Sunday 13 March, 2011

Japan megaquake, as I feel- Tokyo geophysicist's earthquake diary


When the earthquake struck at about 3:00 pm on Friday March 11 (Japan Standard Time), I was in my office on the 7th floor of the School of Science Building of the University of Tokyo, typing away on my notebook PC. Moderate-sized quakes are not uncommon in Tokyo, so I kept on typing for a while, ignoring the shaking.
However, as a seismologist, I immediately recognised that the amplitude of the seismic waves was large, but that the shaking was relatively long-period, with an almost complete absence of the sharp jolts that characterize nearby quakes. (This is because the earth gradually absorbs seismic waves as they travel, and shorter period waves are absorbed over a smaller distance range.) Because I could quickly identify this as a large, relatively distant quake, I didn't worry too much. Even so, as the shaking continued, I ducked under my desk for a while to guard against papers and books falling on my head from the cabinets behind me (in the event almost nothing fell out).
When the shaking stopped after a couple of minutes I got back to work, and when my students looked in to see if I was OK I told them, perhaps a bit too sharply, to get back to work. After a few minutes the safety office decided we should evacuate the building, and I complied (although I – correctly as it turned out -- didn't think this was necessary). Everyone climbed down the stairs, and after a half hour or so milling around we went back in and got back to work. We had to use the stairs, since the elevators were turned off as a safety measure.
Since the trains were stopped as a safety precaution, I walked home (55 min) rather than taking the subway (30 min, 7 of which on the train, the rest walking to and from the stations), which wasn't a problem as the weather was fair. When I got home I found no damage, but the gas had been automatically cut off by a quake detector. Pushing a button on the gas meter restored service.
The phone network was overwhelmed, but eventually (8 hrs after the quake) I got through to my wife and her mother and sister, who were on vacation at a hot spring resort in Northern Japan, and confirmed their safety. I was a bit luckier than most Tokyoites-many were stranded overnight at their workplaces, but even for them there was no danger, only a bit of bother. And now, 32 hrs after the quake as I write this, things in Tokyo are steadily getting back to normal.
Unfortunately, however, the situation is drastically worse in the hardest-hit areas. The TV news has been 100 per cent focused on the quake and the resulting damage. Truly horrific scenes of whole towns that have been almost completely destroyed by the quake and tsunami are replayed regularly. And many survivors, having lost all of their possessions, are taking refuge in temporary facilities under spartan conditions, without electric power or heat in many cases, although they do all seem to have food, water, and blankets.
A nuclear power plant in Fukushima has suffered severe damage and radioactivity has leaked out, with an evacuation of local residents within 20km of the plant having been ordered. The fully severity of the damage to the power plant is not yet clear from news reports.
In summary, many of the earthquake countermeasures taken by Japan have been successful, at least in part, but no conceivable economically realistic countermeasures could have precluded substantial damage from a magnitude 9.1 quake and the resulting tsunami. The immediate focus must now shift to rescue and rebuilding measures. Further down the road, lessons from the quake and its aftermath must be reflected in public policy. Not the least of these is that when we're thinking about future earthquakes we should, as noted by Hiroo Kanamori of Caltech, "expect the unexpected."

By- Robert Geller, University of Tokyo, Japan

Wednesday 9 February, 2011

Simulated Mars Mission Arrives in Simulated Orbit

Six men from Europe, Russia and China on a 520-day mock mission to Mars, have now reached the point in their mission where they have arrived ‘in orbit’ of Mars. Mars500, the first full-duration simulation, is like a real Mars mission, where the crew has been in isolation, living and working like astronauts, eating special food and exercising the same way as crews aboard the International Space Station, and even experiencing lag time in communications. Now after 244 days of virtual interplanetary flight, the crew is getting ready to ‘land’ on Mars on February 12 where they will make three EVAs onto simulated Martian terrain.
Mars500, a pioneering international study of the complex psychological and technical issues that must be tackled for long spaceflights, has been running for more than eight months in hermetically sealed modules imitating a Mars spacecraft at the Institute of Biomedical Problems (IBMP) in Moscow. Mars500 is not a just a flight of fancy or fantasy, but scientists from Russia and the European Space agency say it is a “pioneering international study of the complex psychological and technical issues that must be tackled for long spaceflights.”
The simulation has been running for more than eight months in hermetically sealed modules imitating a Mars spacecraft at the Institute of Biomedical Problems (IBMP) in Moscow.“Mars500 is a visionary experiment,” said Simonetta Di Pippo, ESA Director for Human Spaceflight. “Europe is getting ready to make a step further in space exploration: our technology and our science grow stronger every day. Mars 500 today is only an enriching simulation, but we are working to make it real.”
The crew has now opened a hatch between the mothership and the mockup of a lander that, according to script, was launched separately to Mars.In the coming days, the cargo inside the ‘lander’ will be transferred into the habitat and the lander will be prepared for ‘undocking’ and ‘landing’.
The crew will then divide: Russian Alexandr Smoleevskiy, Italian Diego Urbina and Chinese Wang Yue will enter the lander, while the rest of the crew, Romain Charles from France and Sukhrob Kamolov and Alexey Sitev from Russia ‘remain in orbit’.The hatch between the interplanetary spacecraft and lander will be closed on 8 February. The lander will undock and ‘touch down’ on Mars on 12 February.

Going out

The first sortie onto the simulated martian surface, housed in a large hall alongside the Mars500 modules, will happen on 14 February: Alexandr Smoleevskiy and Diego Urbina will don the modified Russian Orlan spacesuits and exit the lander’s airlock. The next sortie – by Smoleevskiy and Wang Yue – will take place on 18 February, and the last one – by Smoleevskiy and Urbina – is scheduled for 22 February.
On 23 February, the lander will be launched to ‘orbit’ and dock with the mothership on following day. The lander crew will stay in quarantine for three days before the hatch is opened on 27 February and the astronauts are reunited.

Return Journey

On 28 February the lander will be loaded with rubbish and unwanted items and the vehicle will be ‘abandoned’. This will happen 1 March, just before the spacecraft spirals away from Mars by virtually firing its engines. After that, the crew is faced with another monotonous ‘interplanetary cruise’ before arriving home in early November 2011.

Great rendezvous in Space on 14 Feb

"This is the first of many images to come of comet Tempel 1," said Joe Veverka, principal investigator of NASA's Stardust-NExT mission from Cornell University, Ithaca, N.Y. "Encountering something as small and fast as a comet in the vastness of space is always a challenge, but we are very pleased with how things are setting up for our Valentine's Day flyby."
NASA's comet mission spacecraft Stardust-NExT is fine-tuning its approach to an icy comet and has already snapped photos of it ahead of a planned Valentine's Day visit.The space agency's Stardust-Next mission is just one week away from zooming by the comet Tempel-1 Feb. 14 to see what's new since the comet was last visited by a spacecraft in July 2005. Comet Tempel 1 is a ball of ice and rock that orbits the sun every 5½ years.Scientists say the spacecraft is on track for next week's encounter after firing its thrusters last week to refine its path.
Stardust spacecraft marked its 12th anniversary in space on Monday, Feb. 7, with a rocket burn to further refine its path toward a Feb. 14 date with a comet. The half-minute trajectory correction maneuver, which adjusts the spacecraft's flight path, began at about 1 p.m. PST (4 p.m. EST) on Monday, Feb. 7. The 30-second-long firing of the spacecraft's rockets consumed about 69 grams (2.4 ounces) of fuel and changed the spacecraft's speed by 0.56 meters per second (1.3 mph).
NASA's plan for the Stardust-NExT mission is to fly the spacecraft to a point in space about 200 kilometers (124 miles) from comet Tempel 1 at the time of its closest approach. During the encounter, the spacecraft will take images of the surface of comet Tempel 1 to observe what changes have occurred since a NASA spacecraft last visited. (NASA's Deep Impact flew by Tempel 1 in July 2005).
Along with the high-resolution images of the comet's surface, Stardust-NExT will also measure the composition, size distribution and flux of dust emitted into the coma, and provide important new information about how comets evolve. Stardust was launched on Feb. 7, 1999. This current Stardust-NExT target is a bonus mission for the comet chaser, which flew past comet Wild 2 in 2004 and returned particles from its coma to Earth.
While its sample return capsule parachuted to Earth in January 2006, mission controllers were placing the still-viable spacecraft on a path that would allow NASA the opportunity to re-use the already-proven flight system if a target of opportunity presented itself. In January 2007, NASA re-christened the mission "Stardust-NExT" (New Exploration of Tempel), and the Stardust team began a four-and-a-half year journey for the spacecraft to comet Tempel 1. The spacecraft has traveled more than 35 billion miles since launch.

Thursday 3 February, 2011

The Second Earth !

The search for a second Earth has long enthralled readers of science fiction. What rich and varied life could it contain? What would such a discovery mean for humanity's own place in the Universe? How many similar planets are out there? The question is more than a philosophical puzzle, and it comes with a hard scientific edge that should be considered sooner rather than later. As the search for planets beyond the Solar System widens and public interest in the quest grows, at which point should astronomers declare the hunt for another Earth a success?

Hundreds of candidate planets have been identified, and some have been profiled, if not as a second Earth, then as signs that the search is heading in the right direction. Last month, NASA announced the discovery of the smallest extrasolar planet yet: Kepler-10b, which has 1.4 times the diameter and 4.6 times the mass of Earth, and was discovered by NASA's Kepler spacecraft. Although the planet orbits too close to its star to support life, the news was heralded by some media outlets as a landmark in the search for a new Earth, particularly because Kepler-10b is the first exoplanet with a dense and rocky core.
Attention on Kepler's mission will intensify again this week, as NASA publicly releases a batch of its data. The satellite focuses on a single point in the sky, where it can keep track of some 150,000 stars. Kepler observes the decrease in the brightness of these stars as planets pass in front of, or 'transit', them, and the findings are used to target telescopes on the ground.
It takes three to four such confirmed transits before astronomers are confident that they have found a planet, which makes it too soon to be sure whether Kepler has found a world truly similar to Earth. (By definition, Earth-like planets orbiting a star similar to the Sun pass in front of their stars about once a year, and Kepler has only been in place for about 18 months). All exoplanets confirmed to date orbit much closer to their stars than does Earth; they are too close for conditions to allow the existence of liquid water, which is what defines a star's 'habitable zone'.
As more data are analysed, they will probably produce a string of reports of ever-smaller planets, until we get an Earth-sized example. Many of these small planets are likely to orbit M-dwarfs, by far the most numerous type of star in the Universe. The habitable zone around these stars is very narrow, but Kepler may find a rocky planet there. Would that be the first Earth-like planet? Probably not if, as seems likely, it were to be tidally locked, so that one side faced permanently towards the star.
What about planets that orbit larger stars? Does a first Earth-like planet have to orbit in the habitable zone of a G2-type star, similar to the Sun? If so, must the planet be Earth-sized? And is the focus on a habitable zone defined in terms of liquid water appropriate? As the Universe reveals its secrets, we discover it to be a more diverse and stranger place than we had anticipated. Would it be so odd to conceive of life on a dry or frozen world? Must the first Earth-like planet be capable of supporting life, or human life in particular?
The answers to these questions are important because the public-relations rewards of planet-hunting — and planet-finding — are great. The temptation to hype each discovery is equally large, but so is the scope for confusion and public scorn, especially given the rabid response on some blogs to NASA announcements. Set the bar for 'Earth-like' planets too low, and a string of repeated discoveries could be overwhelming. Set the bar too high, and a planet that meets the strict criteria may not emerge at all. If that were to happen, the Kepler mission would risk being viewed as a failure — which it most certainly is not.
Amid the excitement of exploring a new frontier, astronomers should pause to consider the public reaction to their work. Then they should decide how a standard should be set. Perhaps a reasonable starting point would be to define an Earth-like planet as one of similar size to Earth, orbiting in the habitable zone of any star, and not tidally locked. More important than the details of the definition is that the relevant criteria are established before the claims start to pile up. To announce the discovery of the first Earth-like planet would be a stunning success. To announce it more than once could look like carelessness.

Hunting for Earth-like Alien Planets- Q & A with Astronomer Geoff Marcy

Since astronomers discovered the first planet beyond our own solar system back in 1992, they've been on somewhat of a roll — the tally now tops 500.And the finds are about to ramp up dramatically. NASA's planet-hunting Kepler mission will make much of its data public. A press conference will follow tomorrow, during which researchers are expected to announce intriguing new information about many more possible alien planets.Humanity thus appears poised to enter a productive new era in the study of alien worlds. One man leading the charge is Geoff Marcy, an astronomer at the University of California, Berkeley, and a Kepler co-investigator.
Marcy has had a hand in finding more alien planets than anyone else. He helped spot 70 of the first 100. He also found the first multi-planet system around a sun-like star, and he discovered the first planet that transits — or passes in front of — its star from our perspective on Earth.SPACE.com caught up with Marcy last month in Seattle, at the winter meeting of the American Astronomical Society, to chat about the accelerating pace of planet discovery, what we still don't know about alien worlds and whether there might be intelligent life elsewhere in the universe.
SPACE.com: What has led to the recent explosion in alien planet discoveries? Is it primarily better instrumentation, or better techniques?
Marcy: Well, let me give you a different vantage point. There is a bunch of astronomers who've been working really hard, and they're really innovative, pushing on the frontier technically, pushing on the frontier in terms of the science. And basically burning the midnight oil, essentially literally. I'm giving you the human component of all of this, because sometimes you don't get to see it.
What sometimes gets lost in the shuffle when a nice result shows up on all of the Web pages and the newspapers around the world — what you don't realize is to get that result meant that five or 10 people were burning that midnight oil, trimming the errors down to the point that the Earth-size planets are detectable.
It's easy to dismiss the discoveries as, "Oh, it's new computers, or it's new optics." These things happen because amazing people dream and then put their dreams into perspiration-dripping action.
SPACE.com: So if we were to have this conversation in 20 years, where do you think the total exoplanet count would stand?
Marcy: Honestly, Kepler's so good that it's hard to beat it. It gets the numbers. Kepler's going to find thousands. There's going to be another follow-up to Kepler, either from Europe or the U.S. or both. They'll find thousands. I bet by 2020, there'll be 10,000 planets, and by 2030 there might be another 20,000 or 30,000 more planets.
SPACE.com: Will this discovery arc we're on now continue to go up exponentially, or will it plateau?
Marcy: It'll plateau, because you can't do much better than Kepler. But let's be fair here. It's not the number of planets we care about; it's the quality. We want the Earth-size. We want planets in the habitable zone, and ultimately planets that are sending little radio signals to us for some reason or another.
SPACE.com: You've said that, with exoplanets, theory has really struck out. What are some of the things that we thought we knew, but it turns out were totally wrong about?
Marcy: Well, the first thing — I go back to 1996. No one wants to talk about this, because it's so embarrassing. The reason that as a community we struggled to find the first hot Jupiters isn't because we didn't have the technology. It's because the theorists led us astray. I'm speaking slightly jokingly, but not really.
There were theorists who said, "Look at our solar system. Of course the small, rocky planets are close in. The host star burned off the gases, so you're left with rocky planets. And look at the giant planets like Jupiter and Saturn — they had to form farther out, because it's colder, and the gases can gravitationally stick to the planets. Therefore, all planetary systems will have the following architecture: There will be an inner planet. The second planet out will be named Venus. The third planet out will have great lattes." I mean, it was just silly.
SPACE.com: And that's based on a sample size of one.
Marcy: It would be like trying to characterize human psychology by going to one distant Indonesian island and interviewing one person, and thinking that that gave you the full range of human psychology. And in 1996, there were papers where they said, Jupiter-sized planets, Saturn-sized planets, will all orbit far from their host star. Well, that of course tells you what to look for. If you write a proposal to try to find anything else, you're flying in the face of wisdom. And we know now, of course, how near-sighted that was, how parochial that was.
SPACE.com: So do you think we are starting to get a handle on exoplanets now?
Marcy: I think so. We're always a little too confident, so I would hate to say, "Go home, we're all done." We do have these planets we're finding with Doppler work, and now with Kepler, that are five times the size of Earth, three times the size of Earth, 1.4 times the size of the Earth. And I don't think we really know how they formed.
Even the one we announced [the rocky, nearly Earth-size Kepler-10b], there are two main ways it might've formed. It might've formed like the Earth, or it might have formed like Uranus but it got so close to the host star that the gases and the water got evaporated away and left a bare, rocky core remnant.
SPACE.com: What are some of the biggest mysteries that are left?
Marcy: There's one huge one that nobody really wants to talk about. It's the age-old question: Are Earth-like planets common? We know they're out there for sure. I mean, there's too many stars. But there's two parts to the question. What do you mean by "Earth-like?" And then, how common are they?
Basically, we know what we want for Earth-like, so we shouldn't beat around the bush: We would love to know whether there are planets suitable for life as we know it.
And those Earth-like properties are a little bit mysterious, but we have some ideas. You want water in liquid form, you want stable temperatures over the course of millions, preferably billions, of years so that Darwinian evolution can get a good toehold.
You probably want a moon to stabilize the spin axis. You probably want a Jupiter to sweep up the debris. You probably want a stable ocean for a long enough time that it can serve as the solvent for biochemistry.
So that's probably what we mean by "Earth-like." But how common they are, we just don't know.
SPACE.com: Your research suggests that smaller planets may be pretty common — that nearly one in four nearby sun-like stars could host a roughly Earth-size planet.
Marcy: Yeah. But here's the sleeper idea that no one wants to talk about: Because Earth-size planets are so much smaller than the Jupiters, Saturns, Uranuses and Neptunes, and we now know that planets often get thrust into eccentric and misaligned orbits, the Earths are like the Volkswagens on a highway full of 18-wheelers.
The vulnerable planets are the small ones. And so to the extent that planetary systems undergo a billiards era — the Earth would be like putting a small marble on a pool table of 15 billiard balls. As you break, the little planets are going to be the ones slingshot right out of the solar system pool table.
SPACE.com: It's one thing to say they can form. But to say that they'll actually stick around long enough — that's a totally different question.
Marcy: Yeah. And I think they'll form. It's hard to imagine they wouldn't. If you make Jupiters, why wouldn't you make Earth-size planets? But the Earths — and maybe the Volkswagen is giving it too much credit. It's an 18-wheeler and a tricycle. Earth is a tricycle on Highway 5 running up and down the Pacific Coast.
And you don't even have to hit the tricycle. You just have to come close enough that gravity slingshots the poor tricycle right out of the system. So it's possible that Earth-like planets form, they get thrown out into the cold darkness of the galaxy and they have no chance of starting — never mind sustaining — life, because it's too cold out there. And that's possible. We might be rare.
And by the way: Where are the SETI [search for extraterrestrial intelligence] signals? There is a non-detection that's like the elephant in the room. Forty years of Frank Drake and Carl Sagan looking for SETI signals, and we have precisely zero to show for it. So there's an indication — not definitive — that maybe the Earth is more precious than we had thought.
SPACE.com: Our solar system is so young, compared to the universe. And the universe is so big. So there's been lots of time and opportunity for advanced civilizations to get started, and to try to contact us. Some people think that the fact that we seemingly haven't been contacted means that we may well be alone in the universe.
Marcy: Well, you have to fold it in. The absence of an intelligent radio or television wave from any advanced civilization represents one indication, not a proof, that maybe habitable planets that sustain Darwinian evolution for a billion years —maybe they're rare. Maybe.
SPACE.com: What do you reckon? Do you have a gut feeling about this?
Marcy: I do. If I had to bet — and this is now beyond science — I would say that intelligent, technological critters are rare in the Milky Way galaxy. The evidence mounts. We Homo sapiens didn't arise until some quirk of environment on the East African savannah — so quirky that the hominid paleontologists still can't tell us why the australopithecines somehow evolved big brains and had dexterity that could play piano concertos, and things that make no real honest sense in terms of Darwinian evolution.
Why the high chaparral on the East African savannah would've led to a Tchaikovsky piano concerto, never mind the ability to build rocket ships — there's no evolutionary driver that the australopithecines suffered from that leads to rocket ships. And so that — and the fact that we had to wait four billion years without humans. Four billion years?
SPACE.com: Yes, it took four billion years to get there.
Marcy: Since the Cambrian explosion, we had hundreds of millions of years of multi-cellular, advanced life in which, guess what happened with brain size? Nothing.
You know the greatest species ever to roam the Earth? The dinosaurs — every kid knows this. And why? Well, because for 100 million years, the dinosaurs roamed the Earth. There were big ones, there were small ones. Every generation of baby dinosaurs had to outcompete all of the other dinosaurs. And you would think after 100 million years, each generation of baby dinosaur that was a little smarter would have out-survived the others and thereby slowly but surely increased dinosaur cranial size.
The reality from the paleontological record? Dinosaurs had the brains of chickens, and never got bigger. It shows that braininess is not a primary driver in evolution. We humans came across braininess because of something weird that happened on the East African savannah. And we can't imagine whether that's a common or rare thing.
SPACE.com: People assume evolution is directed, and it's always leading toward higher complexity and greater intelligence, but it's not.
Marcy: It's not. Dinosaurs show this in spades.
SPACE.com: You've said that we're about to enter a golden age of direct exoplanet imaging. Is that what the future holds — getting good, direct looks at alien planets to try to gauge their potential to support life?
Marcy: It is. There's two great things that we should be doing. One is that we should, as a species — and this means ESA [the European Space Agency], Japan, China, India, the United States, Canada — work together internationally to fund a space-borne telescope, probably interferometric, that can take pictures of Earth-size and Earth-like planets. We know how to do it.
Yes, it'll be expensive, but we do expensive things in science, and this is a great quest for humanity: Are there Earth-like and, indeed, habitable planets out there? But the other thing to do — we should say it right away. We should have a full-fledged, Apollo-like SETI search. Why haven't we coherently gathered our resources and done SETI right?
SPACE.com: Finding alien intelligent life would be such a huge deal. It would change the way we think about ourselves and our place in the universe.
Marcy: Exactly. So why aren't we putting together our resources, nationally and internationally, and constructing a major radio telescope facility — and maybe, if there's money left over, an infrared facility — and sampling the universe for signals?
We know what to look for. That would be the rat-a-tat-tat of a radio signal. We don't know exactly what the code would be, but we'd be looking for pulses in the radio, in the infrared maybe, in the X-ray or UV. We'd have to think broadly. But this is a great quest for humanity.
It's the Armstrong, it's the Columbus of our time, essentially reaching out with radio waves and hunting for alien intelligent life. It would be a marvelous, inspirational effort. And right now we don't have enough going on, in my opinion.
Because it would mean — all 7 billion people on planet Earth would get up in the morning wondering, "Did they find the signal last night?"
SPACE.com: It makes you wonder why nations haven't joined together to do something like this. Economically, it would be a drop in the bucket.
Marcy: It's a drop in the bucket. Frankly, $1 billion would be good. It sounds like $1 billion is a lot of money. But not really. NASA's budget is $19 billion. Nineteen billion dollars every single year. So how about a billion of that for a SETI search? How about one year — 5 percent — to do SETI in a historic, Apollo-like way? I mean, Wow!
It puts Armstrong and the invention of fire sort of on a par. So it's worth one-nineteenth of one year's NASA budget. I think it's a great idea, and we know how to do it.
Yeah, it's a luxury. We need to feed the people on the planet Earth, we need to provide health care, we need to provide better education, we need to make sure that human beings are living. But we're doing that. And a billion is really a teeny fraction of many countries' annual budget.

Courtesy - space.com

Good News from Keplar

Sitting for an interview in his office at the Harvard-Smithsonian Center for Astrophysics (CFA) in Cambridge, Massachusetts, the normally voluble astronomer Dimitar Sasselov looks nervous. Asked for his favourite among the many potential planets discovered by NASA's Kepler planet-finding mission, for which he is a co-investigator, he hesitates, then sidesteps the question entirely. "Personally, I'm already beyond that point. It's not one. It's not a single planet. It's a whole family."
NASA’s Kepler mission has discovered its first Earth-size planet candidates and its first candidates in the habitable zone, a region where liquid water could exist on a planet's surface. Five of the potential planets are near Earth-size and orbit in the habitable zone of smaller, cooler stars than our sun. Candidates require follow-up observations to verify they are actual planets. Kepler also found six confirmed planets orbiting a sun-like star, Kepler-11. This is the largest group of transiting planets orbiting a single star yet discovered outside our solar system.
Most of the Kepler scientists continue to be cautious. By watching the light from some 150,000 stars for the dimming that could signal a planet crossing in front of them, Kepler is extraordinarily efficient at finding possible planets. But Kepler has yet to find another Earth — a small, rocky planet with an orbit of a few hundred days and well inside the habitable zone in which water can exist and life can arise. That is for a fundamental reason; the blips that Kepler detects show only the radius, and not the mass, of an observed planet, which means that the density and composition generally remain unknown.
"In one generation we have gone from extraterrestrial planets being a mainstay of science fiction, to the present, where Kepler has helped turn science fiction into today's reality," said NASA Administrator Charles Bolden. "These discoveries underscore the importance of NASA's science missions, which consistently increase understanding of our place in the cosmos."
The discoveries are part of several hundred new planet candidates identified in new Kepler mission science data, released on Tuesday, Feb. 1. The findings increase the number of planet candidates identified by Kepler to-date to 1,235. Of these, 68 are approximately Earth-size; 288 are super-Earth-size; 662 are Neptune-size; 165 are the size of Jupiter and 19 are larger than Jupiter.
Of the 54 new planet candidates found in the habitable zone, five are near Earth-sized. The remaining 49 habitable zone candidates range from super-Earth size - up to twice the size of Earth - to larger than Jupiter.
The findings are based on the results of observations conducted May 12 to Sept. 17, 2009, of more than 156,000 stars in Kepler's field of view, which covers approximately one four-hundredth of the sky.
"The fact that we've found so many planet candidates in such a tiny fraction of the sky suggests there are countless planets orbiting sun-like stars in our galaxy," said William Borucki of NASA's Ames Research Center in Moffett Field, Calif., the mission's science principal investigator.
"We went from zero to 68 Earth-sized planet candidates and zero to 54 candidates in the habitable zone, some of which could have moons with liquid water." Among the stars with planetary candidates, 170 show evidence of multiple planetary candidates. Kepler-11, located approximately 2,000 light years from Earth, is the most tightly packed planetary system yet discovered.
All six of its confirmed planets have orbits smaller than Venus, and five of the six have orbits smaller than Mercury's. The only other star with more than one confirmed transiting planet is Kepler-9, which has three. The Kepler-11 findings will be published in the Feb. 3 issue of the journal Nature.
"Kepler-11 is a remarkable system whose architecture and dynamics provide clues about its formation," said Jack Lissauer, a planetary scientist and Kepler science team member at Ames.
"These six planets are mixtures of rock and gases, possibly including water. The rocky material accounts for most of the planets' mass, while the gas takes up most of their volume. By measuring the sizes and masses of the five inner planets, we determined they are among the lowest-mass confirmed planets beyond our solar system."
All of the planets orbiting Kepler-11 are larger than Earth, with the largest ones being comparable in size to Uranus and Neptune. The innermost planet, Kepler-11b, is 10 times closer to its star than Earth is to the sun.
Moving outward, the other planets are Kepler-11c, Kepler-11d, Kepler-11e, Kepler-11f, and the outermost planet, Kepler-11g, which is half as far from its star as Earth is from the sun.
The planets Kepler-11d, Kepler-11e and Kepler-11f have a significant amount of light gas, which indicates that they formed within a few million years of the system's formation.
"The historic milestones Kepler makes with each new discovery will determine the course of every exoplanet mission to follow," said Douglas Hudgins, Kepler program scientist at NASA Headquarters in Washington.
Kepler, a space telescope, looks for planet signatures by measuring tiny decreases in the brightness of stars caused by planets crossing in front of them. This is known as a transit. Since transits of planets in the habitable zone of sun-like stars occur about once a year and require three transits for verification, it is expected to take three years to locate and verify Earth-size planets orbiting sun-like stars.
The Kepler science team uses ground-based telescopes and NASA's Spitzer Space Telescope to review observations on planetary candidates and other objects of interest the spacecraft finds. The star field that Kepler observes in the constellations Cygnus and Lyra can only be seen from ground-based observatories in spring through early fall. The data from these other observations help determine which candidates can be validated as planets.

Friday 28 January, 2011

NASA's Hubble Finds Most Distant Galaxy Candidate Ever Seen in Universe


Astronomers have pushed NASA's Hubble Space Telescope to its limits by finding what is likely to be the most distant object ever seen in the universe. The object's light traveled 13.2 billion years to reach Hubble, roughly 150 million years longer than the previous record holder. The age of the universe is approximately 13.7 billion years.
The tiny, dim object is a compact galaxy of blue stars that existed 480 million years after the big bang. More than 100 such mini-galaxies would be needed to make up our Milky Way. The new research offers surprising evidence that the rate of star birth in the early universe grew dramatically, increasing by about a factor of 10 from 480 million years to 650 million years after the big bang.
"NASA continues to reach for new heights, and this latest Hubble discovery will deepen our understanding of the universe and benefit generations to come,” said NASA Administrator Charles Bolden, who was the pilot of the space shuttle mission that carried Hubble to orbit. “We could only dream when we launched Hubble more than 20 years ago that it would have the ability to make these types of groundbreaking discoveries and rewrite textbooks.”
Astronomers don't know exactly when the first stars appeared in the universe, but every step farther from Earth takes them deeper into the early formative years when stars and galaxies began to emerge in the aftermath of the big bang.
"These observations provide us with our best insights yet into the earlier primeval objects that have yet to be found," said Rychard Bouwens of the University of Leiden in the Netherlands. Bouwens and Illingworth report the discovery in the Jan. 27 issue of the British science journal Nature.
This observation was made with the Wide Field Camera 3 starting just a few months after it was installed in the observatory in May 2009, during the last NASA space shuttle servicing mission to Hubble. After more than a year of detailed observations and analysis, the object was positively identified in the camera's Hubble Ultra Deep Field-Infrared data taken in the late summers of 2009 and 2010.
The object appears as a faint dot of starlight in the Hubble exposures. It is too young and too small to have the familiar spiral shape that is characteristic of galaxies in the local universe. Although its individual stars can't be resolved by Hubble, the evidence suggests this is a compact galaxy of hot stars formed more than 100-to-200 million years earlier from gas trapped in a pocket of dark matter.
"We're peering into an era where big changes are afoot," said Garth Illingworth of the University of California at Santa Cruz. "The rapid rate at which the star birth is changing tells us if we go a little further back in time we're going to see even more dramatic changes, closer to when the first galaxies were just starting to form."
The proto-galaxy is only visible at the farthest infrared wavelengths observable by Hubble. Observations of earlier times, when the first stars and galaxies were forming, will require Hubble’s successor, the James Webb Space Telescope (JWST).
The hypothesized hierarchical growth of galaxies -- from stellar clumps to majestic spirals and ellipticals -- didn't become evident until the Hubble deep field exposures. The first 500 million years of the universe's existence, from a z of 1000 to 10, is the missing chapter in the hierarchical growth of galaxies. It's not clear how the universe assembled structure out of a darkening, cooling fireball of the big bang. As with a developing embryo, astronomers know there must have been an early period of rapid changes that would set the initial conditions to make the universe of galaxies what it is today.
"After 20 years of opening our eyes to the universe around us, Hubble continues to awe and surprise astronomers," said Jon Morse, NASA's Astrophysics Division director at the agency's headquarters in Washington. "It now offers a tantalizing look at the very edge of the known universe -- a frontier NASA strives to explore."
Hubble is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Md., manages the telescope. The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.