I find reading about NASA's various spacecraft always interesting. I just wish I had more time to keep up with the volume of information NASA makes available. This Cassini story is from February and is about the flyby in late Novemver 2009 of Saturn's icy moon Enceladus. I hope you enjoy this story as much as I did. - @dmgerbino

In this unique mosaic image combining high-resolution data from the imaging science subsystem and composite infrared spectrometer aboard NASA's Cassini spacecraft, pockets of heat appear along one of the mysterious fractures in the south polar region of Saturn's moon Enceladus. Image credit: NASA/JPL/GSFC/SWRI/SSI
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Newly released images from last November's swoop over Saturn's icy moon Enceladus by NASA's Cassini spacecraft reveal a forest of new jets spraying from prominent fractures crossing the south polar region and yield the most detailed temperature map to date of one fracture.

The new images from the imaging science subsystem and the composite infrared spectrometer teams also include the best 3-D image ever obtained of a "tiger stripe," a fissure that sprays icy particles, water vapor and organic compounds. There are also views of regions not well-mapped previously on Enceladus, including a southern area with crudely circular tectonic patterns.

The images and additional information are online at http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.

"Enceladus continues to astound," said Bob Pappalardo, Cassini project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "With each Cassini flyby, we learn more about its extreme activity and what makes this strange moon tick."

For Cassini's visible-light cameras, the Nov. 21, 2009 flyby provided the last look at Enceladus' south polar surface before that region of the moon goes into 15 years of darkness, and includes the most detailed look yet at the jets.

Scientists planned to use this flyby to look for new or smaller jets not visible in previous images. In one mosaic, scientists count more than 30 individual geysers, including more than 20 that had not been seen before. At least one jet spouting prominently in previous images now appears less powerful.

"This last flyby confirms what we suspected," said Carolyn Porco, imaging team lead based at the Space Science Institute in Boulder, Colo. "The vigor of individual jets can vary with time, and many jets, large and small, erupt all along the tiger stripes."

Dramatic plumes, both large and small, spray water ice out from many locations along the famed "tiger stripes" near the south pole of Saturn's moon Enceladus. Image credit: NASA/JPL/SSI
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A new map that combines heat data with visible-light images shows a 40-kilometer (25-mile) segment of the longest tiger stripe, known as Baghdad Sulcus. The map illustrates the correlation, at the highest resolution yet seen, between the geologically youthful surface fractures and the anomalously warm temperatures that have been recorded in the south polar region. The broad swaths of heat previously detected by the infrared spectrometer appear to be confined to a narrow, intense region no more than a kilometer (half a mile) wide along the fracture.

In these measurements, peak temperatures along Baghdad Sulcus exceed 180 Kelvin (minus 135 degrees Fahrenheit), and may be higher than 200 Kelvin (minus 100 degrees Fahrenheit). These warm temperatures probably result from heating of the fracture flanks by the warm, upwelling water vapor that propels the ice-particle jets seen by Cassini's cameras. Cassini scientists will be testing this idea by investigating how well the hot spots correspond with the jet sources.

"The fractures are chilly by Earth standards, but they're a cozy oasis compared to the numbing 50 Kelvin (-370 Fahrenheit) of their surroundings," said John Spencer, a composite infrared spectrometer team member based at Southwest Research Institute in Boulder, Colo. "The huge amount of heat pouring out of the tiger stripe fractures may be enough to melt the ice underground. Results like this make Enceladus one of the most exciting places we've found in the solar system."

Some of Cassini's scientists infer that the warmer the temperatures are at the surface, the greater the likelihood that jets erupt from liquid. "And if true, this makes Enceladus' organic-rich, liquid sub-surface environment the most accessible extraterrestrial watery zone known in the solar system," Porco said.

The Nov. 21 flyby was the eighth targeted encounter with Enceladus. It took the spacecraft to within about 1,600 kilometers (1,000 miles) of the moon's surface, at around 82 degrees south latitude.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. The composite infrared spectrometer team is based at NASA's Goddard Space Flight Center, Greenbelt, Md., where the instrument was built.

More details are also available at the imaging team's website http://ciclops.org and the composite infrared spectrometer team's website http://cirs.gsfc.nasa.gov.

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Jia-Rui C. Cook 818-354-0850
Jet Propulsion Laboratory, Pasadena, Calif.
jia-rui.c.cook@jpl.nasa.gov

2010-061

The Mutating Mars Hoax

August 25, 2010:  It spreads, it mutates, it refuses to die.

For the seventh year in a row, the Mars Hoax is infecting email boxes around the world. Passed from one reader to another, the message states that on August 27th Mars will approach Earth and swell to the size of a full Moon. "NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN," the email declares--always in caps.

News flash: It's not true.

Here are the facts. On August 27, 2010, Mars will be 314 million km from Earth, about as far away as it can get. Mars will shine in the western sky after sunset like a tiny red star of ordinary brightness. If you didn't know it was there, you probably wouldn't notice.

The only way to see Mars as large as the full Moon is to board a spaceship.

The origins of the Hoax can be traced back to 2003 when Mars really did swell to unusual proportions. On August 27th of that year, Mars came within 56 million km of Earth—the nearest it has been in 60,000 years. People marveled at the orange brilliance of Mars in the night sky and crowded around telescopes for clear views of the planet's towering volcanoes, ruddy plains and glistening polar ice caps. At the height of the display, Mars was about 75 times smaller than the full Moon.

That's when "the virus" was born.

Someone, somewhere, reasoned as follows: If Mars is 75 times smaller than the Moon, then magnifying it 75 times should make it equal to the Moon. Early versions of the Hoax encouraged readers to get out their telescopes and insert a 75x eyepiece: "At a modest 75 times magnification," the message stated, "Mars will look as big as the full Moon to the naked eye."

Soon, the Hoax was vectoring around the internet, making copies of itself and mutating. Advanced versions of the virus, sleeker and less wordy than its ancestors, omitted the magnification and simply stated, "Mars will look as big as the full Moon to the naked eye!" Before long, the year was omitted, too. August 27, 2003, became August 27, and the Hoax became immortal. Indeed, years of stories contradicting the Hoax have failed to stamp it out. This is the fourth vaccination by Science@NASA alone.

Tolerant readers point out that the Mars Hoax is not really a hoax, because it is not an intentional trick. The original composer probably believed everything he or she wrote in the message. If so, even the name of the Mars Hoax is wrong!

Here's what you should do on August 27th. Go outside at sunset and face west. The bright light you see shining through the twilight is lovely Venus. Grab a pair of binoculars and scan the sky around Venus. A few degrees to the right, you'll come across a little orange star-like object. That is Mars.

Now go back inside and delete that email.

Author: Dr. Tony Phillips | Credit: Science@NASA

For additional information check out Joe Rao's article, Mars Watch: A Complete Viewing Guide on Space.com

A Puzzling Collapse of Earth's Upper Atmosphere

July 15, 2010:  NASA-funded researchers are monitoring a big event in our planet's atmosphere. High above Earth's surface where the atmosphere meets space, a rarefied layer of gas called "the thermosphere" recently collapsed and now is rebounding again.

Layers of Earth's upper atmosphere. Credit: John Emmert/NRL. [larger image]

"This is the biggest contraction of the thermosphere in at least 43 years," says John Emmert of the Naval Research Lab, lead author of a paper announcing the finding in the June 19th issue of the Geophysical Research Letters (GRL). "It's a Space Age record."

The collapse happened during the deep solar minimum of 2008-2009—a fact which comes as little surprise to researchers. The thermosphere always cools and contracts when solar activity is low. In this case, however, the magnitude of the collapse was two to three times greater than low solar activity could explain.

"Something is going on that we do not understand," says Emmert.

The thermosphere ranges in altitude from 90 km to 600+ km. It is a realm of meteors, auroras and satellites, which skim through the thermosphere as they circle Earth. It is also where solar radiation makes first contact with our planet. The thermosphere intercepts extreme ultraviolet (EUV) photons from the sun before they can reach the ground. When solar activity is high, solar EUV warms the thermosphere, causing it to puff up like a marshmallow held over a camp fire. (This heating can raise temperatures as high as 1400 K—hence the name thermosphere.) When solar activity is low, the opposite happens.

Lately, solar activity has been very low. In 2008 and 2009, the sun plunged into a century-class solar minimum. Sunspots were scarce, solar flares almost non-existent, and solar EUV radiation was at a low ebb. Researchers immediately turned their attention to the thermosphere to see what would happen.

These plots show how the density of the thermosphere (at a fiducial height of 400 km) has waxed and waned during the past four solar cycles. Frames (a) and (c) are density; frame (b) is the sun's radio intensity at a wavelength of 10.7 cm, a key indicator of solar activity. Note the yellow circled region. In 2008 and 2009, the density of the thermosphere was 28% lower than expectations set by previous solar minima. Credit: Emmert et al. (2010), Geophys. Res. Lett., 37, L12102.

How do you know what's happening all the way up in the thermosphere?

Emmert uses a clever technique: Because satellites feel aerodynamic drag when they move through the thermosphere, it is possible to monitor conditions there by watching satellites decay. He analyzed the decay rates of more than 5000 satellites ranging in altitude between 200 and 600 km and ranging in time between 1967 and 2010. This provided a unique space-time sampling of thermospheric density, temperature, and pressure covering almost the entire Space Age. In this way he discovered that the thermospheric collapse of 2008-2009 was not only bigger than any previous collapse, but also bigger than the sun alone could explain.

One possible explanation is carbon dioxide (CO₂).

An NCAR video shows how carbon dioxide warms the lower atmosphere, but cools the upper atmosphere. [more]

When carbon dioxide gets into the thermosphere, it acts as a coolant, shedding heat via infrared radiation. It is widely-known that CO₂ levels have been increasing in Earth's atmosphere. Extra CO₂ in the thermosphere could have magnified the cooling action of solar minimum.

"But the numbers don't quite add up," says Emmert. "Even when we take CO₂ into account using our best understanding of how it operates as a coolant, we cannot fully explain the thermosphere's collapse."

According to Emmert and colleagues, low solar EUV accounts for about 30% of the collapse. Extra CO₂ accounts for at least another 10%. That leaves as much as 60% unaccounted for.

In their GRL paper, the authors acknowledge that the situation is complicated. There's more to it than just solar EUV and terrestrial CO₂. For instance, trends in global climate could alter the composition of the thermosphere, changing its thermal properties and the way it responds to external stimuli. The overall sensitivity of the thermosphere to solar radiation could actually be increasing.

"The density anomalies," they wrote, "may signify that an as-yet-unidentified climatological tipping point involving energy balance and chemistry feedbacks has been reached."

Or not.

Important clues may be found in the way the thermosphere rebounds. Solar minimum is now coming to an end, EUV radiation is on the rise, and the thermosphere is puffing up again. Exactly how the recovery proceeds could unravel the contributions of solar vs. terrestrial sources.

"We will continue to monitor the situation," says Emmert.

For more information see Emmert, J. T., J. L. Lean, and J. M. Picone (2010), Record-low thermospheric density during the 2008 solar minimum, Geophys. Res. Lett., 37, L12102.

Author: Dr. Tony Phillips | Credit: Science@NASA

Enlarge

Small Star, Big Finding - A newly discovered super-Earth (illustrated in foreground) orbits a red dwarf star. The planet, GJ 1214b, offers hope that habitable planets will be found, scientists say. Image: David A. Aguilar, CfA

A relatively small planet orbiting a star not far from Earth may be made mostly of water, new observations show.

“This planet is the most Earthlike planet yet discovered,” comments Geoffrey Marcy of the University of California, Berkeley. The observations are reported in the Dec. 17 Nature.

“We’re on the eve of a new phase of exoplanets studies," adds Sara Seager of MIT. "This planet is a harbinger of what’s to come. It’s not just that we can study this one object in more detail. It’s the torch, telling us about this new thing that’s going to happen.”

The planet, called GJ 1214b, is the second super-Earth — a planet with a mass roughly between five and 10 times Earth’s — detected as it crossed in front of its star and the first that is close enough for astronomers to study its atmosphere. It is 6.5 times more massive than Earth and 2.7 times wider.

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This is an amazing discovery. NASA's Kepler telescope is busy finding extrasolar planets orbiting other stars. It is just a matter of time before we find a planet with intelligent life. As of July 3, there are 464 extrasolar planets identified according to The Extrasolar Planets Encyclopaedia.

The rest of the story can be found at Science News.

By Victoria Gill Science reporter, BBC News

The "nanostructure" of tiny rods bends light around a bump in the gold surface

Scientists have created the first device to render an object invisible in three dimensions.

The "cloak", described in the journal Science, hid an object from detection using light of wavelengths close to those that are visible to humans.

Previous devices have been able to hide objects from light travelling in only one direction; viewed from any other angle, the object would remain visible.

This is a very early but significant step towards true invisibility cloaks.

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When I read this I was amazed. I never thought this break through would happen in my lifetime.

Read the rest of the story at the BBC News Site

Tom Keene ( @tomkeene_ ),

Aurora Australis Observed from the International Space Station

Posted June 21, 2010

download large image (334 KB, JPEG) acquired May 29, 2010

Recommend this image

Among the views of Earth afforded astronauts aboard the International Space Station (ISS), surely one of the most spectacular is of the aurora. These ever-shifting displays of colored ribbons, curtains, rays, and spots are most visible near the North (aurora borealis) and South (aurora australis) Poles as charged particles (ions) streaming from the Sun (the solar wind) interact with Earth’s magnetic field.

While aurora are generally only visible close to the poles, severe magnetic storms impacting the Earth’s magnetic field can shift them towards the equator. This striking aurora image was taken during a geomagnetic storm that was most likely caused by a coronal mass ejection from the Sun on May 24, 2010. The ISS was located over the Southern Indian Ocean at an altitude of 350 kilometers (220 miles), with the astronaut observer most likely looking towards Antarctica (not visible) and the South Pole.

The aurora has a sinuous ribbon shape that separates into discrete spots near the lower right corner of the image. While the dominant coloration of the aurora is green, there are faint suggestions of red left of image center. Dense cloud cover is dimly visible below the aurora. The curvature of the Earth’s horizon (the limb) is clearly visible, as is the faint blue line of the upper atmosphere directly above it (at image top center). Several stars appear as bright pinpoints against the blackness of space at image top right.

Auroras happen when ions in the solar wind collide with atoms of oxygen and nitrogen in the upper atmosphere. The atoms are excited by these collisions, and they typically emit light as they return to their original energy level. The light creates the aurora that we see. The most commonly observed color of aurora is green, caused by light emitted by excited oxygen atoms at wavelengths centered at 0.558 micrometers, or millionths of a meter. (Visible light is reflected from healthy (green) plant leaves at approximately the same wavelength.) Red aurora are generated by light emitted at a longer wavelength (0.630 micrometers), and other colors such as blue and purple are also sometimes observed.

Astronaut photograph ISS023-E-58455 was acquired on May 29, 2010, with a Nikon D3 digital camera, and is provided by the ISS Crew Earth Observations experiment and Image Science & Analysis Laboratory, Johnson Space Center. The image was taken by the Expedition 23 crew. The image in this article has been cropped and enhanced to improve contrast. Lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by William L. Stefanov, NASA-JSC.

Instrument: 

ISS - Digital Camera

I stumbled upon this tweet by @SteveLevine1 on Sunday night (5/23/10) claiming that "Amateur skywatchers spot secret space plane". I thought it was a bunch of bull but I clicked on the link anyway.

So what is the Secret Space Plane X-37B? Accoridng to the space.com story, "The reusable X-37B Orbital Test Vehicle 1 was built by Boeing Phantom Works. It is about 29 feet (9 meters) long and has a wingspan of just over 14 feet (4 meters) across. It stands just over 9 1/2 feet (3 meters) tall and weighs nearly 11,000 pounds (about 5,000 kg)." But the really cool fact is that it was designed to stay in space for up to 270 days orbiting the Earth.

If this information was not enough incentive to goto Space.com to read the whole story, then maybe this will: Satellite sleuth Kevin Fetter of Brockville, Ontario, caught this view of the secretive X-37B robotic space plane cruising across the sky during May, 2010. The link for the video is at the bottom of the story.

The amatuer trackers must be having a field day. Thanks to them, we have this great story.

@dmgerbino