NASA's Voyager 1 spacecraft has experienced a new "tsunami wave" from the sun as it sails through interstellar space. Such waves are what led scientists to the conclusion, in the fall of 2013, that Voyager had indeed left our sun's bubble, entering a new frontier.
"Normally, interstellar space is like a quiet lake," said Ed Stone of the California Institute of Technology in Pasadena, California, the mission's project scientist since 1972. "But when our sun has a burst, it sends a shock wave outward that reaches Voyager about a year later. The wave causes the plasma surrounding the spacecraft to sing."
Data from this newest tsunami wave generated by our sun confirm that Voyager is in interstellar space -- a region between the stars filled with a thin soup of charged particles, also known as plasma. The mission has not left the solar system -- it has yet to reach a final halo of comets surrounding our sun -- but it broke through the wind-blown bubble, or heliosphere, encasing our sun. Voyager is the farthest human-made probe from Earth, and the first to enter the vast sea between stars.
"All is not quiet around Voyager," said Don Gurnett of the University of Iowa, Iowa City, the principal investigator of the plasma wave instrument on Voyager, which collected the definitive evidence that Voyager 1 had left the sun's heliosphere. "We're excited to analyze these new data. So far, we can say that it confirms we are in interstellar space."
Our sun goes through periods of increased activity, where it explosively ejects material from its surface, flinging it outward. These events, called coronal mass ejections, generate shock, or pressure, waves. Three such waves have reached Voyager 1 since it entered interstellar space in 2012. The first was too small to be noticed when it occurred and was only discovered later, but the second was clearly registered by the spacecraft's cosmic ray instrument in March of 2013.
Cosmic rays are energetic charged particles that come from nearby stars in the Milky Way galaxy. The sun's shock waves push these particles around like buoys in a tsunami. Data from the cosmic ray instrument tell researchers that a shock wave from the sun has hit.
Meanwhile, another instrument on Voyager registers the shock waves, too. The plasma wave instrument can detect oscillations of the plasma electrons.
"The tsunami wave rings the plasma like a bell," said Stone. "While the plasma wave instrument lets us measure the frequency of this ringing, the cosmic ray instrument reveals what struck the bell -- the shock wave from the sun."
This ringing of the plasma bell is what led to the key evidence showing Voyager had entered interstellar space. Because denser plasma oscillates faster, the team was able to figure out the density of the plasma. In 2013, thanks to the second tsunami wave, the team acquired evidence that Voyager had been flying for more than a year through plasma that was 40 times denser than measured before -- a telltale indicator of interstellar space.
Why is it denser out there? The sun's winds blow a bubble around it, pushing out against denser matter from other stars.
Now, the team has new readings from a third wave from the sun, first registered in March of this year. These data show that the density of the plasma is similar to what was measured previously, confirming the spacecraft is in interstellar space. Thanks to our sun's rumblings, Voyager has the opportunity to listen to the singing of interstellar space -- an otherwise silent place.
Voyager 1 and its twin, Voyager 2, were launched 16 days apart in 1977. Both spacecraft flew by Jupiter and Saturn. Voyager 2 also flew by Uranus and Neptune. Voyager 2, launched before Voyager 1, is the longest continuously operated spacecraft and is expected to enter interstellar space in a few years.
JPL, a division of Caltech, built and operates the twin Voyager spacecraft. The Voyagers Interstellar Mission is a part of NASA's Heliophysics System Observatory, sponsored by the Heliophysics Division of NASA's Science Mission Directorate in Washington. NASA's Deep Space Network, managed by JPL, is an international network of antennas that supports interplanetary spacecraft missions and radio and radar astronomy observations for the exploration of the solar system and the universe. The network also supports selected Earth-orbiting missions. The spacecraft's nuclear batteries were provided by the Department of Energy.
For more information on the Voyager mission, visit: http://voyager.jpl.nasa.gov
Monday, 25 August 2014
Titan's Building Blocks Might Pre-date Saturn
A combined NASA and European Space Agency (ESA)-funded study has found firm evidence that nitrogen in the atmosphere of Saturn's moon Titan originated in conditions similar to the cold birthplace of the most ancient comets from the Oort cloud. The finding rules out the possibility that Titan's building blocks formed within the warm disk of material thought to have surrounded the infant planet Saturn during its formation.
The main implication of this new research is that Titan's building blocks formed early in the solar system's history, in the cold disk of gas and dust that formed the sun. This was also the birthplace of many comets, which retain a primitive, or largely unchanged, composition today.
The research, led by Kathleen Mandt of Southwest Research Institute in San Antonio, was published this week in the Astrophysical Journal Letters. Co-authors on the study include colleagues from France's National Center for Scientific Research (CNRS) and Observatoire de Paris.
Nitrogen is the main ingredient in the atmosphere of Earth, as well as on Titan. The planet-sized moon of Saturn is frequently compared to an early version of Earth, locked in a deep freeze.
The paper suggests that information about Titan's original building blocks is still present in the icy moon's atmosphere, allowing researchers to test different ideas about how the moon might have formed. Mandt and colleagues demonstrate that a particular chemical hint as to the origin of Titan's nitrogen should be essentially the same today as when this moon formed, up to 4.6 billion years ago. That hint is the ratio of one isotope, or form, of nitrogen, called nitrogen-14, to another isotope, called nitrogen-15.
The team finds that our solar system is not old enough for this nitrogen isotope ratio to have changed significantly. This is contrary to what scientists commonly have assumed.
"When we looked closely at how this ratio could evolve with time, we found that it was impossible for it to change significantly. Titan's atmosphere contains so much nitrogen that no process can significantly modify this tracer even given more than four billion years of solar system history," Mandt said.
The small amount of change in this isotope ratio over long time periods makes it possible for researchers to compare Titan's original building blocks to other solar system objects in search of connections between them.
As planetary scientists investigate the mystery of how the solar system formed, isotope ratios are one of the most valuable types of clues they are able to collect. In planetary atmospheres and surface materials, the specific amount of one form of an element, like nitrogen, relative to another form of that same element can be a powerful diagnostic tool because it is closely tied to the conditions under which materials form.
The study also has implications for Earth. It supports the emerging view that ammonia ice from comets is not likely to be the primary source of Earth's nitrogen. In the past, researchers assumed a connection between comets, Titan and Earth, and supposed the nitrogen isotope ratio in Titan's original atmosphere was the same as that ratio is on Earth today. Measurements of the nitrogen isotope ratio at Titan by several instruments of the NASA and ESA Cassini-Huygens mission showed that this is not the case -- meaning this ratio is different on Titan and Earth -- while measurements of the ratio in comets have borne out their connection to Titan. This means the sources of Earth's and Titan's nitrogen must have been different.
Other researchers previously had shown that Earth's nitrogen isotope ratio likely has not changed significantly since our planet formed.
"Some have suggested that meteorites brought nitrogen to Earth, or that nitrogen was captured directly from the disk of gas that formed the sun. This is an interesting puzzle for future investigations," Mandt said.
Mandt and colleagues are eager to see whether their findings are supported by data from ESA's Rosetta mission, when it studies comet 67P/ Churyumov-Gerasimenko beginning later this year. If their analysis is correct, the comet should have a lower ratio of two isotopes -- in this case of hydrogen in methane ice -- than the ratio on Titan. In essence, they believe this chemical ratio on Titan is more similar to Oort cloud comets than comets born in the Kuiper Belt, which begins near the orbit of Neptune (67P/ Churyumov-Gerasimenko is a Kuiper Belt comet).
"This exciting result is a key example of Cassini science informing our knowledge of the history of solar system and how the Earth formed," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.
The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington.
Rosetta is an ESA mission with contributions from its member states and NASA. JPL manages the U.S. contribution of the Rosetta mission for NASA's Science Mission Directorate in Washington.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov
The main implication of this new research is that Titan's building blocks formed early in the solar system's history, in the cold disk of gas and dust that formed the sun. This was also the birthplace of many comets, which retain a primitive, or largely unchanged, composition today.
The research, led by Kathleen Mandt of Southwest Research Institute in San Antonio, was published this week in the Astrophysical Journal Letters. Co-authors on the study include colleagues from France's National Center for Scientific Research (CNRS) and Observatoire de Paris.
Nitrogen is the main ingredient in the atmosphere of Earth, as well as on Titan. The planet-sized moon of Saturn is frequently compared to an early version of Earth, locked in a deep freeze.
The paper suggests that information about Titan's original building blocks is still present in the icy moon's atmosphere, allowing researchers to test different ideas about how the moon might have formed. Mandt and colleagues demonstrate that a particular chemical hint as to the origin of Titan's nitrogen should be essentially the same today as when this moon formed, up to 4.6 billion years ago. That hint is the ratio of one isotope, or form, of nitrogen, called nitrogen-14, to another isotope, called nitrogen-15.
The team finds that our solar system is not old enough for this nitrogen isotope ratio to have changed significantly. This is contrary to what scientists commonly have assumed.
"When we looked closely at how this ratio could evolve with time, we found that it was impossible for it to change significantly. Titan's atmosphere contains so much nitrogen that no process can significantly modify this tracer even given more than four billion years of solar system history," Mandt said.
The small amount of change in this isotope ratio over long time periods makes it possible for researchers to compare Titan's original building blocks to other solar system objects in search of connections between them.
As planetary scientists investigate the mystery of how the solar system formed, isotope ratios are one of the most valuable types of clues they are able to collect. In planetary atmospheres and surface materials, the specific amount of one form of an element, like nitrogen, relative to another form of that same element can be a powerful diagnostic tool because it is closely tied to the conditions under which materials form.
The study also has implications for Earth. It supports the emerging view that ammonia ice from comets is not likely to be the primary source of Earth's nitrogen. In the past, researchers assumed a connection between comets, Titan and Earth, and supposed the nitrogen isotope ratio in Titan's original atmosphere was the same as that ratio is on Earth today. Measurements of the nitrogen isotope ratio at Titan by several instruments of the NASA and ESA Cassini-Huygens mission showed that this is not the case -- meaning this ratio is different on Titan and Earth -- while measurements of the ratio in comets have borne out their connection to Titan. This means the sources of Earth's and Titan's nitrogen must have been different.
Other researchers previously had shown that Earth's nitrogen isotope ratio likely has not changed significantly since our planet formed.
"Some have suggested that meteorites brought nitrogen to Earth, or that nitrogen was captured directly from the disk of gas that formed the sun. This is an interesting puzzle for future investigations," Mandt said.
Mandt and colleagues are eager to see whether their findings are supported by data from ESA's Rosetta mission, when it studies comet 67P/ Churyumov-Gerasimenko beginning later this year. If their analysis is correct, the comet should have a lower ratio of two isotopes -- in this case of hydrogen in methane ice -- than the ratio on Titan. In essence, they believe this chemical ratio on Titan is more similar to Oort cloud comets than comets born in the Kuiper Belt, which begins near the orbit of Neptune (67P/ Churyumov-Gerasimenko is a Kuiper Belt comet).
"This exciting result is a key example of Cassini science informing our knowledge of the history of solar system and how the Earth formed," said Scott Edgington, Cassini deputy project scientist at NASA's Jet Propulsion Laboratory, Pasadena, California.
The Cassini-Huygens mission is a cooperative project of NASA, ESA and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington.
Rosetta is an ESA mission with contributions from its member states and NASA. JPL manages the U.S. contribution of the Rosetta mission for NASA's Science Mission Directorate in Washington.
More information about Cassini is available at the following sites:
http://www.nasa.gov/cassini
http://saturn.jpl.nasa.gov
NASA's Mars Curiosity Rover Marks First Martian Year
This map shows in red the route driven by NASA's Curiosity Mars rover from the "Bradbury Landing" location where it landed in August 2012 to nearly the completion of its first Martian year. The white line shows the planned route ahead. The rover's June 18, 2014, location is marked as 663. Credit: NASA/JPL-Caltech/Univ. of Arizona/USGS
One of Curiosity's first major findings after landing on the Red Planet in August 2012 was an ancient riverbed at its landing site. Nearby, at an area known as Yellowknife Bay, the mission met its main goal of determining whether the Martian Gale Crater ever was habitable for simple life forms. The answer, a historic "yes," came from two mudstone slabs that the rover sampled with its drill. Analysis of these samples revealed the site was once a lakebed with mild water, the essential elemental ingredients for life, and a type of chemical energy source used by some microbes on Earth. If Mars had living organisms, this would have been a good home for them.
Other important findings during the first Martian year include:
-- Assessing natural radiation levels both during the flight to Mars and on the Martian surface provides guidance for designing the protection needed for human missions to Mars.
-- Measurements of heavy-versus-light variants of elements in the Martian atmosphere indicate that much of Mars' early atmosphere disappeared by processes favoring loss of lighter atoms, such as from the top of the atmosphere. Other measurements found that the atmosphere holds very little, if any, methane, a gas that can be produced biologically.
-- The first determinations of the age of a rock on Mars and how long a rock has been exposed to harmful radiation provide prospects for learning when water flowed and for assessing degradation rates of organic compounds in rocks and soils.
Curiosity paused in driving this spring to drill and collect a sample from a sandstone site called Windjana. The rover currently is carrying some of the rock-powder sample collected at the site for follow-up analysis.
"Windjana has more magnetite than previous samples we've analyzed," said David Blake, principal investigator for Curiosity's Chemistry and Mineralogy (CheMin) instrument at NASA's Ames Research Center, Moffett Field, California. "A key question is whether this magnetite is a component of the original basalt or resulted from later processes, such as would happen in water-soaked basaltic sediments. The answer is important to our understanding of habitability and the nature of the early-Mars environment."
Preliminary indications are that the rock contains a more diverse mix of clay minerals than was found in the mission's only previously drilled rocks, the mudstone targets at Yellowknife Bay. Windjana also contains an unexpectedly high amount of the mineral orthoclase, a potassium-rich feldspar that is one of the most abundant minerals in Earth's crust that had never before been definitively detected on Mars.
This finding implies that some rocks on the Gale Crater rim, from which the Windjana sandstones are thought to have been derived, may have experienced complex geological processing, such as multiple episodes of melting.
"It's too early for conclusions, but we expect the results to help us connect what we learned at Yellowknife Bay to what we'll learn at Mount Sharp," said John Grotzinger, Curiosity project scientist at the California Institute of Technology, Pasadena. "Windjana is still within an area where a river flowed. We see signs of a complex history of interaction between water and rock."
Curiosity departed Windjana in mid-May and is advancing westward. It has covered about nine-tenths of a mile (1.5 kilometers) in 23 driving days and brought the mission's odometer tally up to 4.9 miles (7.9 kilometers).
Since wheel damage prompted a slow-down in driving late in 2013, the mission team has adjusted routes and driving methods to reduce the rate of damage.
For example, the mission team revised the planned route to future destinations on the lower slope of an area called Mount Sharp, where scientists expect geological layering will yield answers about ancient environments. Before Curiosity landed, scientists anticipated that the rover would need to reach Mount Sharp to meet the goal of determining whether the ancient environment was favorable for life. They found an answer much closer to the landing site. The findings so far have raised the bar for the work ahead. At Mount Sharp, the mission team will seek evidence not only of habitability, but also of how environments evolved and what conditions favored preservation of clues to whether life existed there.
The entry gate to the mountain is a gap in a band of dunes edging the mountain's northern flank that is approximately 2.4 miles (3.9 kilometers) ahead of the rover's current location. The new path will take Curiosity across sandy patches as well as rockier ground. Terrain mapping with use of imaging from NASA's Mars Reconnaissance Orbiter enables the charting of safer, though longer, routes.
The team expects it will need to continually adapt to the threats posed by the terrain to the rover's wheels but does not expect this will be a determining factor in the length of Curiosity's operational life.
"We are getting in some long drives using what we have learned," said Jim Erickson, Curiosity project manager at NASA's Jet Propulsion Laboratory in Pasadena, California. "When you're exploring another planet, you expect surprises. The sharp, embedded rocks were a bad surprise. Yellowknife Bay was a good surprise."
JPL manages NASA's Mars Science Laboratory Project for NASA's Science Mission Directorate at the agency's headquarters in Washington, and built the project's Curiosity rover.
For more information about Curiosity, visit:
http://www.nasa.gov/msl
and
http://mars.jpl.nasa.gov/msl/
You can follow the mission on Facebook at:
http://www.facebook.com/marscuriosity
and on Twitter at:
http://www.twitter.com/marscuriosity.
Saturn Moon Titan's Underground Ocean May Be Super Salty
Video here; http://www.space.com/23947-tour-the-strange-lakes-of-saturn-s-moon-titan-video.html
The subsurface ocean inside Saturn’s largest moon, Titan, could be as salty as any body of water here on Earth, a new study reports.
Gravity data collected by NASA’s Cassini spacecraft suggest that Titan’s ocean must have an extremely high density. Salt water has a higher density than fresh water because the presence of salt adds more mass to a given amount of water.
Researchers think the ocean could be as salty as the Dead Sea of Israel and Jordan, with a high concentration of dissolved salts made of sulfur, sodium and potassium.
This is an extremely salty ocean by Earth standards," study lead author Giuseppe Mitri, from the University of Nantes in France, said in a statement. "Knowing this may change the way we view this ocean as a possible abode for present-day life, but conditions might have been very different there in the past."
The average salt concentration in Earth’s oceans is around 3.5 percent, but parts of the Dead Sea can reach 40 percent salinity.
Titan is surrounded by an ice shell, but below the surface, scientists believe there is an ocean of liquid water that could be just as salty as the Dead Sea.
Cassini collected gravity and topography data during its flybys of Titan over the past 10 years, allowing researchers to create a new model of the structure of the moon’s outer icy shell.
The new model suggests that the thickness of the icy crust varies across the moon’s surface. This means that the ocean underneath is probably in the process of freezing, too. If the ocean is freezing, it would decrease the chances that the ocean could support life, since freezing would limit the exchange of materials between the water and the surface, researchers said.
The new data could also provide some insight into Titan’s unique atmosphere, which is consistently around 5 percent methane. It is still a mystery how Titan maintains methane in its atmosphere since sunlight quickly breaks up the gas.
Scientists believe some kind of natural process must be cycling the methane into the atmosphere; from there, it falls back down to the surface as methane rain, similar to the water cycle on Earth. Since Titan’s surface is mostly frozen, researchers think any methane rising into the atmosphere must be coming from a few scattered unfrozen "hot spots."
The $3.2 billion Cassini mission launched in 1997 and arrived in orbit around Saturn in 2004. The mission also dropped a probe named Huygens onto the surface of Titan in January 2005.
The new study was published July 1 in the journal Icarus
The subsurface ocean inside Saturn’s largest moon, Titan, could be as salty as any body of water here on Earth, a new study reports.
Gravity data collected by NASA’s Cassini spacecraft suggest that Titan’s ocean must have an extremely high density. Salt water has a higher density than fresh water because the presence of salt adds more mass to a given amount of water.
Researchers think the ocean could be as salty as the Dead Sea of Israel and Jordan, with a high concentration of dissolved salts made of sulfur, sodium and potassium.
This is an extremely salty ocean by Earth standards," study lead author Giuseppe Mitri, from the University of Nantes in France, said in a statement. "Knowing this may change the way we view this ocean as a possible abode for present-day life, but conditions might have been very different there in the past."
The average salt concentration in Earth’s oceans is around 3.5 percent, but parts of the Dead Sea can reach 40 percent salinity.
Titan is surrounded by an ice shell, but below the surface, scientists believe there is an ocean of liquid water that could be just as salty as the Dead Sea.
Cassini collected gravity and topography data during its flybys of Titan over the past 10 years, allowing researchers to create a new model of the structure of the moon’s outer icy shell.
The new model suggests that the thickness of the icy crust varies across the moon’s surface. This means that the ocean underneath is probably in the process of freezing, too. If the ocean is freezing, it would decrease the chances that the ocean could support life, since freezing would limit the exchange of materials between the water and the surface, researchers said.
The new data could also provide some insight into Titan’s unique atmosphere, which is consistently around 5 percent methane. It is still a mystery how Titan maintains methane in its atmosphere since sunlight quickly breaks up the gas.
Scientists believe some kind of natural process must be cycling the methane into the atmosphere; from there, it falls back down to the surface as methane rain, similar to the water cycle on Earth. Since Titan’s surface is mostly frozen, researchers think any methane rising into the atmosphere must be coming from a few scattered unfrozen "hot spots."
The $3.2 billion Cassini mission launched in 1997 and arrived in orbit around Saturn in 2004. The mission also dropped a probe named Huygens onto the surface of Titan in January 2005.
The new study was published July 1 in the journal Icarus
Earth's Largest Solar Telescope Takes Awesome, High-Def Images of Sun
See article; http://www.space.com/26343-largest-solar-telescope-sun-video.html?cmpid=557678
'Magic Island' Possibly Seen in Seas of Saturn's Huge Moon Titan
http://www.space.com/26326-peculiar-island-appears-on-saturn-moon-before-and-after-spacecraft-shots-video.html
Scientists may have spotted waves in the seas of Saturn's moon Titan, as depicted in this image.
A mysteriously bright anomaly winked in and out of existence on the seas of Saturn's largest moon, Titan — potentially the first time waves, bubbles or some other unknown features have been seen there, scientists say.
Scientists usually call this spot a "transient feature," but the researchers have playfully dubbed it "Magic Island." Titan, the largest of Saturn's 62 known moons, is 50 percent wider than Earth's moon and 80 percent more massive. You can watch a video about the "Magic Island" on Space.com.
"What I think is really special about Titan is that it has liquid methane and ethane lakes and seas, making it the only other world in the solar system that has stable liquids on its surfaces," lead study author Jason Hofgartner, a planetary scientist at Cornell University,told Space.com. "It not only has lakes and seas, but also rivers and even rain. It has what we call a hydrological cycle, and we can study it as an analog to Earth's hydrological cycle — and it's the only other place we know of where we can do that." [Titan, Saturn's Largest Moon.
Using radar aboard NASA's Cassini spacecraft, Hofgartner and his colleagues peered through Titan's thick, hazy atmosphere to analyze Ligeia Mare, the second-largest sea on Titan. Ligeia Mare is named after one of the Sirens from Greek mythology, and is about 48,650 square miles (126,000 square kilometers) in size, making it larger than North America's Lake Superior.
After the Cassini probe sent data to researchers in July 2013, the researchers flipped between older Titan photos and the newly processed images, to look for any hints of change. This is a long-standing method used to discover asteroids, comets and other worlds.
"With flipping, the human eye is pretty good at detecting change," Hofgartner said in a statement.
Prior to the July 2013 data, the region the scientists analyzed was completely devoid of features, including waves
Titan's seas and lakes are usually pretty dark, Hofgartner said. "The way the radar system works is by transmitting radio beams at Titan, which scatter off its surface and back at the radar system. The seas are normally so flat; all the radar energy is scattered away and doesn't come back to the spacecraft, so the seas appear perfectly dark," he explained.
However, in July 2013, Cassini detected features that are essentially as bright as the surrounding terrain. The anomaly disappeared after subsequent observations.
"These are not stagnant seas — they are not unchanging and constant in state," Hofgartner said. "They are active and do change."
It remains uncertain "precisely what caused this 'magic island' to appear, but we'd like to study it further," Hofgartner said in a statement. He and his colleagues detailed their findings June 22 in the journal Nature Geoscience.
The bright anomaly occupies an area of about 6.2 by 12.4 miles (10 by 20 km), Hofgartner said.
"We don't think this is one large feature, but it is probably broken up into a few features — some no bigger than about 1 km by 1 km [0.6 by 0.6 miles]," Hofgartner said. "However, we do think at least one of them is bigger than 1 km by 1 km."
The researchers do not think this anomaly is an alien creature or spacecraft. Rather, now that Titan's northern hemisphere is entering its summer season, "it's probably receiving enough solar energy to drive winds and power other phenomena," Hofgartner said.
The seas are normally very smooth on Titan, "with features no taller than 1 to 3 millimeters (.04 to 0.12 inches), making them smoother than any natural surface on Earth," Hofgartner said. "This is because the winds on Titan have likely not been strong enough to create waves. Now, however, the winds might be getting stronger, and we might be seeing waves," he added.
Another possibility is that the bright anomaly could represent gases pushing up from the seafloor and rising as bubbles. It could also represent solids becoming buoyant with the onset of warmer temperatures and floating on the surface, or solids that are neither sunken nor floating, but rather suspended in the sea like silt in a delta on Earth. "As summer comes on Titan, we hope to learn more about the seas there," Hofgartner said.
Discovering more about how the seas of Titan work "can help us with future plans to explore Titan," Hofgartner said. "One plan is to put a boat or raft on Titan's seas to study it in more detail, and understanding what processes are happening there now can tell us what instrumentation to bring and also how to improve the safety of the craft as well," he said
A mysteriously bright anomaly winked in and out of existence on the seas of Saturn's largest moon, Titan — potentially the first time waves, bubbles or some other unknown features have been seen there, scientists say.
Scientists usually call this spot a "transient feature," but the researchers have playfully dubbed it "Magic Island." Titan, the largest of Saturn's 62 known moons, is 50 percent wider than Earth's moon and 80 percent more massive. You can watch a video about the "Magic Island" on Space.com.
"What I think is really special about Titan is that it has liquid methane and ethane lakes and seas, making it the only other world in the solar system that has stable liquids on its surfaces," lead study author Jason Hofgartner, a planetary scientist at Cornell University,told Space.com. "It not only has lakes and seas, but also rivers and even rain. It has what we call a hydrological cycle, and we can study it as an analog to Earth's hydrological cycle — and it's the only other place we know of where we can do that." [Titan, Saturn's Largest Moon.
Using radar aboard NASA's Cassini spacecraft, Hofgartner and his colleagues peered through Titan's thick, hazy atmosphere to analyze Ligeia Mare, the second-largest sea on Titan. Ligeia Mare is named after one of the Sirens from Greek mythology, and is about 48,650 square miles (126,000 square kilometers) in size, making it larger than North America's Lake Superior.
After the Cassini probe sent data to researchers in July 2013, the researchers flipped between older Titan photos and the newly processed images, to look for any hints of change. This is a long-standing method used to discover asteroids, comets and other worlds.
"With flipping, the human eye is pretty good at detecting change," Hofgartner said in a statement.
Prior to the July 2013 data, the region the scientists analyzed was completely devoid of features, including waves
Titan's seas and lakes are usually pretty dark, Hofgartner said. "The way the radar system works is by transmitting radio beams at Titan, which scatter off its surface and back at the radar system. The seas are normally so flat; all the radar energy is scattered away and doesn't come back to the spacecraft, so the seas appear perfectly dark," he explained.
However, in July 2013, Cassini detected features that are essentially as bright as the surrounding terrain. The anomaly disappeared after subsequent observations.
"These are not stagnant seas — they are not unchanging and constant in state," Hofgartner said. "They are active and do change."
It remains uncertain "precisely what caused this 'magic island' to appear, but we'd like to study it further," Hofgartner said in a statement. He and his colleagues detailed their findings June 22 in the journal Nature Geoscience.
The bright anomaly occupies an area of about 6.2 by 12.4 miles (10 by 20 km), Hofgartner said.
"We don't think this is one large feature, but it is probably broken up into a few features — some no bigger than about 1 km by 1 km [0.6 by 0.6 miles]," Hofgartner said. "However, we do think at least one of them is bigger than 1 km by 1 km."
The researchers do not think this anomaly is an alien creature or spacecraft. Rather, now that Titan's northern hemisphere is entering its summer season, "it's probably receiving enough solar energy to drive winds and power other phenomena," Hofgartner said.
The seas are normally very smooth on Titan, "with features no taller than 1 to 3 millimeters (.04 to 0.12 inches), making them smoother than any natural surface on Earth," Hofgartner said. "This is because the winds on Titan have likely not been strong enough to create waves. Now, however, the winds might be getting stronger, and we might be seeing waves," he added.
Another possibility is that the bright anomaly could represent gases pushing up from the seafloor and rising as bubbles. It could also represent solids becoming buoyant with the onset of warmer temperatures and floating on the surface, or solids that are neither sunken nor floating, but rather suspended in the sea like silt in a delta on Earth. "As summer comes on Titan, we hope to learn more about the seas there," Hofgartner said.
Discovering more about how the seas of Titan work "can help us with future plans to explore Titan," Hofgartner said. "One plan is to put a boat or raft on Titan's seas to study it in more detail, and understanding what processes are happening there now can tell us what instrumentation to bring and also how to improve the safety of the craft as well," he said
Higgs Boson Confirms Reigning Physics Model Yet Again
For a subatomic particle that remained hidden for nearly 50 years, the Higgs boson is turning out to be remarkably well behaved.
Yet more evidence from the world's largest particle accelerator, the Large Hadron Collider (LHC) in Switzerland, confirms that the Higgs boson particle, thought to explain why other particles have mass, acts just as predicted by the Standard Model, the dominant physics theory that describes the menagerie of subatomic particles that make up the universe.
"This is exactly what we have expected from the Standard Model," said Markus Klute, a physicist at the Massachusetts Institute of Technology and one of the researchers involved in the Higgs search.
The new results show that the Higgs boson decays into subatomic particles that carry matter called fermions — in particular, it decays into a heavier brother particle of the electron called a tau lepton, Klute said. This decay has been predicted by the Standard Model. Even so, the findings are a bit of a disappointment for physicists who were hoping for hints of completely new physics.
On July 4, 2012, scientists at the LHC announced they had found the Higgs boson, an elusive particle first proposed 50 years ago by English physicist Peter Higgs. In Higgs' conception, in the blink after the Big Bang, an energy field, now dubbed the Higgs field, emerged that imparts mass to the subatomic particles that trawl through it. Particles that are "stickier" and slow down more while traversing the field become heavier.
Because subatomic particles are either matter carriers called fermions, such as electrons and protons, or force-carrying particles called bosons, such as photons and gluons, the existence of the Higgs field implied an associated force-carrying particle, called the Higgs boson, which is like a ripple in that field, Klute said.
The 2012 discovery left little doubt that the Higgs boson exists, and Higgs and his colleague, François Englert, won the Nobel Prize for the theory in 2013. But there were still many unanswered questions. Is there one Higgs boson or multiple? If there are multiple, what are their masses? And just how do these different-flavored Higgs behave?
To answer those questions, physicists still had to pore over tons of data from the LHC, which accelerates protons to just below the speed of light, then smashes them together, creating a shower of subatomic particles.
Of the billions of collisions produced by the LHC every second, just a few hundred had the signature energy levels associated with the Higgs boson, Klute said.
When the LHC collaborators analyzed those Higgs events, they found about 6 percent of the elusive particles decayed into tau leptons, Klute told Live Science. And though not unexpected, the new results show no hint of additional Higgs bosons that would lend credence to alternate theories such as supersymmetry, which predicts that every particle currently known has a "superpartner" with slightly different properties.
The idea of the Higgs decaying to tau leptons was somewhat tacked onto the Standard Model after its creation, yet this "ad hoc addition to the Standard model turns out to be how nature does it," Klute said.
But there are still a few pieces left to complete the picture predicted by the Standard Model, said Nitesh Soni, a particle physicist at the University of Adelaide in Australia, who works on a different experiment at the LHC that focuses on similar physics questions.
"The Higgs is predicted to decay into some other particles too, but those have relatively smaller decay rates and higher background" noise, making it too difficult to detect those particles from the current dataset, Soni said.
Though the Standard Model has been stunningly successful at predicting behavior in the subatomic realm, there has to be more to the laws of nature, Klute said.
For instance, the Standard Model can't explain dark matter or the existence of gravity. So the lack of evidence for something new is a little disappointing, Klute said.
"My hope was that we would already find some new physics," Klute said.
But he's not giving up hope yet. The hunt for new particles will continue once the LHC is turned on again at much higher energies in 2015, Klute said.
The new analysis of the LHC data was published yesterday (June 22) in the journal Nature Physics.
Editor's Note: This story was updated to add information on Nitesh Soni's research.
Yet more evidence from the world's largest particle accelerator, the Large Hadron Collider (LHC) in Switzerland, confirms that the Higgs boson particle, thought to explain why other particles have mass, acts just as predicted by the Standard Model, the dominant physics theory that describes the menagerie of subatomic particles that make up the universe.
"This is exactly what we have expected from the Standard Model," said Markus Klute, a physicist at the Massachusetts Institute of Technology and one of the researchers involved in the Higgs search.
The new results show that the Higgs boson decays into subatomic particles that carry matter called fermions — in particular, it decays into a heavier brother particle of the electron called a tau lepton, Klute said. This decay has been predicted by the Standard Model. Even so, the findings are a bit of a disappointment for physicists who were hoping for hints of completely new physics.
On July 4, 2012, scientists at the LHC announced they had found the Higgs boson, an elusive particle first proposed 50 years ago by English physicist Peter Higgs. In Higgs' conception, in the blink after the Big Bang, an energy field, now dubbed the Higgs field, emerged that imparts mass to the subatomic particles that trawl through it. Particles that are "stickier" and slow down more while traversing the field become heavier.
Because subatomic particles are either matter carriers called fermions, such as electrons and protons, or force-carrying particles called bosons, such as photons and gluons, the existence of the Higgs field implied an associated force-carrying particle, called the Higgs boson, which is like a ripple in that field, Klute said.
The 2012 discovery left little doubt that the Higgs boson exists, and Higgs and his colleague, François Englert, won the Nobel Prize for the theory in 2013. But there were still many unanswered questions. Is there one Higgs boson or multiple? If there are multiple, what are their masses? And just how do these different-flavored Higgs behave?
To answer those questions, physicists still had to pore over tons of data from the LHC, which accelerates protons to just below the speed of light, then smashes them together, creating a shower of subatomic particles.
Of the billions of collisions produced by the LHC every second, just a few hundred had the signature energy levels associated with the Higgs boson, Klute said.
When the LHC collaborators analyzed those Higgs events, they found about 6 percent of the elusive particles decayed into tau leptons, Klute told Live Science. And though not unexpected, the new results show no hint of additional Higgs bosons that would lend credence to alternate theories such as supersymmetry, which predicts that every particle currently known has a "superpartner" with slightly different properties.
The idea of the Higgs decaying to tau leptons was somewhat tacked onto the Standard Model after its creation, yet this "ad hoc addition to the Standard model turns out to be how nature does it," Klute said.
But there are still a few pieces left to complete the picture predicted by the Standard Model, said Nitesh Soni, a particle physicist at the University of Adelaide in Australia, who works on a different experiment at the LHC that focuses on similar physics questions.
"The Higgs is predicted to decay into some other particles too, but those have relatively smaller decay rates and higher background" noise, making it too difficult to detect those particles from the current dataset, Soni said.
Though the Standard Model has been stunningly successful at predicting behavior in the subatomic realm, there has to be more to the laws of nature, Klute said.
For instance, the Standard Model can't explain dark matter or the existence of gravity. So the lack of evidence for something new is a little disappointing, Klute said.
"My hope was that we would already find some new physics," Klute said.
But he's not giving up hope yet. The hunt for new particles will continue once the LHC is turned on again at much higher energies in 2015, Klute said.
The new analysis of the LHC data was published yesterday (June 22) in the journal Nature Physics.
Editor's Note: This story was updated to add information on Nitesh Soni's research.
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