Titan probe delivers atmospheric insight
By Jennifer Lauren Lee
Feb. 10, 2005 9:00 p.m.
Sprawled beneath a pale orange sky, the foreign wind rustling
its recently discharged parachute, a solitary probe sent its first
signal to expectant earthlings nearly a billion miles away.
Last month, the Huygens probe landed with a “splat”
on Saturn’s largest moon, Titan, sending back the first
physical data from the only moon in the solar system known to have
an atmosphere, said Linda Spilker, Cassini project deputy scientist
and co-investigator for the infrared spectrometer on-board
Cassini.
The probe was launched successfully last December from Cassini,
a satellite that has been orbiting and investigating the planet
since July of 2004.
Titan’s atmosphere is thought to resemble that of
primitive Earth, giving some scientists the hope that the Huygens
data will tell scientists more about how Earth’s atmosphere
evolved.
“(We were) just ecstatic,” said Krishan Khurana,
professor of space physics at UCLA and member of the team of UCLA
scientists who worked on Cassini’s magnetic field detector.
“The mission was a complete success in every way
imaginable.”
Since Titan’s orange atmosphere is too thick to allow a
passing satellite such as Cassini to see its surface, Spilker said,
the 700-pound probe, nine feet in diameter, has given scientists
their first close-up look at a moon larger than the planet
Mercury.
“Titan is the biggest moon of Saturn and it has the
densest atmosphere of any moon in the solar system,” said
Christopher Russell, professor of earth and space science and
co-investigator for the magnetometer on-board Cassini. “Both
characteristics made Titan very interesting to
scientists.”
With a covey of cameras, a microphone and instruments for
measuring air composition, pressure, temperature and wind speed,
the Huygens probe sent back nearly four hours of data, which
included a two and a half hour parachute-assisted plummet to the
ground, and more than an hour of ground-based measurements.
The data shows that Titan seems to be able to retain its
atmosphere, Khurana said, further linking it to Earth, which was
also able to maintain its atmosphere.
“We should be able to come up with a fairly good idea
about the future of this atmosphere,” Khurana said.
“Understanding Titan’s atmosphere would be equivalent
to learning about the primitive Earth’s
atmosphere.”
Spilker said she was amazed by how remarkably similar
Titan’s weather system seems to be to Earth’s.
“But Titan does not have a water-based weather system and
its surface does not contain silicate rock,” Russell said.
“The moon (Titan) is very different than the Earth in its
weather system, yet the resulting erosion on the surface ““
whatever it is made of ““ is much the same as we would find
here on Earth.”
Spilker explains that scientists think methane may play the role
that water fulfills on Earth, since Titan’s 290-degree
Fahrenheit environment is too cold to support liquid water.
“Methane is working as rain would work (on Earth),”
Spilker said.
The probe landed on what Spilker said might have been a dry lake
bed, full of “icy pebbles” made of water.
Though all of the retrievable data has been collected from the
Huygens probe, Spilker says it will take several months to process
it. Meanwhile, she says she hopes scientists will be able to use
the available data to answer questions about Titan’s
atmosphere.
“It’s interesting to understand exactly how weather
works on Titan, to put together a complete model for Titan’s
atmosphere,” Spilker said.
