Posted on Jun 17, 2010 07:32:33 PM | Saturn News | 3 Comments
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Cesar Bertucci,
Space Physicist, Instituto de Astronomía y Física del Espacio
This weekend, Cassini will embark on an exciting mission: trying to establish if Titan, Saturn's
largest moon, possesses a magnetic field of its own. This is important for understanding the moon's
interior and geochemical evolution.
For Titan scientists, this is one of the most anticipated
flybys of the whole mission. We want to get as close to the surface with our magnetometer as possible for
a one-of-a-kind scan of the moon. Magnetometer team scientists (including me) have a reputation for
pushing the lower limits. In a world of infinite possibilities, we would have liked many flybys at 800
kilometers. But we went back and forth a lot with the engineers, who have to ensure the safety of the
spacecraft and fuel reserves. We agreed on one flyby at 880 kilometers (547 miles) and both sides were
happy.
Flying at this low altitude will mark the first
time Cassini will be below the moon's ionosphere, a shell of electrons and other charged particles that
make up the upper part of the atmosphere. As a result, the spacecraft will find itself in a region almost
entirely shielded from Saturn's magnetic field and will be able to detect any magnetic signature
originating from within Titan.
Titan orbits within the confines of the magnetic bubble around
Saturn and is permanently exposed to the planet's magnetic disturbances. Previous measurements by NASA's
Voyager spacecraft and Cassini at altitudes above 950 kilometers (590 miles) have shown that Titan does
not possess an appreciable magnetic field capable of counterbalancing Saturn's. However, this does not
imply that Titan's field is zero. We'd like to know what the internal field might be, no matter how
small.
The internal structure of Titan can be probed remotely from its gravitational field or its
magnetic properties. Planets with a magnetic field -- like Titan's parent Saturn or our Earth -- are
believed to generate their global-scale magnetic fields from a mechanism called a dynamo. Dynamo magnetic
fields are generated from currents in a molten core where charge-conducting materials such as metals are
flowing around each other and also undergoing other stresses because of the planet's rotation.
We
might not find a magnetic field at all. A positive detection of an internal magnetic field from Titan
could imply one of the following:
a) Titan's interior still bears enough energy to sustain a
dynamo. b) Titan's interior is "cold" (and therefore has no dynamo), but its crust is magnetized in a
similar way as Mars' crust. If this is the case, we should find out how this magnetization took
place. c) Something under the surface of Titan got charged temporarily by Saturn's magnetic field
before this Cassini flyby. While I said earlier that the ionosphere shields the Titan atmosphere from
Saturn's magnetic bubble, the ionosphere is only an active shield when the moon is exposed to sunlight.
During part of its orbit around the planet, Titan is in the dark and magnetic field lines from Saturn can
reach the Titan surface. A temporary magnetic field can be created if there is a conducting layer, like
an ocean, on or below the moon's crust.
Once Cassini leaves Titan, the spacecraft will perform a
series of rolls to fine-calibrate its magnetometer in order to assess T70 measurements with the highest
precision. We're looking forward to poring through the data coming down, especially after all the
negotiations we had to make for them!
César Bertucci, a space physicist working at the Instituto de Astronomía y Física del Espacio in
Buenos Aires, Argentina, is a Titan expert on the Cassini magnetometer team. He is also a specialist in
the solar wind interaction with weakly magnetized bodies such as Mars, Venus and comets.
3
On Jun 18, 2010 11:39:40 AM
evab
added a comment on your blog post.
Dinamo = dynamics = conductism?
Dinamo is mechanical attraction principally by magnetism or the law of a tension, provoked naturally by the ingression of different phases of the moon Titan upon the suggestion of Saturn and its rings...
Energy is more animalizated than animalist or animist.
But movement is properly magic.
Nobody knows exactly no.
2
On Jun 19, 2010 02:57:56 AM
ami b.b
added a comment on your blog post.
Hi, you'll have to excuse me for this non-engineering question..but we - the laymen guys are looking for real pictures which we will be able to see with our human eyes..in other words, beside collecting magnetic data, will the Cassini try take also some "real" pics while getting near the Titan ground?
1
On Jun 21, 2010 02:59:57 PM
Tylor
added a comment on your blog post.
This will certainly be an exciting time! I have been consistently checking NASA's website to see if there are any results. Do you think that it is probably that Titan can harbor Methane based life organisms?
Cesar Bertucci,
Dinamo = dynamics = conductism?
Dinamo is mechanical attraction principally by magnetism or the law of a tension, provoked naturally by the ingression of different phases of the moon Titan upon the suggestion of Saturn and its rings...
Energy is more animalizated than animalist or animist.
But movement is properly magic.
Nobody knows exactly no.
Hi, you'll have to excuse me for this non-engineering question..but we - the laymen guys are looking for real pictures which we will be able to see with our human eyes..in other words, beside collecting magnetic data, will the Cassini try take also some "real" pics while getting near the Titan ground?
This will certainly be an exciting time! I have been consistently checking NASA's website to see if there are any results. Do you think that it is probably that Titan can harbor Methane based life organisms?