Enceladus seen by Cassini

(Oct. 19, 2011) — NASA's Cassini mission will take advantage of the position of two of the three stars in Orion's belt when the spacecraft flies by Saturn's moon Enceladus on Wed., Oct. 19. As the hot, bright stars pass behind the moon's icy jets, Cassini's ultraviolet imaging spectrograph will acquire a two-dimensional view of these dramatic plumes of water vapor and icy material erupting from the moon's southern polar region. This flyby is the mission's first-ever opportunity to probe the jets with two stars simultaneously, a dual stellar occultation.

 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. (Credit: NASA/JPL/SSI)

From Cassini's viewpoint, the closest of Orion's stars will appear about 9 miles (15 kilometers) above the moon's limb, or outer edge. The second star will appear higher, about 19 miles (30 kilometers) from the limb. In the foreground will be Enceladus' icy plumes, which extend hundreds of miles into space.

As the spacecraft passes Enceladus, its infrared instruments, cameras and other instruments will also be monitoring activity on the moon. The orbiter will fly within about 765 miles (1,230 kilometers) of Enceladus' surface.

This flyby will provide researchers with new insight into the jets--their content, the speed at which they are travelling and how they vary. It will also provide new information on the famed "tiger stripes" from which the jets erupt. These fissures in Enceladus' surface are the "nozzles" from which the plumes are propelled at supersonic speeds. Knowing more about their structure may help unlock some of the secrets within Enceladus' interior, including the source of the water-rich plumes.

The Cassini mission celebrated the 14th anniversary of the spacecraft's launch last week. Having completed its four-year prime mission in 2008, the mission is now on its second extension, the Cassini Solstice Mission. One of the mission's goals is to provide further information on previous Cassini discoveries, such as lakes on Titan and plumes on Enceladus, first detected by Cassini in 2005.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov/.

More information on the Enceladus flyby, called "E15," is available at: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20111019/

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Molecular Oxygen in Orion Nebula

Oxygen Molecules in the Orion Nebula Astronomers have at last identified the distinct signatures of oxygen molecules in space, using observations made with the Herschel Space Observatory. NASA

Astronomers are finding more and more of life’s key ingredients in deep space, from amino acids to a huge water reservoir, and now molecular oxygen.

Teams working with the Herschel Space Telescope have confirmed finding O₂ in the Orion nebula, the first time scientists have been able to pinpoint the crucial yet simple molecule.

Oxygen is the third-most abundant element in the universe, so surely its molecular form is abundant in space, said Bill Danchi, Herschel program scientist at NASA, in a news release. Individual atoms of oxygen are very common, especially around stars, so it’s sort of odd that scientists have not been able to find large quantities of O₂. They have been using balloons and space- and Earth-based telescopes to hunt for it, but to no avail.

Now Danchi, Paul Goldsmith and other NASA scientists have a new paper that may explain where the O₂ is hiding — locked up in water ice that coats interstellar dust. They found some O₂ in the Orion star-forming region, where starlight probably warmed the dust and released water, which was then converted into oxygen molecules.

The Herschel Space Observatory's large viewing area and powerful infrared detectors were able to detect the O₂.

But the researchers didn’t find very much of it, and still can’t explain where the rest of it is. “The universe still holds many secrets,” Goldsmith said.

Molecular oxygen makes up about 20 percent of the air we breathe on Earth, and is a crucial ingredient for metabolism throughout the animal kingdom. If life forms in other places resemble life forms here, then they, too, might require O₂.

Goldsmith and colleagues plan to keep looking for more O₂ in other star-forming regions.

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Orion Spaceship On Tests

DENVER – A spaceship that could carry the next wave of astronauts to an asteroid or beyond is being prepared for a new round of tests at a Lockheed Martin facility near Denver.

Engineers have attached a launch-abort system to the nose of the capsule and will subject the combined spacecraft to a series of experiments to see if it can withstand the rigors of blastoff, Lockheed Martin said Friday.

              The launch-abort system, essentially a rocket attached to the nose of the capsule, could lift the capsule off its booster rocket and carry it to safety if a problem developed before or during launch.

Lockheed Martin, of Bethesda, Md., is building the capsule, called the Orion Multi-Purpose Crew Vehicle, under a $7.5 billion NASA contract issued in 2006.

             The capsule was originally part of President George W. Bush's $100 billion program to return astronauts to the moon, called Constellation. President Barack Obama canceled the program last year, saying the U.S. would concentrate on developing new rocket technology instead.

             Obama then revived the Orion portion of the program amid criticism that his plan lacked details and put U.S. space leadership at risk.

             Orion doesn't yet have a destination. NASA has said it could service the space station in low Earth orbit or take four astronauts on more distant missions of up to 21 days. Lockheed Martin officials have said Orion could explore the far side of the moon, land humans on asteroids or take them to one of the moons of Mars, where they could control robotic instruments on the surface.

             In the next round of tests, the capsule and launch-abort system will be subjected to sound vibrations at a Lockheed Martin facility in Waterton Canyon south of Denver.

            The 55-foot-tall assembly will be lifted by a crane into a tall, elevator shaft-like chamber. Inside, more than a dozen horns powered by compressed nitrogen will create a thunderous low-pitch noise at 150 decibels. That will trigger vibrations like the ones generated by a launch or deployment of the abort system.

            

       "It sounds like a freight train and a tornado all at once," Lockheed Martin's Paul Sannes.

Instruments on the capsule and abort system will tell engineers how well they hold up.

       The abort system was successfully tested in May 2010 at White Sands Missile Range, N.M. An Orion mock-up was rocketed about a mile into the air at speeds of about 450 mph in just 2.5 seconds. The capsule then deployed parachutes and floated to the ground. It landed about a mile north of the launch site.

After the vibration tests are finished, the spacecraft will be taken to the NASA Langley Research Center in Hampton, Va., for landing tests. It would land in the ocean.

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