Phoenix Takes Highest Resolution Image Ever of Dust and Sand on Mars

This mosaic of four side-by-side microscope images shows a 3 millimeter (0.12 inch) diameter silicone target after it has been exposed to dust kicked up by the landing. It is the highest resolution image of dust and sand ever acquired on Mars.

This mosaic of four side-by-side microscope images (one a color composite) was acquired by the Optical Microscope, a part of the Microscopy, Electrochemistry, and Conductivity Analyzer (MECA) instrument suite on NASA’s Phoenix Mars Lander.

Taken on the ninth Martian day of the mission, or Sol 9 (June 3, 2008), the image shows a 3 millimeter (0.12 inch) diameter silicone target after it has been exposed to dust kicked up by the landing. It is the highest resolution image of dust and sand ever acquired on Mars. The silicone substrate provides a sticky surface for holding the particles to be examined by the microscope.

The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

Newly discovered extrasolar planet is the smallest known and has smallest host star

Astronomers have discovered an extrasolar planet only three times more massive than our own, the smallest yet observed orbiting a normal star. The star itself is not large, perhaps as little as one twentieth the mass of our Sun, suggesting to the research team that relatively common low-mass stars may present good candidates for hosting Earth-like planets.

Led by David Bennett of the University of Notre Dame, the international research team presents its findings in a press conference Monday, June 2, 2008 at the American Astronomical Society Meeting in St. Louis, Mo.

“Our discovery indicates that that even the lowest mass stars can host planets,” says Bennett. “No planets have previously been found to orbit stars with masses less than about 20 percent that of the Sun, but this finding indicates that even the smallest stars can host planets.”

The astronomers used a technique called gravitational microlensing to find the planet, a method that can potentially find planets one-tenth the mass of our own.

The gravitational microlensing technique, which came from Einstein’s General Theory of Relativity, relies upon observations of stars that brighten when an object such as another star passes directly in front of them (relative to an observer, in this case on Earth). The gravity of the passing star acts as a lens, much like a giant magnifying glass. If a planet is orbiting the passing star, its presence is revealed in the way the background star brightens. A full explanation of the technique follows this release.

“This discovery demonstrates the sensitivity of the microlensing method for finding low-mass planets, and we are hoping to discover the first Earth-mass planet in the near future,” said Bennett.

Using standard nomenclature, the star hosting the newly discovered planet is dubbed MOA-2007-BLG-192L with MOA indicating the observatory, 2007 designating the year the microlensing event occurred, BLG standing for bulge, 192 indicating the 192nd microlensing observation by MOA in that year and the L indicating the lens star as opposed to the background star further in the distance. The planet maintains the name but adds a letter designating it as an additional object in the star’s solar system, so it is called MOA-2007-BLG-192Lb.

MOA-2007-BLG-192L resides 3,000 light years away and is classified as either a low-mass hydrogen burning star, one that sustains nuclear reactions in its core as our Sun does, or a brown dwarf, an object like a star yet without the mass to sustain nuclear reactions in its core. The researchers were unable to confirm which category the star fits into due to the nature of the observations and the margin of error.

With support from the National Science Foundation (NSF), Bennett has been one of the pioneers in using gravitational microlensing for detecting low mass planets. He has been working with collaborators around the world to find a number of planets that are ever closer in size to our own.

For the most recent discovery, the research collaborators took advantage of two international telescope collaborations: Microlensing Observations in Astrophysics (MOA), which includes Bennett, and the Optical Gravitational Lensing Experiment (OGLE).

Researchers in New Zealand made the initial measurements of the new planet and its star using the new MOA-II telescope at the Mt. John Observatory. The observatory’s MOA-cam3 camera, in one observation, can capture an image of the sky 13 times larger than the area of the full moon. Researchers in Chile made follow-up observations using high angular resolution adaptive optics images at the Very Large Telescope at the European Southern Observatory. Data from the observations was analyzed by scientists around the world hailing from five continents.

“This discovery is very exciting because it implies Earth-mass planets can form around low-mass stars, which are very common,” said Michael Briley, NSF astronomer and the officer who oversees Bennett’s grant. “It is another important step in the search for terrestrial planets in the habitable zones of other stars, and it would not have been possible without the international collaboration of professional and amateur astronomers devoted to measuring these signals.”

A paper describing this result has been accepted for publication in the Astrophysical Journal and is scheduled for publication in the Sept. 1 edition.

Ice Under Phoenix

Take a look at this image sent back from the Phoenix lander. On Friday, Phoenix scientist Ray Arvidson said there may be ice directly under the Phoenix lander, exposed in the blast zone by the retrorockets used for Phoenix’s soft landing. Friday’s image showed a small portion of the exposed area that looks brighter and smoother than the surrounding soil. On Saturday, Sol 5 for Phoenix on Mars, a new image shows a greater portion of the area under the lander. Scientists say the abundance of excavated smooth and level surfaces adds evidence to a hypothesis that the underlying material is an ice table covered by a thin blanket of soil. This is just what the Phoenix mission was hoping to find, and how incredible to land directly over your goal.

The bright-looking surface material in the center, where the image is partly overexposed, may not be inherently brighter than the foreground material in shadow. But the scientists are calling this area “Holy Cow.” Reportedly (via Emily at the Planetary Society) that’s exactly the phrase exclaimed when this image was returned. More pictures of this feature will be imaged using different exposures in an effort to determine if this really is ice.

The other interesting aspect of this image is that the retrorocket nozzles are visible right at the top of the image.

Mars lander prepares for 3-month digging mission

The one snag on the lander occurred when the protective sheath around the trench-digging robotic arm failed to unwrap all the way after touchdown and now covers the arm’s elbow joint.

Deputy project scientist Deborah Bass of NASA’s Jet Propulsion Laboratory said scientists still planned to start the process of unstowing the arm Tuesday, but it could take an extra day to fully stretch the arm.

“I would say this is an inconvenience,” Bass said.

Since landing on Mars on Sunday, Phoenix has delighted scientists with the first-ever peek of the planet’s unexplored northern latitudes. The terrain where Phoenix set its three legs is relatively flat with polygon-shaped patterns in the ground likely caused by the expansion and contraction of underground ice.

Phoenix is on a three-month mission to excavate the soil using its 8-foot-long robotic arm to reach the ice believed to be buried inches to a foot deep.

The lander will study whether the landing site could have supported primitive life. Among the things it will look for is whether the ice melted in Mars’ history and whether the soil samples contain traces of organic compounds, one of the building blocks of life.

On Monday, NASA released a black-and-white image captured during Phoenix’s descent by the Mars Reconnaissance Orbiter, which had a bird’s-eye view of the lander coming down on its parachute. It’s the first time a spacecraft had taken an image of another craft during landing.

Alfred McEwen of the University of Arizona’s Lunar and Planetary Laboratory said the camera aboard Reconnaissance Orbiter has taken many unique pictures of Mars, but “this one’s really unique.”

“It’s the first time any camera has imaged an actual descent through an atmosphere of another planet,” said McEwen, who operates the orbiter’s camera. “This will be on my Top Ten list.”

The $420 million Phoenix mission is led by University of Arizona, Tucson and managed by JPL.

Stephen Hawking calls for Moon and Mars colonies

Stephen Hawking called for a massive investment in establishing colonies on the Moon and Mars in a lecture in honour of NASA’s 50th anniversary. He argued that the world should devote about 10 times as much as NASA’s current budget – or 0.25% of the world’s financial resources – to space.

The renowned University of Cambridge physicist has previously spoken in favour of colonising space as an insurance policy against the possibility of humanity being wiped out by catastrophes like nuclear war and

climate change. He argues that humanity should eventually expand to other solar systems.

But in a speech in Washington, DC, US, delivered in honour of NASA’s 50th anniversary in 2008, Hawking

focused on near-term possibilities, backing the space agency’s goals of returning astronauts to the Moon by 2020 and sending humans to Mars soon after that.

The Moon is a good place to start because it is “close by and relatively easy to reach”, Hawking said. “The

Moon could be a base for travel to the rest of the solar system,” he added. Mars would be “the obvious next target”, with its abundant supplies of frozen water, and the tantalising possibility that life may have been present there in the past.

Some space experts have recently called for NASA to send astronauts to a near-Earth asteroid instead of the Moon as a next step.

Hawking did not mention the idea, but said that any long-term site for a human base should have a significant gravity field. That’s because long missions in microgravity lead to health issues such as bone loss.

Boldly go

He also called for an acceleration of NASA’s plans for human landings on Mars, which one NASA study suggested could be done in the early 2030s. “A goal of a base on the Moon by 2020 and of a manned landing on Mars by 2025 would reignite the space programme and give it a sense of purpose in the same way that President Kennedy’s Moon target did in the 1960s,” he said.

Hawking made a pitch for human space exploration, rather than just sending robots to explore space, a position taken by Nobel laureate Steven Weinberg, among others.

“Robotic missions are much cheaper and may provide more scientific information, but they don’t catch the public imagination in the same way, and they don’t spread the human race into space, which I’m arguing should be our long-term strategy,” Hawking said. “If the human race is to continue for another million years, we will have to boldly go where no one has gone before.”

Interstellar travel

Eventually, Hawking said, humanity should try to expand to Earth-like planets around other stars.

No such planets are known so far. But even if only 1% of the 1000 or so stars within 30 light years of Earth has an Earth-size planet at the right distance from its star for liquid water to exist, that would make for 10 such planets in our solar system’s neighbourhood, he said.

“We cannot envision visiting them with current technology, but we should make interstellar travel a long-term aim,” he said. “By long term, I mean over the next 200 to 500 years.”

Humanity can afford to battle earthly problems like climate change and still have plenty of resources left over for colonising space, he said.

Intelligent life

“Even if we were to increase the international [space exploration] budget 20 times to make a serious effort to go into space, it would only be a small fraction of world GDP,” he said. GDP, or Gross Domestic Product, is a measure of a country’s economic activity.

Hawking argued that the world can afford 0.25% of its collective GDP to devote to space colonisation. “Isn’t our future worth a quarter of a percent?” he asked.

The physicist also speculated on the reasons that SETI (Search for Extra-Terrestrial Intelligence) projects have not yet detected any alien civilisations.

He offered three possibilities: that life of any kind is very rare in the universe; that simple life forms are common, but intelligent life rare; or that intelligent life tends to quickly destroy itself.

“Personally, I favour the second possibility – that primitive life is relatively common, but that intelligent life is very rare,” he said. “Some would say it has yet to occur on Earth.”

Clay tablet holds clue to asteroid mystery

British scientists have deciphered a mysterious ancient clay tablet and believe they have solved a riddle over a giant asteroid impact more than 5,000 years ago.

Geologists have long puzzled over the shape of the land close to the town of Köfels in the Austrian Alps, but were unable to prove it had been caused by an asteroid.

Now researchers say their translation of symbols on a star map from an ancient civilisation includes notes on a mile-wide asteroid that later hit Earth – which could have caused tens of thousands of deaths.

The circular clay tablet was discovered 150 years ago by Sir Austen Henry Layard, a leading Victorian archaeologist, in the remains of the royal palace at Nineveh, capital of ancient Assyria, in what is now Iraq.

The tablet, on display at the British Museum, shows drawings of constellations and pictogram-based text known as cuneiform – used by the Sumerians, the earliest known civilisation in the world.

A historian from Azerbaijan, who believes humans originally came to Earth from another planet, has interpreted it as a description of the arrival of a spaceship. More mainstream academics have failed to decipher its meaning.

Now Alan Bond, the managing director of a space propulsion company, Reaction Engines, and Mark Hempsell, a senior lecturer in astronautics at Bristol University, have cracked the cuneiform code and used a computer programme that can reconstruct the night sky thousands of years ago to provide a new explanation.

They believe their calculations prove the tablet – a copy made by an Assyrian scribe around 700 BC – is a Sumerian astronomer’s notebook recording events in the sky on June 29, 3123 BC.

The pair say its symbols include a note of the trajectory of a large object travelling across the constellation of Pisces which, to within one degree, is consistent with an impact at Köfels.

Mr Hempsell said: “All previous work has drawn a blank on what the tablet is about.

 

“It is such a big jigsaw and the pieces we have found fit together so well that I think we have a definitive proof.”

The Köfels site was originally interpreted as an asteroid impact, however the lack of an obvious impact crater led modern geologists to believe it to be simply a giant landslide.

However, the Bond-Hempsell theory, outlined in their book published today, A Sumerian Observation of the Köfels Impact Event, suggests that the asteroid left no crater because it clipped a mountain and turned into a fireball.

Mr Hempsell said: “The ground heating, though very short, would be enough to ignite any flammable material, including human hair and clothes.

“It is probable more people died under the plume than in the Alps due to the impact blast.”

He added that extreme changes caused to rock and other substances at the site had previously led to the Köfels impact being erroneously dated to around 8,000 years ago.

Mixed signals from NASA about fate of Mars rover

NASA sent conflicting signals Monday evening about what an official told CNN is a planned $4 million budget cut in NASA’s Mars Exploration Rover program.

Initially the Rover program’s principle investigator, Steve Squyres, said one of two vehicles operating on the planet will be suspended because of the cut. He said he learned he would have to trim $4 million from the program’s $20 million budget.

He said the move would probably force the rover Spirit into hibernation.

But, he said, the rover could be reactivated if funding is later restored. Squyres also said the cuts would mean layoffs among a staff of 300 scientists who operate and analyze the rovers.

But shortly after CNN.com published the story, NASA administrator Michael Griffin said the agency will not shut down one of the two Mars rovers, according to spokesman Bob Jacobs.

“There is a process that has to be followed for any mission to be canceled and the cancellation of the Mars Exploration Rovers is not under consideration,” Jacobs said. “There is an ongoing budget review within the agency’s Mars exploration program. However, shutting down of one of the rovers is not an option.”

NASA headquarters spokesman Dwayne Brown confirmed the budget directive had been issued. The cut’s purpose is to offset cost overruns with the Mars Science Laboratory, a rover set to launch next year, he said.

Spirit was designed, along with its twin, Opportunity, to be a robotic geologist. The rovers have examined Martian rocks and soil, looking for telltale signs of water.

Opportunity hit pay dirt when it found evidence that salty sea once stood in the area now called Meridiani Planum.

NASA spent $800 million to build and launch Spirit and Opportunity to Mars. They landed about three weeks apart in January 2004, on opposite sides of the planet. Both were designed for 90-day missions but are still operating more than four years later.

Squyres also said he has been told to expect an $8 million budget cut in fiscal year 2009.

NASA cut means no roving for Mars rover

Scientists plan to put one of the twin Mars rovers to sleep and limit the activities of the other robot to fulfill a NASA order to cut $4 million from the program’s budget, mission team members said Monday.

The news comes amid belt-tightening at NASA headquarters, which is under pressure to juggle Mars exploration and projects to study the rest of the solar system.

The solar-powered rovers Spirit and Opportunity have dazzled scientists and the public with findings of geologic evidence that water once flowed at or near the surface of Mars long ago.

Both rovers were originally planned for three-month missions at a cost of $820 million, but are now in their fourth year of exploration. It costs NASA about $20 million annually to keep the rovers running.

Last week’s directive from NASA to cut $4 million means Spirit will be forced into hibernation in the coming weeks, said principal investigator Steve Squyres of Cornell University.

“It’s very demoralizing for the team,” Squyres said.

Spirit is parked on a sunny slope for the Martian winter and was going to gather atmospheric measurements before the budget cut. Instead, it will now stay in sleep mode for most of the winter and stop all science gathering.

The funding cut was announced in a letter delivered Wednesday to NASA’s Jet Propulsion Laboratory in Pasadena. JPL, which manages the rovers, plans to appeal the cut.

The cut comes at a time when the robots are in the midst of an extensive exploration campaign, said deputy principal investigator Ray Arvidson of Washington University in St. Louis.

“We’re not done. There is still a lot to explore,” Arvidson said.

Besides resting Spirit, scientists will also likely have to reduce exploration by Opportunity, which is probing a large crater near the equator. Instead of sending up commands to Opportunity every day to drive or explore a rock, its activities may be limited to every other day, said John Callas, the Mars Exploration Rover project manager at JPL.

“Any cut at any time when these rovers are healthy would be bad timing,” Callas said. “These rovers are still viable capable vehicles in very good health.”

Google Joins MIT in Search for Earth-like Planets

 

“When starships transporting colonists first depart the solar system, they may well be headed toward a TESS-discovered planet as their new home.”

George R. Ricker, senior research scientist at the Kavli Institute for Astrophysics and Space Research at MIT

Google has joined MIT scientists who are designing a satellite-based observatory -the Transiting Exoplanet Survey Satellite (TESS)- that they say could for the first time provide a sensitive survey of the entire sky to search for earth-like planets outside the solar system that appear to cross in front of bright stars. Google will fund development of the wide-field digital cameras needed for the satellite.

“Decades, or even centuries after the TESS survey is completed, the new planetary systems it discovers will continue to be studied because they are both nearby and bright,” says George Ricker,  leader of the project.

Most of the more than 200 extrasolar planets discovered so far have been much larger than Earth, similar in size to the solar system’s giant planets (ranging from Jupiter to Neptune), or even larger. But to search for planets where there’s a possibility of finding signs of living organisms, astronomers are much more interested in those that are similar to our own world.

Most searches so far depend on the gravitational attraction that planets exert on their stars in order to detect them, and therefore are best at finding large planets that orbit close to their stars. TESS, however, would search for stars whose orbits as seen from Earth carry them directly in front of the star, obscuring a tiny amount of starlight. Some ground-based searches have used this method and found about 20 planets so far, but a space-based search could detect much smaller, Earth-sized planets, as well as those with larger orbits.

This transit-detection method, by measuring the exact amount of light obscured by the planet, can pinpoint the planet’s size. When combined with spectroscopic follow-up observations, it can determine the planet’s temperature, probe the chemistry of its atmosphere, and perhaps even find signs of life, such as the presence of oxygen in the air.

The satellite will be equipped with six high-resolution, wide-field digital cameras, which are now under development. Two years after launch, the cameras–which have a total resolution of 192 megapixels–will cover the whole sky, getting precise brightness measurements of about two million stars in total.

Statistically, since the orientation of orbits is random, about one star out of a thousand will have its planets’ orbits oriented perpendicular to Earth so that the planets will regularly cross in front of it, which is called a planetary transit. So, out of the two million stars observed, the new observatory should be able to find more than a thousand planetary systems within two years.

In fact, if a new estimate based on recent observations of dusty disks is confirmed, there might even be up to 10 times as many such planets.

Because the satellite will be repeatedly taking detailed pictures of the entire sky, the amount of data collected will be enormous. As a result, only selected portions will actually be transmitted back to Earth. But the remaining data will be stored on the satellite for about three months, so if astronomers want to check images in response to an unexpected event, such as a gamma-ray burst or supernova explosion, “they can send us the coordinates [of that event] and we could send them the information,” Ricker says.

Because of the huge amount of data that will be generated by the satellite, which could launched as early as 2012, Google has an interest in working on the development of ways of process that data to find useful information.

Regardless of the funding for the satellite, the same wide-field cameras being developed for TESS could also be used for a planned ground-based search for dark matter in the universe–the invisible, unknown material that astronomers believe is more prevalent in space than the ordinary matter that we can see. Some of the unknown dark-matter particles must constantly be striking the Earth, and the plan is to train a bank of cameras inside tanks of fluid deep underground, to detect flashes of light produced by the impacts of these dark particles. Ricker’s Kavli group is participating with MIT physics professor Peter Fisher’s team in this new physics research initiative.

The electronic detectors for the new cameras are being developed in collaboration with MIT’s Lincoln Laboratory. The lab’s expertise in building large, highly sensitive detectors is a significant factor in making possible these unique cameras, which have no moving parts at all. If all goes well and funding is secured, the satellite could be launched in 2012 with NASA support, or even earlier with a private sponsor.

Nearest star’s wobbles could reveal Earth’s twin

Another Earth may be orbiting the star next door, and we could detect its presence within a few years, a new study argues. A telescope trained permanently on Alpha Centauri should be able to pick up the slight stellar wobbles induced by a small, rocky, Earth-like planet.

Alpha Centauri lies just over 4 light years away and is the closest star system to the Sun. It appears to be a triple system, with two Sun-like stars orbiting each other relatively closely (about 23 times the Earth-Sun distance). The two stars have high concentrations of heavy elements, which is characteristic of stars that are born surrounded by dusty, planet-forming discs.

Previous computer simulations suggested terrestrial planets probably formed around one or both stars. That is borne out by the work of Javiera Guedes at the University of California, Santa Cruz (UCSC), US, and colleagues, who have gone a step further and worked out how to detect such planets.

“If our understanding of terrestrial planet formation is at all correct, then there should definitely be terrestrial planets orbiting both members of the Alpha Centauri binary pair,” team member Greg Laughlin of UCSC told New Scientist.

What’s more, any such planets might boast the conditions thought to be necessary to support life. In the team’s simulations of planet formation around the smaller star, Alpha Centauri B, an Earth-like world often coalesced in or near the star’s habitable zone, where liquid water could exist on the planet’s surface.

Finding these planets could be time-consuming, but it does not require any new techniques, they say. They suggest using the “radial velocity” method, which looks for spectral signs that a star is wobbling due to gravitational tugs from an orbiting planet.

Calm atmosphere

The method has discovered most of the 228 known exoplanets. But until now, it has turned up only giant Jupiter-like planets, which produce relatively large wobbles in their host stars.

“Our aim is to find rocky planets by muscling up the same technique that has been so successful in finding more massive planets,” says team member Debra Fischer of San Francisco State University in California, US.

Laughlin realised that Alpha Centauri B was an exceptionally good target for this method, in part because it is a calm star. The atmospheres of most stars of its type churn more violently, which would obscure the slight movement caused by orbiting Earth-like planets.

And because it is so near to Earth, Alpha Centauri B is very bright. That means astronomers can rapidly capture a precise spectrum of its light, which is ideal for measuring small Doppler shifts due to terrestrial planets.

Faint signal

Even so, the researchers think they will need several years of data to smooth out random noise in their observations to be able to spot the faint signal of another Earth. That’s because a terrestrial planet would cause Alpha Centauri B to wobble at speeds of only about 10 centimetres per second.

Laughlin and his team will start to monitor Alpha Centauri in May, using a 1.5-metre telescope at the Cerro Tololo Inter-American Observatory in Chile. As well as searching for planets, their observations will be used to analyse the stars’ natural oscillations, which could reveal details about their internal structures.