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Meteorites from Jupiter's Moons?



I remember reading somehwere that someone theorized that some meteorites
may have come from Jupiter's large Galilean moons (Ganymede, Callisto, 
Eurupa and Io).  Does anybody have any details on this?  On a related
note, the Galileo spacecraft will have its next encounter with Europa
in two days.

Ron Baalke

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GALILEO - COUNTDOWN TO EUROPA
February 18, 1997

It is now 2 days, 45 minutes to the Galileo spacecraft's closest 
approach to Europa.

A special Countdown to Europa home page is now available on the Galileo
Home Page:

http://www.jpl.nasa.gov/galileo/countdown/

Launched in October 1989, Galileo entered orbit around Jupiter on December 5,
1995, and is currently in the middle of its 2 year orbital tour around the 
solar system's largest planet.  Galileo's orbital tour consists of 11 
elliptical orbits around  Jupiter, and each orbit (except one) will include a 
close flyby and gravity assist of one of the Galilean moons (Ganymede, Callisto
or Europa).  In addition to closeup observations of a Galilean moon, distant 
scientific encounters with additional satellites are scheduled and Io will be 
observed at medium range on every orbit.  

The first five orbits have been completed and the next close encounter 
on the 6th orbit is scheduled for Europa on February 20, 1997 17:03 UT.  
With a diameter of  3,138 km, Europa is slighty smaller than our own Moon and 
is the smoothest object in the solar system.  On Galileo's first close
flyby of Europa in December 1996, ice volcanoes were discovered for the
on the icy satellite (though none were observed to be active) and 
ice flows were observed for the first time on a Galilean satellite.
Galileo will attempt to find evidence of a liquid ocean underneath Europa's 
icy crust and look for signs of active volcanism on the moon's young surface.
On the upcoming encounter, Galileo will pass by Europa at only 587 km,
its closest ever approach to this fascinating moon during Galileo's orbital 
tour.  This is nearly 350 times closer than Voyager's closest approach.
Also scheduled for the Europa 6 encounter are observations of the other 
satellites of Jupiter: Io, Ganymede, Callisto, Amalthea, and Thebe.  
Observations of the White Ovals on Jupiter are also planned as well as a 
survey of Jupiter's magnetosphere.

Highlights of the Countdown to Europa home page:

o A virtual flyby of Europa with computer-generated approach images 
  displayed at the top of the home page, including Galileo's view of Jupiter 
  and Europa.  These images will be updated daily up to encounter day 
  (Feb 20), and on encounter day will be updated every five minutes.
o Live Doppler plots of Galileo spacecraft radio signal as it received on
  Earth.  Watch the gravity of Europa change the frequency of the radio 
  signal in real-time.  The Doppler plots will be updated every 
  minute on encounter day (Feb 20).
o The latest Galileo status reports reporting on the Europa 6 encounter. 
o Galileo's current position, updated every minute.  This includes the 
  distances from Jupiter, the Earth and Sun, and relative speeds. 
o Fact sheets and Callisto, Ganymede, Europa, Io and Amalthea.
o A detailed timeline of events and sequences that the spacecraft will
  perform for the Europa 6 encounter.
o Galileo SSI planning images provided by the Galileo imaging team.
o Voyager 1 & 2 images of Callisto, Ganymede, Europa and Io.
o Hubble Space Telescope images of the Galilean satellites.
o Pioneer 10 & 11 images of Callisto, Ganymede, Europa and Io.
o Europa flyby animations.

Ron Baalke
baalke@kelvin.jpl.nasa.gov
Galileo Home Page Curator


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