[meteorite-list] NASA Teleconference to Preview Historic Flyby of Saturn Moon

[Ron Baalke]

http://www.jpl.nasa.gov/news/news.php?feature=4747

NASA Teleconference to Preview Historic Flyby of Saturn Moon
Jet Propulsion Laboratory
Oct 22, 2015

NASA's Cassini spacecraft will sample an extraterrestrial ocean on Wednesday, 
Oct. 28, when it flies directly through a plume of icy spray coming from 
Saturn's moon Enceladus. The agency will hold a news teleconference at 
11 a.m. PDT (2 p.m. EDT) on Monday, Oct. 26, to discuss plans for and 
anticipated science results from the historic flyby.

The teleconference participants are:

-- Curt Niebur, Cassini program scientist at NASA Headquarters in Washington
-- Earl Maize, Cassini project manager at NASA's Jet Propulsion Laboratory 
(JPL) in Pasadena, California
-- Linda Spilker, Cassini project scientist at JPL

Questions can be submitted during the briefing via social media using 
the hashtag #askNASA.

Audio of the event will stream live on the NASA website, where visitors 
also can find accompanying visuals. Event audio also will stream live 
online, with visuals, on Ustream.

The spacecraft will make its closest approach to Enceladus at 8:22 a.m. 
PDT (11:22 a.m. EDT) Wednesday at an altitude of 30 miles (49 kilometers) 
above the moon's south polar region. The encounter will be Cassini's deepest-ever 
dive through the Enceladus plume, and is expected to provide valuable 
data about activity in the global ocean stirring beneath the moon's frozen 
surface.

Cassini scientists are hopeful the flyby will provide insights into how 
much hydrothermal activity is occurring within Enceladus, and how this 
hot-water chemistry might impact the ocean's potential habitability for 
simple forms of life. If the spacecraft's ion and neutral mass spectrometer 
instrument (INMS) detects molecular hydrogen as it travels through the 
plume, scientists may get the measurements they need to answers these 
questions.

"Confirmation of molecular hydrogen in the plume would be an independent 
line of evidence that hydrothermal activity is taking place in the Enceladus 
ocean, on the seafloor," said Hunter Waite, INMS team lead at Southwest 
Research Institute in San Antonio. "The amount of hydrogen would reveal 
how much hydrothermal activity is going on."

Using Cassini's cosmic dust analyzer (CDA) instrument, scientists expect 
the flyby will lead to a better understanding of the chemistry of the 
plume. The low altitude of the encounter is, in part, intended to increase 
the spacecraft's access to heavier, more massive molecules -- including 
organics -- than the spacecraft has observed during previous, higher altitude 
passes through the plume. The CDA instrument, which is capable of detecting 
up to 10,000 particles per second from the plume, also is expected to 
reveal how much material the plume is spraying from the moon's ocean into 
the space around Saturn.

"There's really no room for ambiguity," said Sascha Kempf, a CDA team 
co-investigator at the University of Colorado at Boulder. "The data will 
either match what our models are telling us about the rate at which the 
plume is producing material, or our concept of how the plume works needs 
additional thought."

Scientists also hope the flyby will help solve the mystery of whether 
the plume is comprised of column-like, individual jets, or sinuous, icy 
curtain eruptions -- or a combination of both.

Given the important astrobiology implications of these observations, the 
scientists caution that it will be several months before they are ready 
to present their detailed findings.

Cassini will acquire images of Enceladus both before and after the encounter. 
For the time of closest approach, the cameras' fields of view will drag 
across the surface. These observations are expected to capture some of 
the highest-resolution views ever of the icy south polar terrain, lit 
by reflected light from Saturn. Post-flyby processing will be used to 
remove blurring caused by the spacecraft's movement during exposure.

"Cassini truly has been a discovery machine for more than a decade," said 
Curt Niebur, Cassini program scientist at NASA Headquarters in Washington. 
"This incredible plunge through the Enceladus plume is an amazing opportunity 
for NASA and its international partners on the Cassini mission to ask, 
'Can an icy ocean world host the ingredients for life?'"

The last of Cassini's three final close flybys of this icy moon, targeted 
at an altitude of 3,106 miles (4,999 kilometers) on Dec. 19, will examine 
how much heat is coming from the moon's interior. The closest-ever Enceladus 
flyby took place in October 2008 at an altitude of 16 miles (25 kilometers). 
Cassini flew closer to the moon's icy surface during that encounter, but 
passed through the plume at a much higher altitude than it will during 
the Oct. 28 flyby.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European 
Space Agency) and the Italian Space Agency. JPL manages the mission for 
NASA's Science Mission Directorate in Washington.

An online toolkit for all three final Enceladus flybys is available at:

http://solarsystem.nasa.gov/finalflybys

For more information about Cassini, visit:

http://www.nasa.gov/cassini

and

http://saturn.jpl.nasa.gov


Media Contact

Preston Dyches
Jet Propulsion Laboratory, Pasadena, Calif.
818-354-7013
preston.dyches at jpl.nasa.gov 

Dwayne Brown / Laurie Cantillo
NASA Headquarters, Washington
202-358-1726 / 202-358-1077
dwayne.c.brown at nasa.gov / laura.l.cantillo at nasa.gov 

2015-325