NASA lunar probes slated for New Year's arrival

In this Aug. 25, 2011 photo made available by NASA, technicians add a payload fairing to the Gravity Recovery And Interior Laboratory (GRAIL) booster at the Kennedy Space Center in Cape Canaveral, Fla.

In this undated image provided by NASA on Wednesday, Dec. 28, 2011, shows two sides of the moon. Twin NASA probes traveling for the past 3 1/2 months are scheduled to arrive at the moon during the New Year's weekend to study lunar gravity.

 This frame grab image from NASA-TV shows the twin GRAIL satellites atop a United Launch Alliance Delta II rocket as they clear the gantry after launch Saturday Sept. 10, 2011 from the launch pad at the Cape Canaveral Air Force Station after being scrubbed in Cape Canaveral, Fla., Thursday. NASA is sending the probes on a long, roundabout trip to the moon. The spacecraft will orbit the moon, chasing one another in circles so researchers can measure the gap and the gravity below. It will be the first lunar mission devoted to studying the insides of the moon. By measuring the entire gravity field of the moon, scientists hope to learn what the moon is made of all the way to its core.

 This undated artist rendering provided by NASA on Dec. 21,2011 shows the twin Grail spacecraft mapping the lunar gravity field. The two probes are scheduled to enter orbit around the moon over New Year's weekend.

 A Delta II rocket, the Gravity Recovery and Interior Laboratory (GRAIL) mission, sits on the launch pad at the Cape Canaveral Air Force Station after being scrubbed in Cape Canaveral, Fla., Thursday, Sept. 8, 2011. NASA will make another attempt to launch on Friday.

 This image provided by NASA shows NASA's GRAIL twin spacecraft await launch atop a United Launch Alliance Delta II rocket at Cape Canaveral Air Force Station, Fla. Thursday Evening Sept. 8, 2011

 Spectators wait on the pier at Jetty Park, in Cape Canaveral, Fla., moments before a Delta II rocket, the Gravity Recovery and Interior Laboratory (GRAIL) mission, was scrubbed because of weather, Thursday, Sept. 8, 2011. NASA will make another attempt to launch on Friday.

Images: AP

This framegrab image from NASA-TV shows the twin GRAIL satellites atop a United Launch Alliance Delta II rocket as they launch Saturday Sept. 10, 2011 from the launch pad at the Cape Canaveral Air Force Station after being scrubbed in Cape Canaveral, Fla., Thursday.

A spacecraft confirms the first alien world sitting in its star's "habitable zone"

NASA Telescope Confirms Alien Planet in Habitable Zone

MOUNTAIN VIEW, Calif. — NASA's planet-hunting Kepler spacecraft has confirmed the discovery of its first alien world in its host star's habitable zone — that just-right range of distances that could allow liquid water to exist — and found more than 1,000 new explanet candidates, researchers announced today (Dec. 5).

The new finds bring the Kepler space telescope's total haul to 2,326 potential planets in its first 16 months of operation.These discoveries, if confirmed, would quadruple the current tally of worlds known to exist beyond our solar system, which recently topped 700.

The potentially habitable alien world, a first for Kepler, orbits a star very much like our own sun. The discovery brings scientists one step closer to finding a planet like our own — one which could conceivably harbor life, scientists said.

"We're getting closer and closer to discovering the so-called 'Goldilocks planet,'" Pete Worden, director of NASA's Ames Research Center in Moffett Field, Calif., said during a press conference today. [Gallery: The Strangest Alien Planets]

The newfound planet in the habitable zone is called Kepler-22b. It is located about 600 light-years away, orbiting a sun-like star.

Kepler-22b's radius is 2.4 times that of Earth, and the two planets have roughly similar temperatures. If the greenhouse effect operates there similarly to how it does on Earth, the average surface temperature on Kepler-22b would be 72 degrees Fahrenheit (22 degrees Celsius). 

Hunting down alien planets

The $600 million Kepler observatory launched in March 2009 to hunt for Earth-size alien planets in the habitable zone of their parent stars, where liquid water, and perhaps even life, might be able to exist.

Kepler detects alien planets using what's called the "transit method." It searches for tiny, telltale dips in a star's brightness caused when a planet transits — or crosses in front of — the star from Earth's perspective, blocking a fraction of the star's light.

The finds graduate from "candidates" to full-fledged planets after follow-up observations confirm that they're not false alarms. This process, which is usually done with large, ground-based telescopes, can take about a year.

The Kepler team released data from its first 13 months of operation back in February, announcing that the instrument had detected 1,235 planet candidates, including 54 in the habitable zone and 68 that are roughly Earth-size.

Of the total 2,326 candidate planets that Kepler has found to date, 207 are approximately Earth-size. More of them, 680, are a bit larger than our planet, falling into the "super-Earth" category. The total number of candidate planets in the habitable zones of their stars is now 48.

To date, just over two dozen of these potential exoplanets have been confirmed, but Kepler scientists have estimated that at least 80 percent of the instrument's discoveries should end up being the real deal.

More discoveries to come

The newfound 1,094 planet candidates are the fruit of Kepler's labors during its first 16 months of science work, from May 2009 to September 2010. And they won't be the last of the prolific instrument's discoveries.

"This is a major milestone on the road to finding Earth's twin," Douglas Hudgins, Kepler program scientist at NASA headquarters in Washington, D.C., said in a statement.

Mission scientists still need to analyze data from the last two years and on into the future. Kepler will be making observations for a while yet to come; its nominal mission is set to end in November 2012, but the Kepler team is preparing a proposal to extend the instrument's operations for another year or more.

Kepler's finds should only get more exciting as time goes on, researchers say.

"We're pushing down to smaller planets and longer orbital periods," said Natalie Batalha, Kepler deputy science team lead at Ames.

To flag a potential planet, the instrument generally needs to witness three transits. Planets that make three transits in just a few months must be pretty close to their parent stars; as a result, many of the alien worlds Kepler spotted early on have been blisteringly hot places that aren't great candidates for harboring life as we know it.

Given more time, however, a wealth of more distantly orbiting — and perhaps more Earth-like — exoplanets should open up to Kepler. If intelligent aliens were studying our solar system with their own version of Kepler, after all, it would take them three years to detect our home planet.

"We are getting very close," Batalha said. "We are homing in on the truly Earth-size, habitable planets."

Washington: Forty thousand web users worldwide have been assisting astronomers analyze light from 150,000 stars in hopes of finding earth-like or exoplanets. Now the web users have discovered two such potential plants.

Citizen scientists, under the project Planet Hunters launched last December, analyzed real scientific data collected by NASA's Kepler mission. The mission has been searching for planets beyond our own solar system - called exoplanets, since its launch in March 2009.

The astronomers at the Yale University have announced the first two potential exoplanets discovered by Planet Hunters users, the journal Monthly Notices of the Royal Astronomical Society reports.

"This is the first time that the public has used data from a NASA space mission to detect possible planets orbiting other stars," said Yale astronomer Debra Fischer, who helped launch the Planet Hunters project.

The candidate planets orbit their host stars with periods ranging from 10 to 50 days - much shorter than the 365 days it takes the Earth to orbit the Sun - and have radii that range in size from two-and-a-half to eight times the Earth's radius, according to a NASA statement.

Despite those differences, one of the two candidates could be a rocky planet similar to the size of the Earth (as opposed to a giant gas planet like Jupiter), although they aren't in the so-called "habitable zone" where water and therefore life as we know it, could exist.

Next, the Planet Hunters team used the W.M. Keck Observatory in Hawaii to analyze the host stars.

"I think there's a 95 per cent chance or greater that these are bona fide planets," Fischer said.

"These. . . candidates might have gone undetected without Planet Hunters and its citizen scientists," said Meg Schwamb, Yale researcher and Planet Hunters co-founder.

"Obviously Planet Hunters doesn't replace the analysis being done by the Kepler team. But it has proven itself to be a valuable tool in the search for other worlds," added Schwamb.