2013년 2월 28일 목요일

1st Photo of Alien Planet Forming Snapped by Telescope

Astronomers have captured what may be the first-ever direct photograph of an alien planet in the process of forming around a nearby star.
The picture, which captured a giant alien planet as it is coming together, was snapped by the European Southern Observatory's Very Large Telescope in Chile. It shows a faint blob embedded in a thick disk of gas and dust around the young star HD 100546. The object appears to be a baby gas giant planet, similar to Jupiter, forming from the disk's material, scientists say.
"So far, planet formation has mostly been a topic tackled by computer simulations," astronomer Sascha Quanz of ETH Zurich in Switzerland, leader of the research team, said in a statement. "If our discovery is indeed a forming planet, then for the first time scientists will be able to study the planet formation process and the interaction of a forming planet and its natal environment empirically at a very early stage."
The star HD 100546, which lies 335 light-years from Earth, was already thought to host another giant planet that orbits it about six times farther out than the Earth is from the sun. The new potential planet lies even farther, about 10 times the distance of its sibling, at roughly 70 times the stretch between the Earth and sun.

The possible planet seems to fit the picture scientists are building of how worlds form. Stars themselves are born in clouds of gas and dust, and after the form, a disk of leftover material often orbits them. From this disk, baby planets can take shape. That's what appears to be happening here.
For example, the new photo reveals structures in the disk surrounding the star that could be caused by interactions between its material and the forming planet. Furthermore, the data suggest the material around the planet-blob has been heated up, which is consistent with the planet-forming hypothesis.
The observations were made possible by the NACO adaptive optics instrument on the Very Large Telescope, which compensates for the blurring caused by Earth's atmosphere. The instrument also uses a special coronagraph that observes in near-infrared wavelengths to block out the bright light from the star, so as to see its surroundings better.
"Exoplanet research is one of the most exciting new frontiers in astronomy, and direct imaging of planets is still a new field, greatly benefiting from recent improvements in instruments and data analysis methods," said Adam Amara, another member of the team. "In this research we used data analysis techniques developed for cosmological research, showing that cross-fertilization of ideas between fields can lead to extraordinary progress."

Source of Article : space.com

Alien Life Could be Detectable on Planets Around Dying Stars

A white dwarf is a dead star that slowly cools down until it fades into oblivion. Yet it has been predicted that habitable planets can orbit a white dwarf. If we can somehow detect these planets, would we also be able to spot signs of life?
Scientists have created an artificial spectrum showing that the upcoming James Webb Space Telescope (JWST) will be capable of detecting oxygen and water on an Earth-like planet orbiting a white dwarf.
A white dwarf is the end stage of evolution of a low mass star, and it is tiny compared to its former self. The habitable zone around a white dwarf would therefore have once been located deep within the region of space the star once inhabited, requiring planets to migrate inwards to experience temperatures that are just right for surface liquid water. Infrared observations also have revealed disks of dust surrounding some white dwarfs, which could be the birthplace of a new generation of planets.
Searching for signs of life on a white dwarf exoplanet will involve inspecting the spectral fingerprint of the planet's atmosphere. Exoplanet atmospheres can be detected and analyzed during a planetary transit, when a planet passes in front of a star from our point of view, as the background starlight shines through the planet's atmosphere. Elements in the atmosphere will absorb some of the starlight, meaning that more light than normal will be blocked at the particular wavelengths associated with that element, giving us a spectrum of the planet.
This technique, called transmission spectroscopy, is difficult to utilize because the parent star is incredibly bright and thus washes out most of the planetary signal. However, if the host star is a white dwarf instead of a main sequence star, then the small stellar radius will result in a very prominent transit signal. The diameter of the average white dwarf is around 17,000 kilometers, which isn't much bigger than the Earth's diameter of 12,800 kilometers. Therefore, although white dwarfs are dim and hard to detect, it should still be possible to see the signal of an Earth-like planet transiting one.
A sign of life
Certain elements in a planet’s atmosphere may indicate the presence of life.  Such "biomakers" include oxygen and methane, gases that are produced by different forms of life on Earth and would quickly degrade if they weren’t constantly being generated.
Some of Earth's biomarkers are prominent in the infrared region of the spectrum, making JWST ideal to search for signs of life on other planets. The JWST, due to launch in a few years time, will be looking in the infrared part of the light spectrum, and it will be able to observe atmospheres on planets that are only a few times the mass of the Earth in the habitable zones of M-type stars (red stars that are cooler than our Sun). However, the total amount of observing time needed for this far exceeds that which is needed to observe planets around white dwarfs, since the planetary signal is much weaker for the brighter M-dwarfs.
Avi Loeb from Harvard University and Dan Maoz from Tel-Aviv University in Israel decided to test what kind of information they might be able to pry from the atmosphere of a planet orbiting a white dwarf by creating a simulated JWST spectrum. Their synthetic spectrum showed that the oxygen (O2) “A-band” should be easily visible, as well as signatures of water (H2O), assuming they exist on the planet.
"Detecting any of these biomarkers in the atmosphere of an Earth-copy planet around a nearby normal star, using JWST, will be extremely challenging, if not impossible," Maoz told Astrobiology Magazine. "The difficulty lies in the extreme faintness of the signal, which is hidden in the glare of the 'parent' star. The novelty of our idea is that, if the parent star is a white dwarf, that glare is greatly reduced, and one can now realistically contemplate seeing the O2 biomarker. Detecting other biomarkers will require future space telescopes that are even more ambitious than JWST."
A strong signature of oxygen in a planetary spectrum could indicate that life is present, since oxygen needs to be produced in vast quantities in order to counteract how easily it reacts with other substances. Biological processes are the main cause for high amounts of oxygen: the 21 percent of oxygen in the Earth's atmosphere is produced by photosynthesis in plants and algae. If life on Earth were suddenly to be extinguished, then all the oxygen would be removed in one or two million years as it combines with rocks and dissolves in the ocean.
The search for elusive planets
No planets have yet been detected orbiting a white dwarf, due to the difficulty in observing these faint stars, however there is some evidence to suggest that such planets might exist. White dwarfs should typically have a pristine spectrum of either hydrogen or helium, as any heavier elements will sink deep within the star. However, many white dwarfs show signs of pollution by heavy elements, possibly due to rocky material in circumstellar disks being perturbed inwards by unseen planets.
Some eclipsing binaries which contain a white dwarf have been observed to have unusual variations in the timing of the eclipses, which could indicate that a planet is present. Planets have also been discovered around pulsars, showing that it is possible for planets to orbit compact stellar remnants.
In order to detect Earth-like planets around white dwarfs, a survey will first need to be performed to select the brightest, nearest white dwarfs suitable for JWST observations. Many white dwarfs will need to be monitored in order to guarantee the best chance of detecting a planet. For instance, if a third of all white dwarfs host an Earth-mass planet within their habitable zones, then 500 white dwarfs would need to be monitored to discover just one transiting Earth.
"We expect to find maybe one or two Earth-like planets that transit white dwarfs, and are observable with JWST, *if* such planets at all exist around white dwarfs," said Maoz.
A survey searching for an O2 biomarker would probably benefit from focusing on white dwarfs that are over three billion years old. It took around two billion years for life on Earth to start producing significant amounts of O2, so neglecting young white dwarfs would turn the focus more on planets where life has had time to evolve. While this is obviously biased, scientists feel it makes more sense to invest limited observing time on the most likely candidates.
Although Earth-like planets are the most interesting targets from an astrobiology perspective, it turns out that they are also the optimum targets when one is looking to detect signs of life on white dwarf planets. A planet with a diameter similar to that of the Earth is just the right size for astronomers to be able to detect a good spectrum of the planet's atmosphere. If a planet is larger than the white dwarf, the probability of the planet's atmosphere transiting the star will be similar to that of an Earth-size planet. However, the greater surface gravity of the bigger planet will mean that the height of the atmosphere would likely be much lower, meaning less starlight passes through it, thus making it harder to detect.
The advantage to using JWST to observe exoplanetary atmospheres lies in the fact that, since it will be a space-based telescope, it will be liberated from the Earth's atmosphere. If an exoplanet atmosphere is very similar to the Earth's atmosphere, then a ground-based telescope will have great difficulty disentangling it from the Earth's atmospheric spectrum. (However, if the exoplanet atmosphere is vastly different, then it could be detected amid the Earth's own signal, and large ground-based telescopes could then help to provide measurements.)  As we move into the era of searching for biomarkers on extrasolar planets, Earth-like planets around white dwarfs may be the first alien worlds where we can detect such indications of life.

Source of Article : space.com

Black Hole's Mystery 'Wave' Surprises Scientists

Astronomers studying an unusual black hole system have spotted a never-before-seen structure in the disk of matter encircling the system.
Swift J1357.2, an X-ray binary system that regularly emits outbursts of high energy, consists of a black hole slowly consuming its companion star. Matter from the doomed star falls into the accretion disk, which surrounds the black hole, feeding it dust and gas.
While observing the system, a team of scientists noticed an unusual vertical feature traveling through the material.
"It's the first time we can resolve such [a] structure in an accretion disk, and it might be ubiquitous in X-ray binaries during the outburst state," Jesus Corral-Santana, of the Astrophysical Institute of the Canary Islands in Spain, told.
A hidden structure
The black hole contained in Swift J1357.2 is one of the millions of stellar black holes that dot the Milky Way galaxy.
About three times as massive as the sun, the behemoth likely formed when a single star collapsed inward on itself. The resulting, city-sized body packed a great deal of mass into a tiny package, creating a strong gravitational pull on nearby dust and gas.
Located in the Virgo constellation, approximately 4,900 light-years from Earth, Swift J1357.2 also contains a small companion star, which has only a quarter the mass of the sun. This companion star orbits the pair's center of mass every 2.8 hours, one of the shortest known orbital periods for such systems.
The black hole pulls material from the companion star into its accretion disk, occasionally emitting the X-ray bursts that enabled scientists to find this otherwise hard-to-spot system, researchers said.
Corral-Santana and his team took hundreds of optical images of the system using the Isaac Newton and the William Herschel Telescopes, both of which are in the Canary Islands. Studying the light produced by the accretion disk, the researchers noticed a periodic dimming in the system, sometimes occurring over the course of only a few seconds.
"Since the orbital period of the system is 2.8 hours, those dips cannot be produced by eclipses of the companion star. They are much faster," Corral-Santana said. "Therefore, they must be produced by a hidden structure placed very close to the black hole, in the inner accretion disk."
The new find can only been seen in the outer, optical portion of the accretion disk, not on the inside, where X-ray bursts originate. The X-ray emission, which shows no periodic variation, unlike its optical counterpart, indicated a vertical structure was hiding the black hole, Corral-Santana said.
Rather than appearing at a set, predictable time, the structure shows up over a steadily increasing period, indicating a wave-like movement through the accretion disk.
"It is a wave produced in the accretion disk, moving outward," Corral-Santana said, "like the wave produced when a stone is dropped in calm water."
he missing population
The wave-like feature also provides information about the orientation of the black hole.
Objects in space face Earth at a variety of angles, or inclinations. They can be seen edge-on, face-on or somewhere in between. Swift J1357.2 is the only one of 50 suspected similar black-hole systems found with an edge-on accretion disk — what scientists call a high inclination. However, astronomers think approximately 20 percent of these systems should provide such a perspective.
In order to see the wave-like structure in the accretion disk, scientists must have such an edge-on view of the disk, or one close to it. A view from a lower inclination, closer to face-on, would not reveal the sudden rises and falls in the total light coming from the system.
"Swift J1357.2 is the prototype of the hitherto missing population of high-inclination black holes in transient X-ray binaries," Corral-Santana said.
Because Swift J1357.2 is the first such system to allow such an edge-on view, the presence of the vertical structure takes on an added significance. No signs of such structures appear in other similar systems, but that could result simply from their unfortunate angles. Such structures could in fact exist in other, previously discovered transient X-ray binary systems, hidden only by their observational angles.

Source of Article : space.com

Private Mission to Mars in 2018: Who Should Go?

A new, privately funded campaign is on to launch a manned mission to fly by Mars in 2018. Of the numerous open questions about the voyage, one of the most pressing is, who should go?
Space tourist Dennis Tito announced the plans Wednesday (Feb. 27) during a press conference in Washington, D.C., at which he described a new nonprofit organization he founded, the Inspiration Mars Foundation, to plan the mission.
Tito envisions sending two crewmembers on a roughly 500-day trip to Mars and back. To combat the isolation and loneliness that could set in, the Inspiration Mars team hopes to recruit a married male-female couple to make the private Mars mission in 2018 together.
"It's important that this is a man and a woman because they represent humanity," said Jane Poynter, president and chairwoman of Paragon Space Development Corporation, and a member of the Inspiration Mars team. "After all, we are more or less 50 percent men and 50 percent women [on Earth]. It represents our children — whether they are a girl or a boy, they see themselves reflected in that crew."

Married couples
Poynter and her husband, Taber MacCallum, who is chief technology officer for Inspiration Mars, spent two years living inside the Biosphere 2 experiment, and learned the benefits of having a close companion to lean on.
"It was extremely helpful to have somebody that I could problem solve with," Poynter said. "It was also fantastic to have the opportunity to be there and share the experience when we had those wondrous moments."
Inspiration Mars plans to recruit highly qualified crewmembers with the technical background necessary to serve as space mechanics on all aspects of their vehicle, should it need repairs.
For their part, Poynter and MacCallum aren't just mission planners — they also plan to throw their hats in the ring as crew applicants.
Spartan conditions
The trip, which would capitalize on a rare planetary alignment that allows for a boomerang mission around the Red Planet much more quickly than normal trajectories, would largely use existing hardware, spacecraft and rockets, but with some modifications to support a crew for such an extended period.
Thus, whoever signs up for the trip will be in for some Spartan conditions.
"This going to be a very austere mission," MacCallum said, comparing the Mars voyagers to Lewis and Clark, blazing a trail through the unknown.
"It scares me a little bit," Poynter told. "I'd be lying if I said it didn't. But the opportunity to look back at the Earth from Mars — that's an experience not to miss."
The right stuff

Whoever undertakes the mission will need "the right stuff times 50," Tito said.
The successful applicants must be resilient, even-keel, and able to maintain a happy attitude in the face of adversity, Poynter said.
Despite the challenges, though, Inspiration Mars is expecting a flood of applications from people eager for the chance to make history by traveling farther into space than ever before.
The team's medical expert, Jonathan Clark of the Center for Space Medicine at Baylor College of Medicine, said the crewmembers must also be prepared to face some health challenges. In addition to the havoc that a year and a half of microgravity will weak on the human body, the Mars travelers will face a strong dose of radiation, which could elevate their risk for cancer by about three percent.
"The crew would know about it, they would have to decide, 'I realize that I'm going to have an excess cancer risk," Clark said. "Ultimately it's going to have to be those personal decisions."

Source of Article : space.com

NASA Discovers New Radiation Belt Around Earth

A ring of radiation previously unknown to science fleetingly surrounded Earth last year before being virtually annihilated by a powerful interplanetary shock wave, scientists say.
NASA's twin Van Allen space probes, which are studying the Earth's radiation belts, made the cosmic find. The surprising discovery — a new, albeit temporary, radiation belt around Earth — reveals how much remains unknown about outer space, even those regions closest to the planet, researchers added.
After humanity began exploring space, the first major find made there were the Van Allen radiation belts, zones of magnetically trapped, highly energetic charged particles first discovered in 1958.
"They were something we thought we mostly understood by now, the first discovery of the Space Age," said lead study author Daniel Baker, a space scientist at the University of Colorado.
These belts were believed to consist of two rings: an inner zone made up of both high-energy electrons and very energetic positive ions that remains stable in intensity over the course of years to decades; and an outer zone comprised mostly of high-energy electrons whose intensity swings over the course of hours to days depending primarily on the influence from the solar wind, the flood of radiation streaming from the sun.
The discovery of a temporary new radiation belt now has scientists reviewing the Van Allen radiation belt models to understand how it occurred.

Radiation rings around Earth
The giant amounts of radiation the Van Allen belts generate can pose serious risks for satellites. To learn more about them, NASA launched twin spacecraft, the Van Allen probes, in the summer of 2012.
The satellites were armed with a host of sensors to thoroughly analyze the plasma, energetic particles, magnetic fields and plasma waves in these belts with unprecedented sensitivity and resolution.
Unexpectedly, the probes revealed a new radiation belt surrounding Earth, a third one made of super-high-energy electrons embedded in the outer Van Allen belt about 11,900 to 13,900 miles (19,100 to 22,300 kilometers) above the planet's surface. This stable ring of space radiation apparently formed on Sept. 2  and lasted for more than four weeks.
"The feature was so surprising, I initially foolishly thought the instruments on the probes weren't working properly, but I soon realized the lab had built such wonderful instruments that there wasn't anything wrong with them, so what we saw must be true," Baker said.
This newfound radiation belt then abruptly and almost completely disappeared on Oct. 1. It was apparently disrupted by an interplanetary shock wave caused by a spike in solar wind speeds.
"More than five decades after the original discovery of these radiation belts, you can still find new unexpected things there," Baker said. "It's a delight to be able to find new things in an old domain. We now need to re-evaluate them thoroughly both theoretically and observationally."
A radiation mystery
It remains uncertain how this temporary radiation belt arose. Van Allen mission scientists suspect it was likely created by the solar wind tearing away the outer Van Allen belt.
"It looks like its existence may have been bookended by solar disturbances," Baker said.
Future study of the Van Allen belts can reveal if such temporary rings of radiation are common or rare.
"Do these occur frequently, or did we get lucky and see a very rare circumstance that happens only once in a while?" Baker said. "And what other unusual revelations might come now that we are really looking at these radiation belts with new, modern tools?"

Source of Article : space.com

2013년 2월 26일 화요일

Extraterrestrial Life May be Common Around Binary Stars

Planets orbiting binary star systems have to deal with the stresses of more than one star. But new research reveals that close binaries could be as good as singles when it comes to hosting habitable planets. Low-mass twins could make the best hosts, because their combined energy extends the habitable region farther away than would exist around a single star.
After modeling a variety of binary systems, two astronomers determined that stars 80 percent as massive as the Sun, if close enough together, could allow for conditions that would be ideal for hosting habitable planets.
"Potentially, life could exist even more in binary systems than it does in single systems," Joni Clark, an undergraduate at New Mexico State University, told Astrobiology Magazine. Clark worked with astrophysicist Paul Mason of the University of Texas at El Paso.
Pushing the boundaries
Low-mass stars are two to three times more common than the Sun. Their sheer numbers may give them greater odds for hosting planets. But their smaller size also means they have more ultraviolet radiation early in the life of the star and dangerous solar winds in the habitable zone, both important when it comes to maintaining a niche for life to exist. Planets must lie extremely close to small single stars to reap the benefits, a position that brings a number of challenges. Such planets are more prone to be tidally locked, with one face permanently turned toward its sun, and to receive the brunt of any stellar activity.

But when two such stars are closely paired, their combined energy extends the habitable region farther away and makes it larger, minimizing some of the threats faced by planets orbiting low-mass stars.
"We have much more room here for planets to hang out," Clark said.
Not just any binary system will work, however. Habitable zones receive the best effect when the low-mass stars are close together, circling each other every ten days or less. Radiation of all types coming from two such closely bound stars would be more consistent, and the planets orbiting them would resemble that of a planet orbiting a single star.
But when the stars are farther apart, the planet's orbit is more likely to be unstable as it feels the tug of gravity stronger from first one star and then the other. When stars are spread out over a distance, orbiting planets would experience significant changes in temperature. With a large enough gap, planets would travel around only one star, with the possibility of occasionally entering the danger zone of the other.
"There are many regions around binary star systems where having a stable orbit simply isn't possible," said Stephen Kane, of the California Institute of Technology. Kane, who studies the habitable zones of planets orbiting binary stars, was not involved in Clark and Mason's research.

Living conditions
Living conditions on the planets would vary based on cloud cover, which could help to both insulate the planet and shelter it from ultraviolet radiation. Such cloud cover could help to protect the planet from the changes it would encounter as it orbits closer first to one star and then to the other.
"How the temperature at the surface of the planet will vary depends on the properties of the atmosphere and its ability to absorb this flux and temperature variation," Kane said.
Clark and Mason simulated a number of close binary systems, calculating the temperatures and radiation that could exist for planets in orbit over the lifetime of the star. They presented their results at the American Astronomical Society meeting in January. After factoring in cloud cover and flux from the stars, they determined that the steadiest situations would come from binary twins, stars of approximately the same mass. Of these, a pair of stars 80 percent as massive as the Sun would hit what Clark called "the sweet spot," though a range of twins and other special combinations would also work well.

For close twin stars, "because they're similar masses and so close, it is very likely that they were, if you will, born at the same time," Clark said.
Such stars would have similar lifetimes, dying out in approximately the same time frame, but have a habitable zone 40 percent farther away than the single star counterparts.  In the case of the lower-mass stars, such periods could far supersede the Sun's lifetime, lasting as long as twenty billion years.
"Other groups have recently shown that planets close to stars of any type suffer water loss, like Venus, and atmosphere erosion, mostly early in the star’s life. These effects may occur even for planets with magnetic field protection," Mason said.  "The beauty of close binaries is that their habitable zones are located farther out."
Tatooine system
Kepler-47 provides a different system with fascinating properties. Instead of twins, the famous "Tatooine" system contains one star as massive as the Sun, and another only a third the size. A single planet orbits in the habitable zone, though it is too massive to be considered a good candidate for life. Eventually, the larger star will suffer the same fate as our Sun, swelling up into a massive red giant and changing the survivability for the planets orbiting the pair. The smaller star would live on, scant comfort for the planets that saw their habitable regions shift. Still, over the lifetime of the more massive star, the smaller star would provide extra light and heat that could be a bonus to potential life.
Because low-mass stars are so pervasive, and because most stars in the galaxy are locked in binary pairs, the chances of finding close, low-mass binaries is high, according to Clark and Mason. Though they caution that they haven't run the exact numbers, Mason says that such systems would be "not uncommon at all," potentially ranking such pairings as numerous as Sun-like single stars.
"I can imagine that a 0.8 solar mass binary, with a separation of less than a tenth of an astronomical unit [the distance from the Earth to the Sun], would have many possibilities of stable orbits within the habitable zone," Kane said.

Source of Article : space.com

NASA's Curiosity Rover Eats 1st Mars Rock Sample

NASA's Mars rover Curiosity has consumed its first samples from inside a Martian rock in order to analyze the chemistry and mineralogy of the Red Planet.
The Curiosity rover deposited the powder-like samples, drilled from the interior of the Mars rock "John Klein," into two onboard laboratories so they could be studied in detail, rover mission scientists said in a statement Monday (Feb. 25).
Curiosity's first Mars rock samples were placed inside the Chemistry and Mineralogy (or CheMin) instrument, as well as the rover's Sample Analysis at Mars instrument during a two-day operation on Friday and Saturday (Feb. 22 and 23).
"Data from the instruments have confirmed the deliveries," said Curiosity Mission Manager Jennifer Trosper of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif.

The small Mars laboratories are built into the body of the car-size Curiosity rover. They are two of 10 instruments built to determine if Mars is now, or ever has been, capable of supporting microbial life.
Curiosity used a percussive drill mounted on its robotic arm to dig into the Mars rock John Klein on Feb. 8, revealing a surprisingly gray-colored interior of the rock. The discovery is intriguing to Mars scientists because it suggests that the rusty reddish-orange color of Mars is only skin deep.
The gray-colored rock powder "may preserve some indication of what iron was doing in these samples without the effect of some later oxidative process that would've rusted the rocks into this orange color that is sort of typical of Mars," Joel Hurowitz, sampling system scientist for Curiosity at JPL, told reporters on Wednesday (Feb. 20).
NASA's $2.5 billion Mars rover Curiosity landed on the Red Planet on Aug. 5 to begin a two-year primary mission to study its landing site, the vast Gale Crater. The rover is currently studying the John Klein rock target as a pit stop on the way to a destination called Glenelg, which is near the base of a mountain that rises up 3 miles (5 kilometers) from the center of Gale Crater.

Source of Article : space.com

NASA Spacecraft Discovers Particle Accelerator at Saturn

NASA's Cassini spacecraft has spotted solar particles moving at incredible speeds near Saturn, giving scientists a rare up-close look at phenomena that occur during dramatic star explosions.
The particles flowed from the sun during a strong blast of solar wind, then plowed into Saturn's magnetic field shortly thereafter. This encounter, which Cassini observed in February 2007, created a shockwave that accelerated the particles to super-high energies, scientists said.
Similar shockwaves commonly form in the aftermath of massive star explosions called supernovas, ramping up nearby particles to nearly the speed of light. Researchers think supernova shockwaves are the primary source of cosmic rays, high-energy particles that pervade our Milky Way galaxy and slam into Earth's atmosphere continuously.
It can be tough to study distant supernovas and their shockwaves, so Cassini's observations provide a welcome proxy, scientists said.
"Cassini has essentially given us the capability of studying the nature of a supernova shock in situ in our own solar system, bridging the gap to distant high-energy astrophysical phenomena that are usually only studied remotely," Adam Masters, of the Institute of Space and Astronautical Science, Sagamihara, Japan, said in a statement.
Masters is lead author of a study reporting the Cassini findings, which was published this week in the journal Nature Physics.
The Saturn shockwave may be the most powerful ever detected at the ringed planet and suggests that certain kinds of shocks can be surprisingly efficient particle accelerators, researchers said.
The $3.2 billion Cassini mission is a joint effort of NASA, the European Space Agency and the Italian Space Agency. Cassini launched in 1997 and arrived at the Saturn system in 2004, delivering a lander called Huygens to the planet's huge moon Titan in January 2005.
Cassini will continue studying the ringed planet and its many moons for several years to come; Cassini's mission has been extended through at least 2017.

Source of Article : space.com

2013년 2월 25일 월요일

Asteroid-Smashing Mission Picks Space Rock Target

A mission that aims to slam a spacecraft into a near-Earth asteroid now officially has a target — a space rock called Didymos.
The joint European/U.S. Asteroid Impact and Deflection Assessment mission, or AIDA, will work to intercept Didymos in 2022, when the space rock is about 6.8 million miles (11 million kilometers) from Earth, European Space Agency officials announced Friday (Feb. 22).
Didymos is actually a binary system, in which a 2,625-foot-wide (800 meters) asteroid and a 490-foot (150 m) space rock orbit each other. Didymos poses no threat to Earth in the foreseeable future.

The proposed asteroid-smashing AIDA mission will send one small probe crashing into the smaller asteroid at about 14,000 mph (22,530 kph) while another spacecraft records the dramatic encounter. Meanwhile, Earth-based instruments will record so-called  "ground-truthing" observations.
The goal is to learn more about how humanity could ward off a potentially dangerous space rock. The necessity of developing a viable deflection strategy was underlined in many people's minds by the events of last Friday (Feb. 15), when the 130-foot (40 m) asteroid 2012 DA14 gave Earth a historically close shave just hours after a 55-foot (17 m) object exploded above the Russian city of Chelyabinsk, injuring 1,200 people and damaging thousands of buildings.

The AIDA impact will unleash about as much energy as that released when a big piece of space junk hits a satellite, researchers said, so the mission could also help improve models of space-debris collisions.
"The project has value in many areas, from applied science and exploration to asteroid resource utilization," Andy Cheng, AIDA lead at Johns Hopkins University's Applied Physics Laboratory, said in a statement.
The European Space Agency (ESA) has asked scientists around the world to propose experiments that AIDA could carry in space or that could increase its scientific return from the ground. Researchers have until March 15 to pitch their ideas.
Johns Hopkins’ Applied Physics Laboratory is providing AIDA's impactor, which is called DART (short for Double Asteroid Redirection Test). The observing spacecraft is known as AIM (Asteroid Impact Monitor) and will come from ESA.

Source of Article : space.com

Mars May Be Habitable Today, Scientists Say

While Mars was likely a more hospitable place in its wetter, warmer past, the Red Planet may still be capable of supporting microbial life today, some scientists say.
Ongoing research in Mars-like places such as Antarctica and Chile's Atacama Desert shows that microbes can eke out a living in extremely cold and dry environments, several researchers stressed at "The Present-Day Habitability of Mars" conference held here at the University of California Los Angeles this month.
And not all parts of the Red Planet's surface may be arid currently — at least not all the time. Evidence is building that liquid water might flow seasonally at some Martian sites, potentially providing a haven for life as we know it.

"We certainly can't rule out the possibility that it's habitable today," said Alfred McEwen of the University of Arizona, principal investigator for the HiRise camera aboard NASA's Mars Reconnaissance Orbiter spacecraft.
Surface water on Mars?
McEwen discussed some intriguing observations by HiRise, which suggest that briny water may flow down steep Martian slopes during the local spring and summer.
Sixteen such sites have been identified to date, mostly on the slopes of the huge Valles Marineris canyon complex, McEwen said. The tracks seem to repeat seasonally as the syrupy fluids descend along weather-worn pathways.
While the brines may originate underground, Caltech's Edwin Kite noted, there is an increasing suspicion that a process known as deliquescence — in which moisture present in the atmosphere is gathered by compounds on the ground, allowing it to become a liquid — may be responsible.
Astrobiologists are keen to learn more about these brines, for not much is known about them at the moment.
"Briny water on Mars may or may not be habitable to microbes, either from Earth or from Mars," McEwen said.

Hardy microbes
Martian life may be able to survive even in places where water doesn't seep and flow, some scientists stressed.
For example, microbes here on Earth make a living in the Atacama and the dry valleys of Antarctica, both of which are extremely cold and arid, said Chris McKay of NASA's Ames Research Center in Moffett Field, Calif.
Antarctic sites also receive seasonally high ultraviolet radiation doses thanks to a hole in the ozone layer that tends to develop every August through November. This provides yet another parallel to Mars, whose thin atmosphere and lack of a protective magnetic field make the planet more radiation-bombarded than Earth.
In the Antarctic dry valleys, McKay said, organisms dwell within rocks, just deep enough to be shielded from the worst of the UV but close enough to the surface to receive the benefits of photosynthesis. Something similar might be happening on Mars today, if life ever evolved there.
McKay also discussed deliquescence, which in the Atacama allows salts to gather enough water to support the existence of life.
McKay offered some advice to NASA's Mars rover Curiosity, which landed in August to determine whether Mars could ever have supported microbial life: "Watch for salt along the road!"
A possible energy source
A number of presenters spent some time talking about perchlorate, a chlorine-containing chemical that NASA's Phoenix lander spotted near the Martian north pole in 2008.
McKay and other researchers think perchlorate may be the reason that NASA's twin Viking landers didn't detect any organic compounds — the carbon-containing building blocks of life as we know it — on the Red Planet back in the 1970s.
The Vikings vaporized Martian soil and looked for any organics boiling off. They found nothing but a few chlorine compounds that were attributed to contamination. But after Phoenix's perchlorate find, McKay and some other researchers performed an experiment.
They added perchlorate to some desert dirt from Chile known to contain organics. They heated the soil up and found the same chlorine compounds the Vikings did, suggesting that organics may have been present in the Vikings' samples but were broken down by the combination of heat and perchlorate.
While this backstory is interesting in its own right, perchlorate is also relevant to the possible habitability of present-day Mars.
"Perchlorate, it turns out, is a potent chemoautotrophic energy source," said Carol Stoker, also of NASA Ames, noting that the chemical could potentially sustain microbes in the dark Martian subsurface, where photosynthesis is not an option.
And some Earth microbes use perchlorate for food, so that could be happening on Mars as well, scientists have pointed out.

Source of Article : space.com

'Vulcan' and 'Cerberus' Win Pluto Moon Naming Poll

The votes are in, and it looks like 'Vulcan' could be the new name for one of Pluto's smallest moons.
After weeks of online ballot casting by people around the world, the poll asking the public to name two of Pluto's moons — currently called P4 and P5 — ended today (Feb. 25).
As of 12 p.m. (1700 GMT), the polls closed with a total of 450,324 total votes cast since Feb. 11 with 'Vulcan,' a Pluto moon name proposed by Star Trek's William Shatner, is the clear winner.
"174,062 votes and Vulcan came out on top of the voting for the naming of Pluto's moons. Thank you to all who voted! MBB," wrote Shatner via Twitter.
Cerberus came in a clear second with nearly 100,000 votes.
Vulcan was a late addition to the Pluto moon name contenders, and pulled into the lead after Shatner, building on his Capt. James T. Kirk persona, plugged the name on Twitter. Vulcan, the home planet of Kirk's alien-human hybrid first officer Spock, is not just a fictional world in the Star Trek universe. It is also the name of the god of fire in Roman mythology, and officials at SETI added the sci-fi favorite to the ballot for that reason.
"Vulcan is the Roman god of lava and smoke, and the nephew of Pluto. (Any connection to the Star Trek TV series is purely coincidental, although we can be sure that Gene Roddenberry read the classics.)," wrote SETI scientist Mark Showalter in a blog officially adding the name to the list on Feb. 12. "Thanks to William Shatner for the suggestion!"

These votes don't necessarily mean that P4 and P5 will end up being called Vulcan and Cerberus, however. SETI is going to recommend the winning names to the International Astronomical Union — the organization responsible for naming the moons. The IAU will take the results into consideration, but ultimately they have final say over what the tiny moons are called.
Pluto has five moons  that astronomers currently know of. Scientists first caught sight of Pluto's largest moon Charon in 1978, but it was not until 2005 that astronomers discovered two other moons (Nix and Hydra) using the Hubble Space Telescope.
The moon P5 was discovered in 2012, also using the Hubble telescope. The moon P4 was discovered in 2011. Both P4 and P5 are only 15 to 20 miles (20 to 30 km) in diameter.

Source of Article : space.com

Ambitious Mission to Jupiter's Icy Moons Gets Science Instruments

An ambitious European mission that will launch a robotic probe to explore Jupiter's icy moons in 2022 has got its science gear.
The European Space Agency has picked 11 instruments for the planned JUpiter ICy moons Explorer, or JUICE, spacecraft. The mission is expected to reach Jupiter, the largest planet in the solar system, in 2030 and spend at least three years studying the gas giant's major moons Callisto, Europa, and Ganymede. The Jovian satellites are intriguing to scientists because they are thought to have vast oceans beneath their icy outer crust.
"Jupiter and its icy moons constitute a kind of mini-Solar System in their own right, offering European scientists and our international partners the chance to learn more about the formation of potentially habitable worlds around other stars," said Dmitrij Titov, JUICE study scientist for ESA, in a Feb. 21 statement.
The JUICE mission will observe Jupiter's atmosphere and magnetosphere, as well all four Galilean moons: Europa, Callisto, Ganymede and the volcanic Io. The spacecraft is expected to make 12 flybys of crater-covered Callisto, as well as two close passes of Europa in an attempt to gather the first-ever measurements of the thickness of that moon's frozen crust, ESA officials said.

The spacecraft will eventually end up orbiting Ganymede, the largest moon in our solar system, to study its surface and internal structure. Ganymede is also the only known moon in the solar system with its own magnetic field, and JUICE will closely observe the moon's interactions with Jupiter's magnetosphere, ESA officials said.
The collection of approved instruments to help scientists complete these tasks includes cameras, spectrometers, a laser altimeter and an ice-penetrating radar, as well as a magnetometer, plasma and particle monitors, and radio science hardware, ESA officials said. Teams from 15 European countries and the United States and Japan will develop the tools.
"The suite of instruments addresses all of the mission's science goals, from in-situ measurements of Jupiter's vast magnetic field and plasma environment, to remote observations of the surfaces and interiors of the three icy moons," Luigi Colangeli, coordinator of ESA's solar system missions, said in a statement.
NASA will provide one of the instruments on JUICE — a radar to peer deep inside Jupiter's icy moons — as well as the parts for two European instruments, the U.S. space agency said.
"NASA is thrilled to collaborate with ESA on this exciting mission to explore Jupiter and its icy moons," said John Grunsfeld, NASA's associate administrator for science in Washington, in a statement. "Working together with ESA and our other international partners is key to enabling future scientific progress in our quest to understand the cosmos."
While the JUICE mission will launch in 2022, NASA currently has another spacecraft en route to the giant planet. The Juno spacecraft launched in 2011 and is expected to arrive in orbit around Jupiter in July 2016 to study the planet's magnetic field and peer through its cloudy atmosphere.
JUICE and Juno are the first missions dedicated to Jupiter exploration since NASA's Galileo mission from 1989 to 2003.

Source of Article : space.com

2013년 2월 24일 일요일

Is Millionaire Space Tourist Planning Trip to Mars?

Buzz is building about a planned 2018 private mission to Mars, which may launch the first humans toward the Red Planet.
A nonprofit organization called the Inspiration Mars Foundation — which is led by millionaire Dennis Tito, the world's first space tourist— will hold a news conference on Feb. 27 to announce the 501-day roundtrip mission, which will aim for a January 2018 launch.
"This 'Mission for America' will generate new knowledge, experience and momentum for the next great era of space exploration," Inspiration Mars officials wrote in a media advisory yesterday (Feb. 20). "It is intended to encourage all Americans to believe again, in doing the hard things that make our nation great, while inspiring youth through Science, Technology, Engineering and Mathematics (STEM) education and motivation."
Tito made history in 2001, plunking down a reported $20 million for an eight-day trip to the International Space Station aboard a Russian Soyuz spacecraft.
Tito will participate in the Feb. 27 news conference. So will Taber MacCallum and Jane Poynter, CEO and president, respectively, of Paragon Space Development Corp., which has expertise in life-support systems; and space-medicine expert Jonathan Clark of the Baylor College of Medicine.
The speakers' backgrounds and the lofty goals articulated in the media advisory have led some people to speculate that Inspiration Mars is planning a manned mission to the Red Planet. And it looks like that may be the case, according to some media reports.
On March 3, Tito will give a talk called "Feasibility Analysis for a Manned Mars Free Return Mission in 2018" at an aerospace conference in Montana, the NewSpace Journal reported today (Feb. 21).
The NewSpace Journal says it obtained a copy of the paper Tito plans to present in Montana and gives a summary of its main thrust.
Tito's paper discusses "a crewed free-return Mars mission that would fly by Mars, but not go into orbit around the planet or land on it. This 501-day mission would launch in January 2018, using a modified SpaceX Dragon spacecraft launched on a Falcon Heavy rocket," the NewSpace Journal writes. "According to the paper, existing environmental control and life support system (ECLSS) technologies would allow such a spacecraft to support two people for the mission, although in Spartan condition."

The mission would be privately financed and cheaper than previous estimates for manned Mars efforts, the NewSpace Journal adds, though no overall cost is given.
The purported involvement of California-based SpaceX is not a huge surprise, as company founder Elon Musk has repeatedly stressed his desire to help humanity reach and eventually colonized Mars. Indeed, SpaceX has been developing a mission concept called "Red Dragon," which would use its Dragon capsule to send astronauts to the Red Planet.
A 501-day mission would pose potentially serious physiological and psychological issues for astronauts (standard stints aboard the space station are currently just six months).
Researchers have tried to understand the psychological and sociological effects of being isolated in cramped quarters for long stretches, notably during the Russia-based Mars500 mock mission, which wrapped up in November 2011. But the physiological effects may be tougher to simulate and mitigate, experts say.

Source of Article : space.com

2013년 2월 20일 수요일

Curiosity Rover to Eat Mars Rock Dust After Drilling Success

NASA's Mars rover Curiosity has beamed home photos confirming that it recovered samples from deep within a Red Planet rock, cementing the robot's place in exploration history.
The Curiosity rover drilled 2.5 inches (6.4 centimeters) into a Martian outcrop on Feb. 8, and today (Feb. 20) mission scientists first set eyes on images showing drill tailings sitting in Curiosity's scoop, waiting to be transferred to analytical instruments on the robot's body.
The photos confirm that Curiosity has pulled off an historic achievement, scientists said.
"This is the first time any robot, fixed or mobile, has drilled into a rock to collect a sample on Mars," Louise Jandura, sample system chief engineer for Curiosity at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., told reporters today.
"In fact, this is the first time any rover has drilled into a rock to collect a sample anywhere but on Earth," Jandura added. "In the five-decade history of the space age, this is indeed a rare event."

Breaking open a time capsule
Curiosity landed inside Mars' huge Gale Crater on the night of Aug. 5, kicking off a two-year prime mission to determine if the area has ever been capable of supporting microbial life.
Along with its 10 science instruments and 17 cameras, Curiosity's hammering drill is considered key to this quest, for it allows scientists to peer deep into Martian rocks for evidence of past habitability — something no other Red Planet robot has been able to do.
The arm-mounted drill "allows us to go beyond the surface layer of the rock, unlocking a kind of time capsule of evidence about the state of Mars going back three or four billion years," Jandura said.

The first drilling location is an intriguing time capsule indeed, scientists say. Curiosity bored into part of an outcrop called "John Klein," which is shot through with light-colored mineral veins and other evidence of long-ago exposure to liquid water.
"All of these features tell us that the rocks in this area have a really rich geological history, and they have the potential to give us information about multiple interactions between water and rock at this location," said JPL's Joel Hurowitz, sampling system scientist for Curiosity.
Mission scientists will learn more about that history when the drilled sample is transferred to two of Curiosity's key instruments, CheMin (short for Chemistry and Mineralogy) and SAM (Sample Analysis at Mars).
"That'll play out over the next few days here," said JPL's Daniel Limonadi, lead systems engineer for Curiosity's surface sampling and science system.
A few glitches
The recovered powder has already been used to clean out Curiosity's sample-handling system, to help ensure that the system is scrubbed free of potential contaminants from Earth. A minor software glitch has delayed the delivery of the sample to CheMin and SAM, but the team found a workaround, researchers said.
The Curiosity team has also become aware of another potential issue with the the sample-handling hardware. Engineers built two models of this hardware to run tests here on Earth, and the sieve — which screens out particles more than 0.006 inches (150 microns) wide — has begun to detach on one of them.
But this only happened after extensive use, and the sieve remained functional, rover team members said. And they stressed that there is no sign of any problem with the sample-handling gear Curiosity toted to Mars, though they'll take some measures to lessen the sieve's workload on the Red Planet (such as sieving samples for 20 minutes rather than 60 minutes, which Curiosity had done previously with soil samples).
"Based on the test results to date, and based on how we expect to use the hardware on Mars, we really have pretty good confidence that we're going to be able to use this hardware through the prime mission and beyond," Limonadi said.

Source of Article : space.com

Venus and Moon Rise Serenely Over India's Ganges River (Photo)

This stunning photo sequence shows the crescent moon and planet Venus  rising over India’s Ganges River.
Veteran astrophotographer Ajay Talwar of the photography group The World at Night captured this image from Uttarakhand, India in October 2012.
The sequence illustrates the path of the two celestial objects every few minutes over the sacred river. The Ganges is the national river of India and many regard its waters as deeply spiritual.