnership here,” said Batalha.

You can watch the press conference on Universe Today at this link.

Posted on by Nancy Atkinson

Earth Orbiting Satellites Maneuvered to Now Study the Moon

ARTEMIS maneuvers. Credit: NASA

In another case of NASA reusing and recycling spacecraft, two of the five THEMIS spacecraft — which were studying the cause of geomagnetic substorms here on Earth — have a new mission. They made some very unique and complex maneuvers to reach two different LaGrange Points, and will turn their focus on the Moon. Particularly, they will try to determine how the solar wind electrifies, alters and erodes the lunar surface. This is timely since the discovery last year of water across the surface of the Moon which may be created by the solar wind interacting with the lunar surface.

The original THEMIS mission (Time History of Events and Macroscale Interactions during Substorms) featured five satellites that have now successfully completed their 2 year mission. Because they are continuing to work perfectly, NASA is re-directing the outermost two spacecraft to special orbits at and around the Moon. This new mission, which is called ARTEMIS: Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun.

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It took more than a year and nearly all remaining fuel aboard the satellites to get them to the L1 and L2 Lagrangian points, where one is located on the far side of the Moon, and the other on the Earth-facing side. ARTEMIS-P1 is the first spacecraft to navigate to and perform stationkeeping operations around the Earth-Moon L1 and L2 Lagrangian points.

On August 25, 2010, ARTEMIS-P1 reached the L2 Lagrange point on the far side of the Moon. Following close behind, ARTEMIS-P2 entered the opposite L1 Lagrange point on Oct. 22nd.

Recently, one of the spacecraft was hit by a meteoroid but still seems to be operating.

As the Moon orbits the Earth, it passes in and out of the Earth’s magnetic field and the million-mile per hour stream of solar wind particles. While in these regions, the two ARTEMIS spacecraft will seek evidence for turbulence, particle acceleration, and magnetic reconnection, three fundamental phenomena that control the nature of the solar wind’s interaction with the Earth’s magnetosphere.

By using their instruments and unique two-point vantage points, the spacecraft will study the vacuum the Moon carves out in the solar wind, and the processes that eventually fill this lunar wake. Nearer the Moon, they will observe the effects of surface electric fields, ions sputtered off the lunar surface, and determine the internal structure of the Moon from transient variations in its magnetic field induced by external changes.

Posted on by Nancy Atkinson

Human Spaceflight Briefs

Quite a few things going on in the human spaceflight world, so will just post a few briefs:

Of course top on the agenda is that space shuttle Discovery is scheduled to lift-off on its last flight ever, for the STS-133 mission. Launch is scheduled for Monday, Nov. 1 at 4:40 p.m. EDT from Launch Pad 39A. The faulty fuel line that threatened to delay the mission has been fixed, so everything is go for the oldest of the shuttle fleet’s final mission, a trip to the International Space Station to bring up Robonaut 2 and a new module. We’ll keep you posted for the latest on launch day.

Learn more about the mission from our previous preview articles here and here, or at NASA’s website.

NASA Administrator Charlie Bolden took a trip to China (link to NASA’s website) in hopes of encouraging future cooperation between our two nations, but not sure if it did much good. Besides upsetting people who think he should be concentrating on the issues at home at NASA (from NASAWatch), a news report just came out that China says they are considering their own manned space station by 2020. (PhysOrg)

A Progress resupply ship launched to the ISS just yesterday, Oct. 27, and will meet up with the ISS in 3 days. It is carrying 2 tons of food, fuel and supplies for the Expedition 25 crew, and should dock at the Pirs Docking Compartment on Oct. 30. Watch the video of the launch below.

And here’s a “trailer” about Robonaut 2:

Posted on by Nancy Atkinson

Podcast: More From Tony Colaprete on LCROSS

Artist concept of the Centaur and LCROSS heading towards the Moon. Credit: NASA

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I had the chance to interview LCROSS principal investigator Anthony Colaprete about the latest findings released from the lunar impact of the spacecraft a year ago, and in addition to the article we posted here on Universe Today, I also did a podcast for the NASA Lunar Science Institute. If you would like to actually “hear” from Colaprete, you can listen to the podcast on the NLSI website, or you can also find it on the 365 Days of Astronomy podcast.

Posted on by Nancy Atkinson

25% of Sun-Like Stars Could Host Earth-Sized Worlds

Artists impression of a distant solar system. Credit: ESO

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A five-year survey of nearby solar-mass stars has provided astronomers with an estimate of how many stars of this type could have Earth-size planets. Andrew Howard and Geoffrey Marcy from the University of California Berkeley studied 166 G and K stars within 80 light-years of Earth, determining the number, mass and orbital distance of any of the stars’ planets. Since Earth-sized worlds have not yet been found, they extrapolated the number of that size of planets, based on the fraction of stars that host Neptune to super-Earth sized planets. Their findings are encouraging, since it means planets the size of Neptune and smaller are probably much more common than gas-giant planets, like Jupiter. But what they found also conflict with current models of planet formation and migration.


“Of about 100 typical sun-like stars, one or two have planets the size of Jupiter, roughly six have a planet the size of Neptune, and about 12 have super-Earths between three and 10 Earth masses,” said Howard. “If we extrapolate down to Earth-size planets – between one-half and two times the mass of Earth – we predict that you’d find about 23 for every 100 stars.”

“This is the first estimate based on actual measurements of the fraction of stars that have Earth-size planets,” said Marcy. Previous studies have estimated the proportion of Jupiter and Saturn-size exoplanets, but never down to as small as this study, and the astronomers say this enabled them to estimate the Earth-size planets.

“What this means,” Howard added, “is that, as NASA develops new techniques over the next decade to find truly Earth-size planets, it won’t have to look too far.”

Using the 10-meter Keck telescopes in Hawaii, the astronomers measured the small wobble of each star from the tug of orbiting planets. For systems with multiple planets, teasing out the radial velocity signature of each planet is very complex, since each signature is extremely small. The more times a star is observed, the better the data. Current techniques allow detection of planets massive enough and near enough to their stars to cause a wobble of about 1 meter per second. That means they saw only massive, Jupiter-like gas giants up to three times the mass of Jupiter (1,000 times Earth’s mass) orbiting as far as one-quarter of an astronomical unit (AU) from the star, or smaller, closer super-Earths and Neptune-like planets (15-30 times the mass of the earth). An AU is 93 million miles, the average distance between the earth and the sun.

Histogram of stellar masses for Eta-Earth stars. Credit: Howard, et al.

Only 22 of the stars had detectable planets – 33 planets in all – within this range of masses and orbital distances. After accounting statistically for the fact that some stars were observed more often than others, the researchers estimated that about 1.6 percent of the sun-like stars in their sample had Jupiter-size planets and 12 percent had super-Earths (3-10 Earth masses). If the trend of increasing numbers of smaller planets continues, they concluded, 23 percent of the stars would have Earth-size planets.

Based on these statistics, Howard and Marcy, — who is also member of NASA’s Kepler mission to survey 156,000 faint stars in search of transiting planets — estimate that the telescope will detect 120-260 “plausibly terrestrial worlds” orbiting some 10,000 nearby G and K dwarf stars with orbital periods less than 50 days.

“One of astronomy’s goals is to find ‘eta-Earth,’ the fraction of sun-like stars that have an earth,” Howard said. “This is a first estimate, and the real number could be one in eight instead of one in four. But it’s not one in 100, which is glorious news.”

They were able to only detect close-in planets, so they say there could be even more Earth-size planets at greater distances, including within the habitable zone — or Goldilocks zone — located at a distance form the star where conditions are not too hot or too cold to allow the presence of liquid water.

But the researchers note that their results conflict with current models of planet formation and migration, where it is thought that nascent planets spiral inward towards the sun because of interactions with the gas in the disk. Such models predict a “planet desert” in the inner region of solar systems. But that’s where all the planets are being found.

“Just where we see the most planets, models predict we would find no cacti at all,” Marcy said. “These results will transform astronomers’ views of how planets form.”

Howard and Marcy report their results in the Oct. 29 issue of the journal Science.

Sources: UC Berkeley, Science

Posted on by Nancy Atkinson

New Water-Related Discovery from Hibernating Spirit Rover

A mosaic of images shows the soil in front of the Mars Exploration Rover Spirit. Bright-toned soil was freshly exposed by the rover's left-front wheel. The inset show a magnified view of the nearby rectangles within the mosaic, showing the differences between undisturbed and disturbed soil. Credit: NASA/JPL-Caltech/Cornell University

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She may be down, but she’s not out – out of the discovery department, anyway. Data from the Spirit Mars rover – currently in hibernation – shows evidence that water, perhaps as snow melt, trickled into the subsurface fairly recently and may be doing so on a continuing basis.

The area where Spirit became stuck in sandy soil in April of 2009 was churned up by her spinning wheels as engineers at the Jet Propulsion Laboratory attempted to drive her out of a veritable sand trap. This wheel-churning brought subsurface soil layers — which include the water soluble mineral ferric sulfate — up to the surface. Under a thin covering of windblown sand and dust, relatively insoluble minerals such as hematite, silica and gypsum are concentrated near the surface and more-soluble ferric sulfates have higher concentrations below that layer. This pattern suggests water has moved downward through the soil, dissolving and carrying the ferric sulfates.

In combination with another recent discovery — that underground aquifers may have fed ancient seas on Mars — shows a water cycle likely was present in the past on the Red Planet, and may even be present today.

The deputy principal investigator for the Spirit and Opportunity rover, Ray Arvidson and his team say that thin films of water may have entered the ground from frost or snow. (The Phoenix lander saw evidence of current snowfall.) The seepage could have happened during cyclical climate changes in periods when Mars tilted farther on its axis.

“The lack of exposures at the surface indicates the preferential dissolution of ferric sulfates must be a relatively recent and ongoing process since wind has been systematically stripping soil and altering landscapes in the region Spirit has been examining,” said Arvidson.

This isn’t the first time that Spirit’s wheels have churned up interesting stuff. Back in 2008, researchers said Spirit’s bum front wheel uncovered signs minerals that are found in hot springs, similar to what is at Yellowstone National Park on Earth, and similar hot springs may have once bubbled or steamed on Mars.

But there’s been no word from the rover since March 22, 2010, after she went into cold-induced hibernation. Because Spirit was stuck, the rover drivers could not get her in the best position to receive maximum sunlight.

“With insufficient solar energy during the winter, Spirit goes into a deep-sleep hibernation mode where all rover systems are turned off, including the radio and survival heaters,” said John Callas, project manager for Spirit and Opportunity. “All available solar array energy goes into charging the batteries and keeping the mission clock running.”

While she was stuck and still awake, researchers took advantage and examined in great detail soil layers the wheels had exposed, and also neighboring surfaces, making comparisons between the two. While trying to drive back out of her predicament, Spirit made 13 inches of progress in its last 10 backward drives before energy levels fell too low. Those drives exposed a new area of soil for possible examination if Spirit does awaken and if its robotic arm is still usable.

However, it is thought that the aging Spirit rover experienced the coldest temperatures ever, and it may not survive. Everyone is still holding out hope that the rover may yet make contact through one of the orbiting spacecraft and the Deep Space Network.

If Spirit does get back to work, the top priority is a multi-month study that can be done without driving the rover. The study would measure the rotation of Mars through the Doppler signature of the stationary rover’s radio signal with enough precision to gain new information about the planet’s core.

Meanwhile, over on the other side of Mars, the rover Opportunity has been making steady progress toward a large crater, Endeavour, which is now approximately 8 kilometers (5 miles) away.

The newest findings were published in the Journal of Geophysical Research.

Source: JPL