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Cassini's First Glimpse of Saturn
EccentricAnomaly writes "The Cassini spacecraft has snapped its first picture of Saturn from 177 million miles away. Cassini is due to arrive at Saturn in July 2004, becoming the first spacecraft to orbit Saturn (Pioneer 11 and Voyagers 1 and 2 just did quick flybys of Saturn). Cassini carries the Huygens probe which will land on Saturn's moon Titan in January 2005."
Yep, way back in 1999.
The lighting of pictures taken in space requires an f stop setting of the camera that makes the stars invisible. Photographs taken of the Saturn don't show stars because the bright light (reflective) of Saturn requires camera settings which make the stars invisible.
All the worlds indeed a
The parent asks about the portion of Cassini's trajectory which passed very close to the Earth. On August 18, 1999, the spacecraft swept past the Earth at a minimum altitude of just over 700 miles. You can read about it here:
http://www.jpl.nasa.gov/releases/99/csearthflyby.h tml
Why fly so close? The JPL team arranged it so that Cassini went past the "back" side of the Earth. The earth circles around the Sun at a pretty good clip (about 30 km/sec). Cassini came towards the Earth from behind in its orbit. The gravitational force of the Earth on the spacecraft pulled it forward, speeding it up as it went by. By the same token, the spacecraft slowed the Earth down a little bit, but by an insignificant amount. This is one of the two sorts of "gravitational slingshot" manuevers the celestial mechanics can use to give spacecraft more speed without using lots of fuel.
Simple analogy: stand on a sidewalk as cars drive past at 30 mph. Just as one car is about to pass you, toss a tennis ball out in front of it. The collision will greatly increase the speed of the tennis ball in the direction of the car's motion (and only very slightly decrease the speed of the car). We can't bounce spacecraft off the Earth in the same way :-), but we can use gravity to pull spacecraft forward in a much gentler manner.
For information on the risks associated with the flyby, please read
http://a188-l009.rit.edu/richmond/answers/cassini. html
Michael Richmond "This is the heart that broke my finger."
mwrsps@rit.edu http://stupendous.rit.edu
That little white pixel is Saturns largest moon Titan - If you read the link you will find that this was a test of the camera (A monochrome camera shot through various color filters) depending on the aperature of the camera, the integration time, and any image processing routines the stars were lost most likely due to the fact that Saturn is such a bright planet - I am sure that if they adjusted the image to see the stars the image of Saturn would be saturated and just a bright blob.
but that -178 Celsius surface temp sure puts a damper on things.
Huygens (Christiaan thereof) was the Dutch physicist/astronomer who came up with the wave theory of light. He also used a telescope to study Saturn's rings and also discovered one of Saturn's many moons. He lived in the 17th century, although I'm not exactly sure of his DOB and DOD, because I'm too lazy to look.
Giovanni Cassini was another who studied the rings of Saturn. He found a division between the rings, aptly named the Cassini Division, and also discovered several (four, I believe) new Saturnian moons.
I'm sure this will help connect Huygens, Cassini, and Saturn.
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RTG (radioisotope thermal generators) are very safe. A rocket that carried one blew up in the 60's. The RTG survived perfectly intact. They are even built better today. You have got to understand that these things are strong. They are designed to withstand reentry, an exploding rocket, and crashing into the ground
If you don't understand any of my sayings, come to me in private and I shall take you in my German mouth.
There used to be plans for a whole set of Europa probes - first an orbiter, then landers to use seismographs to determing the thickness of the crust and whether there's water down there, then eventually a submarine... Sadly, this all seems to have been cancelled.
The NASA page about the Europa project is still there, and loads - momentarily - before redirecting you to their updated site, from which all references to Europa seem to have been expunged...
Incidentally, there might be less confusion if you call them 'Europans' rather than 'Europeans'. There are about half a billion Europeans already, and we don't live anywhere near Jupiter.
Real Daleks don't climb stairs - they level the building.
...stars were lost most likely due to the fact that Saturn is such a bright planet - I am sure that if they adjusted the image to see the stars the image of Saturn would be saturated and just a bright blob.
There's an even more detailed explanation of this phenomenon at the Bad Astronomy web site, in the section where research astronomer and part-time hoax debunker Phil Plait explains in great detail why there are no stars in the pictures from the moon. Plait debunks the Fox TV least-common-denominator showcase "Conspiracy Theory: Did We Land on the Moon?" point by point... too bad the rubes the show was targeted to probably can't figure out that "Internit thang" anyway.
Stressed? Me? Of course not. Stress is what a rubber band feels before it breaks, silly.