2013년 12월 27일 금요일

Scientists Petition U.S. Congress for Return to the Moon

China’s Chang’e 3 robotic landing on the moon has helped spur a political crusade in the United States to more aggressively explore and utilize the moon.

At the heart of the campaign is the Lunar Exploration Analysis Group (LEAG), a group chartered by NASA Headquarters to assist in planning the scientific exploration of the moon.  LEAG is organizing a letter writing campaign to Congress to underscore the importance of the moon.

The LEAG scripted strategy is being orchestrated under the banner “Destination Moon” with a key, straightforward goal highlighted in a flyer: “Use the moon to create a sustained human space-faring capability, advancing exploration of the Solar System.”

The flyer is to be sent, along with a cover letter, to all members of the U.S. House of Representatives and Senate committees that have influence on NASA funding, and to all the lawmakers of the LEAG executive committee members.

Gateway to the solar system

“We were waiting to see if Chang’e 3 landed successfully and it did! Now we want to champion the moon from the U.S. side,” Clive Neal, a leading lunar scientist at the University of Notre Dame’s Department of Civil and Environmental Engineering and Earth Sciences told SPACE.com. He is a member of LEAG’s executive committee.

The Destination Moon movement is predicated on the value of exploring the moon, from opening the gateway to the solar system, pioneering development of new technologies, as well as advancing economic expansion, enabling new scientific discoveries and promoting international partnerships.

“The moon is the most accessible destination for realizing commercial, exploration, and scientific objectives beyond low Earth orbit,” the flyer reads.

Destination Moon supporters are rallying around other key points:
  • Lunar resources can be used for fuel and life support for operations in Earth-moon space as well as for voyages to Mars and beyond.
  • America can still lead the world beyond low Earth orbit by forging collaborations to make the frontier of space accessible to all.
  • Scientific investigations on the surface of the moon uniquely support studies of early Solar System events that have been erased from Earth’s record.
Nearest near-Earth object

Stephen Mackwell, director of the Lunar and Planetary Institute in Houston, advocates a return to the moon.

“The brief Apollo missions were terminated before we could start investigating the requirements for longer term missions away from Earth,” Mackwell told SPACE.com.

“Before we set off to distant destinations, like Mars, it makes sense to use our nearest near-Earth object — the moon — as a test-bed to see how humans will cope with longer duration periods distant from Earth, including on the surface of another planetary body, and how effectively we can make use of in-situ resources to sustain our presence elsewhere,” Mackwell said.

Political boost

Independent of the LEAG letter writing campaign, a U.S. return to the moon is getting a political boost from Rep. Frank Wolf (R-VA).

In a Dec. 19 letter to President Barack Obama, the lawmaker calls on the president to hold a White House conference early in 2014 to develop a mission concept for a U.S.-led return to the moon within the next 10 years. The conference would bring together “the best minds from around the country and among our international partners” to forge the initiative, Wolf said.

“As China prepares to send a series of increasingly advanced rovers to the moon in preparation for what most observers believe will ultimately be human missions, many are asking why the U.S. is not using this opportunity to lead our international partners in an American-led return to the moon,” Wolf said.

Wolf’s letter said that the Obama administration’s “recalcitrance in leading a lunar mission is creating a crisis of confidence in the U.S. space program, both at home but also among our partners, including Europe, Canada, Japan and Russia.”

In his three-page letter, Wolf urges Obama to direct the U.S. space program toward a “lunar-focused human exploration program that will reaffirm America's space leadership for the 21st Century.”

Lunar development

How United States politics and China’s moon landing of Chang’e 3 play together is far from clear, said Mike Gold, director of Wash., D.C. Operations and Business Growth for Bigelow Aerospace, a private space firm eager to kick up its own commercial lunar dust.

“The success of this mission was yet another victory for long-term Chinese aerospace planning, progress, and execution,” Gold said. “Chinese leadership clearly understands the importance and potential benefits of lunar activities and we here at home ignore the moon at our own peril.”

Gold told SPACE.com that it’s not a matter of if the moon will be utilized for commercial activities, it’s a matter of when and who will enjoy those benefits.

“The moon represents an unparalleled commercial opportunity, and Congress should be looking for ways to expand commercial space operations beyond low-Earth orbit," Gold said. "I hope Chang’e 3 inspires a renewed effort for commercial lunar development but I’m afraid the lack of reaction in Washington speaks volumes."

By: Leonard David, SPACE.com’s Space Insider Columnist 
Source of Article: Space.com

2013년 12월 20일 금요일

Weight of the World: New Technique Could Weigh Alien Planets

A new way to weigh the mass of distant alien worlds could help reveal key details about how friendly they may be to life, scientists say.

In the past two decades, astronomers have confirmed the existence of more than 900 planets outside the solar system and discovered more than 2,300 potential worlds. Now, instead of just detecting these exoplanets, scientists want to analyze them in detail, helping answer questions such as whether they are potentially habitable.

Knowing the mass of a planet can help scientists understand more about the exoplanet's atmospheric makeup and whether its insides are rocky or gassy. Both of these factors are linked to each planet's ability to support life. Knowing the mass of a planet can also lend some insight into how it cools, its plate tectonics, how it generates magnetic fields and whether gas escapes from its atmosphere, researchers said.

"The mass affects everything on a planetary level," Julien de Wit, a researcher at MIT and the study's lead author, said in a statement. "If you don't get it, there is a large part of the planet's properties that remains undetermined."

However, current methods for weighing exoplanets are limited. The main technique scientists use now is radial velocity strategy. This method looks for repeated wobbles in a star's movements, which are signs of a planet's gravity yanking it back and forth; a planet's gravitational pull is linked to its mass.

The problem is that the radial velocity method does not work on a large variety of worlds that do not visibly tug much on their stars. This includes planets with low masses, those orbiting a fair distance away from their stars, those around faint stars, and those circling highly active stars where a planet's tugging can be masked by disturbances on the star.
Now, scientists have developed a strategy to weigh a planet just by looking at its atmosphere.

To understand how this method works, imagine that an exoplanet's atmosphere gets thinner with altitude, just as Earth's does. This is because the strength of a planet's gravitational pull weakens the greater the distance from the planet.

Since the strength of a planet's gravitational pull depends on its mass, researchers can deduce an exoplanet's mass by seeing how the planet's atmosphere thins with altitude. This involves gazing at exoplanets as they pass in front of their stars and looking at starlight shining through the atmospheres of those worlds to determine the atmospheric pressure drops with altitude. (A limitation of this approach is that it only works on planets with atmospheres, de Wit noted.)

To test this method, known as MassSpec, the researchers applied it on an exoplanet known as HD 189733b, a world about 63 light-years away from Earth discovered in 2005. The estimate they calculated for its mass closely agreed with estimates calculated via the radial velocity technique: about 1.15 times Jupiter's mass.

Currently, MassSpec only works on gas giants — worlds about the size ofJupiter and Saturn, the researchers said, adding that this method could help pin down the mass of gas giants whose stars are too active to allow mass estimates via the radial velocity method.
If and when space telescopes such as NASA's James Webb Space Telescope and the European Space Agency's potential Exoplanet Characterisation Observatory (EChO) launch, MassSpec will be able to weigh planets with a mass about the same as Earth's; super-Earth planets with a mass of up to 10 times Earth's mass; and gaseous planets known as mini-Neptunes that have a mass of up to 10 times Earth's mass.

"We now have a method to get the mass of Earth-sized planets that are far enough from their stars to be potentially habitable," de Wit told SPACE.com. "We show that our method could be applicable to potentially habitable Earth-sized planets within the next decade."

By Charles Q. Choi, SPACE.com Contributor
Source of Article: Space.com

Reactivated NASA Asteroid-Hunting Probe Takes First Photos in 2.5 Years

A NASA asteroid-hunting spacecraft has opened its eyes in preparation for a renewed mission, beaming home its first images in more than 2.5 years.

The Near-Earth Object Wide-field Infrared Survey Explorer spacecraft, or NEOWISE, has taken its first set of test images since being reactivated in September after a 31-month-long hibernation, NASA officials announced today (Dec. 19). The space agency wants NEOWISE to resume its hunt for potentially dangerous asteroids, some of which could be promising targets for future human exploration.

"The spacecraft is in excellent health, and the new images look just as good as they were before hibernation," Amy Mainzer, principal investigator for NEOWISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. 

"Over the next weeks and months we will be gearing up our ground-based data processing and expect to get back into the asteroid-hunting business, and acquire our first previously undiscovered space rock, in the next few months," Mainzer added.

NEOWISE began its scientific life as WISE, which launched to Earth orbit in December 2009 on a 10-month mission to scan the entire sky in infrared light. WISE catalogued about 560 million celestial objects, ranging from faraway galaxies to nearby asteroids and comets, NASA officials have said.

WISE ran out of hydrogen coolant in October 2010, making two of its four infrared detectors inoperable. But NASA didn't shut the probe down at this point; rather, the agency granted a four-month mission extension known as NEOWISE, which focused on hunting asteroids. (The satellite could still spot nearby objects with its other two detectors, which did not have to be super-cooled).

NEOWISE discovered more than 34,000 asteroids and characterized 158,000 space rocks before being shut down in February 2011, NASA officials said.
And the spacecraft is now gearing up for another three-year space-rock hunt, partly to help find potential targets for NASA's ambitious asteroid-capture project. This "Asteroid Initiative," which was announced in April, seeks to drag a near-Earth asteroid to a stable orbit around the moon, where it would be visited by astronauts using the agency's Space Launch System rocket and Orion crew vehicle.

The plan represents a way to meet a major goal laid out by President Barack Obama, who in 2010 directed NASA to get astronauts to a near-Earth asteroid by 2025, then on to the vicinity of Mars by the mid-2030s.

NEOWISE employs a 16-inch (40 centimeters) telescope and infrared cameras to find previously unknown asteroids and gauge the size, reflectivity and thermal properties of space rocks, NASA officials said.

"It is important that we accumulate as much of this type of data as possible while the spacecraft remains a viable asset," said Lindley Johnson, NASA's NEOWISE program executive in Washington. "NEOWISE is an important element to enhance our ability to support the [asteroid] initiative."

By Mike Wall, Senior Writer
Source of Article: Space.com

Private Mars Lander Launching in 2018 Will Build on NASA Legacy

Mars One is gearing up to send an unmanned lander to the Red Planet that would follow in the mold of NASA's successful Mars landers.
The Netherlands-based nonprofit has sealed a deal with security and aerospace company Lockheed Martin to develop a mission concept for its lander. This surface craft is slated to launch toward the Red Planet along with a communications satellite in 2018 — six years before Mars One aims to blast four people toward the Red Planet on a one-way colonization mission.

Based on NASA's Phoenix lander, Mars One's lander will include new thin-film solar cells, a water extraction experiment, and other demonstration technologies that will be required for human settlement on Mars.

"Phoenix is a proven delivery system," Ed Sedivy, a civil space chief engineer at Lockheed Martin who was the program manager for NASA's Phoenix lander flight system, said in a news briefing Dec. 10. "There are very few impediments to continuing on beyond the study concept."

The objectives of the Phoenix mission, which lasted from May to November 2008, were to study the history of water in all its phases on Mars and to search for evidence of habitability. The lander had a robotic arm to dig through the top layer of soil on Mars to get to the water ice below, and it found evidence of water vapor in soil samples it heated up in an onboard oven.

The planned Mars One lander will be very similar to Phoenix, Sedivy told SPACE.com. It will have a robotic digging arm for excavating the soil, as well as an experiment to extract water, the design of which has not yet been finalized.

For power, the lander will sport two circular solar panel arrays, like Phoenix, as well as an experimental thin-film solar panel — the long "tongue" shown in the artist's impression above. Mars One co-founder and CEO Bas Lansdorp said the organization will open a call for proposals for the new solar panel, whose size will depend on the tradeoffs of payload weight and power-generating ability.

"The solar panels will be very important for a manned mission, because we don’t want to depend on nuclear power," Lansdorp said.

The lander will also have a camera, which will relay video from the surface of Mars to Earth via a satellite orbiter expected to launch with the lander in 2018. To help fund its manned missions, the first of which is slated to launch in 2024, Mars One has said it plans to organize a global media event around the colonists and their journey to (and stay on) the Red Planet.

Lockheed Martin is also developing a Phoenix lander derivative for NASA's proposed InSight mission. InSight, which is slated to launch in 2016, will place a lander on Mars to drill down to investigate the planet's deep interior, in an attempt to understand the rocky planet's evolution.

By Tanya Lewis, Staff Writer 
Source of Article: Space.com

Humanoids to 4-Legged Machines: 'Robot Olympics' Shows Off Diverse Designs

This week, teams of engineers from around the world are competing in the DARPA Robotics Challenge Trials, a prestigious robotics competition that will showcase some of the most advanced machines in development. From two-legged creations that resemble humans to bots that drive around on tracks like a tank, the contest boasts a diverse range of robot designs.

The DARPA Robotics Challenge Trials is being held today and tomorrow (Dec. 20-21) here at the Homestead Miami Speedway. The 17 participating teams will be evaluated based on how well their robots tackle eight challenging tasks, which are designed to mimic actions that robots could perform in place of human responders in the wake of natural or man-made disasters. 

DARPA, a branch of the U.S. Department of Defense tasked with developing new technologies for the military, hopes the Challenge will foster the development of robots that could one day work in emergency settings deemed too dangerous for humans, said Gill Pratt, program manager of the DARPA Robotics Challenge (DRC).

The robots on display in Florida will be various shapes and sizes, with each robotic design having inherent benefits and drawbacks, he added. As such, it can be difficult to predict which type of robot may prevail at the trials.

Different designs, different functions

At this week's Challenge, the majority of competing robots will stand upright on two legs, and were built to resemble human beings. This is largely because DARPA envisions these robots eventually working alongside, and in the same environment, as humans, Pratt said. 

"If you want a robot to get around and do things in that environment, there's a pull, or engineering desire, to make robots have the same form [as humans]," Pratt told reporters in a news briefing.

Machines that resemble humans, the thinking goes, may operate more seamlessly in a world built around human specifications, such as being able to wield tools designed for human hands. But, there are downsides, said Chris Jones, director of strategic technology development at iRobot Corporation, the Bedford, Mass.-based company behind the well-known robotic Roomba vacuum, which can autonomously clean floors while avoiding obstacles around the house.

"Legged [robots] are interesting, but technically very challenging to accomplish," Jones told LiveScience. "Yes, you can build humanoid robots, and yes, they can fit in the human environment, but can you do it in a cost-effective fashion to justify the inherent complexity?"

iRobot is not competing in the Robotics Challenge, but the company did design a three-fingered robotic hand that will be used by several groups that qualified for the DARPA trials.

Tackling mobility

With a humanoid robot, some of the most challenging issues involve figuring out how it will move around effectively, said Rodney Brooks, founder and CTO of Rethink Robotics, a commercial robotics company based in Boston, Mass. (Rethink is not participating in the DARPA Challenge.) Brooks, who was a professor of robotics at MIT, also co-founded iRobot in 1990, but he is no longer affiliated with the company. 

"You have to balance, and that's really hard," Brooks told LiveScience. "There's also a lot of work to be done in figuring out efficient walking algorithms to get good performance."
With four- and six-legged robots, maintaining balance is less precarious. Similarly, robots on tracks are more stable when they move, compared with two-legged machines.

"Tracked vehicles can get over rough terrain without having to worry about where to put a foot down, or how to control the dozen motors required for the walking motion," Jones said. "It's easier that way to keep balance."

Pushing the limits

Right now, human muscles are also simply more agile than their mechanical counterparts. This becomes particularly challenging for larger, humanoid robots, because their mechanical legs have to contend with a greater distribution of mass.

"Building a big thing that walks is harder than building a small thing that walks — things work differently on a micro scale," Brooks said. "It has to do with the strength to weight ratio. This is why an elephant's legs are much weaker, relative to its body mass, compared to an ant."

And then there's a clumsiness of sorts. "Where we are right now, robots are roughly at the same level of dexterity and mobility of a 1-year-old child," Pratt said. "They fall down, they drop things out of their hands all the time — in general, they need to try things many times to get them right. That's about where the field is now."

Yet, DARPA is well aware that the robotics industry has a ways to go before these types of machines live up to the imaginations of Hollywood filmmakers and science-fiction writers, and the agency hopes incentive-based contests like the Robotics Challenge will spur continued growth in the field. But for now at the DARPA trials, the robots that do walk on two legs will likely take slow and deliberate steps, event organizers have said. Even the multi-legged robots, and those that will move on tracks, represent advanced technologies in a fledgling industry.

And, testing a variety of robot designs at the DARPA trials will help engineers better understand which features work best in different disaster scenarios.
"That's part of the point," Brooks said. "You take a bunch of designs and see how far you can push them."

By Denise Chow, Staff Writer
Source of Article: Space.com

Mercury Crater Named After John Lennon

Beatles legend John Lennon, "Breakfast at Tiffany's" author Truman Capote and sculptor Alexander Calder are among the 10 artists and writers now immortalized on Mercury with impact craters bearing their names.

The International Astronomical Union (IAU), the global authority for all planetary and satellite nomenclature, approved the new monikers this week. The names were proposed by the science team for NASA's Messenger spacecraft, which has beamed back hundreds of pictures of Mercury from its orbit around the tiny planet.

According to the IAU's naming rules, craters on Mercury can only be named after creative types, or more specifically, "deceased artists, musicians, painters, and authors who have made outstanding or fundamental contributions to their field and have been recognized as art historically significant figures for more than 50 years."

The IAU has been arbitrating cosmic names since 1919 and it has strict guidelines for different celestial bodies and planetary features. Pluto's satellites, for example, must be named after mythological deities associated with the underworld (thus, Styx and Kerberos). Moons of Jupiter, meanwhile, are named for Jupiter's lovers and descendants (such as Europa and Io).

Messenger — which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging — launched in 2004 and arrived in orbit around Mercury in March 2011. The spacecraft completed its first flyby of our solar system's smallest planet in January 2008, and since then, more than 100 craters on Mercury have been named.
"The Messenger team is delighted that the IAU has named an additional 10 impact craters on Mercury," the mission's principal investigator, Sean Solomon of Columbia University, said in a statement. "We are particularly pleased that eight of the 10 individuals honored made all or many of their artistic contributions in the Twentieth Century, the same century in which the Messenger mission was conceived, proposed, and approved for flight."

Here's the list of all 10 newly named craters, courtesy of the Messenger team:
  • Barney, for Natalie Clifford Barney (1876-1972), an American writer and expat who hosted a famous salon in Paris.
  • Berlioz, for Hector Berlioz (1803-1869), a French Romantic composer known for "Symphonie fantastique."
  • Calder, for Alexander Calder (1898-1976), the American artist most famous for his "mobile" sculptures.
  • Capote, for Truman Capote (1924-1984), the American author of "Breakfast at Tiffany's" and "In Cold Blood."
  • Caruso, for Enrico Caruso (1873-1921), an Italian tenor and opera star.
  • Ensor, for James Sidney Ensor (1860-1949), a Belgian painter and printmaker.
  • Giambologna, for Jean Boulogne Giambologna (1529-1608), a Dutch sculptor, perhaps best known for "The Rape of the Sabine Women."
  • Lennon, for John Lennon (1940-1980), the English musician of Beatles fame.
  • Remarque, for Erich Maria Remarque (1898-1970), a German novelist who wrote "All Quiet on the Western Front."
  • Vieira da Silva, for Maria Elena Vieira da Silva (1908-1992), a Portuguese-born French abstract painter.

By Megan Gannon, News Editor
Source of Article: Space.com

Rugged Martian Terrain Chewing Up Curiosity Rover's Wheels

Engineers are gearing up to perform a check of the Mars rover Curiosity's six wheels, which have accumulated a lot of wear and tear during the robot's 16 months on the Red Planet.

In the near future, the mission team plans to drive NASA's 1-ton Curiosity rover to a smooth patch of ground and photograph its six aluminum wheels using the robot's arm-mounted Mars Hand Lens Imager camera (MAHLI), officials said.

"We want to take a full inventory of the condition of the wheels," Curiosity project manager Jim Erickson, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement today (Dec. 20).

"Dents and holes were anticipated, but the amount of wear appears to have accelerated in the past month or so," Erickson added. "It appears to be correlated with driving over rougher terrain. The wheels can sustain significant damage without impairing the rover's ability to drive. However, we would like to understand the impact that this terrain type has on the wheels, to help with planning future drives."

Routes to future destinations may prioritize reducing the time Curiosity spends trundling over sharp rocks and other rough terrain, mission officials added.

Engineers also just finished upgrading the rover's software, marking the third such installation performed since Curiosity touched down inside Mars' huge Gale Crater in August 2012.

Among other features, this latest version improves Curiosity's ability to use its robotic arm while on slopes, mission team members said. This skill should come in handy when the rover reaches the base of Mount Sharp, which rises 3.4 miles (5.5 kilometers) into the Martian sky from Gale Crater's center.

Mount Sharp has long been Curiosity's main destination. Mission scientists want the rover to climb up through the mountain's foothills, reading the history of Mars' changing environmental conditions as it goes.

The chief goal of Curiosity's $2.5 billion mission is to determine if Mars has ever been capable of supporting microbial life. Mission scientists have already answered that question in the affirmative, finding that a spot near Curiosity's landing site called Yellowknife Bay was indeed habitable billions of years ago.

Curiosity departed Yellowknife Bay for Mount Sharp in July. It should reach the mountain's base around the middle of next year, officials have said.

By: Mike Wall, Senior Writer
Source of Article: Space.com

2013년 12월 14일 토요일

Age of Saturn's Rings Revealed

Saturn's iconic rings likely formed about 4.4 billion years ago, shortly after the planet itself took shape, a new study suggests.

The origin of Saturn's ring system has long been the subject of debate, with some researchers arguing that it's a relatively young structure and others holding that it coalesced long ago, at roughly the same time as the gas giant's many satellites.

The new study, conducted using data gathered by NASA's Saturn-orbiting Cassini spacecraft, strongly supports the latter scenario, researchers said here Tuesday (Dec. 10) at the annual meeting of the American Geophysical Union.

Cassini's measurements imply that "the main rings would be [extremely] old, rather than hundreds of millions of years old," Sascha Kempf, of the University of Colorado in Boulder, said.

Saturn's main ring system is huge but razor-thin, measuring about 175,000 miles (280,000 kilometers) across but just 33 feet (10 meters) or so in the vertical direction. The rings are composed primarily of water ice, but they contain small amounts of rocky material contributed by micrometeoroid bombardment.

Kempf and his colleagues used Cassini's Cosmic Dust Analyzer instrument to measure just how frequently such tiny particles cruise through the Saturn system.

They found that a surprisingly small amount of dusty material comes into contact with the rings. On average, just 0.0000000000000000001 grams — or, in scientific notation, 10^-19 g — of dust per square centimeter zooms through space every second at a distance of five to 50 Saturn radii from the planet.

Having measured this low rate of dust recruitment, the team then calculated that the rings have likely existed for about 4.4 billion years.

"It would be consistent with an old ring system," Kempf said.
Kempf and his colleagues were also able to reconstruct the orbits of many of these particles, finding that the lion's share likely come from the Kuiper Belt, the ring of icy bodies beyond Neptune's orbit. However, some of the dust probably hails from the even more distant Oort Cloud and some from interstellar space, Kempf said.

That makes the Saturn-area dust quite different from the stuff seen near Earth and other parts of the inner solar system — a situation caused by Jupiter and its huge gravitational pull.

"Jupiter is basically splitting the solar system with respect to the dust into an inner and an outer system," Kempf said.

The $3.2 billion Cassini mission launched in 1997 and reached Saturn in 2004. The mission's operations have been extended through 2017, when the spacecraft will end its life with a dramatic plunge into Saturn's atmosphere.

By: Mike Wall, Senior Writer
Source of Article: Space.com

China Lands On The Moon: Historic Robotic Lunar Landing Includes 1st Chinese Rover

China has landed its first robotic lander on the moon, a historic lunar arrival that makes the country only the third nation to make a soft-landing on Earth's celestial neighbor.

China's Chang'e 3 moon lander and its Yutu rover touched down on the moon Saturday (Dec. 14) at about 8:11 a.m. EST (1311 GMT), though it was late Saturday night local time at the mission's control center in Beijing during the landing. It is the first soft-landing on the moon by any spacecraft in 37 years. 

Chang'e 3 launched toward the moon on Dec. 2 Beijing time to begin its two-week trek to the lunar surface. The spacecraft arrived in lunar orbit about five days after launch, and then began preparing for landing. A camera on the spacecraft snapped 59 photos of the moon during the descent, including a view straight from the lunar surface just after touchdown.

Following a lengthy engine burn Saturday, the mooncraft lowered itself to the lunar surface on autopilot, making what appeared to be a smooth touchdown on the Bay of Rainbows in the moon's northern hemisphere. The descent from lunar orbit to the moon's surface took about 12 minutes.

Shortly after landing, Chang'e 3 deployed its vital solar arrays, which were folded for the landing, to begin generating power for its lunar surface mission. The lander is now expected to unleash the instrument-laden Yutu rover, built to trundle across the dusty, time-weathered terrain for months.

China's Chang'e 3 lunar arrival is the first soft-landing on the moon since 1976. Not since the former Soviet Union's Luna 24 sample-return mission has a spacecraft made a controlled, soft touchdown on the lunar surface. The last soft-landing on the moon by NASA was in 1972 during the Apollo 17 manned lunar landing mission.

The Yutu rover (its name means "Jade Rabbit") is named after the pet rabbit that travels with the goddess Chang'e to the moon in Chinese legends. Chang'e 3 is China's third lunar mission to carry the name, but the first to soft-land on the moon. The first two Chinese lunar missions were built to orbit the moon.  

The six-wheeled Yutu rover is a solar-powered vehicle equipped with cameras, a robotic arm tipped with science gear and a radar system attached to its underbelly.
The stationary lander itself also is geared to observe Earth, astronomically eye other celestial objects from the moon, as well as watch the Yutu rover wheel across the lunar terrain.

By: Leonard David, SPACE.com's Space Insider Columnist 
Source of Article: Space.com

2013년 12월 12일 목요일

Sun's Current Solar Activity Cycle Is Weakest in a Century

The sun's current space-weather cycle is the most anemic in 100 years, scientists say.

Our star is now at "solar maximum," the peak phase of its 11-year activity cycle. But this solar max is weak, and the overall current cycle, known as Solar Cycle 24, conjures up comparisons to the famously feeble Solar Cycle 14 in the early 1900s, researchers said.

"None of us alive have ever seen such a weak cycle. So we will learn something," Leif Svalgaard of Stanford University told reporters here today (Dec. 11) at the annual meeting of the American Geophysical Union.

The learning has already begun. For example, scientists think they know why the solar storms that have erupted during Solar Cycle 24 have caused relatively few problems here on Earth.

The sun often blasts huge clouds of superheated particles into space, in explosions known as coronal mass ejections (CMEs). Powerful CMEs that hit Earth squarely can trigger geomagnetic storms, which in turn can disrupt radio communications, GPS signals and power grids.

But such effects have rarely been seen during Solar Cycle 24, even though the total number of CMEs hasn't dropped off much, if at all. The explanation, researchers said, lies in the reduced pressure currently present in the heliosphere, the enormous bubble of charged particles and magnetic fields that the sun puffs out around itself.

This lower pressure has allowed CMEs to expand greatly as they cruise through space, said Nat Gopalswamy of NASA's Goddard Space Flight Center in Greenbelt, Md. Indeed, Solar Cycle 24 CMEs are, on average, 38 percent bigger than those measured during the last cycle — a difference with real consequences for folks here on Earth.

"When the CMEs expand more, the magnetic field inside the CMEs has lower strength," Gopalswamy said. "So when you have lower-strength magnetic fields, then they cause milder geomagnetic storms."

Scientists also think they know why relatively few super-fast solar energetic particles, or SEPS, have been measured in Earth's neighborhood during the current cycle, which began in early 2008. It has to do with a weakened interplanetary magnetic field, another characteristic of Solar Cycle 24, they say.

Large SEP events, which can pose a danger to astronauts in Earth orbit, are created by the shock waves driven by CMEs. But fewer of these particles are getting accelerated by such shocks these days, said Joe Giacalone of the University of Arizona.

"When the magnetic field is weaker, the particles are not trapped near the shock as effectively," Giacalone said. "They're going much farther upstream and downstream of the shock wave, and it takes a lot longer for them to get to very high energies."

The strength or weakness of a solar cycle appears to be driven by the intensity of the sun's polar magnetic field during the previous cycle. The polar field is thought to feed the sunspots— dark and relatively cool patches on the sun that are the source of CMEs and solar flares — that come in during the next cycle, Gopalswamy said.

The polar field was weak during Solar Cycle 23, so researchers suspected that Solar Cycle 24 would be underwhelming. Predictions about Solar Cycle 25 should start coming in two or three years, when the polar field reappears, Svalgaard said.

By:Mike Wall, Senior Writer 
Source of Article: Space.com

2013년 12월 11일 수요일

Puzzling Streaks On Mars May Be From Flowing Water

Dark seasonal streaks on slopes near the Martian equator may be a sign of flowing salt water on Mars, liquid runoff that melts and evaporates during the planet's warmer months, scientists say.       

NASA's Mars Reconnaissance Orbiter spotted the dark streaks on Mars as they formed and grew in the planet's late spring and summer seasons, when the Martian equatorial region receives the most sunlight. 

The streaks then faded the next season as cooler temperatures prevailed.

These seasonally occurring flows — known as Recurring Slope Lineae — were previously seen on Martian slopes at mid-latitudes, but the MRO spacecraft has now detected them near the equator of the Red Planet. While there have been no direct detections of liquid water, the new findings hint at a surprisingly active water cycle on Mars today, said study leader Alfred McEwen, a professor of planetary geology at the University of Arizona in Tucson.

"Now we've found them in equatorial regions," McEwen told SPACE.com. "This is more surprising, given peoples' expectations that the equatorial region was completely dry. It suggests there may be much more water in the near-surface crust than we imagined before."

Flowing water on Mars?

The dark, narrow lines were observed on long, steep slopes in Valles Marineris, an extensive series of canyons located along the equator of Mars. In some cases, the fingerlike streaks stretched nearly 3,700 feet (1,130 meters).

The discovery is detailed in the Dec. 10 edition of the journal Nature Geoscience and will be discussed today at the annual American Geophysical Union meeting in San Francisco.

Researchers are still puzzling over the likely cause of these tantalizing streaks, but McEwen said they could be produced by the melting and subsequent evaporation of frozen salty water trapped deep in the planet's crust.

But, much is still unknown about whether the streaks are actually caused by liquid water, and if so, where the water is coming from. So far, researchers say the best explanation is that the liquid is a salty, or briny, solution. Salty water can stay liquid at colder temperatures, which means brines could conceivably flow on the frigid surface of Mars.
"Water should be rapidly evaporating, so it's difficult to explain long flows unless it's sufficiently salty water," McEwen said.

Also, Mars has a very dry atmosphere, which makes it unlikely that freshwater flows on the surface of the planet, said Vincent Chevrier, a planetary scientist at the University of Arkansas in Fayetteville, who was not involved with the new study.
"Water has a tendency to evaporate very quickly when it's exposed at the surface," he told SPACE.com.

Chasing streaks on Mars

Last year, Chevrier led a team of researchers who investigated the seasonal flows found on Martian slopes at mid-latitudes. The scientists modeled the behaviors of different brine mixtures to see if any could exhibit similar characteristics to what had been observed on Mars.

Chevrier and his colleagues found that calcium chloride did not immediately evaporate, and left behind some liquid that could create the types of streaks seen on the Red Planet.
Others have attempted to explain the seasonal markings with "non-liquid" solutions, such as wind patterns, but so far none have seemed plausible, McEwen said.

"So far, there aren’t any good dry hypotheses," he said. "There are some possibilities, and we keep them open as working hypotheses, but no one has been able to come up with a detailed model that makes sense."

While scientists have long viewed present-day Mars as a dry and dusty world, evidence abounds that water once flowed across much of the planet billions of years ago. Frozen water has been detected near the planet's surface at middle-to-high latitudes, but so far, no definitive evidence of liquid water has been found.

The new findings raise intriguing questions about the possibility of liquid water on present-day Mars, which has ties to the ongoing search for life on the Red Planet.

"It's certainly very surprising to me that this is happening on Mars today," McEwen said. "If it is water, that really changes our thinking of the planet's water cycle and habitability."
On Earth, life teems wherever liquid water is found, which means a wetter Mars could have tantalizing prospects for hosting extraterrestrial life.

"Earth is loaded with liquid water —it's a liquid water paradise," Chevrier said. "I'm not saying this means life is possible on Mars, but this is a good small step."

By: Denise Chow, Staff Writer
Source of Article: Space.com

Exoplanet Habitable Zone Around Sunlike Stars Bigger Than Thought

Earth's place in the solar system is just right. It's not too hot, like Venus, and it's not too cold, like Mars, and this "Goldilocks zone" of habitability around other stars like the sun just might be bigger than thought, scientists say.

A new study, unveiled today (Dec. 11), expands the habitable zone — the sweet spot in a solar system where liquid water and therefore life could potentially exist — surrounding stars like the sun.

Previous studies on the habitability zone around sunlike stars have placed the innermost edge of so-called Goldilocks zoneat about 0.99 AU (1 AU, or astronomical unit, is the average distance from Earth to the sun, about 93 million miles, or 150 million kilometers). But a new computer model study pushes that border closer to its parent star, to a distance of about 0.95 AU (about 88 million miles, or 142 million kilometers).

The study in the journal Nature, led by Jeremy Leconte, now a postdoc at the Canadian Institute for Theoretical Astrophysics of the University of Toronto, used 3D computer modeling to find that the runaway greenhouse effect isn't an issue unless the planet is less than 0.95 AU from its star.

The new inner boundary for habitable zones might not make a big difference for scientists trying to determine if an alien planet is habitable, but it does make a big difference for future life on Earth, Leconte said.

Eventually, the sun will become brighter, heating the Earth and potentially creating a runaway greenhouse effect — a feedback loop that eventually causes a planet's oceans to boil away. But that eventuality is long way off, and it may now actually be farther off than previously expected, Leconte suggests.

"For example, if we believe that the limit is at 0.99, it means that Earth would start losing oceans around 150 million years from now," Leconte told SPACE.com. "Now, with our new estimate, it's not 150 million years, but it's actually 1 billion years, so almost an order of magnitude bigger."

Seeing in 3D

Unlike previous one-dimensional studies, the new modeling takes clouds and circulation into account, jputting the inner edge of the habitable zone closer to a star. This buys Earth a little more time, although the planet is still quite close to the near end of the habitable zone.

"From the perspective of the Earth, this is a big change, and it's because the Earth is thought to be quite close to the inner edge," Leconte, who conducted this research while at the Intitut Pierre- Simon Laplace in Paris, said. "We now find that it's not that close. It's still very close into the habitable zone compared to what could be other planets we see out there."

Leconte did use climate data collected for Earth science in the model, but he took out some of the more specific information to create a general model for rocky planets circling sunlike stars.

Alien planets

The new model could help scientists more fully understand what constitutes a habitable alien planet as well.

"We now have the real framework for understanding these objects not as just dots but as real planets that have a surface, an atmosphere where complex processes like cloud formation can happen like on the Earth," Leconte said. "In a way we see them more as worlds than just as planets."

Although the size of the habitable zone calculated by Leconte is larger than other estimates in the past, it is also much smaller than more recent estimates used to analyze data from the alien- planet-hunting Kepler space telescope.

Earlier this year, scientists using the Kepler data estimated that 22 percent of sunlike stars may harbor a rocky planet in their habitable zones, however, the research team used a broad definition for the habitable zone, marking the inner edge at 0.5 AU, James Kasting, a professor of geosciences at the University of Pennsylvania, said.

"If you take the Petigura analysis [Kepler-based study] at face value, their number might be too high by a factor of two," Kasting, who wrote a News & Views piece about Leconte's study in this week's Nature, told SPACE.com.

Oceans on Venus?

Leconte's new work does help constrain the habitable zone around sunlike stars, but it could also have a bearing on the Goldilocks zones around other, dimmer stars. Scientists hope to use 3D modeling in the future to understand how a rocky planet around a dim star could fare as well.

By applying the cutting-edge form of modeling to Venus during the earlier days of the solar system, scientists may catch a glimpse of what a rocky planet around a dim star could be like. When the sun was younger, it was also smaller and dimmer, therefore it's possible that Venus harbored liquid oceans that evaporated as the sun aged and grew brighter.
Leconte has done some initial modeling to investigate these ideas, however, he hasn't found anything conclusive yet.

By: Miriam Kramer, Staff Writer
Source of Article: Space.com

Europe Launches Wake-Up Call Contest for Comet-bound Spacecraft

In the chilly reaches of deep space, the unmanned Rosetta probe will soon awaken from a years-long hibernation for a 2014 comet rendezvous, and the European scientists want you to help wake the slumbering spacecraft.

The European Space Agency is asking comet fans around the world to create a special video message to rouse the Rosetta spacecraft under the new 'Wake Up Rosetta' campaign.

The project invites everyone to create and share a video clip of themselves, alone or in a group, shouting "Wake Up, Rosetta!" The top 10 selections will receive prizes, including having their message transmitted to Rosetta as it closes in on its target.

Launched in 2004, Rosetta has traveled around the sun five times, gathering energy from the orbits of Earth and Mars to help slingshot into deep space. In August 2014, the craft will rendezvous with comet 67P/Churyumov-Gerasimenko and follow it for a year, observing the frozen dustball as it makes its closest approach to the sun.

After observing two small asteroids, Rosetta entered a 31-month hibernation in June 2011 for the longest, coldest part of its trip. Following its wakeup, it will prepare for a deep-space maneuver, ultimately arriving at the comet in August 2014, just outside the orbit of Jupiter. 

Three months later, Rosetta will drop its Philae lander onto the comet's surface, where it will study how 67P/Churyumov-Gerasimenko changes as it travels closer to the sun.
The contest, which started 10 December, will run until 17:30 GMT (18:30 CET) on January 20. Rosetta itself will be waking up at 10:00 GMT (11:00 CET) that same day. Winners will be announced on January 24.

Contestants can post their videos to the ESA's Facebook page, where other users can vote.

The top ten videos will be transmitted to Rosetta using one of the ESA's deep-space tracking stations. A gift bag of selected ESA-branded souvenirs will be awarded to each eligible participant submitting one of the top ten videos. Furthermore, two of the authors from one of the top ten will be invited to Rosetta's control center in Darmstadt, Germany in November 2014 for the VIP event celebrating the first-ever landing on a comet.

People around the world are also invited to participate in the Wake Up Rosetta campaign on Twitter, by following and shouting #WakeUpRosettta at @ESA_Rosetta. Shouts will be welcome at any time, but particularly during the Wake Up Rosetta event on Jan. 20 between 10:00 and 17:30 GMT (5 a.m. and 12:30 p.m. EST).

By: Nola Taylor Redd, SPACE.com contributor
Source of Article: Space.com