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Launching on the shuttle

Video cameras on the boosters and tank, plus a cockpit camera show what the shuttle and its astronauts experience during the trek to space.

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STS-120: In review

The STS-120 crew narrates highlights from its mission that delivered the station's Harmony module and moved the P6 power truss.

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 Mission film

STS-123: TCDT

The STS-123 astronauts complete their countdown dress rehearsal at Kennedy Space Center.

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STS-123: To the pad

Endeavour travels to pad 39A in the overnight hours of Feb. 18 in preparation for liftoff on STS-123.

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Progress docking

The 28th Progress resupply ship launched to the International Space Station successfully docks.

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NASA '09 budget

NASA officials present President Bush's proposed Fiscal Year 2009 budget for the agency.

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Introduction to ATV

Preview the maiden voyage of European's first Automated Transfer Vehicle, named Jules Verne. The craft will deliver cargo to the International Space Station.

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Station repair job

Station commander Peggy Whitson and flight engineer Dan Tani replace a broken solar array drive motor during a 7-hour spacewalk.

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Mercury science

Scientists present imagery and instrument data collected by NASA's MESSENGER spacecraft during its flyby of Mercury.

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Earth science update

NASA leaders discuss the agency's Earth science program and preview major activities planned for 2008, including the launch of three new satellites.

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Cassini to dive into water plume of Saturn moon
NASA/JPL NEWS RELEASE
Posted: March 11, 2008

PASADENA, Calif. - NASA's Cassini spacecraft will make an unprecedented "in your face" flyby of Saturn's moon Enceladus on Wednesday.


This is an artist concept of Cassini flying past Enceladus. Credit: NASA/JPL
 
The spacecraft, orchestrating its closest approach to date, will skirt along the edges of huge Old-Faithful-like geysers erupting from giant fractures on the south pole of Enceladus. Cassini will sample scientifically valuable water-ice, dust and gas in the plume.

The source of the geysers is of great interest to scientists who think liquid water, perhaps even an ocean, may exist in the area. While flying through the edge of the plumes, Cassini will be approximately 200 kilometers (120 miles) from the surface. At closest approach to Enceladus, Cassini will be only 50 kilometers (30 miles) from the moon.

"This daring flyby requires exquisite technical finesse, but it has the potential to revolutionize our knowledge of the geysers of Enceladus. The Cassini mission team is eager to see the scientific results, and so am I," said Alan Stern, associate administrator of NASA's Science Mission Directorate, Washington.

Scientists and mission personnel studying the anatomy of the plumes have found that flying at these close distances poses little threat to Cassini because, despite the high speed of Cassini, the plume particles are small. The spacecraft routinely crosses regions made up of dust-size particles in its orbit around Saturn.

Cassini's cameras will take a back seat on this flyby as the main focus turns to the spacecraft's particle analyzers that will study the composition of the plumes. The cameras will image Enceladus on the way in and out, between the observations of the particle analyzers.

Images will reveal northern regions of the moon previously not captured by Cassini. The analyzers will "sniff and taste" the plume. Information on the density, size, composition and speed of the gas and the particles will be collected.

"There are two types of particles coming from Enceladus, one pure water-ice, the other water-ice mixed with other stuff," said Sascha Kempf, deputy principal investigator for Cassini's Cosmic Dust Analyzer at the Max Planck Institute for Nuclear Physics in Heidelberg, Germany. "We think the clean water-ice particles are being bounced off the surface and the dirty water-ice particles are coming from inside the moon. This flyby will show us whether this concept is right or wrong."

In 2005, Cassini's multiple instruments discovered that this icy outpost is gushing water vapor geysers out to a distance of three times the radius of Enceladus. The moon is only 500 kilometers (310 miles) in diameter, but despite its petite size, it's one of the most scientifically compelling bodies in our solar system. The icy water particles are roughly one ten-thousandth of an inch, or about the width of a human hair. The particles and gas escape the surface at jet speed at approximately 400 meters per second (800 miles per hour). The eruptions appear to be continuous, refreshing the surface and generating an enormous halo of fine ice dust around Enceladus, which supplies material to one of Saturn's rings, the E-ring.

Several gases, including water vapor, carbon dioxide, methane, perhaps a little ammonia and either carbon monoxide or nitrogen gas make up the gaseous envelope of the plume.

"We want to know if there is a difference in composition of gases coming from the plume versus the material surrounding the moon. This may help answer the question of how the plume formed," said Hunter Waite, principal investigator for Cassini's Ion and Neutral Mass Spectrometer at the Southwest Research Institute, San Antonio.

This is the first of four Cassini flybys of Enceladus this year. In June, Cassini completes its prime mission, a four-year tour of Saturn. Cassini's next flyby of Enceladus is planned for August, well into Cassini's proposed extended mission. Cassini will perform seven Enceladus flybys in its extended mission. If this encounter proves safe, future passes may bring the spacecraft even closer than this one. How close Cassini will be allowed to approach will be determined based on data from this flyby.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the Cassini-Huygens mission for NASA's Science Mission Directorate. The Cassini orbiter was designed, developed and assembled at JPL.


This graphic shows the trajectory for the Cassini spacecraft during its close brush with the icy outpost of Enceladus on March 12. Credit: NASA/JPL
 

STS-134 Patch

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The final planned flight of space shuttle Endeavour is symbolized in the official embroidered crew patch for STS-134. Available in our store!
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Final Shuttle Mission Patch

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The crew emblem for the final space shuttle mission is now available in our store. Get this piece of history!
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Apollo Collage
This beautiful one piece set features the Apollo program emblem surrounded by the individual mission logos.
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STS-133 Patch

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The final planned flight of space shuttle Discovery is symbolized in the official embroidered crew patch for STS-133. Available in our store!
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Anniversary Shuttle Patch

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This embroidered patch commemorates the 30th anniversary of the Space Shuttle Program. The design features the space shuttle Columbia's historic maiden flight of April 12, 1981.
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Mercury anniversary

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Celebrate the 50th anniversary of Alan Shephard's historic Mercury mission with this collectors' item, the official commemorative embroidered patch.
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