Thursday, June 09, 2005

The Cassini Spacecraft Delivers Again........


These pics are truly just amazing, I can't help but post some more....

One View, Multiple Worlds
June 9, 2005 Full-Res: PIA07518

Three very different worlds crowd the frame in this unique view from the Cassini spacecraft, which although partly overexposed, provides a splendid look at several major targets of interest for the mission.
Titan (at the top) has a thick, hazy atmosphere. Cassini has observed it to be a world where complex geological and atmospheric processes are occurring. At 5,150 kilometers (3,200 miles) across, it is Saturn's largest moon, and is the second largest moon in the solar system, after Jupiter's moon Ganymede (5,262 kilometers, or 3,270 miles across).

Tethys (at the bottom) has been battered by impacts over the eons, and some of its many craters are visible in this image. Tethys (1,071 kilometers, or 665 miles across) is one of Saturn's major icy moons, having a density close to that of water. This moon shows evidence that icy tectonic processes have occurred on its frozen surface, such as the immense canyon system called Ithaca Chasma.

Epimetheus (center) is one of Saturn's "ring moons": small, porous bodies that orbit within or just beyond the rings. Cassini acquired the closest-ever view of cratered Epimetheus (116 kilometers, or 72 miles across) in March, 2005.

Also near center are Saturn's F ring and the outer edge of the A ring to the left. In addition to the F ring's usually bright core, several other ringlets are resolved here, giving the ring a soft, wispy character that shows contrast with the more sharply defined A ring.

Appearances can be deceiving in two dimensional images like this one where it is difficult to tell which objects are in the foreground and which are farther away. In this scene, Tethys is the closest object to Cassini, at 1.2 million kilometers (700,000 miles) away. Epimetheus is on the near side of the rings and is 1.4 million kilometers (900,000 miles) distant. The giant moon Titan is 2.7 million kilometers (1.7 million miles) away, more than twice as far from Cassini as Tethys.

This view is a mosaic of two images taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 19, 2005. The image scale in the scene ranges from 16 kilometers (10 miles) per pixel on Titan to 7 kilometers (4 miles) per pixel on Tethys.


We also have the latest from the Deep Impact Mission, which is now T-minus 24 days before the impactor is released from the main spacecraft.

June 9, 2005


Dolores Beasley
NASA Headquarters, Washington

D.C. Agle
Jet Propulsion Laboratory, Pasadena, Calif.

NEWS RELEASE: 2005-098


After a voyage of 173 days and 431 million kilometers (268 million miles), NASA's Deep Impact spacecraft will get up-close and personal with comet Tempel 1 on July 4 (EDT).

The first of its kind, hyper-speed impact between space-borne iceberg and copper-fortified probe is scheduled for approximately 1:52 a.m. EDT on Independence Day (10:52 p.m. PDT on July 3). The potentially spectacular collision will be observed by the Deep Impact spacecraft, and ground and space-based observatories.

"We are really threading the needle with this one," said Rick Grammier, Deep Impact project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "In our quest of a great scientific payoff, we are attempting something never done before at speeds and distances that are truly out of this world."

During the early morning hours of July 3 (EDT), the Deep Impact spacecraft will deploy a 1-meter-wide (39-inch-wide) impactor into the path of the comet, which is about half the size of Manhattan Island, N.Y. Over the next 22 hours, Deep Impact navigators and mission members located more than 133 million kilometers (83 million miles) away at JPL, will steer both spacecraft and impactor toward the comet. The impactor will head into the comet and the flyby craft will pass approximately 500 kilometers (310 miles) below.

Tempel 1 is hurtling through space at approximately 37,100 kilometers per hour (23,000 miles per hour or 6.3 miles per second). At that speed you could travel from New York to Los Angeles in less than 6.5 minutes. Two hours before impact, when mission events will be happening so fast and so far away, the impactor will kick into autonomous navigation mode. It must perform its own navigational solutions and thruster firings to make contact with the comet.

"The autonav is like having a little astronaut on board," Grammier said. "It has to navigate and fire thrusters three times to steer the wine cask-sized impactor into the mountain-sized comet nucleus closing at 23,000 miles per hour."

The crater produced by the impact could range in size from a large house up to a football stadium, and from two to 14 stories deep. Ice and dust debris will be ejected from the crater, revealing the material beneath. The flyby spacecraft has approximately 13 minutes to take images and spectra of the collision and its result before it must endure a potential blizzard of particles from the nucleus of the comet.

And in case anyone was wondering-

"In the world of science, this is the astronomical equivalent of a 767 airliner running into a mosquito," said Dr. Don Yeomans, a Deep Impact mission scientist at JPL. "The impact simply will not appreciably modify the comet's orbital path. Comet Tempel 1 poses no threat to the Earth now or in the foreseeable future."

However, it sure wouldn't hurt to find out if we ya know, COULD appreciably modify a comet or asteroid if it WAS going to pose a threat to the earth, right?............


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