First discovered in 2007, “fast radio bursts” continue to defy explanation. These cosmic chirps last for only a thousandth of a second. The characteristics of the radio pulses suggested that they came from galaxies billions of light-years away. However, new work points to a much closer origin – flaring stars within our own galaxy.
“We propose that fast radio bursts aren’t as exotic as astronomers first thought,” says lead author Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA).
Fast radio bursts are both brief and bright, packing a lot of energy into a short time. Only six have been discovered to date, all of them in archival data. Each was detected only once, making follow-up studies difficult.
A detailed analysis of the bursts showed that the pulses passed through a large column of electrons on their way to Earth. If those electrons were spread out across intergalactic space, then the pulses must have crossed billions of light-years. As a result, they would have to come from extremely energetic events. Gamma-ray bursts don’t produce the right radio frequencies, so astronomers looked to other extreme events like the collapse of a neutron star into a black hole.
NASA’s Cassini spacecraft is providing scientists with key clues about Saturn’s moon Titan, and in particular, its hydrocarbon lakes and seas.
Titan is one of the most Earth-like places in the solar system, and the only place other than our planet that has stable liquid on its surface.
Cassini’s recent close flybys are bringing into sharper focus a region in Titan’s northern hemisphere that sparkles with almost all of the moon’s seas and lakes. Scientists working with the spacecraft’s radar instrument have put together the most detailed multi-image mosaic of that region to date. The image includes all the seas and most of the major lakes. Some of the flybys tracked over areas that previously were seen at a different angle, so researchers have been able to create a flyover of the area around Titan’s largest and second largest seas, known as Kraken Mare and Ligeia Mare, respectively, and some of the nearby lakes.
“Learning about surface features like lakes and seas helps us to understand how Titan’s liquids, solids and gases interact to make it so Earth-like,” said Steve Wall, acting radar team lead at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “While these two worlds aren’t exactly the same, it shows us more and more Earth-like processes as we get new views.”
The NASA/ESA Hubble Space Telescope has discovered water vapour erupting from the frigid surface of Jupiter’s moon Europa, in one or more localised plumes near its south pole.
Europa is already thought to harbour a liquid ocean beneath its icy crust, making the moon one of the main targets in the search for habitable worlds away from Earth. This new finding is the first observational evidence of water vapour being ejected off the moon’s surface.
“The discovery that water vapour is ejected near the south pole strengthens Europa’s position as the top candidate for potential habitability,” said lead author Lorenz Roth of the Southwest Research Institute in San Antonio, Texas. “However, we do not know yet if these plumes are connected to subsurface liquid water or not.” The Hubble findings will be published in the 12 December online issue of Science Express, and are being reported today at the meeting of the American Geophysical Union in San Francisco, California, USA.
A new analysis of data from NASA’s Galileo mission has revealed clay-type minerals at the surface of Jupiter’s icy moon Europa that appear to have been delivered by a spectacular collision with an asteroid or comet. This is the first time such minerals have been detected on Europa’s surface. The types of space rocks that deliver such minerals typically also often carry organic materials.
“Organic materials, which are important building blocks for life, are often found in comets and primitive asteroids,” said Jim Shirley, a research scientist at NASA’s Jet Propulsion Laboratory, Pasadena, Calif. Shirley is giving a talk on this topic at the American Geophysical Union meeting in San Francisco on Friday, Dec. 13. “Finding the rocky residues of this comet crash on Europa’s surface may open up a new chapter in the story of the search for life on Europa,” he said.
Many scientists believe Europa is the best location in our solar system to find existing life. It has a subsurface ocean in contact with rock, an icy surface that mixes with the ocean below, salts on the surface that create an energy gradient, and a source of heat (the flexing that occurs as it gets stretched and squeezed by Jupiter’s gravity). Those conditions were likely in place shortly after Europa first coalesced in our solar system.
When NASA’s Juno spacecraft flew past Earth on Oct. 9, 2013, it received a boost in speed of more than 8,800 mph (about 3.9 kilometers per second), which set it on course for a July 4, 2016, rendezvous with Jupiter, the largest planet in our solar system. One of Juno’s sensors, a special kind of camera optimized to track faint stars, also had a unique view of the Earth-moon system. The result was an intriguing, low-resolution glimpse of what our world would look like to a visitor from afar.
“If Captain Kirk of the USS Enterprise said, ‘Take us home, Scotty,’ this is what the crew would see,” said Scott Bolton, Juno principal investigator at the Southwest Research Institute, San Antonio. “In the movie, you ride aboard Juno as it approaches Earth and then soars off into the blackness of space. No previous view of our world has ever captured the heavenly waltz of Earth and moon.”
NASA’s Mars Reconnaissance Orbiter has revealed to scientists slender dark markings — possibly due to salty water – that advance seasonally down slopes surprisingly close to the Martian equator.
“The equatorial surface region of Mars has been regarded as dry, free of liquid or frozen water, but we may need to rethink that,” said Alfred McEwen of the University of Arizona in Tucson, principal investigator for the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera.
Tracking how these features recur each year is one example of how the longevity of NASA orbiters observing Mars is providing insight about changes on many time scales. Researchers at the American Geophysical Union meeting Tuesday in San Francisco discussed a range of current Martian activity, from fresh craters offering glimpses of subsurface ice to multi-year patterns in the occurrence of large, regional dust storms.
Thousands of amateur (ham) radio operators around the world were able to say “Hi” to NASA’s Juno spacecraft Oct. 9 as it swung past Earth on its way to Jupiter.
According to Donald Kirchner, University of Iowa research engineer on Juno and one of the coordinators of the all-volunteer “Say Hi to Juno” project, all licensed amateur radio operators were invited to participate by visiting a website and following posted instructions.
“The idea was to coordinate the efforts of amateur radio operators all over the world, and send a message in Morse code that could be received by the University of Iowa-designed-and-built instrument on the Juno spacecraft,” he says. “We know that over a thousand participated, and probably many more than that.”