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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Close-up view of Enceladus from Cassini's Aug. 11 flyby. Credit" NASA/JPL
Scientists for the Cassini mission called their flyby of Saturn’s small moon Enceladus on August 11 a “skeet shoot,” partially in honor of the current Olympic games underway, but mostly because the spacecraft would be trying to shoot rapidly at the moon with its array of cameras and scientific instruments. As the images begin to stream back, the scientists are definitely excited about what they’re seeing.
“What a dazzling success!” said Carolyn Porco, the Cassini Imaging Team Leader. “There doesn’t even appear to be any smear.” Scientists compared Cassini’s fast flyby of Enceladus to trying to capture a sharp, unsmeared picture of a roadside billboard about a mile away with a 2,000 mm telephoto lens held out the window of a car moving at 50 mph. The imaging team is still poring over the pictures to see if they were successful in “shooting” their target: the active vent regions on the tiger stripe-like features on the moon’s south pole that create the geysers on Enceladus. But the amazingly clear images show a fractured surface littered with boulders and what Porco said could possibly be ice blocks.
Cassini flew over the surface of Enceladus at tremendous speed; about 18 km/sec (about 40,000 mph), which makes taking clear images very difficult. The imaging team devised a technique of turning the spacecraft while taking pictures in rapid succession, shooting at seven, very high priority surface targets. The suite of images ranged in resolution from 8 to 28 meters/pixel, using exposure times that were long enough to see the surface in the twilight near the terminator yet short enough to avoid smear.
Overview of Cassini's flyby. Credit: NASA/JPL
The tiger stripes, officially called sulci, have been identified by the imaging cameras on earlier flybys of Enceladus as the sources of the jets, and also as the “hot spots” or warmer areas on the moon identified by the Cassini’s Composite Infrared Spectrograph.
Porco said the team still has much work to do to decipher all the information in the images and data from the other instruments. “In this painstaking work, we proceed, step by step, to lay bare those things which hold the greatest promise of comprehension, the greatest significance for piecing together the story of the origins of the bodies in our solar system, our Earth, and indeed ourselves,” she wrote in her blog.
We’ll provide further updates on the flyby images as information becomes available.
The space-time bubble. Unfortunately, quantum physics may have the final word (Michael Alcubierre)
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Standard in almost every Star Trek episode are warp drives and cloaking devices. But in reality these science fiction gadgets defy the laws of physics. Or do they? Different scientists have been working on developing these two devices and they say they are getting closer to actually creating working prototypes. While warp drive won’t be available anytime soon, scientists are gaining a better understanding of how faster-than-light speed could possibly be achieved. And as for cloaking devices, don’t look now, but researchers recently cloaked three-dimensional objects using specially engineered materials that redirects light around objects.
Previously, scientists at the University of California, Berkley were only able to cloak very thin, two dimensional objects. But now, using meta-materials, which are mixtures of metal and circuit board materials such as ceramic, Teflon or fiber composite, scientists have deflected light waves around an object, like water flowing around a smooth rock in a stream. Objects are visible because they scatter the light that strikes them, reflecting some of it back to the eye. But the meta-materials would ward off light, radar or other waves. In effect, it would be a type of optical camouflage.
The research group, led by Xiang Zhang say they are a step closer to being able to render people and objects invisible. Their findings will be released later this week in the journals Nature and Science. The path that light rays would take through a theoretical cloaking device. Credit: John Pendry
Another scientist and one of the leaders in cloaking research is John Pendry, a theoretical physicist at Imperial College, London. It was he who first worked out how a cloak could be built in theory, and then he helped build the first working cloak. Pendry recently submitted an abstract that discusses what he says is a new type of cloak, one that gives all cloaked objects the appearance of a flat conducting sheet. Pendry says this type of cloak has the advantage in that nothing remarkable is required to create the cloak. Pendry said the device could be “made isotropic. It makes broadband cloaking in the optical frequencies one step closer.” This type of cloak seemingly creates a mirage to render an object invisible to the eye. Pendry’s own website says information on his new cloak will be available soon.
While cloaking devices would have military applications, a group of scientists researching warp drives say they just want to have the ability to travel to Earth-like exoplanets, like Gliese 581c to better understand the origin and development of life. “The only way we could realistically visit these worlds in time-frames on the order of a human lifespan would be to develop what has been popularly termed a `warp drive,'” said researchers Gerald Cleaver and Richard Obousy from Baylor University in Texas.
Their work expands on research done by theoretical physicist Michael Alcubierre from the University of Mexico, who in 1994 demonstrated space could be made to move around a spacecraft by `stretching’ space so that space itself would expand behind a hypothetical spacecraft, while contracting in front of the craft, creating the effect of motion. So, the ship itself doesn’t move, but space moves around it.
Their new research tries to take advantage of advances in understanding dark energy and why our universe is ever-expanding in every direction. Comprehending that might give us a leg up in being able to generate an asymmetric bubble around a spacecraft. “If we can understand why spacetime is already expanding, we may be able to use this knowledge to artificially generate an expansion (and contraction) of spacetime,” said Cleaver and Obousy in their abstract.
They propose manipulating the 11th dimension, a special theoretical part of an offshoot of string theory called the “m-theory” to create a bubble of dark energy by shrinking the 11th dimension in front of the ship and expanding it behind.
Obviously, this is highly theoretical, but if it leads researchers to a better understanding of dark energy, so much the better.
There’s one hitch, however. Cleaver and Obousy calculated that the energy needed to distort the space around a spacecraft-sized object is about 10^45 Joules or the total energy of an object the size of Jupiter if all its mass were converted into energy.
This creates a chicken and the egg type of conundrum. Which comes first: understanding dark energy or having the ability to create huge amounts of energy?
But Cleaver and Obousy are upbeat about it all. “This is a hypothetical propulsion device that could theoretically circumvent the traditional limitations of special relativity which restricts spacecraft to sub-light velocities. Any breakthrough in this field would revolutionize space exploration and open the doorway to interstellar travel.”
Hubble's 100,000th Orbit Celebration Image. Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
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This morning at 7:42 EDT, the Hubble Space Telescope completed it’s 100,000th orbit around the Earth. That’s about 4.38 billion kilometers (2.72 billion miles), as it clicks along at 8 km per second (5 miles/s), orbiting Earth once every 90 minutes. Hubble’s been in orbit for over 18 years now, since its launch on the space shuttle Discovery on April 24, 1990. To commemorate occasion, scientists at the Space Telescope Science Institute in Baltimore, Md., released a special image taken with Hubble’s Wide Field Planetary Camera 2 of a nebula near the star cluster NGC 2074 (upper, left) , showing a dazzling region of celestial birth and renewal. And soon, Hubble will have a little renewal of its own, with the upcoming fifth and final servicing mission in October.
In preparation for the STS-125 servicing mission to Hubble, on Friday engineers mated the external tank (ET-127) to the two solid rocket boosters. Things are going well with getting Atlantis ready to go, and NASA is looking at actually moving up the launch date for the mission a few days, from the currently scheduled October 8 to October 2. Read more about the mission here, and interviews with the seven astronauts who will be part of the mission are available to read on that page, or you can watch them on NASA TV this week.
The above image released today shows a firestorm of raw stellar creation, perhaps triggered by a nearby supernova explosion. It lies about 170,000 light-years away near the Tarantula nebula, one of the most active star-forming regions in our Local Group of galaxies. This representative color image was taken just yesterday on August 10, 2008. Red shows emission from sulfur atoms, green from glowing hydrogen, and blue from glowing oxygen.
Hubble remains in orbit without any fuel; it just uses its speed and Earth’s gravity to maintain its circular orbit, and gyroscopes to maintain the correct attitude. The astronauts on Atlantis will make one final mechanic’s check to replace worn gyroscopes, batteries and a fine guidance sensor and to install new instruments to extend Hubble’s vision. These include a new Wide Field Camera 3 and a Cosmic Origins Spectrograph, to observe the light put out by extremely faint, far-away quasars.
Hubble has been an incredible spacecraft that has changed our view of the universe. Happy 100,000th orbit Hubble!
Fireworks at the 2008 Olympics Opening Ceremony. Credit: Clive Rose, Getty Images
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Space and the Olympics might not be synonymous in most people’s minds — although this image of the Opening Ceremony fireworks makes it look like Olympic Stadium is going supernova — but there are a few connections between the two for this year’s Summer Olympics in Beijing, China. Google Earth recently updated the satellite imagery it uses for the Beijing area to provide users with better maps. They also used satellite imagery to create a 3-D tour of all the facilities for the 2008 Olympics (see video below). Other space connections include several space explorers who carried the Olympic torch on its running tour around the world, and NASA space spinoff technology used in some of the clothing and equipment for Olympic use.
The first woman in space, Russian cosmonaut Valentina Tereshkova, one of 80 Russian runners, carried the Olympic torch during its tour of that country in early April. Sheikh Muszaphar Shukor, the first Malaysian in space, ran with the torch along the top of Kuala Lumpur Tower on April 21, just six months after his visit as a “spaceflight participant” to in International Space Station. Fittingly, several Chinese taikonauts carried the torch: Fei Junlong and Nie Haisheng, the two-man crew from China’s second spaceflight, Shenzou 6 ran with the torch when it arrived in China in May. China’s first space explorer, Yang Liwei who flew solo on Shenzou 5 in 2003, carried the torch when it first arrived in Beijing on August 6.
While no US astronauts carried the torch, NASA astronaut Scott Parazynski was at Base Camp when Chinese climbers carried the torch to the summit of Mt. Everest on May 8.
NASA developed “riblet” technology to aid in the aerodynamic properties of airplanes. Riblets are V-shaped grooves with angles that point in the direction of the air flow. They are no bigger than a scratch, and they look like very tiny ribs. Riblets help reduce “skin-friction” drag. But it also helps reduce friction from water, and riblets have been used in rowing shells in the four-oar-with-coxswain category. Swimsuits with riblets have also been used in competition at the Pan American games.
And of course, everyone is probably familiar with the lore that today’s athletic shoes use the same cushioning technology that was developed for the moon boots used in the Apollo missions to the moon.
Images and data from the Mars Reconnaissance Orbiter (MRO) have revealed layers of clay-rich rock that suggests abundant water was once present on Mars. Scientists from the SETI Institute, the Jet Propulsion Laboratory and several universities have been studying data focused on the Mawrth Vallis area on Mars’ northern highland region. This is a heavily cratered, ancient area of the Red Planet whose surface geology resembles a dried-up, river valley through which water may have flowed. While their findings don’t provide evidence for life, it does suggest widespread and long-term liquid water in Mars’ past.
The researchers used the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard MRO to examine infrared light reflected from clays situated in the many-kilometer wide channel of Mawrth Vallis.
The infrared spectra from CRISM show an extensive swath of phyllosilicate-bearing material. This is a type of iron and magnesium-rich clay that forms in liquid water, and can be found on Earth in oceans and river beds. It is familiar to anyone who’s nearly broken a shovel while trying to plant a tree. There is also evidence in the spectra for hydrated silica, which in its pure, clean form is known as opal.
The researchers combined their data on the composition of soils in this region with topographic information collected by MOLA, the Mars Orbiter Laser Altimeter, on board the Mars Global Surveyor spacecraft. They found layered aluminum clays lying on top of hydrated silica and iron/magnesium clays. These clays were likely formed when water came in contact with basalt – which is the dominant component of the Martian highlands, and probably was produced from volcanic ash, which once blanketed the planet.
CRISM image overlayed with MOLA data of Mawrth Vallis. This covers an area about 10 kilometers (6.2 miles) wide. Fe/Mg-phyllosilicate is shown in red, Al-phyllosilicate is shown in blue, hydrated silica and an Fe2+ phase are shown in yellow/green.
“We were surprised by the variety of clay minerals in this region,†says Janice Bishop of the SETI Institute. “But what’s interesting is that we find the same ordering of the clay materials everywhere in Mawrth Vallis. It’s like a layer-cake of clays, one on top of another. All these layers are topped with a ‘frosting’ of lava and dust. We can see the clay layers where an impact crater has carved a hole through the surface or where erosion has exposed them.â€
Since phyllosilicates have been found in a number of outcrops on Mars in CRISM images, these new data suggest that whatever mechanism formed clays at Mawrth Vallis has probably operated over much greater areas of the Red Planet. Alteration by liquid water may have been widespread on early Mars.
Bishop is careful to note that this work is part of the long-term effort to establish just how widespread, and for what period of time, liquid water may have existed on Mars.
“This is not evidence for life,†she notes. “But it does suggest the long-term and common presence of liquid water – and concomitant active chemistry – on the Red Planet in the distant past.â€
Betcha thought I forgot about this week’s “Where In the Universe” challenge. Sorry its late, but summer is the time for vacations and partaking in hobbies like rock hunting and late night stargazing. Here’s an image that might provide the opportunity for both. That’s just a little hint for this week’s challenge. Your mission, should you choose to accept, is to name the location in the universe this image was taken, or maybe in this instance, what this is an image of. Give yourself extra points if you can name the spacecraft responsible for the image (that might be the easy part this week). No peeking below until you make your guess. And to be honest, I should say that this image is part of a larger image, which can be seen below.
image credit: Hubble Space Telescope
In this unusual image, the Hubble Space Telescope captures a rare view of the celestial equivalent of a geode — a gas cavity carved by the stellar wind and intense ultraviolet radiation from a hot young star. The object, called N44F, is being inflated by a torrent of fast-moving particles –a stellar wind –from an exceptionally hot star once buried inside a cold dense cloud. N44F is located about 160,000 light-years in our neighboring dwarf galaxy the Large Magellanic Cloud, in the direction of the southern constellation Dorado.
Real geodes are baseball-sized, hollow rocks that start out as bubbles in volcanic or sedimentary rock. Only when these geodes are split in half by a geologist, do we get a chance to appreciate the inside of the rock cavity that is lined with crystals. In the case of Hubble’s 35 light-year diameter “celestial geode” the transparency of its bubble-like cavity of interstellar gas and dust reveals the treasures of its interior.
Compared with our Sun, the central star in N44F is ejecting more than a 100 million times more mass per second. The hurricane of particles moves much faster at about 4 million miles per hour (7 million kilometers per hour), as opposed to about 0.9 million miles per hour (1.5 million kilometers per hour) for our Sun. Because the bright central star does not exist in empty space but is surrounded by an envelope of gas, the stellar wind collides with this gas, pushing it out, like a snowplow. This forms a bubble, whose striking structure is clearly visible in the crisp Hubble image.
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We humans like to think we’re special, but astronomically speaking we’ve been shot down quite severely and humbly put in our place. We’re not at the center of our solar system, nowhere near the center of our galaxy and certainly not at the center of the universe. But now comes great news for the human psyche from scientists trying to explain solar system formation. As far as solar systems go, we have thought ours was just average and that all solar systems were like ours. But in looking at the 300 plus extrasolar planets that have been discovered and the systems they are in, none so far are anything like our home solar system. In fact, say scientists at Northwestern University, we may be special after all. In a study using computer simulations (this is the week for computer simulations, see here and here), researchers ran more than a hundred simulations, and the results show that the average planetary system’s origin was full of violence and drama but that the formation of something like our solar system required conditions to be “just right” and quite special indeed.
The study illustrates that if early conditions had been just slightly different, very unpleasant things could have happened — like planets being thrown into the sun or jettisoned into deep space. This was the first simulation to model the formation of planetary systems from beginning to end, starting with the generic disk of gas and dust that is left behind after the formation of the central star and ending with a full planetary system.
Before the first exoplanets were discovered in the early 1990’s we only had our own solar system from which to create a model, and astronomers had no reason to think our solar system unusual.
“But we now know that these other planetary systems don’t look like the solar system at all,” said Frederic A. Rasio, a theoretical astrophysicist and professor of physics and astronomy at Northwestern.
“The shapes of the exoplanets’ orbits are elongated, not nice and circular. Planets are not where we expect them to be. Many giant planets similar to Jupiter, known as ‘hot Jupiters,’ are so close to the star they have orbits of mere days. Clearly we needed to start fresh in explaining planetary formation and this greater variety of planets we now see.”
The simulations suggest that an average planetary system’s origin is extremely dramatic. The gas disk that gives birth to the planets also pushes them mercilessly toward the central star, where they crowd together or are engulfed. Among the growing planets, there is cut-throat competition for gas, a chaotic process that produces a rich variety of planet masses.
Also planets orbiting close to each other can create a slingshot encounter that flings the planets elsewhere in the system; occasionally, one is ejected into deep space. Despite its best efforts to kill its offspring, the gas disk eventually is consumed and dissipates, and a young planetary system emerges.
“Such a turbulent history would seem to leave little room for the sedate solar system, and our simulations show exactly that,” said Rasio. “Conditions must be just right for the solar system to emerge.”
Too massive a gas disk, for example, and planet formation is an anarchic mess, producing “hot Jupiters” and noncircular orbits galore. Too low-mass a disk, and nothing bigger than Neptune — an “ice giant” with only a small amount of gas — will grow.
“We now better understand the process of planet formation and can explain the properties of the strange exoplanets we’ve observed,” said Rasio. “We also know that the solar system is special and understand at some level what makes it special.”
“The solar system had to be born under just the right conditions to become this quiet place we see. The vast majority of other planetary systems didn’t have these special properties at birth and became something very different.”
Update: A recorded version of the interview is available here or just listen in the embedded media below.
Nancy will be on the Starlight Zone today at 3:50 Central time (20:50 GMT) for a 5 minute interview with Col Maybury about the new Phobos images from Mars Express. The Starlight Zone is on Australian radio station 2NUR from the Univeristy of Newcastle. Here’s the link to the radio station’s webpage, and to listen live, click on “Listen” link on the left nagivation bar. I’ll also post the link to a recorded version when its available.
Artist concept of Cassini flying by Saturn's moon Enceladus. Image credit: NASA/JPL
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Saturn’s tiny moon Enceladus is of big interest to planetary scientists trying to understand the dynamics of the moon’s geysers and fissures. On August 11, the Cassini spacecraft will swoop by Enceladus for a close flyby, just 50 kilometers (30 miles) from the surface, with the fractures, or “tiger stripes” near the moon’s south pole, where icy jets erupt as the target of study for the Cassini instruments. “Our main goal is to get the most detailed images and remote sensing data ever of the geologically active features on Enceladus,” said Paul Helfenstein, a Cassini imaging team associate at Cornell University in Ithaca, NY. “From this data we may learn more about how eruptions, tectonics, and seismic activity alter the moon’s surface. We will get an unprecedented high-resolution view of the active area immediately following the closest approach.”
Cassini will actually try to see inside one of the fissures in high resolution, which may provide more information on the terrain and depth of the fissures, as well as the size and composition of the ice grains inside. Refined temperature data could help scientists determine if water, in vapor or liquid form, lies close to the surface and better refine their theories on what powers the jets.
Cassini discovered evidence for the geyser-like jets on Enceladus in 2005, finding that the continuous eruptions of ice water create a gigantic halo of ice and gas around Enceladus, which helps supply material to Saturn’s E-ring. Just after closest approach, all of the spacecraft’s cameras — covering infrared wavelengths, where temperatures are mapped, as well as visible light and ultraviolet — will focus on the fissures running along the moon’s south pole. That is where the jets of icy water vapor emanate and erupt hundreds of miles into space. The image resolution will be as fine as 7 meters per pixel (23 feet) and will cover known active spots on three of the prominent “tiger stripe” fractures.
This will be Cassini’s second flyby of Enceladus this year. During the last flyby in March, the spacecraft snatched up precious samples and tasted comet-like organics inside the little moon. Two more Enceladus flybys are coming up in October, and they may bring the spacecraft even closer to the moon. The Oct. 9 encounter is complimentary to the March one, which was optimized for sampling the plume. The Oct. 31 flyby is similar to this August one, and is again optimized for the optical remote sensing instruments.
The Cassini web page has a mission blog that will follow the fly by, and you can also find images and videos as well.
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One of the leading theories for how the universe evolved after the Big Bang is the Cold Dark Matter Theory (CDM). This theory proposes that chilly dark matter moved slowly in the early universe, allowing matter to clump together to form the clusters of galaxies that we see, instead of matter being distributed evenly across the universe. Using the properties of the CDM theory, astronomers recently ran an intensive computer program using one of the world’s most powerful supercomputers to simulate the halo of dark matter that envelopes our galaxy. The simulation revealed dense clumps and streams of the mysterious dark matter lurking within our Milky Way galaxy, including the region of our solar system.
“In previous simulations, this region came out smooth, but now we have enough detail to see clumps of dark matter,” said Piero Madau, professor of astronomy and astrophysics at the University of California, Santa Cruz.
This simulation, detailed in an article in the journal Nature, may help may help scientists figure out what dark matter actually is. So far, it has been detected only through its gravitational effects on stars and galaxies. Another part of the CDM theory says that dark matter consists of weakly interacting massive particles (WIMPs), which can annihilate each other and emit gamma rays when they collide. Gamma rays from dark matter annihilation could be detected by the recently launched Gamma-ray Large Area Space Telescope (GLAST).
“That’s what makes this exciting,” Madau said. “Some of those clumps are so dense they will emit a lot of gamma rays if there is dark matter annihilation, and it might easily be detected by GLAST.”
If so, it would be the first direct detection of WIMPS.
Although the nature of dark matter remains a mystery, it appears to account for about 82 percent of the matter in the universe. The clumps of dark matter created “gravitational well” that draws in ordinary matter, giving rise to galaxies in the centers of dark matter halos.
Using the Jaguar supercomputer at Oak Ridge National Laboratory, the simulation took about one month to run and simulated the distribution of dark matter from for 13.7 billion years – from near the time of the Big Bang until the current epoch. Running on up to 3,000 processors in parallel, the computations used about 1.1 million processor-hours.
