Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond.
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China successfully launched its third manned spacecraft today with three astronauts on board. During the mission, they will attempt the country’s first-ever space walk. The Long March II-F rocket carrying the Shenzhou-7 spacecraft blasted off from the Jiuquan Satellite Launch Center in the northwestern Gansu Province at 9:10 p.m. local time. Onboard pilots Zhai Zhigang, Liu Boming and Jing Haipeng are will orbit Earth for three days. The astronauts, called taikonauts, told the ground control center that they felt “physically sound” in the first few minutes of the flight.
Two of the taikonauts will conduct a spacewalk, wearing Chinese-made spacesuits called Feitian which literally means flying in the sky, and is the name of a legendary Buddhist goddess. They will retrieve test samples loaded on the outside of the spacecraft, said Zhou Jianping, chief designer of the country’s manned space project.
“We wish we could fly freely in space just like Feitian on the ancient Buddhist murals, so we gave this name to the homemade spacesuit,” said Zhou. Chinese taikonauts inside Shenzou 7. Credit: Xinhuanet
The third taikonaut will remain inside the pressurized spacecraft, and will wear a Russian Orlan suit.
Other tasks of the Shenzhou-7 crew include the release of a small monitoring satellite and a trial of the data relay of the satellite Tianlian-I.
If successful, the mission would be of great significance to the country’s future plans to build a space lab and a space station, said Zhang Jianqi, deputy chief commander of the manned space project. “China pursues the principle of making peaceful use of space in its exploration and development,” Zhang said, adding the country was willing to carry out various forms of international cooperation in space exploration.
The taikonauts, all 42 years old, are scheduled to land in the central region of north China’s Inner Mongolia Autonomous Region in a re-entry module after their mission is completed
Composite image of the nearby Circinus Galaxy. Credit: X-ray (NASA/CXC/Columbia/F.Bauer et al); Visible light (NASA/STScI/UMD/A.Wilson et al.)
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Back in 2001, astronomer Franz Bauer noticed a bright, variable source in the Circinus spiral galaxy, using NASA’s Chandra X-ray Observatory. Although the source displayed some exceptional properties Bauer and his Penn State colleagues could not identify its nature confidently at the time. But now, seven years later Bauer and his team have confirmed this object was a supernova. By combining online data in the public archives from 18 different ground- and space-based telescopes, one of the nearest supernovae in the last 25 years, SN1996cr, has finally been identified. “It’s a bit of a coup to find SN 1996cr like this, and we could never have nailed it without the serendipitous data taken by all of these telescopes. We’ve truly entered a new era of ‘internet astronomy’,” said Bauer.
Because this object was found in an interesting nearby galaxy, the public archives of these telescopes contained abundant observations. Clues from a spectrum obtained by ESO’s Very Large Telescope led Bauer and his team to start the real detective work of searching through data from various telescopes.
The data show that SN 1996cr is among the brightest supernovae ever seen in radio and X-rays. Visible-light images from the archives of the Anglo-Australian Telescope in Australia show that SN 1996cr exploded sometime between 28 February 1995 and 15 March 1996, but it is the only one of the five nearest supernovae of the last 25 years that was not seen shortly after the explosion.
It also bears many striking similarities to the famous supernova SN 1987A, which occurred in a neighbouring galaxy only 160,000 light-years from Earth. Until now, it was the only known supernova with and X-ray output that increased over time. SN1996cr has the same attributes, but is much brighter.
“This supernova appears to be a wild cousin of SN 1987A,” says Bauer. “The two look alike in many ways, except this newer supernova is intrinsically a thousand times brighter in radio and X-rays.” Two optical imagas show the Circinus galaxy before and after the supernova. Credit: Anglo-Australian Observatory.
The combined data, in conjunction with theoretical work, have led the team to develop a model for the explosion. Before the parent star exploded, it cleared out a large cavity in the surrounding gas, either via a strong wind or from an outburst from the star late in its life. So the blast wave from the explosion itself could expand relatively unimpeded into this cavity. Once the blast wave hit the dense material surrounding SN1996cr, the impact caused the system to glow brightly in X-ray and radio emission. The X-ray and radio emission from SN 1987A is probably fainter because the surrounding material is less compact.
Astronomers think that both SN 1987A and SN 1996cr show evidence for these pre-explosion clear-outs by a star doomed to explode. Having two nearby examples suggests that this type of activity could be relatively common during the death of massive stars.
“Not only does our work suggest that SN 1987A isn’t as unusual as previously thought, but it also teaches us more about the tremendous upheavals that massive stars can undergo over their lifetimes,” said co-author Vikram Dwarkadas of the University of Chicago.
So all you internet astronomers, get out there and start clicking! Who knows what you’ll find.
Christa McAuliffe. Credit: Challenger's Lost Lessons
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Christa McAuliffe’s life tragically ended on January 28th, 1986 when Space Shuttle Challenger exploded 73 seconds after launch, killing all seven crewmembers. She was about to make history, becoming the first teacher in space, giving unique lessons from orbit to students back on Earth. McAuliffe never had the chance to fulfill her dream of teaching from space and in the aftermath of the accident, her lesson plans were filed away by NASA with sadness and grief. The lessons were incomplete, unfinished, and most regrettably, they were never were taught. But now, 22 years later, the lessons are alive again, brought back to life by NASA engineer Jerry Woodfill who says he came across McAuliffe’s lessons by accident.
Woodfill has worked for NASA for 43 years as an electrical engineer. Most notably, he helped design the alarm system for the Apollo program. So, on Apollo 13 when Jim Lovell said, “Houston, we’ve had a problem,” Woodfill was monitoring the spacecraft.
But in 1989 Woodfill joined the New Initiatives Office, where NASA employees were asked to come up with new concepts on how to make NASA information public and easily accessible. This was about the time that PC’s and Macs were becoming popular. Woodfill had the idea of taking NASA resources that were public domain, scanning them and putting them on diskettes. He was especially interested in the educational materials NASA had. “In fact, if I hadn’t been an engineer I probably would have enjoyed being a teacher,” he said. “I like to communicate to children and adults as well, especially about science and the space program.”
Woodfill worked on compiling the NASA educational materials, and created the Space Educator’s Handbook. It was on diskettes and free for teachers. Woodfill put the word out and distributed hundreds of them. This wasn’t his day job, however. At that time he was designing concepts for going to Mars or returning to the moon. But he was able to devote some of his working hours to the New Initiatives program and the Space Educator’s Handbook, although he worked on it on his own time as well. He tried to be innovative. “I tried to create a space education encyclopedia with an attitude,” he said. “There are space comic books and coloring books, all kinds of things you wouldn’t find on an erudite space or astronomy site.”
When the internet came into vogue, Woodfill created a website and put the Space Educator’s Handbook online. He tried to keep things up to date, adding new astronaut biographies and educational materials from the various NASA missions. “All this stuff is owned by the American people who pay their taxes to support NASA,” said Woodfill.
But there were a lot of materials for one man to manage it all. “I had file cabinets full of old materials; astronaut biographies, old Toys in Space information and other things on aviation, etc.,” he said. “So last September (2007) I was thinking after working here 43 years, I should try to straighten things up a bit.”
As Woodfill was going through folder after folder of papers he came across an article about 30 pages long that included a study by an education specialist named Bob Mayfield about the Challenger mission. It proposed how Christa McAuliffe’s eight lessons would be performed on orbit.
Woodfill was intrigued. These papers probably hadn’t seen the light of day for over 20 years.
Christa McAuliffe. Credit: Challenger's Lost Lessons
“This article by Bob Mayfield was descriptions only, no sketches or anything,” said Woodfill. “But it was an excellent narrative. He did a wonderful job of writing this, but I’ve never been able to locate him. He went into great detail to consider how these things would work in Zero G, and how the experiments might affect the environment in the crew cabin – if it would be safe. I was so impressed with it. I thought, I’ve always wanted to do something about the fact that Christa and the crew never got to perform those lessons. Challenger was lost and the lessons were lost, too in that tragedy. I thought it would be wonderful if I could resurrect them in some fashion.”
So Woodfill set to work. As good as Mayfield’s narrative was, it was incomplete without McAuliffe’s input of actually doing the lessons in space. Woodfill was trying to piece everything together into cohesive lesson plans that teachers today could use, but it was difficult. At the end of Mayfield’s article was a list of videos that had been shot of McAuliffe, her backup Barbara Morgan, and Mayfield practicing and choreographing how the lessons would be done.
Woodfill thought the videos might be helpful. He started hunting for them, but had a little trouble. These videos would have been recorded in 1985, and 22 years later Woodfill wasn’t even sure they would still be in NASA’s archives. But after a few days of searching, with the help from various people in several different NASA offices, the videos were found.
They showed McAuliffe, Morgan and Mayfield, as well as some of the crew including pilot Mike Smith, and mission specialist Judy Resnick practicing the experiments. They were just short snippets, shot 20-30 seconds at a time in a shuttle simulator or in a KC-135 spacecraft (the Vomit Comet) that provided short periods of zero G to test out the procedures. Woodfill converted the videos to DVD and went through 2-3 hours of videos frame by frame to sort everything out.
Using the videos, Bob Mayfield’s paper and his own background in education in creating the Space Educator’s Handbook, Woodfill began re-creating the lessons for classroom use. Woodfill worked on the project for three months, 2-4 hours a day, some of it after hours on his own time. “I had a desire to see Christa’s work brought back to life,” he said. “There was pride, but there’s sadness and a real loss comes through because you see the crew and you remember that they didn’t survive. That motivated and drove me. It was kind of heart wrenching to work on it.”
Christa McAuliffe. Credit: Challenger's Lost Lessons
Woodfill said Mayfield’s paper covered about 15-20 per cent of all the information needed. The other 80 per cent Woodfill had to re-create. “Bob had a goal for each lesson, but I had to find the theory behind each lesson and create the materials lists, step by step processes, what the results might be and follow-up questions.
For example in the hydroponics lesson, Mayfield described it, but Woodfill had to go to the video and enlarge the frames and examine it very closely to correlate everything. Woodfill added sketches, and since there weren’t any high resolution photos of McAuliffe practicing her lessons, Woodfill captured a few good screen shots from the videos.
Christa McAuliffe. Credit: Challenger's Lost Lessons
Finally, when Woodfill finished putting everything together, he decided the best place for these lessons would be with the Challenger Learning Center, the educational centers created in memory of the Challenger crew. He sent out the completed lessons to a few of the 50 Challenger Centers, including to Rita Karl, the Director of Educational Programs at the Challenger Learning Center headquarters in Virginia.
“As you can imagine, I’ve been looking for these lessons my entire career,” said Karl, who was familiar with Woodfill from his Space Educator’s Handbook. “For Jerry to actually work with the material that was available and put these lessons together in a way that teachers could use it was really wonderful. As soon as we saw them, we immediately asked if we could host the lessons on our website.”
The lessons are now complete and available on the Challenger Center website for teachers and students around the world to use and experience what McAuliffe undoubtedly wanted to share from space.
“These lessons are really perfect for teachers who are trying to recognize the Teacher in Space mission, both Christa’s and Barbara’s and also for getting kids interested in science, technology, engineering and mathematics,” said Karl. “That’s what the Challenger families intended when they started the Challenger Center. Personally, this is a great moment, as if everything has come full circle to get these lessons available online.”
The Challenger Center recently put out a press release to let teachers know the “Challenger Lost Lessons,” as they are called, are now available. “It’s exciting to see teachers starting to use the lessons, and hopefully by the end of the year we’ll have some really good feedback. My feeling is that Christa’s lessons will be really popular,” said Karl.
Included with the lessons are clips taken from the videos of McAuliffe practicing her lessons from space. Christa McAuliffe practices teaching from space. Credit: Challenger's Lost Lessons
“If you watch the videos, Christa’s personality and her excitement really come through,” said Woodfill. “I got to know her from working with this. You really see what a bright person she was and how innovative she was. You can see all the things she contributed to the performance of the lessons.”
Woodfill says he has received calls and emails from many people, including Barbara Morgan, thanking him for his efforts in bringing back the Lost Lessons. “It’s remarkable that I came across them,” said Woodfill. “I think after the accident, nothing was done with them because Christa never got to teach the lessons from space. But it’s appropriate to do it now, because of the technology available. There’s no way you could have given this kind of treatment of these materials even 15 years ago. But now you can watch the videos and watch Christa perform her lessons. So it does resurrect them, it really does. It’s Christa’s work and it gives honor to her.”
Thanks to Woodfill, McAuliffe’s often-used quote of “I touch the future, I teach” was never more true.
Below is the Challenger Center’s video about the Lost Lessons:
It’s time once again for this week’s Where In The Universe challenge. Take a look at the image above and try to determine where in the universe this image was taken. Give yourself extra points if you can name the spacecraft responsible for taking this image. As always, no peeking below before you make your guess. And comments are welcome if you want to share how well you did!
Make your guess, and then proceed.
This prominent circular feature, known as the Richat Structure, is found on our home planet Earth, in the Sahara Desert. Lots of astronauts have noted it and taken pictures of it because it forms a conspicuous 50-kilometer-wide (30-mile-wide) bullet’s-eye on the otherwise rather featureless expanse of the desert. Initially it was thought to be an impact crater, but it is now known to be an eroded circular anticline (structural dome) of layered sedimentary rocks.
This image was generated from a Landsat satellite image draped over an elevation model produced by the Shuttle Radar Topography Mission (SRTM), so if you said either a satellite or an astronaut took this image, you can consider yourself correct. The view uses a 6-times vertical exaggeration to greatly enhance topographic expression. To give a scale for this image, the height of the mesa ridge in the back center of the view is about 285 meters (about 935 feet) tall. This is a color enhanced image, using both visible and infrared bands, which helps to differentiate bedrock (browns), sand (yellow, some white), minor vegetation in drainage channels (green), and salty sediments (bluish whites). Some shading of the elevation model was included to further highlight the topographic features.
This is quite a striking image from the old home planet.
Sedimentary deposits in Delta Nanedi on Mars. Credit: NASA's HiRISE Camera
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Images of layered sedimentary deposits and deltas on Mars have provided evidence for lakes and flowing rivers that carried eroded material downstream. A team of researchers also believes there is evidence for precipitation in the Red Planet’s past. “For years scientists have been suspecting that the current appearance of the landscape has, in part, been shaped by rivers that cut into the surface,” said Ernst Hauber of the German Aerospace Center. “We can see layered sediments where these valleys open into impact craters. The shape of certain sediments is typical for deltas formed in standing water.” Hauber and his team also believe that surface runoff from rain or snowmelt completes the picture of past water on Mars.
The researchers explored the Xanthe Terra area located near the equator in the Martian highlands using image from four cameras on three different spacecraft; High-Resolution Stereo Camera (HRSC) on board the European Mars Express mission, the Mars Orbiter Camera (MOC) from NASA’s Mars Global Surveyor Mission and the HiRISE and CTX camera experiments on board NASA’s Mars Reconnaissance Orbiter (MRO) mission.
A crater lake and river on the Xanthe Terra region. Credit: ESA/DL
The images paint this picture of Mars’ past: About four billion years ago, there were lakes on the Red Planet which may have been fed by short-lived rivers that were, in turn, fed by precipitation. These lakes filled craters that were formed by the impact of meteorites. Water accumulated in places where rivers broke through the crater rims. Deltas were formed at the mouths of the rivers, similar to how they are formed where rivers flow into lakes or seas on Earth.
Junction of the Nanedi valleys in the Xanthe highlands on Mars. Credit: ESA/DLR/FU Berlin (G. Neukum).
The researchers say were also able to narrow down the period when the craters were filled with lakes by analyzing the distribution of impact craters of different sizes, which gives an indication of the age of a planetary surface. The more craters are counted on a surface, the older the area is. The crater counts revealed that water was flowing through the valleys between about 3.8 and 4 billion years ago.
The valleys themselves could have formed relatively fast, and the deposits could have formed over a period ranging from decades to millennia.
But what led the researchers to surmise that there must have been precipitation on early Mars? “This is actually not at all self-evident: for a long time, scientists have been trying to figure out whether the valleys on Mars were formed by groundwater seepage and headward erosion, or by surface runoff caused by rainfall or snowmelt”, said Hauber. His team believes surface runoff was the cause. “Our findings also point in this direction and we are convinced that both processes have played an important role in Xanthe Terra”.
However, this situation did not last very long. Between 3.5 and 3.8 billion years ago, the precipitation became less intense and the valleys dried up. Erosion on Mars has been minimal ever since, which has contributed to the fact that deposits can still be observed although they should in fact be very susceptible to erosion. Today, Mars is a dry desert planet and water is no longer flowing through its valleys.
Atlantis and Endeavour on pads 39 A and B. Credit: NASA
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Because of delays and complications from Hurricane Ike, the launch date for space shuttle Atlantis’ STS-125 mission to service the Hubble Space Telescope has been delayed four days until Oct. 14 at 10:19 p.m. EDT. The delay is not a surprise. The crew and mission controllers missed out on a week of valuable training time when they were forced to evacuate the Houston area when Hurricane Ike which hit on September 13. “You come to the question of either slipping the launch or cutting out events,” said STS-125 Commander Scott Altman when the crew arrived at Kennedy Space Center on Tuesday to prepare for a launch rehearsal. “All [our training] needs to be done and we have to make it happen before we fly… And that, of course, may mean a bit of a slip.” With Atlantis’ launch delay, subsequently shuttle Endeavour’s STS-126 supply mission to the International Space Station, also will move from Nov. 12 to Nov. 16 at 7:07 p.m. EST.
The astronauts are training for a grueling mission, with five back-to-back spacewalks to install two new science instruments, as well as repair two others and to install six new gyroscopes, six batteries, a fine guidance sensor and insulation.
“The bottom line to me is this mission is really hard,” said John Grunsfeld, lead spacewalker and veteran of two previous Hubble repair missions. “After 109, I thought we’d really maxed out what we could do on a space mission. This time, we’ve added a lot of content with inspections (for the shuttle heat shield). From an EVA standpoint, we’ve gone from doing heart surgery on Hubble to what is comparable to doing brain surgery on Hubble with the instrument repairs. So this is going to be a very complex mission, it’s going to be very hard.” STS-125 crew. Credit: NASA
From left are, Mission Specialist Megan McArthur, Pilot Gregory C. Johnson, Mission Specialist Mike Massimino, Commander Scott Altman and Mission Specialists Andrew Feustel, John Grunsfeld and Michael Good.
Fellow spacewalker Mike Massimino said the crew will do everything they can to be ready, and the short delay will allow the team to be fully prepared. “We’ve been training hard and long and I feel pretty confident we’re going to be able to pull those two repairs off,” he said. “I think we’re ready for them and it’s just to be fresh, have it fresh in your mind, we’re going to hopefully recover those NBL runs and do a little more training in the simulator. But I think we’re as ready as we’re ever going to be to do that. Hopefully it’ll go as we expect it to. There’ll probably be some surprises in there that we didn’t anticipate. But I think we’re going to be ready to react to those as well.”
If the shuttle does indeed launch on Oct. 14, the first spacewalk would be on October 17.
"Headless" after being moved. Credit: NASA/JPL/Caltech/U of AZ
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The robotic arm on NASA’s Phoenix Mars Lander slid a rock out of the way during the mission’s 117th Martian day (Sept. 22, 2008) in order to take a look at the soil underneath the rock, and to see at what depth the subsurface ice was under the rock. The lander’s Surface Stereo Imager took this image later the same day, showing the rock, called “Headless,” after the arm pushed it about 40 centimeters (16 inches) from its previous location. “The rock ended up exactly where we intended it to,” said Matt Robinson of NASA’s Jet Propulsion Laboratory, robotic arm flight software lead for the Phoenix team. And what was underneath the rock? Take a look:
It’s hard to tell, exactly since the ground was disturbed from the moving. Some white material appears to be where the rock used to sit, but the Phoenix science team will have to study the area more closely. Look for official word from the team soon. It looks from this second image as though the thermal and conductivity probe was stuck in the ground a few times around the rock, searching for clues of any water molecules in the soil (look for the two separate marks left by the probe just to the right of the trench.)
RAC (via the SSI). Credit: NASA/JPL/Caltech/U of AZ
Also in recent days, the two Phoenix cameras took portraits of each other. Above is the Robotic Arm Camera (RAC) and below is the the Surface Stereo Imager:
Projection of radio sources onto plane perpendicular to line between Cassini and the centre of Saturn
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While Saturn and its rings are beautiful and wondrous, the sounds of Saturn are eerie and strange. Scientists have been trying to understand the bizarre radio emissions that come from the ringed planet, called the Saturn Kilometric Radiation (SKR). Scientists have used observations from NASA’s Cassini spacecraft build a 3-D picture of these intense radio emissions emanating from Saturn’s magnetic field. The SKR radio emissions are generated by high-energy electrons spiraling around magnetic field lines threaded through Saturn’s auroras.
Previous Cassini observations have shown that the SKR is closely correlated with the intensity of Saturn’s UV aurora and the pressure of the solar wind. “The animation shows radio sources clustered around curving magnetic field lines,” said Dr. Baptiste Cecconi, of LESIA, Observatoire de Paris. “Because the radio signals are beamed out from the source in a cone-shape, we can only detect the sources as Cassini flies through the cone. When Cassini flies at high altitudes over the ring planes, we see the sources clearly clustered around one or two field lines. However, at low latitudes we get more refraction and so the sources appear to be scattered.”
Link to 3-D animation.
The active area of the magnetic field matched up with near-polar latitudes degrees in both the northern and southern hemisphere, the location of Saturn’s UV aurora.
“For the purposes of the model, we’ve imagined a screen that cuts through the middle of Saturn, set up at right-angles to the line between Cassini and the centre of the planet. We’ve mapped the footprints of the radio sources projected onto the screen, which tilts as Cassini moves along its orbital path and its orientation with respect to Saturn changes. We’ve also traced the footprints of the magnetic field lines back to the cloud tops of Saturn,” said Cecconi.
Although there were some minor differences between emissions in the northern and southern hemispheres, the emissions were strongest in the western part of Saturn’ss sunlit hemisphere. This area corresponds to a region of Saturn’s magnetopause where electrons are thought to be accelerated by the interaction of the solar wind and Saturn’s magnetic field.
The measurements were made using Cassini’s Radio and Plasma Wave Science (RPWS) experiment.
Cecconi presented his results at the European Planetary Science Congress on Tuesday, September 23rd.
Just as unseen dark energy is increasing the rate of expansion of the universe, there’s something else out there causing an unexpected motion in distant galaxy clusters. Scientists believe the cause is the gravitational attraction of matter that lies beyond the observable universe, and they are calling it “Dark Flow,” in the vein of two other cosmological mysteries, dark matter and dark energy. “The clusters show a small but measurable velocity that is independent of the universe’s expansion and does not change as distances increase,” said lead researcher Alexander Kashlinsky at NASA’s Goddard Space Flight Center in Greenbelt, Md. “The distribution of matter in the observed universe cannot account for this motion.”
“We never expected to find anything like this,” he said.
Using NASA’s Wilkinson Microwave Anisotropy Probe’s (WMAP) three-year view of the microwave background and a catalog of clusters, the astronomers detected hundreds of galaxy clusters that appear to be carried along by a mysterious cosmic flow. The bulk cluster motions are traveling at nearly 2 million miles per hour. The clusters are heading toward a 20-degree patch of sky between the constellations of Centaurus and Vela.
Several astronomers teamed up to identify some 700 X-ray clusters that exhibited a subtle spectral shift. This sample includes objects up to 6 billion light-years — or nearly half of the observable universe — away.
They found this motion is constant out to at least a billion light-years. “Because the dark flow already extends so far, it likely extends across the visible universe,” Kashlinsky says.
The finding flies in the face of predictions from standard cosmological models, which describe such motions as decreasing at ever greater distances.
Cosmologists view the microwave background – a flash of light emitted 380,000 years after the big bang – as the universe’s ultimate reference frame. Relative to it, all large-scale motion should show no preferred direction.
Big-bang models that include a feature called inflation offer a possible explanation for the flow. Inflation is a brief hyper-expansion early in the universe’s history. If inflation did occur, then the universe we can see is only a small portion of the whole cosmos.
WMAP data released in 2006 support the idea that our universe experienced inflation. Kashlinsky and his team suggest that their clusters are responding to the gravitational attraction of matter that was pushed far beyond the observable universe by inflation. “This measurement may give us a way to explore the state of the cosmos before inflation occurred,” he says.
The next step is to narrow down uncertainties in the measurements. “We need a more accurate accounting of how the million-degree gas in these galaxy clusters is distributed,” says Atrio-Barandela.
“We’re assembling an even larger and deeper catalog of X-ray clusters to better measure the flow,” Ebeling adds. The researchers also plan to extend their analysis by using the latest WMAP results, released in March.
The result will appear in the October 20 edition of Astrophysical Journal Letters, which is available electronically this week.
Saturn’s enigmatic rings may be much older and also much more massive than previously thought, according to a new study. Because Saturn’s rings look so clean and bright, it was thought the rings were younger than the planet itself, which is estimated to be about 4.5 billion years old. But using data from the Cassini spacecraft’s UVIS (Ultraviolet Imaging Spectrograph) instrument, Principal Investigator Dr. Larry Esposito and his team used computer simulations to study colliding particles in Saturn’s rings and their erosion by meteorites. Their results support the possibility that Saturn’s rings formed billions of years ago, perhaps at the time when giant impacts excavated the great basins on the Moon. The findings also suggest that giant exoplanets may also commonly have rings.
“Both Cassini observations and theoretical calculations can allow the rings of Saturn to be billions of years old. This means we humans are not just lucky to see rings around Saturn. This would lead us to expect massive rings also to surround giant planets circling other stars,” said Esposito.
Also, simulations run by Esposito’s colleagues Glen Stewart and Stuart Robbins from the University of Colorado showed that Saturn’s ring particles clump together, meaning previous estimates of the mass might be too low, perhaps by a factor of 3. Saturns rings strip. Credit: NASA/JPL
Meteorites slowly grind and shatter the particles in the ring. Gradually, a layer of dust and fragments builds up and covers each particle, making each particle more massive while “cleaning up” the rings.
Recycling of ring material extends their lifetime and reduces the darkening that was expected previous to this study if the rings were older.
One problem with this proposal for more massive and ancient rings is that the Pioneer 11 space mission to Saturn in 1979 measured the ring mass indirectly by observing charged particles created by cosmic rays bombarding the rings.
“Those mass estimates were similar to the ones from Voyager star occultations, apparently confirming the previous low mass value. However, we now recognize that the charged particles are double-valued. That means they could arise from either a small or large mass. We now see that the larger mass value could be consistent with the underestimates due to ring clumpiness,” said Esposito.
