Posted on by Nancy Atkinson

How Old Am I? Star Cluster Perplexes Astronomers

Ever have one of those moments when you can’t remember how old you are? A group of astronomers may have felt they were having a “senior moment” when they couldn’t seem to figure out exactly the age of stars in the open star cluster NGC 6791, located in the constellation Lyra. Conventional thinking among astronomers is that stars in open clusters form at the same time, but in this particular cluster, researchers found stars at three different ages: one group of white dwarf stars appeared to be 4 billion years old, a second group of white dwarfs seemed to 6 billion years old, while the other regular stars were calculated to be 8 billion years of age. The astronomers say this dilemma may fundamentally challenge the way astronomers estimate cluster ages. Ivan King of the University of Washington and leader of the group using the Hubble Space Telescope to study this star cluster said: “This finding means that there is something about white dwarf evolution that we don’t understand.”

I just love it when astronomers say something like that, because it means they’ll return to their telescopes and the data in order to figure out the dilemma, and we’ll learn something new. And that’s just what they did. At least, partially.

“The age discrepancy is a problem because stars in an open cluster should be the same age. They form at the same time within a large cloud of interstellar dust and gas. So we were really puzzled about what was going on,” explained astronomer Luigi Bedin, who works at the Space Telescope Science Institute in Baltimore, Md.

After extensive analysis, members of the research team realized how the two groups of white dwarfs can look different and yet have the same age. It is possible that the younger- looking group consists of the same type of stars, but the stars are paired off in binary-star systems, where two stars orbit each other. Because of the cluster’s great distance, astronomers see the paired stars as a brighter single star.

Their brightness made them look younger.

Binary systems are also a significant fraction of the normal stellar population in NGC 6791, which contains over 10,000 stars, and are also observed in many other clusters. However, this would be the first time they have been found in a white-dwarf population.

“Our demonstration that binaries are the cause of the anomaly is an elegant resolution of a seemingly inexplicable enigma,” said team member Giampaolo Piotto the University of Padova in Italy.

Bedin and his colleagues are relieved that they now have only two ages to reconcile: an 8- billion-year age of the normal stellar population and a 6-billion-year age for the white dwarfs. All they need now is a process that slows down white-dwarf evolution.

Hubble’s Advanced Camera for Surveys analyzed the cooling rate of the entire population of white dwarfs in NGC 6791, from brightest to dimmest. White dwarfs are the smoldering embers of Sun-like stars that no longer generate nuclear energy and have burned out. Their hot remaining cores radiate heat for billions of years as they slowly fade into darkness. Astronomers have used white dwarfs as a reliable measure of the ages of star clusters, because they are the relics of the first cluster stars that exhausted their nuclear fuel.

White dwarfs have long been considered dependable because they cool down at a predictable rate. The older the dwarf, the cooler it is, making it a seemingly perfect clock that has been ticking for almost as long as the cluster has existed.

All right, astronomers, back to your telescopes to get this all figured out! And when they do, the rest of you can read about it on Universe Today. In the meantime, enjoy the lovely images above of star cluster NGC 6791.

News Source: Hubble press release

Posted on by Nancy Atkinson

One More Item Found in Astounding HiRise Image of Phoenix Descending

Remember the amazing image that the HiRISE Camera on the Mars Reconnaissance Orbiter captured of the Phoenix Lander as it descended to Mars’ surface via parachute back on May 25? Well, the HiRISE scientists have done a little more processing of the image, and have turned up an additional detail they didn’t see at first: Phoenix’s heat shield. The heat shield, which had been jettisons just after parachute deployment, can be seen falling toward the surface. You have to look really, really close to see it. But that’s what these HiRISE folks do. It was incredible that they found the lander with the parachute in the image (go see the big, huge image they had to hunt for it HERE) and these guys get the eagle eyes of the year award for finding the heat shield.

HiRISE made history by taking the first image of a spacecraft as it descended toward the surface of another planetary body. Here’s the image again:

The image shows NASA’s Phoenix Mars Lander when the spacecraft was still tucked inside its aeroshell, suspended from its parachute, at 4:36 p.m. Pacific Daylight Time on landing day. Although Phoenix appears to be descending into an impressive impact crater, it actually landed 20 kilometers, or 12 miles, away.

Mars Reconnaissance Orbiter was about 760 kilometers, or 475 miles, away when it pointed the HiRISE camera obliquely toward the descending Phoenix lander. The camera viewed through the hazy Martian atmosphere at an angle 26 degrees above the horizon when it took the image. The 10-meter, or 30-foot, wide parachute was fully inflated. Even the lines connecting the parachute and aeroshell are visible, appearing bright against the darker, but fully illuminated Martian surface.

In further analyzing the image, the HiRISE team discovered a small, dark dot located below the lander.
Phoenix was equipped with a heat shield that protected the lander from burning up when it entered Mars’ atmosphere and quickly decelerated because of friction. Phoenix discarded its heat shield after it deployed its parachute.

“Given the timing of the image and of the release of the heat shield, as well as the size and the darkness of the spot compared to any other dark spot in the vicinity, we conclude that HiRISE also captured Phoenix’s heat shield in freefall,” said HiRISE principal investigator Alfred McEwen.

The multigigabyte HiRISE image also includes a portion recorded by red, blue-green and infrared detectors, and scientists have processed that color part of the image.

HiRISE’s color bands missed the Phoenix spacecraft but do show frost or ice in the bowl of the relatively recent, 10-kilometer (6-mile) wide impact crater unofficially called “Heimdall.” The frost shows up as blue in the false-color HiRISE data, and is visible on the right wall within the crater.

The HiRISE camera doesn’t distinguish between carbon dioxide frost and water frost, but another instrument called CRISM on the Mars Reconnaissance Orbiter could.

News Source: SpaceRef

Posted on by Nancy Atkinson

The Sunny Side of Asteroids

Asteroids with moons, called binary asteroids, are fairly common in the solar system. But scientists haven’t been able to figure out the dynamics of these asteroids, especially how the moons form. But a group of astronomers studying binary asteroids say the surprising answer is sunlight, which can increase or decrease the spin rate of an asteroid. The researchers also say that since there are a number of “double craters” on Earth – side-by side craters that appear to have formed at about the same time — these binary asteroids may have hit our planet in the past. The image above is of twin circular lakes in Quebec, Canada, formed by the impact of an asteroidal pair which slammed into the planet approximately 290 million years ago. Similar double craters also can be found on other planets, as well.

Derek Richardson, of the University of Maryland, and Kevin Walsh and Patrick Michel at the Cote d’Azur Observatory, France outline a model showing that when solar energy “spins up” a “rubble pile” asteroid to a sufficiently fast rate, material is slung off from around the asteroid’s equator. This process also exposes fresh material at the poles of the asteroid.

If the spun off bits of asteroid rubble shed sufficient excess motion through collisions with each other, then the material coalesces into a satellite that continues to orbit its parent.

Link to an animated model of the spin-up and binary formation from two views, on the left is an overhead view. The right pane of the movie looks at the equator of the primary body, which is also the plane in which the asteroid’s satellite is formed (courtesy of the authors of the study).

Because the team’s model closely matches observations from binary asteroids, it neatly fills in missing pieces to a solar system puzzle. And, it could have much more down-to-earth implications as well. The model gives information on the shapes and structure of near-Earth binary asteroids that could be vital should such a pair need to be deflected away from a collision course with Earth.
The authors say that their current findings also suggest that a space mission to a binary asteroid could bring back material that might shed new light on the solar system’s early history. The oldest material in an asteroid should lie underneath its surface, explained Richardson, and the process of spinning off this surface material from the primary asteroid body to form its moon, or secondary body, should uncover the deeper older material.

“Thus a mission to collect and return a sample from the primary body of such a binary asteroid could give us information about the older, more pristine material inside an asteroid,” Richardson said.

Original News Source: PhysOrg

Posted on by Nancy Atkinson

Phoenix Relegated to Scraping the Sidewalk

If humans ever build a city on Mars, perhaps (in its retirement) the Phoenix Lander can apply for a job with the city’s public works department to scrape ice off sidewalks. Phoenix has been trying to dig down deeper into the “Snow White” trench and has been digging, scooping and scraping the ice layer that earlier soil scooping exposed. The robotic arm team is working to get an icy sample into the Robotic Arm scoop for delivery to the Thermal and Evolved Gas Analyzer (TEGA). Ray Arvidson of the Phoenix team, known as the “dig czar,” said the hard Martian surface that Phoenix has reached is proving to be a difficult target, and compared the process to scraping a sidewalk. “We have three tools on the scoop to help access ice and icy soil,” Arvidson said. “We can scoop material with the backhoe using the front titanium blade; we can scrape the surface with the tungsten carbide secondary blade on the bottom of the scoop; and we can use a high-speed rasp that comes out of a slot at the back of the scoop.”

“We expected ice and icy soil to be very strong because of the cold temperatures. It certainly looks like this is the case and we are getting ready to use the rasp to generate the fine icy soil and ice particles needed for delivery to TEGA,” he said.

Scraping action produced piles of scrapings at the bottom of a trench on Monday, but did not get the material into its scoop, evidenced from images returned to Earth by the lander. The piles of scrapings produced were smaller than previous piles dug by Phoenix, which made it difficult to collect the material into the Robotic Arm scoop.

“It’s like trying to pick up dust with a dustpan, but without a broom,” said Richard Volpe, an engineer from NASA’s Jet Propulsion Laboratory, Pasadena, Calif., on Phoenix’s Robotic Arm team.

The mission teams are now focusing on use of the motorized rasp within the Robotic Arm scoop to access the hard icy soil and ice deposits. They are conducting tests on Phoenix’s engineering model in the Payload Interoperability Testbed in Tucson to determine the optimum ways to rasp the hard surfaces and acquire the particulate material produced during the rasping. The testbed work and tests on Mars will help the team determine the best way to collect a sample of Martian ice for delivery to TEGA.

The Phoenix team also continues to analyze results from the Wet Chemistry Lab, as a sample was delivered to the lab on July 6. Results should be forthcoming.

News Source: Phoenix News

Posted on by Nancy Atkinson

Where In The Universe Challenge #11

Blue is my favorite color. Especially the shade of blue in the image for this week’s “Where In The Universe” challenge. It’s just such an uplifting color. But back to the challenge. The goal of this challenge is to test your skills and knowledge of our solar system. Guess where this image is from, and give yourself extra points if you can guess which spacecraft is responsible for the image. As always, don’t peek below before you make your guess. Comments on how you did are welcome.

Ready? Go!

This image was taken by the HiRISE Camera on the Mars Reconnaissance Orbiter. It shows the central uplift within an impact crater to the west of Nili Fossae on Mars. Planetary scientists love to see central uplifts, because they provide rare views of the rock types that exist miles beneath the modern-day surface of Mars. The impact process has shuffled different rock types into a disorganized array known as impact breccia.

This is an enhanced color image, to help discern between the different types of rock. Some of the materials that appear dark blue are probably patches of sand overlying the lighter-toned breccia.

Central uplifts are features that form on the floor of an impact crater shortly after the impact occurs. The crater’s central floor rebounds upward, forming a ring of hills and raising deeply buried rocks up to Martian surface. Infrared spectrometers such as THEMIS and CRISM have found that some of the rocks in this crater’s central uplift contain minerals that are intriguing and atypical for Mars, such as quartz, clays, and other water-bearing silicate minerals.

This image is just part of a larger swath taken by HiRISE. This portion of the image shows some of the central uplift rocks in fine detail. Blocks measuring from a few meters to over a hundred meters (10 to over 300 feet) across have coloration differences, suggesting that their compositions are different. Some of the largest blocks are internally layered, implying that they are blocks of sedimentary rock.

How did you do?

More about this image and to download a larger version in all its glory

Posted on by Nancy Atkinson

Wind Power From the Ocean (With Help from Space)

I drive regularly through Iowa and southern Minnesota in the US, and over the past few years wind farms have been popping up in that region up almost faster than corn grows. These massive wind turbines are awesome to see. But there may be an even better location for future wind farms than the breezy plains of the central United States: our oceans. Experts say ocean winds blow harder and with more reliable consistency than wind on land, which more than offsets the greater cost of building windmills offshore. Efforts to harness the energy potential of Earth’s ocean winds could soon gain an important new tool: global satellite maps from NASA. Scientists have been creating maps using nearly a decade of data from NASA’s QuikSCAT satellite that reveal ocean areas where winds could produce wind energy.

“Wind energy is environmentally friendly. After the initial energy investment to build and install wind turbines, you don’t burn fossil fuels that emit carbon,” said study lead author Tim Liu, a senior research scientist and QuikSCAT science team leader at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “Like solar power, wind energy is green energy.”

The new maps created by QuickSCAT have many potential uses including planning the location of offshore wind farms to convert wind energy into electric energy. Ocean wind farms have less environmental impact than onshore wind farms, whose noise tends to disturb sensitive wildlife in their immediate area.

QuikSCAT, launched in 1999, tracks the speed, direction and power of winds near the ocean surface. Data from QuikSCAT, collected continuously by a specialized microwave radar instrument named SeaWinds, also are used to predict storms and enhance the accuracy of weather forecasts.

Wind energy has the potential to provide 10 to 15 percent of future world energy requirements, according to Paul Dimotakis, chief technologist at JPL. If ocean areas with high winds were tapped for wind energy, they could potentially generate 500 to 800 watts of energy per square meter, according to Liu’s research. Dimotakis notes that while this is slightly less than solar energy (which generates about one kilowatt of energy per square meter), wind power can be converted to electricity more efficiently than solar energy and at a lower cost per watt of electricity produced.

The new QuikSCAT maps, which add to previous generations of QuikSCAT wind atlases, also will be beneficial to the shipping industry by highlighting areas of the ocean where high winds could be hazardous to ships, allowing them to steer clear of these areas.

Scientists use the QuikSCAT data to examine how ocean winds affect weather and climate, by driving ocean currents, mixing ocean waters, and affecting the carbon, heat and water interaction between the ocean and the atmosphere.

News Source: NASA

Posted on by Nancy Atkinson

Sun-like Stars May Have Low Probability of Forming Planets

This protoplanetary disk in the Orion Nebula has a mass more than one hundredth that of the sun, the minimum needed to form a Jupiter-sized planet. Image credit: Bally et al 2000/Hubble Space Telescope & Eisner et al 2008/CARMA, SMA)

The Orion Nebula shines brilliantly, as it is packed with over 1,000 young stars in a region just a few light-years wide. With all those stars, there’s probably the potential for thousands of planets to one day form from the dust and gas surrounding these stars, right? Actually, according to a new study, fewer than 10 percent of stars in the Orion Nebula have enough surrounding dust to make a planet the size of Jupiter. And that doesn’t bode well for the planet-forming abilities of most stars, at least in forming planets the size of Jupiter or larger. “We think that most stars in the galaxy are formed in dense, Orion-like regions, so this implies that systems like ours may be the exception rather than the rule,” said Joshua Eisner lead author of the study from the University of California Berkeley. This finding is also consistent with the results of current planet searches, which are finding that only about 6 percent of stars surveyed have planets the size of Jupiter or larger.

In the observations of Orion’s central region of more than 250 known stars, the findings showed that only about 10 percent emit the wavelength radiation typically emitted by a warm disk of dust, (1.3-millimeter). Even fewer – less than 8 percent of stars surveyed – were found to have dust disks with masses greater than one-hundredth the mass of the sun, which is thought to be the lower mass limit for the formation of Jupiter-sized planets. The average mass of a protoplanetary disk in the region was only one-thousandth of a solar mass, the researchers calculated.

The study was done using the Combined Array for Research in Millimeter Astronomy (CARMA) in California, and the Submillimeter Array (SMA) atop Mauna Kea in Hawaii. Both facilities observe at millimeter wavelengths, which is ideal for piercing the clouds of dust and gas surrounding young stars to see their dense, dusty disks.

Four billion years ago our own sun may have been in a dense, open cluster like Orion. Because open clusters like Orion eventually become gravitationally unbound, they disperse over the course of billions of years, and as a result, the sun’s birth neighbors are long gone.

Eisner said studying star clusters like the Orion Nebula Cluster “helps our understanding of the typical mode of star and planet formation.”

However, another survey of the Taurus cluster, which is a lower-density star-forming region showed that more than 20 percent of its stars have enough mass to form planets. The difference is probably related to the tightly packed, hot stars of the Orion cluster, said John Carpenter, colleague of Eisner’s in the study.

“Somehow, the Orion cluster environment is not conducive to forming high mass disks or having them survive long, presumably due to the ionization field from the hot, massive OB stars , which you might expect would photoevaporate dust and lead to small disk masses,” he said.

News Source: UC Berkley

Posted on by Nancy Atkinson

The Yin and Yang of the NeXT Spacecraft

Hard and soft. Dark and bright. High and low. Wide and thin. JAXA and NASA. And that’s just one spacecraft. Japan’s space agency, JAXA and NASA are teaming up to create a new spacecraft to study the extreme environments of the universe. NeXT, which stands for New exploration X-Ray Telescope is a next generation x-ray astronomy satellite currently under development, with launch scheduled in 2013. While Japan will provide the main spacecraft and several instruments, NASA, and in particular the Goddard Space Flight Center just announced they will be adding a new instrument to the spacecraft, the High-Resolution Soft X-Ray Spectrometer (SXS). While the spacecraft’s main instrument will be its Hard X-ray Telescope (HXTs) the addition of SXS is just one of several complementary instruments that provide a “yin and yang” aspect to NeXT’s explorations, which hope to reveal new facets of the universe.

The concept of yin and yang involves two opposing, but at the same time, complementary aspects of any one phenomenon, or comparison of any two phenomena. NeXT will employ both those aspects. With the addition of NASA’s SXS, NeXT will be observing both so-called “hard” and “soft” x-rays. Hard x-rays are the highest energy x-rays, typically having energies greater than 10,000 electron volts (or 10 keV) while the lower energy x-rays are referred to as soft x-rays, which have less energy and longer wavelengths. Different types of instruments are needed to detect each kind.

Conventional X-ray mirrors usually can just concentrate on only soft X-rays up to 10 keV. NeXT’s HXTs will use a “super mirror” which has a multi-layer coating on the reflecting surface in order to observe hard X-rays. The mission designers plan to utilize this technique to extend the energy band of the X-ray mirrors by nearly an order of magnitude. Observation of hard X-rays will enable the study of the various acceleration phenomena in the universe, such as dark energy, cosmic rays and supernova remnants, which astronomers say can never be completely understood through the observations of the thermal phenomena below 10 keV.

We have known for some time that cosmic X-rays are accelerated by supernova remnants. But some cosmic X-rays have energy levels so high that they cannot possibly come from a supernova remnant. These high-energy or hard cosmic X-rays may have been created when galaxy clusters evolved. According to this theory, when the galaxy clusters, which were small at first, were colliding and merging into large ones, shock waves were created, which greatly accelerated the particles. NeXT, may confirm or refute this theory.

NeXT will have both a soft x-ray telescope and soft x-ray spectrometer. With these instruments, the spacecraft can investigate the nature of dark matter on large scales in the universe, and can also explore how bright galaxies and clusters of galaxies form and evolve.

“We are thrilled to have the opportunity to create a powerful new x-ray spectrometer that will open up a whole new realm in high energy astrophysics in collaboration with our partners in Japan,” said Richard L. Kelley, the Principal Investigator for the SXS mission at Goddard. We have a great team in place that is anxiously waiting to start work.”

To compliment the x-ray telescopes there will also be Wide-band X-ray Imagers (WXI) to cover a wide energy range. Because it is difficult to cover such a wide energy range with a single detector, NeXT will use a hybrid detector, which consists of an upper-stage, soft X-ray detector and a lower-stage, hard X-ray detector. It will use thinned X-ray CCDs (charged coupled devices) for the upper stage, which stop only the soft X-rays and and a CdTe (cadmium telluride) pixel detector for the lower stage.

Also in the suite of instruments is a Soft Gamma-ray detector (SGD), which is still under development. It will include an ultra-low background, high-sensitivity detector in soft gamma-ray band by combining an active shield and an pixel detector.

Charles Gay, deputy associate administrator for NASA’s Science Mission Directorate in Washington said missions like SXS and NeXT “expand NASA’s science through partnerships with international and commercial organizations,” – just another complimentary aspect of a mission full of yin and yang.

Original News Source: NASA,

Posted on by Nancy Atkinson

Phoenix Brings New Sample to Wet Chemistry Lab

The Phoenix Mars Lander used its robotic arm to deliver a second sample of soil for analysis by the spacecraft’s wet chemistry laboratory. Data received from Phoenix on Sunday night confirmed the soil was in the lab’s cell number 1. This image taken by the the lander’s Surface Stereo Imager shows the Robotic Arm scoop positioned over the Wet Chemistry Lab Cell 1 delivery funnel on Sol 41, or July 6. Test results will be compared in coming days to the results from the first Martian soil analyzed by the wet chemistry laboratory two weeks ago. That laboratory is part of Phoenix’s Microscopy, Electrochemistry and Conductivity Analyzer.



On Monday, Phoenix also tested a method for scraping up a sample of icy material and getting it into the scoop at the end of the robotic arm. Photography before, during and after the process will allow evaluation of this method. If the test goes well, the science team plans to use this method for gathering the next sample to be delivered to Phoenix’s bake-and-sniff instrument, the Thermal and Evolved-Gas Analyzer (TEGA). The science team wants to be as precise and quick as possible in delivering the next sample to TEGA, as it possibly could be the last time the ovens can be used because of a short circuit that may occur the next time the oven is activated.

News Source: U of Arizona

Posted on by Nancy Atkinson

Exploding Asteroid Theory Gains Evidence

About 13,000 years ago, woolly mammoths roamed the North American continent and the first known human society in that region, known as the Clovis civilization, lived there as well. But geologic and archeological evidence shows they both suddenly disappeared, and scientists have long debated the mystery of the mass extinction of both animals and humans about 12,900 years ago. At that time, climatic history suggests the Ice Age should have been drawing to a close, but instead rapid climate change initiated an additional 1,300 years of glacial conditions. But scientists couldn’t agree on the cause of the sudden change in climate. However, about two years ago geophysicist Allen West proposed that an asteroid or comet exploded just above the earth’s surface at that time over modern-day Canada, sparking a massive shock wave and heat-generating event that set large parts of the northern hemisphere ablaze, setting the stage for the extinctions. Another scientist set out to prove West wrong, but ended up finding evidence to support the exploding asteroid/comet theory.

Ken Tankersley, Anthropology professor at the University of Cincinnati studied sites in Ohio and Indiana that offers the strongest support yet for the exploding comet/asteroid theory. Samples of diamonds, gold and silver found in the region have been conclusively sourced through X-ray diffractometry to have come from the diamond fields region of Canada.

Tankersley and West both believe the best scenario to explain the presence of these materials this far south is the kind of cataclysmic explosive event described by West’s theory. “We believe this is the strongest evidence yet indicating a comet impact in that time period,” says Tankersley.

Previously, geologists believed the deposits of the gems and precious metals were brought south from the Great Lakes region by glaciers. But they are found at a soil depth consistent with the time frame of the comet/asteroid event.

“My smoking gun to disprove (West) was going to be the gold, silver and diamonds,” Tankersley says. “But what I didn’t know at that point was a conclusion he had reached that he had not yet made public – that the likely point of impact for the comet wasn’t just anywhere over Canada, but located over Canada’s diamond-bearing fields. Instead of becoming the basis for rejecting his hypothesis, these items became the very best evidence to support it.”

Additional work is being done at the sites looking for iridium, micro-meteorites and nano-diamonds that bear the markers of the diamond-field region, which also should have been blasted by the impact into this region.

As Tankersley, West and additional scientists compile more data, they’ll be looking for more clues to help explain the history of our planet and its climate.

“The kind of evidence we are finding does suggest that climate change at the end of the last Ice Age was the result of a catastrophic event,” Tankersley says. “The ultimate importance of this kind of work is showing that we can’t control everything,” he says. “Our planet has been hit by asteroids many times throughout its history, and when that happens, it does produce climate change.”

Original Source: Science Daily