Cassini missie // Saturnus in de picture

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Cassini-Huygens approaching Saturn and Titan
26 May 2004



ESA PR 28-2004. Launched in October 1997, the ESA/NASA Cassini-Huygens mission is currently heading for Saturn. While ESA’s Huygens probe will be the first ever to land on the surface of a moon in the outer Solar System, NASA’s Cassini orbiter will continue to explore Saturn and its rings.

After an almost seven-year journey and four gravity-assist swing-by manoeuvres the spacecraft will be inserted into its orbit around Saturn on 30 June (Pacific Daylight Time, 1 July CET) and reach its closest approach to Saturn. The Huygens probe will be detached from its mother ship on 25 December and land on Titan in January next year.
On 3 June a press conference will take place at NASA Headquarters, Washington, with ESA participation, to present the mission and outline milestones and upcoming media activities.

Media representatives can follow this press conference from ESA/ESOC, where several project representatives will be present, together with David Southwood, ESA Director of Science, or from one of the other ESA establishments. They are requested to complete the attached reply form and fax it to the Communication office at the establishment of their choice.

The ESA TV service will also broadcast the press conference via Eutelsat W1. Further information concerning the retransmission schedule can be found on http://television.esa.int.

Note to editors:

The Cassini-Huygens mission is a cooperation between NASA, the European Space Agency and ASI, the Italian space agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, is managing the mission for NASA’s Office of Space Science, Washington.

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Op donderdag 27 mei 2004 20:05 schreef Pinobot het volgende:
Kicke, Mimas lijkt op de Deathstar.

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Op woensdag 2 juni 2004 04:16 schreef k3vil het volgende:

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Zij bevinden zich natuurlijk niet allemaal op dezelfde afstand van Saturnus. Overigens moet je niet vergeten dat de ringen van Saturnus vol met andere natuurlijke satelieten zitten. Dat vergeet men nog wel eens, dat het immers net zoals die manen ook satalieten zijn

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Op donderdag 27 mei 2004 20:05 schreef Pinobot het volgende:
Kicke, Mimas lijkt op de Deathstar.

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Op maandag 14 juni 2004 23:26 schreef -CRASH- het volgende:

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En nog meer
Die rotsblokken in de krater
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[afbeelding]

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Op vrijdag 25 juni 2004 11:28 schreef pfaf het volgende:
Wat een wonderschone foto.

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Op dinsdag 29 juni 2004 20:58 schreef motown het volgende:
Spannend!

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Op donderdag 1 juli 2004 09:55 schreef zakjapannertje het volgende:

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http://www.hbvl.be/nieuws(...)E-834D-BDDC77CE605C}

's middags dus mogelijk de eerste beelden

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Last night, Cassini-Huygens approached Saturn from below the plane of its rings. Using its high-gain antenna dish as a shield to protect its fragile body from dust impacts, it first crossed the ring plane at 02:03 UT, some 158 500 kilometres from the centre of Saturn, in the gap that separates the F-ring from the G-ring. About 25 minutes later, at 02:36 UT, the probe fired one of its twin main engines for a 96-minute burn to enter orbit. The signal confirming this ignition took 84 minutes to reach Earth, some 1500 million kilometres from Saturn.

The burn went smoothly and reduced Cassini-Huygens’ relative velocity to Saturn while the probe passed only 19 000 kilometres from the planet’s upper clouds. After completion of the burn, the probe was tilted first toward Earth to confirm insertion and then toward Saturn’s rings in order to take close-up pictures as it flew only a few thousand kilometres above them. This was a unique opportunity to attempt to discriminate individual components within the rings, as Cassini is not planned to come this close to them again. The orbiter’s instruments also took advantage of its proximity to the planet to make an in-depth study of its atmosphere and environment.

A second crossing of the ring plane took place at 05:50 UT.

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Op donderdag 1 juli 2004 15:04 schreef pfaf het volgende:
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After becoming the first spacecraft to enter Saturn's orbit, Cassini sent back this image of a portion of the planet's rings. It was taken by the spacecraft's narrow angle camera and shows the dark, or unlit, side of the rings.

Image credit: NASA/JPL

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Op donderdag 1 juli 2004 21:05 schreef whosvegas het volgende:
Gaaf die plaatjes van de ringen, dat wordt de komende paar jaar genieten
Cassini homepage:
http://saturn.jpl.nasa.gov/home/index.cfm

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Op zaterdag 3 juli 2004 22:43 schreef Lemmax het volgende:
Titan\'s Surface Revealed

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dit gaat over TITAN:
\"A methane cloud is visible near the south pole. It\'s made of unusually large particles compared to the typical haze particles surrounding the moon, suggesting a dynamically active atmosphere there.\"

This is the first time scientists are able to map the mineralogy of Titan. Using hundreds of wavelengths, many of which have never been used in Titan imaging before, they are creating a global map showing distributions of hydrocarbon-rich regions and areas of icy material.

Cassini\'s camera also sees through the haze in some wavelengths. \"We\'re seeing a totally alien surface,\" said Dr. Elizabeth Turtle of the University of Arizona, Tucson. \"There are linear features, circular features, curvilinear features. These suggest geologic activity on Titan, but we really don\'t know how to interpret them yet. We\'ve got some exciting work cut out for us.\"
[...]
During the ring plane crossing, the radio and plasma wave science instrument on Cassini measured little puffs of plasma produced by dust impacts. While crossing the plane of Saturn\'s rings, the instrument detected up to 680 dust hits per second.

\"The particles are comparable in size to particles in cigarette smoke,\" said Dr. Don Gurnett of the University of Iowa, Iowa City, principal investigator for the instrument. \"When we crossed the ring plane, we had roughly 100,000 total dust hits to the spacecraft in less than five minutes. We converted these into audible sounds that resemble hail hitting a tin roof.\"

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A massive oxygen buildup was seen by Cassini\'s Ultraviolet Imaging Spectrograph (UVIS) instrument earlier this year, while the spacecraft was en route to Saturn, mission scientists said Friday. Saturn\'s rings are composed, for the most part, of pure water ice, good ol\' H2O.

As this icy material is bombarded by charged particles from Saturn\'s magnetosphere, it breaks down into its constituents, hydrogen and oxygen. So there is always some oxygen floating around in the ring system. But what UVIS detected in Saturn\'s E ring wasn\'t just \"some\" oxygen; it was a tremendous burst of the stuff, that seemed suddenly to come out of nowhere.

The E ring is Saturn\'s outermost and widest ring. Its inner edge lies 181,000 kilometers (112,000 miles) from the planet and the ring extends outward for more than 300,000 kilometers (188,000 miles). In observations of Saturn\'s rings made between late December 2003 and mid-January 2004, UVIS measured normal oxygen levels in the E ring.

Then, for about a month, UVIS stopped taking measurements. Bad timing, it turns out. Because when UVIS checked back again in mid-February, it found that while it was napping something had caused a massive buildup of oxygen in the E ring. The total amount of oxygen detected, said UVIS Co-investigator Donald Shemansky, was 4 times the mass of all of the known material in the E ring.

There is an explanation - or at least a theory.
[...] scientists suspect that a collision between a pair of these ice balls (size between roughly 1 and 10 kilometers in diameter) provided the material that led to the oxygen buildup.

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Titan\'s oily surface and smoggy skies bring together a photographer\'s most exotic imagination. When the Huygens probe attempts its descent to the surface around the second week of January 2005, the moon may present all the meteorological signals that we have come to associate only with earth\'s weather: lightning, rain (oily), clouds and continental shores.

Titan\'s name derives from the union between the Greek gods of the sky (Uranus) and land (Gaia)--a fitting combination for what is likely the only other place in our solar system to harbor a potential shoreline.
[…]
If the probe strikes land, it will impact at the speed approximated by jumping off a table top (5 meters per second) and register 16 times earth gravity when decelerating from its atmospheric top (Mach 20, or twenty times the speed of sound).

It the probe splashes down in what some anticipate as lakes of oil, Huygens will have confirmed the remarkable liquid environment thought to be unique to such a distant, frozen position in the solar system. But if the Huygens descent ends in such a splashdown, the expected lifetime for the probe will likely last only minutes before sinking beneath an ethane or methane pool.
[…]
After nearly three weeks (22 days) traveling ballistically from its stowage onboard the Cassini probe to its final Titan encounter, Huygens descent through the smog will last about 2.5 hours.

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Op woensdag 7 juli 2004 14:27 schreef Mighty_Mike het volgende:
waneer komen er weer nieuwe foto's ?

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Op vrijdag 30 juli 2004 21:33 schreef Yosomite het volgende:
Wanneer wordt een brokje steen een maan genoemd?
Aangezien Saturnus zo ontzettend veel brokjes steen om zich heen heeft circuleren, zouden er nog veel meer manen kunnen zijn.

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Shepherding The Lightweight World
Moffett Field CA (SPX) Aug 25, 2004
by Astrobiology Magazine


Prometheus and Pandora are often called the "F ring shepherds" as they control and interact with Saturn's interesting F ring, seen between them.

Saturn is the only planet less dense than water (about 30 percent less). In the unlikely event that a large enough ocean could be found, Saturn would float in it. Viewing this strange world up close, one's picture of how a planet should behave- with a solid surface and - has to be turned upside down.
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Saturn and its rings are prominently shown in the right color image, along with three of Saturn's smaller moons. These rings may be composed of icebergs and/or snowballs from a few centimeters to a few meters in size. From left to right, three of the moons shaping these rings are Prometheus, Pandora and Janus.

Prometheus and Pandora are often called the "F ring shepherds" as they control and interact with Saturn's interesting F ring, seen between them.
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This F-ring image was taken on June 18, 2004, with the Cassini spacecraft narrow angle camera 8.2 million kilometers (5.1 million miles) from Saturn.

With just a bit of detail visible on its lit hemisphere, Saturn's moon Tethys was imaged (not shown in this article) by Cassini on July 20, 2004. A round feature, likely a large crater, can be seen near the boundary where day and night meet, at the bottom of the image.
[...]

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Cassini-Huygens Periapsis Raising Manoeuvre
Paris (ESA) Aug 25, 2004

The Cassini-Huygens spacecraft has successfully performed its scheduled Periapsis Raising Manoeuvre (PRM). A 51 minute burn of the primary engine corrected the spacecraft trajectory to place it on a course to encounter Saturn's largest moon, Titan, in October. The manoeuvre also raised the periapsis (point of closest approach to Saturn) by over 400 000 km.

If left in this orbit the spacecraft would not encounter Titan with the correct velocity to make further orbital changes for the successful deployment of the Huygens probe, and would return to a periapsis point 20 000 km above Saturn's cloud tops and also a second ring plane crossing.
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Titan Encounters

During the first three orbits around Saturn (Orbit A, B and C) Cassini-Huygens will make three encounters with Titan. The Huygens probe will be released on 25 December 2004 to descend in Titan's atmosphere on 14 January 2005.

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Enceladus: Grand Tours
by Astrobiology Magazine
Moffet Field CA (SPX) Aug 30, 2004


Saturn's moon Enceladus. Image Credit: NASA/JPL

Two hundred and fifteen years ago today (August 28), Sir William Herschel discovered Saturn's moon Enceladus (499 kilometers, 310 miles across). A mission goal for Cassini is to determine the composition of moons like Enceladus.

Along with most of the other 33 satellites, Enceladus appears to have an icy crust. Condensed ices give the moons very high albedo (reflection coefficients) but are mottled with darker regions that may be rich in organic chemicals like methane or ammonia.

These building blocks for primitive biochemistry may offer insight into how a similar, but much warmer environment on Earth, might have given rise to primordial life.

Cassini will conduct its four-year orbital mission, circling Saturn 77 times and cruising by more than 50 close encounters (and another dozen or so more-distant encounters) with the planet's moons.

In all, Cassini will aim its instruments at 8 of Saturn's 33 known moons. Cassini has already discovered a few that were unknown from ground observation and an earlier Voyager flyby.

Titan will get the lion's share of attention: 45 close flybys are planned for the giant moon. Titan will also be the target of the Huygens probe, which will be released by Cassini on Christmas day (Christmas eve in the U.S.) for descent through Titan's atmosphere 3 weeks later.

Titan is of particular interest to scientists because, like Earth, it has an atmosphere that contains nitrogen and organic molecules such as methane. Some scientists speculate that Titan's chemistry may offer a snapshot of what Earth's chemistry was like before life took hold.

After Cassini releases the Huygens probe, it will spend about 10 exploring several of Saturn's icy satellites. Cassini will make close flybys of Enceladus, Hyperion, Dione and Rhea during this grand lunar tour.

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Op dinsdag 31 augustus 2004 20:19 schreef Yosomite het volgende:

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Helaas niet op die site, maar er staat wel veel op . Ik ben verder gaan zoeken. En hier
http://www.space.com/scienceastronomy/moon_definition_040103.html
haal ik onderstaande vandaan:

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Met andere woorden: er is geen definitie voor een maan.