In Two Weeks This 50-Meter Asteroid Will Buzz Our Planet

 Asteroid 2012-DA14 will pass Earth closely on Feb. 15, 2013 (NASA)

On February 15 a chunk of rock about 50 meters wide will whiz by Earth at nearly 8 km/s, coming within 27,680 km of our planet’s surface — closer than many weather and communications satellites.

For those of you more comfortable with imperial units, that’s 165 feet wide traveling 17,800 mph coming within 17,200 miles. But regardless whether you prefer meters or miles, in astronomy that’s what’s called a close call.

Scientists stress that there’s no danger of an impact by this incoming asteroid, designated 2012-DA14, but it’s yet another reminder that in our neck of the Solar System we are definitely not alone.

“2012-DA14 will definitely not hit Earth,” says JPL’s near-Earth object specialist Don Yeomans. “The orbit of the asteroid is known well enough to rule out an impact.”

But with 2012-DA14’s upcoming February flyby Yeomans notes, “this is a record-setting close approach.”

The rocky asteroid will come within about 4 Earth radii, which is well within the orbits of geosynchronous satellites. During its closest approach at 19:26 UTC it should be visible in the sky to amateur telescopes (but not the naked eye), becoming as bright as an 7th- or 8th-magnitude star.

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Radar observatories will be watching 2012-DA14 during the days leading up to and following its approach in an attempt to better determine its size, shape and trajectory. NASA’s Goldstone facility will have an eye — er, dish — on DA14, but it won’t be visible to Arecibo. Stay tuned for more info!

Read more about 2012-DA14 on the JPL Near-Earth Object Program page here.

Titan Shines in Latest Cassini Shots

Color-composite raw image of Titan’s southern hemisphere. Note the growing south polar vortex. (NASA/JPL/SSI/Jason Major)

Last Thursday, November 29, Cassini sailed past Titan for yet another close encounter, coming within 1,014 kilometers (603 miles) of the cloud-covered moon in order to investigate its thick, complex atmosphere. Cassini’s Visible and Infrared Mapping Spectrometer (VIMS), Composite Infrared Spectrometer (CIRS) and Imaging Science Subsystems (ISS) instruments were all busy acquiring data on Titan’s atmosphere and surface… here are a couple of color-composites made from raw images captured in visible light channels as well as some of the more interesting monochrome raw images. Enjoy!

The structure of Titan’s upper-level hazes, which extend ten times the height of Earth’s atmosphere. (NASA/JPL/SSI)

Cassini captured this view of Titan’s crescent during its approach, from a distance of 193,460 kilometers (NASA/JPL/SSI/Jason Major)

Cassini’s continuum filter (CB3) allows it to image Titan’s surface. The dark areas are vast fields of hydrocarbon sand dunes (NASA/JPL/SSI)

These images have not been validated or calibrated by NASA or the mission team.

Read more about the T-88 flyby here.

On the Edge of Titan

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Here’s a quick look at one of my favorite cosmic photo subjects – the varying layers of atmosphere that enshroud Saturn’s enormous moon Titan. The image above is a color-composite made from three raw images acquired by Cassini during its latest flyby.

On June 7 Cassini approached Titan within 596 miles (959 km) and imaged portions of the moon’s northwest quadrant with its radar instrument, as well as conducted further investigations of areas near the equator where surface changes were detected in 2010.

The image here was assembled from three raw images captured in red, green and blue visible light channels. It reveals some structure in the upper hydrocarbon haze layers that extend upwards above the moon’s opaque orange clouds — reaching 400-500 km in altitude, Titan’s atmosphere is ten times thicker than Earth’s!

The June 6 flyby was the second in a series of passes that will take Cassini into a more inclined orbit, where it will reside for the next three years as it investigates Saturn’s polar regions and obtains better views of its ring system.

Read more about the flyby here.

Image: NASA/JPL/Space Science Institute. Composite by J. Major.

Cassini Captures a Rarely-Seen Moon

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While many of us here on Earth were waiting for the Moon to take a bite out of the Sun this past Sunday, Cassini was doing some moon watching of its own, 828.5 million miles away!

The image above is a color-composite raw image of Methone (pronounced meh-tho-nee), a tiny, egg-shaped moon only 2 miles (3 km) across. Discovered by Cassini in 2004, Methone’s orbit lies between Mimas and Enceladus, at a distance of 120,546 miles (194,000 km) from Saturn — that’s about half the distance between Earth and the Moon.

At an altitude of 1,200 miles (1900 km) this was Cassini’s closest pass ever of Methone, a rare visit that occurred after the spacecraft departed the much larger Tethys.

Along with sister moons Pallene and Anthe, Methone is part of a group called the Alkyonides, named after daughters of the god Alkyoneus in Greek mythology. The three moons may be leftovers from a larger swarm of bodies that entered into orbit around Saturn — or they may be pieces that broke off from either Mimas or Enceladus.

Earlier on Sunday, May 20, Cassini paid a relatively close visit to Tethys (pronounced tee-this), a 662-mile (1065-km) -wide moon made almost entirely of ice. One of the most extensively cratered worlds in the Solar System, Tethys’ surface is dominated by craters of all sizes — from the tiniest to the giant 250-mile (400-km) -wide Odysseus crater — as well as gouged by the enormous Ithaca Chasma, a series of deep valleys running nearly form pole to pole.

Saturn's icy moon Tethys with Ithaca Chasma visible, seen by Cassini on May 20, 2012.
Tethys' rugged and heavily-cratered surface near the terminator
Cassini looks down into the 62 mile (100 km) wide Ithaca Chasma

Cassini passed within 34,000 miles (54,000 km) of Tethys on May 20, before heading to Methone and then moving on to its new path toward Titan, a trajectory that will eventually take it up out of Saturn’s equatorial plane into a more inclined orbit in order to better image details of the rings and  Saturn’s poles.

Read more about this flyby on the Cassini mission site here. and see more raw images straight from the spacecraft on the CICLOPS imaging lab site here.

Image credit: NASA / JPL / Space Science Institute. (Color-composite image edited by J. Major.)

Exploration at its Finest: Cassini Visits Dione

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After completing its most recent flyby of Enceladus, Cassini made a pass by Dione — its final visit of the icy moon for the next three years. Coming within  5,000 miles (8000 km) of Dione on May 2, Cassini captured some fantastic images of the moon’s heavily-cratered and frozen surface. Here’s just a few of the raw images that arrived back here on Earth earlier today:

Crescent-lit Dione, with some reflected light via Saturnshine
A nearly fully-lit Dione, with Saturn's rings in the background
Dione's extensively-cratered limb
Some of Dione's signature "wispy lines", bright icy faces of sheer cliffs now known to be tectonic in origin
A color-composite image of an ancient impact crater on the edge of Dione's Saturn-facing side - this could be from the impact that spun the moon 180 degrees. (NASA/JPL/SSI/J. Major)

698 miles (1123 km) in diameter, Dione orbits Saturn at about the same distance that the Moon orbits Earth. Its composition is two-thirds water ice, which at the incredibly cold temperatures found around Saturn behaves like rock does here on Earth.

 

Cassini won’t visit Dione so closely again until June 2015, after spending three years angled high out of the equatorial plane while it studies Saturn’s rings and polar regions.

As Carolyn Porco, Cassini Imaging Team Leader said today, “This is exploration at its finest. It won’t continue forever. So, enjoy it while it lasts!”

See more on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site here.

Image credits: NASA/JPL/Space Science Institute 

 

Enceladus On Display In Newest Images From Cassini

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The latest images are in from Saturn’s very own personal paparazzi, NASA’s Cassini spacecraft, fresh from its early morning flyby of the ice-spewing moon Enceladus. And, being its last closeup for the next three years, the little moon didn’t disappoint!

The image above is a composite I made from two raw images (this one and this one) assembled to show Enceladus in its crescent-lit entirety with jets in full force. The images were rotated to orient the moon’s southern pole — where the jets originate — toward the bottom.

Cassini was between 72,090 miles (116,000 km) and 90,000 miles (140,000 km) from Enceladus when these images were acquired.

This morning’s E-19 flyby completed a trio of recent close passes by Cassini of the 318-mile (511-km) -wide moon, bringing the spacecraft as low as 46 miles (74 km) above its frozen surface. The goal of the maneuver was to gather data about Enceladus’ internal mass — particularly in the region around its southern pole, where a reservoir of liquid water is thought to reside — and also to look for “hot spots” on its surface that would give more information about its overall energy distribution.

Cassini had previously discovered that Enceladus radiates a surprising amount of heat from its surface, mostly along the “tiger stripe” features — long, deep furrows (sulcae) that gouge its southern hemisphere, they are the source of the water-ice geysers.

Cassini also used the flyby opportunity to study Enceladus’ gravitational field.

By imaging the moon with backlit lighting from the Sun the highly-reflective ice particles in the jets become visible. More direct lighting reduces the jets’ visibility in images, which must be exposed for the natural light of the scene or risk “blowing out” due to Enceladus’ natural high reflectivity.

The images below are raw spacecraft downloads right from the Cassini’s imaging headquarters in Boulder, CO.

Enceladus' geysers in action on May 2, 2012. (NASA/JPL/SSI)
Enceladus sprays ice into the hazy E ring, which orbits Saturn (NASA/JPL/SSI)

Cassini also swung closely by Dione during this morning’s flyby but the images from that encounter aren’t available yet. Stay tuned to Universe Today for more postcards from Saturn!

As always, you can follow along with the ongoing Cassini mission on JPL’s dedicated site here, as well as on the Cassini Imaging Central Laboratory for Operations (CICLOPS) site.

Cassini Slips Through Enceladus’ Spray

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Spray it again, Enceladus! This Saturday the Cassini spacecraft paid another visit to Enceladus, Saturn’s 318-mile-wide moon that’s become famous for its icy geysers.During its latest close pass Cassini got a chance to “taste” Enceladus’ spray using its ion and neutral mass spectrometer, giving researchers more information on what sort of watery environment may be hiding under its frozen, wrinkled surface.

The image above shows a diagonal view of Enceladus as seen from the night side. (The moon’s south pole is aimed at a 45-degree angle to the upper right.) Only by imaging the moon backlit by the Sun can the geysers of fine, icy particles be so well seen.

During the flyby Cassini passed within 46 miles (74 km) of Enceladus’ surface.

This image was captured during the closest approach, revealing the distressed terrain of Enceladus’ south pole. Although a bit blurry due to the motion of the spacecraft, boulders can be made out resting along the tops of high , frozen ridges. (Edited from the original raw image to enhance detail.)

Enceladus' southern fissures, the source of its spray. (NASA/JPL/SSI/J. Major)

This flyby occurred less than three weeks after Cassini’s previous visit to Enceladus. Why pay so much attention to one little moon?

Basically, it’s the one place in our solar system that we know of where a world is spraying its “habitable zone” out into space for us to sample.

“More than 90 jets of all sizes near Enceladus’s south pole are spraying water vapor, icy particles, and organic compounds all over the place,” said Carolyn Porco, planetary scientist and Cassini Imaging science team leader, during a NASA interview in March. “Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth’s oceans.

“In the end, it’s the most promising place I know of for an astrobiology search,” said Porco. (Read the full interview here.)

A crescent-lit Enceladus sprays its "habitable zone" out into space.

Not to be left out, Tethys was also paid a visit by Cassini. The 662-mile-wide moon boasts one of the most extensively cratered surfaces in the Solar System, tied with its sister moons Rhea and Dione. In this raw image captured by Cassini on April 14, we can see some of the moon’s ancient, larger craters, including Melanthius with its enormous central peak.

Saturn's moon Tethys, imaged by Cassini on April 14, 2012.

Cassini passed Tethys at a distance of about 6,000 miles (9000 km) after departing Enceladus. Cassini’s composite infrared spectrometer looked for patterns in Tethys’ thermal signature while other instruments studied the moon’s geology.

Image credits: NASA/JPL/Space Science Institute. See more images from the Cassini mission on the CICLOPS site here.

 

“Snowing Microbes” On Saturn’s Moon?

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Enceladus, Saturn’s 318-mile-wide moon that’s become famous for its ice-spraying southern jets, is on astronomers’ short list of places in our own solar system where extraterrestrial life could be hiding — and NASA’s Cassini spacecraft is in just the right place to try and sniff it out.

On March 27, Cassini came within 46 miles (74 km) of Enceladus’ south pole, the region where the moon’s many active water-ice jets originate from. This was Cassini’s closest pass yet over the southern pole, allowing the spacecraft to use its ion and neutral mass spectrometer — as well as its plasma spectrometer, recently returned to service — to taste the icy spray emanating from deep fissures called “tiger stripes” that scar Enceladus’ surface.

(Fly along with Cassini toward Enceladus’ jets here.)

“More than 90 jets of all sizes near Enceladus’s south pole are spraying water vapor, icy particles, and organic compounds all over the place,” said Carolyn Porco, planetary scientist and Cassini Imaging science team leader. “Cassini has flown several times now through this spray and has tasted it. And we have found that aside from water and organic material, there is salt in the icy particles. The salinity is the same as that of Earth’s oceans.”

In addition to water, salt and organics, there is also a surprising amount of heat — heat generated in part by tidal friction, helping keep Enceladus’ underground water reserves liquid.

“If you add up all the heat, 16 gigawatts of thermal energy are coming out of those cracks,” Porco said.

This creates, in effect, a so-called “Goldilocks zone” of potential habitability orbiting around Saturn… a zone that Cassini has easy access to.

“It’s erupting out into space where we can sample it. It sounds crazy but it could be snowing microbes on the surface of this little world,” Porco said. “In the end, it’s the most promising place I know of for an astrobiology search. We don’t even need to go scratching around on the surface. We can fly through the plume and sample it. Or we can land on the surface, look up and stick our tongues out. And voilà…we have what we came for.”

Cassini's view down into a jetting "tiger stripe" in August 2010

Cassini’s latest results — and images! — from the flyby should be landing on Earth any time now. Stay tuned to Universe Today for more updates on Cassini and Enceladus.

Read more on NASA Science News here.

Image credits: NASA/JPL/SSI.

UPDATE: For images from Cassini’s flyby, showing closeups of Enceladus as well as Dione and Janus, check out the CICLOPS team page here.

Titan’s Colorful Crescent

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Made from one of the most recent Cassini images, this is a color-composite showing a backlit Titan with its dense, multi-layered atmosphere scattering sunlight in different colors. Titan’s atmosphere is made up of methane and complex hydrocarbons and is ten times as thick as Earth’s. It is the only moon in our solar system known to have a substantial atmosphere.

Titan’s high-level hydrocarbon haze is nicely visible as a pale blue band encircling the moon.

Color image of Titan and sister moon Dione, seen by Cassini on Dec. 10. (NASA/JPL/SSI and J. Major)

At 3,200 (5,150 km) miles wide, Titan is one of the largest moons in the solar system – even larger than Mercury. Its thick atmosphere keeps a frigid and gloomy surface permanently hidden beneath opaque clouds of methane and hydrocarbons.

This image was made from three raw images acquired by Cassini on December 13. The raw images were in the red, green and blue visible light channels, and so the composited image you see here approximates true color.

This particular flyby of Titan (designated T-79) gave Cassini’s instruments a chance to examine Titan in many different wavelengths, as well as map its surface and measure its atmospheric temperature. Cassini passed by the giant moon at a distance of about 2,228 miles (3,586 kilometers) traveling 13,000 mph (5.8 km/sec). Read more on the flyby page here.

Credit: NASA / JPL / Space Science Institute. Edited by Jason Major.

See more color-composite images of Titan and other moons of Saturn on my Flickr set here.

NASA Prepares for Asteroid’s Close Pass by Earth

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On Tuesday, November 8, at 6:28 p.m. EST, an asteroid the size of an aircraft carrier will soar past our planet at a distance closer than the Moon… and NASA scientists will be watching!

2005 YU55, a 400-meter (1,300-foot) -wide C-type asteroid, was discovered in December 2005 by Robert McMillan of the Spacewatch Program at the University of Arizona, Tucson. It’s pretty much spherical in shape and dark – darker than charcoal, in fact! Scientists with NASA’s Near-Earth Objects Observation Program will begin tracking it on November 4 using the 70-meter radar telescope at the Deep Space Network in Goldstone, California , as well as with the Arecibo Planetary Radar Facility in Puerto Rico beginning November 8. They will continue tracking 2005 YU55 through November 10.

Animation of 2005 YU55's trajectory on Nov. 8. (NASA/JPL) Click to play.

YU55’s orbit is well understood by scientists. It has come this way before, and although this is the closest it’s come to Earth in at least two centuries it will still be at least 324,600 kilometers (201,700 miles) away at nearest approach. That’s about 85% of the distance to the Moon.

It will approach from the sunward side, making viewing in visible light difficult until after it’s made its closest pass.

Other than the excitement it will most likely cause amongst radar astronomers, 2005 YU55 will have no physical effect on our planet. (There have been some rumors circulating online about this particular asteroid’s upcoming pass, in regards to earthquakes and tidal fluctuations and atmospheric disturbances and other such nonsense… the bottom line is that, like the ill-fated comet Elenin, 2005 YU55 has never been known to pose any threat to Earth.)

“YU55 poses no threat of an Earth collision over, at the very least, the next 100 years,” said Don Yeomans, manager of NASA’s Near-Earth Object Program Office at JPL. “During its closest approach, its gravitational effect on the Earth will be so miniscule as to be immeasurable. It will not affect the tides or anything else.”

The 70m telescope at the Goldstone Deep Space Communications Complex in California's Mojave Desert. (NASA/JPL)

Scientists are very eager though to have a prime opportunity to study this quarter-mile-wide world as it makes its closest pass. The giant telescopes at Goldstone and Arecibo will bounce radar waves off the asteroid, mapping its size and shape, and hopefully obtain some very high-resolution images.

“Using the Goldstone radar operating with the software and hardware upgrades, the resulting images of YU55 could come in with resolution as fine as 4 meters per pixel. We’re talking about getting down to the kind of surface detail you dream of when you have a spacecraft fly by one of these targets.”

– Lance Benner, JPL radio astronomer

Even though YU55 will remain at a safe distance the event is still quite notable. The last time an object this large came so close to Earth was in 1976… and scientists weren’t even aware of it at the time. Luckily we now have programs like the Near-Earth Objects Observations Program – a.k.a. “Spaceguard” –  to identify asteroids like this, hopefully in time to know if they could become a danger to our planet in either the near or distant future.

As of now, no large space rock with Earth’s name on it has been positively identified… but that doesn’t mean there’s nothing out there either. We need to keep diligent, keep looking and, above all, keep funding programs like this. If anything, this pass should serve as a reminder – however harmless – that we certainly are not alone in the solar system!

Read more on the NASA/JPL press release here.

UPDATE: NASA will be holding a live Q&A on 2005 YU55 and other near-Earth objects on November 1 at 2:30 p.m. PDT (5:30 p.m. EDT)… watch live here.