Cassini Exposes Saturn's Two-Face Moon (Iapetus)

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov


Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Heidi Finn (720) 974-5859
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.

Image Advisory: 2004-182 July 15, 2004

Cassini Exposes Saturn's Two-Face Moon

The moon with the split personality, Iapetus, presents a perplexing
appearance in the latest images snapped by the Cassini spacecraft.

One hemisphere of the moon is very dark, while the other is very
bright. Scientists do not yet know the origin of the dark material or
whether or not it is representative of the interior of Iapetus.

Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known
moons. Its diameter is about one third that of our own moon at 1,436
kilometers (892 miles). This image was taken in visible light with
the Cassini spacecraft narrow angle camera on July 3, 2004, from a
distance of 3 million kilometers (1.8 million miles) from Iapetus.
The brightness variations in this image are not due to shadowing, they
are real.

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).

Iapetus was discovered by the Italian-French astronomer Jean Dominique
Cassini in 1672. He correctly deduced that the trailing hemisphere is
composed of highly reflective material, while the leading hemisphere
is strikingly darker.

This sets Iapetus apart from Saturn's other moons and Jupiter's moons,
which tend to be brighter on their leading hemispheres. Voyager
images show that the bright side of Iapetus, which reflects nearly 50
percent of the light it receives, is fairly typical of a heavily
cratered icy satellite. The leading side consists of much darker,
redder material that has a reflectivity of only about 3 to 4 percent.

One scenario for the outside deposit of material has dark particles
being ejected from Saturn's little moon Phoebe and drifting inward to
coat Iapetus. One observation lending credence to an internal origin
is the concentration of material on crater floors, which is suggestive
of something filling in the craters.

Iapetus is odd in other respects. It is in a moderately inclined
orbit, one that takes it far above and below the plane in which the
rings and most of the moons orbit. It is less dense than many of the
other satellites, which suggests a higher fraction of ice or possibly
methane or ammonia in its interior.

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 Cassini-Huygens mission for NASA's Office of
Space Science, Washington, D.C. The Cassini orbiter and its two
onboard cameras were designed, developed and assembled at JPL. The
imaging team is based at the Space Science Institute, Boulder, Colo.

For this and other images and information about the Cassini-Huygens
mission, visit

http://saturn.jpl.nasa.gov

and

http://www.nasa.gov/cassini

Images are also available at the Cassini imaging team home page,

http://ciclops.org .


Credit: NASA/JPL/Space Science Institute

-end-

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).


WHEN EXACTLY?
Thanks
bubo

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).


WHEN EXACTLY?
Thanks
bubo

When, and with what, is next Cassini encounter?

T.

Ron wrote:

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Heidi Finn (720) 974-5859
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.

Image Advisory: 2004-182 July 15, 2004

Cassini Exposes Saturn's Two-Face Moon

The moon with the split personality, Iapetus, presents a perplexing
appearance in the latest images snapped by the Cassini spacecraft.

One hemisphere of the moon is very dark, while the other is very
bright. Scientists do not yet know the origin of the dark material or
whether or not it is representative of the interior of Iapetus.

Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known
moons. Its diameter is about one third that of our own moon at 1,436
kilometers (892 miles). This image was taken in visible light with
the Cassini spacecraft narrow angle camera on July 3, 2004, from a
distance of 3 million kilometers (1.8 million miles) from Iapetus.
The brightness variations in this image are not due to shadowing, they
are real.

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).

Iapetus was discovered by the Italian-French astronomer Jean Dominique
Cassini in 1672. He correctly deduced that the trailing hemisphere is
composed of highly reflective material, while the leading hemisphere
is strikingly darker.

This sets Iapetus apart from Saturn's other moons and Jupiter's moons,
which tend to be brighter on their leading hemispheres. Voyager
images show that the bright side of Iapetus, which reflects nearly 50
percent of the light it receives, is fairly typical of a heavily
cratered icy satellite. The leading side consists of much darker,
redder material that has a reflectivity of only about 3 to 4 percent.

One scenario for the outside deposit of material has dark particles
being ejected from Saturn's little moon Phoebe and drifting inward to
coat Iapetus. One observation lending credence to an internal origin
is the concentration of material on crater floors, which is suggestive
of something filling in the craters.

Iapetus is odd in other respects. It is in a moderately inclined
orbit, one that takes it far above and below the plane in which the
rings and most of the moons orbit. It is less dense than many of the
other satellites, which suggests a higher fraction of ice or possibly
methane or ammonia in its interior.

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 Cassini-Huygens mission for NASA's Office of
Space Science, Washington, D.C. The Cassini orbiter and its two
onboard cameras were designed, developed and assembled at JPL. The
imaging team is based at the Space Science Institute, Boulder, Colo.

For this and other images and information about the Cassini-Huygens
mission, visit

http://saturn.jpl.nasa.gov

and

http://www.nasa.gov/cassini

Images are also available at the Cassini imaging team home page,

http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

-end-

When, and with what, is next Cassini encounter?

T.

Ron wrote:

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Heidi Finn (720) 974-5859
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.

Image Advisory: 2004-182 July 15, 2004

Cassini Exposes Saturn's Two-Face Moon

The moon with the split personality, Iapetus, presents a perplexing
appearance in the latest images snapped by the Cassini spacecraft.

One hemisphere of the moon is very dark, while the other is very
bright. Scientists do not yet know the origin of the dark material or
whether or not it is representative of the interior of Iapetus.

Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known
moons. Its diameter is about one third that of our own moon at 1,436
kilometers (892 miles). This image was taken in visible light with
the Cassini spacecraft narrow angle camera on July 3, 2004, from a
distance of 3 million kilometers (1.8 million miles) from Iapetus.
The brightness variations in this image are not due to shadowing, they
are real.

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).

Iapetus was discovered by the Italian-French astronomer Jean Dominique
Cassini in 1672. He correctly deduced that the trailing hemisphere is
composed of highly reflective material, while the leading hemisphere
is strikingly darker.

This sets Iapetus apart from Saturn's other moons and Jupiter's moons,
which tend to be brighter on their leading hemispheres. Voyager
images show that the bright side of Iapetus, which reflects nearly 50
percent of the light it receives, is fairly typical of a heavily
cratered icy satellite. The leading side consists of much darker,
redder material that has a reflectivity of only about 3 to 4 percent.

One scenario for the outside deposit of material has dark particles
being ejected from Saturn's little moon Phoebe and drifting inward to
coat Iapetus. One observation lending credence to an internal origin
is the concentration of material on crater floors, which is suggestive
of something filling in the craters.

Iapetus is odd in other respects. It is in a moderately inclined
orbit, one that takes it far above and below the plane in which the
rings and most of the moons orbit. It is less dense than many of the
other satellites, which suggests a higher fraction of ice or possibly
methane or ammonia in its interior.

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 Cassini-Huygens mission for NASA's Office of
Space Science, Washington, D.C. The Cassini orbiter and its two
onboard cameras were designed, developed and assembled at JPL. The
imaging team is based at the Space Science Institute, Boulder, Colo.

For this and other images and information about the Cassini-Huygens
mission, visit

http://saturn.jpl.nasa.gov

and

http://www.nasa.gov/cassini

Images are also available at the Cassini imaging team home page,

http://ciclops.org .

Credit: NASA/JPL/Space Science Institute

-end-

In article ,
Replicator Creator wrote:

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).


WHEN EXACTLY?

It appears to be currently scheduled for September 2007, but these
things can change.

There's some nice moon-encounter schedule at:
http://en.wikipedia.org/wiki/Cassini-Huygens_timeline

--
Hud Nordin Silicon Valley

In article ,
Replicator Creator wrote:

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).


WHEN EXACTLY?

It appears to be currently scheduled for September 2007, but these
things can change.

There's some nice moon-encounter schedule at:
http://en.wikipedia.org/wiki/Cassini-Huygens_timeline

--
Hud Nordin Silicon Valley

In article ,
Tequila wrote:
When, and with what, is next Cassini encounter?

October 26, Titan, 1200 km.

http://en.wikipedia.org/wiki/Cassini-Huygens_timeline
--
Hud Nordin Silicon Valley

In article ,
Tequila wrote:
When, and with what, is next Cassini encounter?

October 26, Titan, 1200 km.

http://en.wikipedia.org/wiki/Cassini-Huygens_timeline
--
Hud Nordin Silicon Valley

Tequila (or somebody else of the same name) wrote thusly in message
:

When, and with what, is next Cassini encounter?

T.

Ron wrote:

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Carolina Martinez (818) 354-9382
Jet Propulsion Laboratory, Pasadena, Calif.

Heidi Finn (720) 974-5859
Cassini Imaging Central Laboratory for Operations
Space Science Institute, Boulder, Colo.

Image Advisory: 2004-182 July 15, 2004

Cassini Exposes Saturn's Two-Face Moon

The moon with the split personality, Iapetus, presents a perplexing
appearance in the latest images snapped by the Cassini spacecraft.

One hemisphere of the moon is very dark, while the other is very
bright. Scientists do not yet know the origin of the dark material or
whether or not it is representative of the interior of Iapetus.

Iapetus (pronounced eye-APP-eh-tuss) is one of Saturn's 31 known
moons. Its diameter is about one third that of our own moon at 1,436
kilometers (892 miles). This image was taken in visible light with
the Cassini spacecraft narrow angle camera on July 3, 2004, from a
distance of 3 million kilometers (1.8 million miles) from Iapetus.
The brightness variations in this image are not due to shadowing, they
are real.

During Cassini's four-year tour, the spacecraft will continue to image
Iapetus and conduct two close encounters. One of those encounters,
several years from now, will be at a mere 1,000 kilometers (622
miles).

Iapetus was discovered by the Italian-French astronomer Jean Dominique
Cassini in 1672. He correctly deduced that the trailing hemisphere is
composed of highly reflective material, while the leading hemisphere
is strikingly darker.
[snip]
Iapetus is odd in other respects. It is in a moderately inclined
orbit, one that takes it far above and below the plane in which the
rings and most of the moons orbit. It is less dense than many of the
other satellites, which suggests a higher fraction of ice or possibly
methane or ammonia in its interior.

Has a darker body crashed onto Iapetus in the moderately recent past,
smearing its leading half with dark stuff - and at the same time jogging it
out of its formerly equatorial orbit?
--
Paul Townsend
I put it down there, and when I went back to it, there it was GONE!

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