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Explanation: This high cliff occurs not on a planet, not on a moon, but on a comet. It was discovered to be part of the dark nucleus of Comet Churyumov-Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA that rendezvoused with the Sun-orbiting comet in 2014. The ragged cliff, as featured here, was imaged by Rosetta in 2014. Although towering about one kilometer high, the low surface gravity of Comet CG would likely make it an accessible climb -- and even a jump from the cliff survivable. At the foot of the cliff is relatively smooth terrain dotted with...

And now it’s down to two: Dragonfly and CAESAR. Those are the finalists vying for a billion dollar space shot—and a place in NASA’s coveted New Frontiers program. The agency announced the decision Wednesday at its Washington, D.C. headquarters. To win the chance to send a robotic probe into space, Dragonfly and CAESAR beat out proposals from ten other science teams. “This is a very tough competition,” says Jim Green, NASA's Planetary Science Division director. "And these are very exciting missions." Dragonfly—a visual mashup of a drone and helicopter—would land on Titan, a mysterious moon of Saturn that might...

Explanation: Spacecraft Rosetta continues to circle and map Comet Churyumov-Gerasimenko. Crossing the inner Solar System for ten years to reach the vicinity of the comet in 2014, the robotic spacecraft continues to image the unusual double-lobed comet nucleus. The featured image, taken one year ago, shows dust and gas escaping from the comet's nucleus. Although appearing bright here, the comet's surface reflects only about four percent of impinging visible light, making it as dark as coal. Comet 67P/Churyumov–Gerasimenko spans about four kilometers in length and has a surface gravity so low that an astronaut could jump off of it. With...

Researchers last got a signal from the Philae lander back in July, since then pinging it has resulted in no word from it—and i'’s all coming to a head now, says the ESA, because time is running out as the comet moves further and further away from the sun. With just a little time left, the plan is to try some off-label uses of Philae's momentum wheel. If the problem is that the lander is simply too dusty to power on, the hope is that spinning the wheel could clear off enough to let it wake itself up one last...

Explanation: Not a bright comet, 67P/Churyumov-Gerasimenko now sweeps slowly through planet Earth's predawn skies near the line-up of planets along the ecliptic. Still, this composite of telescopic images follows the comet's progress as it moves away from the Sun beyond the orbit of Mars, from late September (left) through late November (far right). Its faint but extensive coma and tails are viewed against the colorful background of stars near the eastern edge of the constellation Leo. A year ago, before its perihelion passage, the comet was less active, though. Then the Rosetta mission's lander Philae made it's historic landing, touching...

Explanation: There she blows! A dramatic demonstration of how short-lived some comet jets can be was documented in late July by the robotic Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko. The featured animation depicts changes in the rotating comet with three illuminating stills. Although the first frame shows nothing unusual, the second frame shows a sudden strong jet shooting off the 67P's surface only 20 minutes later, while the third frame -- taken 20 minutes after that -- shows but a slight remnant of the once-active jet. As comets near the Sun, they can produce long and beautiful tails...

How would you like to see one of the most famous comets with your own eyes? Comet 67P/Churyumov-Gerasimenko plies the morning sky, a little blot of fuzzy light toting an amazing visitor along for the ride — the Rosetta spacecraft. When you look at the coma and realize a human-made machine is buzzing around inside, it seems unbelievable. If you have a 10-inch or larger telescope, or you’re an experienced amateur with an 8-inch and pristine skies, 67P is within your grasp. The comet glows right around magnitude +12, about as bright as it will get this apparition. Periodic comets...

Explanation: This dramatic outburst from the nucleus of Comet 67P/Churyumov-Gerasimenko occured on August 12, just hours before perihelion, its closest approach to the Sun. Completing an orbit of the Sun once every 6.45 years, perihelion distance for this periodic comet is about 1.3 astronomical units (AU), still outside the orbit of planet Earth (at 1 AU). The stark image of the 4 kilometer wide, double-lobed nucleus in bright sunlight and dark shadows was taken by the Rosetta spacecraft's science camera about 325 kilometers away. Too close to see the comet's growing tail, Rosetta maintains its ringside seat to watch the...

Popular Science (8/11, Fecht) reports that on July 29, the Rosetta spacecraft was able to capture what the ESA called a “dramatic outburst” from Comet 67P, which was strong enough to affect the solar wind. The article notes that the ESA said that “unpredictable outbursts” like this one are occurring more frequently as the comet reaches perihelion, or its closest point to the sun in its orbit, on August 13.

After first touching down, Philae was able to use its gas-sniffing Ptolemy and COSAC instruments to determine the makeup of the comet’s atmosphere and surface materials. COSAC analyzed samples that entered tubes at the bottom of the lander and found ice-poor dust grains that were rich in organic compounds containing carbon and nitrogen. It found 16 in all including methyl isocyanate, acetone, propionaldehyde and acetamide that had never been seen in comets before. Ptolemy sampled the atmosphere entering tubes at the top of the lander and identified water vapor, carbon monoxide and carbon dioxide, along with smaller amounts of carbon-bearing...

Experts discover dark material is being constantly replenished and say: "Something must be doing that at a fairly prolific rate."Evidence of alien life is "unequivocal" on the comet carrying the Philae probe through space, two leading astronomers have said. The experts say the most likely explanation for certain features of the 67P/Churyumov-Gerasimenko comet, such as its organic-rich black crust, is the presence of living organisms beneath an icy surface. Rosetta, the European spacecraft orbiting the comet, is also said to have picked up strange "clusters" of organic material that resemble viral particles. But neither Rosetta nor its lander probe, Philae,...

You may be hearing some exciting news about comet 67P/Churyumov-Gerasimenko, the place where the Philae lander woke up last month. Astronomer and astrobiologist Chandra Wickramasinghe says that the comet's core might harbor singled-celled extremophile life! But while he could be right, you should take his comments with a comet-sized grain of salt. Wickramashinghe and his colleague Max Wallis made a case for a life-filled comet at this year's Royal Astronomical Society's National Astronomy Meeting in Llandudno, Wales. Wickramasinghe's theory is tied mostly to the cosmic ice ball's structure and black crust. According to Wickramasinghe:

On average, each of these quasi-circular holes are as wide as two football fields placed together, and some are as deep as the Washington monument is tall. ... The pits can be found clustered in just a few regions on the comet's surface. There are small groups of them on both the "head" and "body" of the rubber-duck-shaped comet, but nearly all of them appear in the comet's northern hemisphere. Cameras on Rosetta's OSIRIS instrument have spotted dust jets shooting out of some of the deeper depressions, but those that are more shallow do not seem to be active. The...

European scientists are celebrating after receiving a remarkable communication from space. The solar-powered Philae comet probe is sending signals back to earth after seven months of silence. The Philae spacecraft has been in touch with Earth from a speeding comet for the second time since waking up a few days ago, mission control said Monday, and scientists hope to improve communications with the lander by shifting the trajectory of its mother ship. Philae in November became the first spacecraft ever to settle on a comet when it touched down on icy 67P/Churyumov-Gerasimenko, but it managed to send data to Earth...

The comet lander "spoke" for 85 seconds via its orbiter, "Rosetta" The comet lander that went into hibernation last last year has made contact with its team back on Earth, European space officials said on Sunday. In a brief and excited statement, the European Space Agency said the unmanned Philae, which landed on 67P/Churyumov-Gerasimenko in November to become the first spacecraft to touch down on a comet, sent a number of signals via its orbiter (“Rosetta”) to an operations center in Darmstadt, Germany. They were received on June 13 at 10:28 p.m., local time. Dr. Stephan Ulamec, Philae Project Manager...

The lander “spoke” with its team on ground via Rosetta for 85 seconds — its first contact since going into hibernation in November. Signals were received at ESA’s European Space Operations Center in Darmstadt at 4:28 p.m. EDT yesterday June 13. The lander sent more than 300 data packets reporting on its condition as well as information about the comet. ... If coming out of hibernation isn’t surprising enough, it appears Philae has been awake for a while because it included historical data along with its current status in those packets. There are still more than 8000 data packets in...

It’s only a bright dot in a landscape of crenulated rocks, but the Rosetta team thinks it might be Philae, the little comet lander lost since November. The Rosetta and Philae teams have worked tirelessly to search for the lander, piecing together clues of its location after a series of unfortunate events during its planned landing on the surface of Comet 67P/Churyumov-Gerasimenko last November 12. ... Rosetta’s navigation and high-resolution cameras identified the first landing site and also took several pictures of Philae as it traveled above the comet before coming down for a final landing. Magnetic field measurements taken...

Images acquired by the OSIRIS instrument aboard ESA’s Rosetta spacecraft in April 2015 reveal that some of the comet’s dust jets keep on firing even after the Sun has “set” across those regions. This shows that, as the comet continues to approach its August perihelion date, it’s now receiving enough solar radiation to warm deeper subsurface materials. ... Comet 67P and Rosetta (and Philae too!) will come within 185.9 million km of the Sun during perihelion on Aug. 13, 2015 before heading back out into the Solar System.

Rosetta spacecraft has made a very surprising discovery – namely that the molecular breakup mechanism of “water and carbon dioxide molecules spewing from the comet’s surface” into the atmosphere of comet 67P/Churyumov-Gerasimenko is caused by “electrons close to the surface.” The surprising results relating to the emission of the comet coma came from measurements gathered by the probes NASA funded Alice instrument and is causing scientists to completely rethink what we know about the wandering bodies, according to the instruments science team. “The discovery we’re reporting is quite unexpected,” said Alan Stern, principal investigator for the Alice instrument at the...

Scientists from Rosetta’s OSIRIS team have discovered an extraordinary formation on the larger lobe of comet 67P/Churyumov-Gerasimenko in the Aker region. From a group of three boulders the largest one with a diameter of approximately 30 meters stands out: images obtained on 16 September 2014 from a distance of 29 kilometers with the help of Rosetta’s scientific imaging system OSIRIS show it to perch on the rim of a small depression. There seems to be only a very small contact area with the nucleus. Similar geological formations are found also on Earth. So-called balancing rocks touch the underground with only...