Fresh Crater on Mars Spied by NASA Spacecraft

A NASA Mars probe has photographed an impact crater that was blasted out of the Red Planet in just the last few years.

The HiRISE camera aboard NASA's Mars Reconnaissance Orbiter (MRO) captured the crater, which lies in the Red Planet's equatorial Elysium Planitia region, on Dec. 2, 2014. Scientists say the impact that gouged out the hole must have occurred between February 2012 and June 2014, based on previous images of the area.

The crater is about 40 feet (12 meters) wide, said HiRISE team member Ingrid Daubar of NASA's Jet Propulsion Laboratory in Pasadena, California.

"We've been finding new craters like this for a few years now, and from studying their frequency, we've come up with a cratering rate for Mars based on them," Daubar told Space.com via email.

"For craters this size (12 m diameter), we expect about 30 of these are forming over all of Mars each year," she added. "We only find a few of them, though, because we have to be looking in the right area. They're not as easy to find over non-dusty areas where they don't form these huge dark blast zones around the impact site."

The new photo is the first one HiRISE — short for High Resolution Imaging Science Experiment — has taken of the crater. The feature was actually discovered by MRO's Mars Context Camera, NASA officials said.

The objects that create Martian craters such as this one strike the surface at very high speeds — an average of 22,000 mph (35,400 km/h) — and are almost always completely destroyed in the process, Daubar said.

Indeed, there is no sign of the impactor in the new HiRISE photo. The silvery crescent toward the right side of the crater is just the illuminated interior wall of the crater, Daubar said. (In the image, sunlight is coming from the lower left.)

The $720 million MRO mission launched in August 2005 and arrived in orbit around Mars in March 2006. The spacecraft has been studying the Red Planet ever since with six scientific instruments. MRO also serves as a vital communications link between Earth and NASA's active Mars surface craft, the Opportunity and Curiosity rovers.

Retro NASA Travel Posters Invite You to Real Alien Worlds

These amazingly retro NASA travel posters feature three real-life alien planets: Kepler 186f, HD 40307g and Kepler 16b. They were created for NASA's PlanetQuest project at the agency's Jet Propulsion Laboratory in Pasadena, California to share facts about the strange new worlds with the public.

Opportunity Rover Snaps Mars Panorama from Crater Rim

The Opportunity rover took the photo on Tuesday (Jan. 6) from atop "Cape Tribulation," on the western rim of Endeavour Crater. The summit sits about 440 feet (135 meters) above the surrounding plains — higher than any other point Opportunity has reached since arriving at Endeavour's rim in August 2011, NASA officials said

Researchers in remote East Antarctica think a massive area of fractured ice discovered last month could be a newfound meteorite impact crater.

The mile-wide crater (about 2 kilometers across) is a circular scar marked by fractured, rumpled ice — a striking blot in this otherwise smooth section of Antarctica's King Baudouin Ice Shelf. It was spotted by German scientist Christian Müller during an aerial survey by plane on Dec. 20, 2014.

"I looked out of the window, and I saw an unusual structure on the surface of the ice," Müller said in a video describing the discovery. "There was some broken ice looking like icebergs, which is very unusual on a normally flat ice shelf, surrounded by a large, wing-shaped, circular structure," said Müller, a geoscientist with Fielax, a private company assisting Antarctic research.

Lucky find

The possible impact crater is about twice the size of Arizona's Barringer Meteor Crater. Satellite images suggest the broken-up ice could be at least 25 years old.

The crater was a serendipitous find, sighted by chance north of Belgium's Princess Elisabeth Research Station. German researchers at the station intended to remotely survey the surrounding bedrock, in order to gather new details on the Gondwana supercontinent's formation and breakup between 550 million and 180 million years ago. Flying over busted-up ice shelves — the floating extensions of the Antarctic Ice Sheet — was not part of the research plan.

"We were only flying that far in the north because the radar equipment had broken, and we didn't want to waste a good flying day," said Graeme Eagles, a scientist at Germany's Alfred Wegener Institute who is currently leading the geophysical research survey. "It's been a tremendously exciting couple of weeks," he added. "It really is a very raw form of science, with a lot of people speculating on what might or might not be the cause."
Antarctic researchers

At first, Müller connected the crater to a 2004 meteor blast detected above this part of East Antarctica. Recently, however, the German research team discovered the crater in satellite images dating back to 1996, Eagles said. "The [connection] to the 2004 event really piqued our interest in the first place, but I don't think what we've seen in the satellite images rules out the possibility of an impact origin," Eagles told Live Science. "It just fuzzies the story a little bit."

Extraordinary claims

If a space rock did crash-land on the ice shelf, the meteorite was likely relatively large. Indeed, the crater's sheer size warrants skepticism, experts said. [Crash! 10 Biggest Impact Craters on Earth]

As a rule of thumb, an object that formed a crater is usually about 10 to 20 times smaller than the crater itself, said Peter Brown, director of the Center for Planetary Science and Exploration at the University of Western Ontario in Canada. That means a 1.2-mile (2 km) crater would result from an object that measures roughly 325 feet (100 meters) across, Brown said.

"A very large explosion would have caused a 2-kilometer-wide crater — much larger than anything detected impacting Earth in recent history," Brown said. "So the feature seen is almost certainly not due to any meteorite impact."

Meteorite hunter Peter Jenniskens also found the crater idea implausible. "I don't think this is an impact crater," said Jenniskens, who holds dual affiliations at the SETI Institute and at NASA's Ames Research Center, both in California.

However, Eagles hinted that the German researchers have not shown all their cards. The scientists collected photos, video and data on a Dec. 26 trip to the crater site. The team mapped the ice surface in great detail with a laser-scanning instrument that records precise changes in topography. They also surveyed the area with a radar instrument that penetrates the upper surface of the ice and snow. A number of smaller circular and subcircular structures were spotted nearby on this trip. The researchers haven't yet analyzed the data, but they hope to publish their results in a scientific journal if the structure is indeed an impact crater, Eagles said.

"This thing is very unusual indeed," Eagles said. "Extraordinary claims require extraordinary evidence, and in this case, as far as we can tell, is does look like it is extraordinary evidence."

Rock hunters

The researchers now must complete their Gondwana study before squeezing in any more trips to the crater, Eagles said. For instance, the team would like to eventually hunt for meteorites around the site.

Antarctica's cold, dry conditions preserve meteorites that weather away on other continents, and more than 20,000 space rocks have been discovered in targeted searches on the frozen surface.

While scientists do come to Antarctica specifically to hunt for meteorites, finding a potential impact crater was an unexpected thrill for everyone at the research station, the researchers said. "There are new and exciting things to be discovered at any moment, anytime, in Antarctica, and you don't have to send probes to land on comets to make people's eyes sparkle," Eagles said.

NASA's Kepler Marks 1,000th Exoplanet Discovery, Uncovers More Small Worlds in Habitable Zones

How many stars like our sun host planets like our Earth? NASA's Kepler Space Telescope continuously monitored more than 150,000 stars beyond our solar system, and to date has offered scientists an assortment of more than 4,000 candidate planets for further study -- the 1,000th of which was recently verified.
Using Kepler data, scientists reached this millenary milestone after validating that eight more candidates spotted by the planet-hunting telescope are, in fact, planets. The Kepler team also has added another 554 candidates to the roll of potential planets, six of which are near-Earth-size and orbit in the habitable zone of stars similar to our sun.
Three of the newly-validated planets are located in their distant suns' habitable zone, the range of distances from the host star where liquid water might exist on the surface of an orbiting planet. Of the three, two are likely made of rock, like Earth.
"Each result from the planet-hunting Kepler mission's treasure trove of data takes us another step closer to answering the question of whether we are alone in the universe," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate at the agency's headquarters in Washington. "The Kepler team and its science community continue to produce impressive results with the data from this venerable explorer."
To determine whether a planet is made of rock, water or gas, scientists must know its size and mass. When its mass can't be directly determined, scientists can infer what the planet is made of based on its size.
Two of the newly validated planets, Kepler-438b and Kepler-442b, are less than 1.5 times the diameter of Earth. Kepler-438b, 475 light-years away, is 12 percent bigger than Earth and orbits its star once every 35.2 days. Kepler-442b, 1,100 light-years away, is 33 percent bigger than Earth and orbits its star once every 112 days.
Both Kepler-438b and Kepler-442b orbit stars smaller and cooler than our sun, making the habitable zone closer to their parent star, in the direction of the constellation Lyra. The research paper reporting this finding has been accepted for publication in The Astrophysical Journal.
"With each new discovery of these small, possibly rocky worlds, our confidence strengthens in the determination of the true frequency of planets like Earth," said co-author Doug Caldwell, SETI Institute Kepler scientist at NASA's Ames Research Center at Moffett Field, California. "The day is on the horizon when we'll know how common temperate, rocky planets like Earth are."
With the detection of 554 more planet candidates from Kepler observations conducted May 2009 to April 2013, the Kepler team has raised the candidate count to 4,175. Eight of these new candidates are between one to two times the size of Earth, and orbit in their sun's habitable zone. Of these eight, six orbit stars that are similar to our sun in size and temperature. All candidates require follow-up observations and analysis to verify they are actual planets.
"Kepler collected data for four years -- long enough that we can now tease out the Earth-size candidates in one Earth-year orbits," said Fergal Mullally, SETI Institute Kepler scientist at Ames who led the analysis of a new candidate catalog. "We're closer than we've ever been to finding Earth twins around other sun-like stars. These are the planets we're looking for."
These findings also have been submitted for publication in The Astrophysical Journal Supplement.
Work is underway to translate these recent discoveries into estimates of how often rocky planets appear in the habitable zones of stars like our sun, a key step toward NASA's goal of understanding our place in the universe.
Scientists also are working on the next catalog release of Kepler's four-year data set. The analysis will include the final month of data collected by the mission and also will be conducted using sophisticated software that is more sensitive to the tiny telltale signatures of small Earth-size planets than software used in the past.

Alien Oceans May Flow on 'Super-Earth' Planets

 SEATTLE — Alien worlds more massive than Earth could harbor long-lasting oceans, according to new research.

Scientists have used computer modeling to show that so-called "super-Earth" planets — worlds that are up to five times more massive than Earth — can play host to long-lived oceans. The modeling shows that the oceans can potentially remain on the planet for billions of years, possibly allowing life to develop on the alien planet. Researchers presented the new super-Earth findings during a news conference at the 225th meeting of the American Astronomical Society here in Seattle.

"When people consider whether a planet is in the habitable zone, they think about its distance from the star and its temperature," lead author of the super-Earth study Laura Schaefer of the Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Massachusetts said in a statement. "However, they should also think about oceans, and look at super-Earths to find a good sailing or surfing destination."

Scientists think that Earth's oceans have existed for almost the entire history of the planet, and water is key to life as humanity understands it. Therefore, finding other worlds with long-lived oceans could help scientists narrow down planets that might have a good chance of hosting life.

Earth's oceans are recycled. Water from the planet's oceans is pulled into the mantle from the crust due to geological activity, but water is also released from the mantle and back into the surface oceans through volcanic activity. The new computer model produced by Schaefer and her team was designed to test if this water recycling can occur on super-Earths with plate tectonics as well, according to the CfA.

In fact, some planets larger than Earth could be even better at maintaining oceans than this planet. Schaefer's model shows that a planet two to four times the mass of Earth could host oceans continuously for 10 billion years. The largest planet in the study, which was about five times more massive than Earth, didn't develop an ocean in the computer model for about 1 billion years, but those planets' oceans, once formed, continue to persist on the surface for a long amount of time. .

Schaefer and her team suggest that it might be better to hunt for life on older super-Earths. Researchers might have a better chance of finding complex life on planets that are 1 billion years older than Earth, the team said.

"It takes time to develop the chemical processes for life on a global scale, and time for life to change a planet's atmosphere," the CfA's Dimitar Sasselov, a co-author on the study, said in a statement. "So, it takes time for life to become detectable."

Planets with Odd, Mercury-Like Orbits Could Host Life

Mercury has an oddball orbit — it takes longer for it to rotate on its axis and complete a day than it takes to orbit the sun and complete a year. Now, researchers suggest photosynthesis could take place on an alien planet with a similarly bizarre orbit, potentially helping support complex life.
However, the scientists noted that the threat of prolonged periods of darkness and cold on these planets would present significant challenges to alien life, and could even potentially freeze their atmospheres. They detailed their findings in the International Journal of Astrobiology.
Astronomers have discovered more than 1,700 alien planets in the past two decades, raising the hope that at least some might be home to extraterrestrial life. Scientists mostly focus the search for alien life on exoplanets in the habitable zones of stars. These are regions where worlds would be warm enough to have liquid water on their surfaces, a potential boon to life.

Although many exoplanets are potentially habitable, they may differ from Earth significantly in one or more ways. For instance, habitable planets around dim red dwarf stars orbit much closer than Earth does to the sun, sometimes even closer than Mercury's distance.
Red dwarfs are of interest as possible habitats for life because they are the most common stars in the universe — if life can exist around red dwarfs, then life might be very common across the cosmos. Recent findings from NASA's Kepler Space Observatory suggest that at least half of all red dwarfs host rocky planets that are one-half to four times the mass of Earth.
Since a planet in the habitable zone of a red dwarf orbits very near its star, it experiences much stronger gravitational tidal forces than Earth does from the sun, which slows the rate at which those worlds spin. The most likely result of this slowdown is that the planet enters what is technically called a 1:1 spin orbit resonance, completing one rotation on its axis every time it completes one orbit around its star.

This rate of rotation means that one side of that planet will always face toward its star, while the other side will permanently face away, just as the moon always shows the same side to Earth. One recent study suggests that such "tidally locked" planets may develop strange lobster-shaped oceans basking in the warmth of their stars on their daysides, while the nightsides of such worlds are mostly covered in an icy shell.

However, if a habitable red dwarf planet has a very eccentric orbit — that is, oval-shaped — it could develop what is called a 3:2 spin orbit resonance, meaning that it rotates three times for every two orbits around its star. Mercury has such an unusual orbit, which can lead to strange phenomena. For instance, at certain times on Mercury, an observer could see the sun rise about halfway and then reverse its course and set, all during the course of one mercurial day. Mercury itself is not habitable, since it lacks an atmosphere and experiences temperatures ranging from 212 to 1,292 degrees Fahrenheit (100 to 700 degrees Celsius).

“If the sun were less intense, Mercury would be within the habitable zone, and therefore life would have to adapt to strange light cycles," said lead study author Sarah Brown, an astrobiologist at the United Kingdom Center for Astrobiology in Edinburgh, Scotland.
Light is crucial for photosynthesis, the process by which plants and other photosynthetic organisms use the sun's rays to create energy-rich molecules such as sugars. Most life on Earth currently depends on photosynthesis or its byproducts in one way or the other, and while primitive life can exist without photosynthesis, it may be necessary for more complex multicellular organisms to emerge because the main source for oxygen on Earth comes from photosynthetic life, and oxygen is thought to be necessary for multicellular life to arise.
To see what photosynthetic life might exist on a habitable red dwarf planet with an orbit similar to Mercury's, scientists calculated the amount of light that reached all points on its surface. Their model involved a planet the same mass and diameter as the Earth with a similar atmosphere and amount of water on its surface. The red dwarf star was 30 percent the sun's mass and 1 percent as luminous, giving it a temperature of about 5,840 degrees Fahrenheit (3,225 degrees Celsius) and a habitable zone extending from 10 to 20 percent of an astronomical unit (AU) from the star. (One AU is the average distance between Earth and the sun.)
The scientists found that the amount of light the surface of these planets received concentrated on certain bright spots. Surprisingly, the amount of light these planets receive does not just vary over latitude as it does on Earth, where more light reaches equatorial regions than polar regions, but also varies over longitude. Were photosynthetic life to exist on worlds with these types of orbits, "one would expect to find niches that depend on longitude and latitude, rather than just latitude," said study co-author Alexander Mead, a cosmologist at the Royal Observatory, Edinburgh, in Scotland.
The research team found these planets could experience nights that last for months. This could pose major problems for photosynthetic life, which depends on light. Still, the scientists noted that many plants can store enough energy to last through 180 days of darkness. Moreover, some photosynthetic microbes spend up to decades dormant in the dark, while others are mixotrophic, which means they can survive on photosynthesis when light is abundant and switch to devouring food when light is absent.

Another problem these long spans of darkness pose for life is the cold, which could freeze the atmospheres of these planets. Still, the investigators note that heat can flow from the dayside of such a planet to its nightside and prevent this freezing if that planet's atmosphere is sufficiently dense and can trap infrared light from the planet's star. This heat flow could lead to very strong winds, but this does not necessarily make the world uninhabitable, they added. [The Strangest Alien Planets]
"Life having to cope with such tidally driven resonances could be common in the universe," Mead said. "It changes one's perception of what habitable planets in the universe would be like. There are many possibilities that are very un-Earth-like."

However, the researchers noted that the strength of a world's magnetic field depends in large part on how quickly it spins, which suggests that planets with orbits like Mercury's might have relatively weak magnetic fields. This could mean these worlds are not as good at deflecting harmful electrically charged particles streaming from their red dwarfs and other stars that can damage organisms and strip off the atmospheres of these planets.

The investigators suggested that dense atmospheres could help keep such planets habitable in the face of radiation from space. They added that life might be confined to certain spots on the surfaces of those planets that experience relatively safe levels of radiation.
Are astronomers capable of detecting habitable planets with a 3:2 spin orbit resonance?
"Measuring the day length of extrasolar planets is enormously difficult, and the first day length measurements for any extrasolar planets were only published this year," Mead said. "Such a measurement for the planets we discuss would be much more difficult due to the fact that they are small, rocky planets around faint stars. This means that we are probably a long way from measuring the spin rates of such habitable worlds."