From: LARRY KLAES (ljk4@msn.com)
Date: Thu Nov 07 2002 - 05:19:47 PST
----- Original Message -----
From: baalke@jpl.nasa.gov
Sent: Wednesday, November 06, 2002 4:51 PM
To: undisclosed-recipients:;
Subject: Galileo Millennium Mission Status - November 6, 2002
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
GALILEO MILLENNIUM MISSION STATUS
November 6, 2002
NASA's long-lived Galileo spacecraft achieved partial success in a
dash through Jupiter's inner radiation belts and past the small moon
Amalthea on Tuesday, its final flyby before a deliberate impact into
Jupiter next September.
This was Galileo's last flyby, after 37 other close encounters with
various planets, asteroids and Jupiter's four large moons since launch
13 years ago.
As the orbiter headed closer to Jupiter than it had ever ventured
before, it gathered measurements of the energy fields and charged
particles in the inner region of Jupiter's magnetic environment. It
also examined dust grains that form a "gossamer" ring around the
planet.
However, Galileo placed itself in a standby precautionary mode after
its closest approach to Amalthea. It flew past Amalthea at a targeted
altitude of 160 kilometers (99 miles) at 06:19 Tuesday, Universal Time
(10:19 p.m. Nov. 4, Pacific time), then went into "safe" mode about 30
minutes later. In that mode, onboard fault-protection software
suspends many operations until receiving further instructions from the
ground.
"We knew this would be a challenging encounter for Galileo, so we are
not surprised to have some things go awry," said Dr. Eilene Theilig,
Galileo project manager at NASA's Jet Propulsion Laboratory, Pasadena,
Calif. "Not only was the spacecraft going through a region with more
intense radiation than it had ever experienced before, but it was also
doing this after it had already survived four times the cumulative
radiation dosage it was designed to take and had already operated
nearly five years past its original mission."
The flight team at JPL is working on recovery operations, diagnosing
what happened and preparing new commands to Galileo that will restore
the orbiter to normal and enable the playback of scientific data
stored on the spacecraft's tape recorder. Two tape tracks of science
data were recorded during the encounter period, out of four tracks
planned. Also, the intended type of two-way radio link with Earth for
the period closest to the flyby was not achieved.
Now receding again from Jupiter, the spacecraft left the region of
radiation danger about 11 hours after passing Amalthea.
Amalthea orbits about halfway between Jupiter and Io, the innermost of
the planet's four large moons. Amalthea is an elongated body, about
270 kilometers (168 miles) long.
Galileo has nearly depleted its supply of the propellant needed for
pointing its antenna toward Earth and controlling its flight path.
While still controllable, it has been put on a course for impact into
Jupiter. That's so there will be no risk of it drifting to an unwanted
impact with the moon Europa, where Galileo discovered evidence of a
subsurface ocean that is of interest as a possible habitat for
extraterrestrial life.
Sixty-four minutes after speeding over Amalthea's cratered surface,
Galileo passed within about 71,400 kilometers (44,366 miles) of
Jupiter's cloud tops. That marked the beginning of Galileo's final
orbit, which will end with a plunge into the crushing pressure of
Jupiter's atmosphere on Sept. 21, 2003.
Going into a standby mode does not jeopardize Galileo's disposal at
Jupiter. No further commanding of the spacecraft is necessary to
assure that it is on an impact trajectory, Theilig said.
Additional information about Galileo and the discoveries is available
at
JPL, a division of the
California Institute of Technology in Pasadena, manages the Galileo
mission for NASA's Office of Space Science, Washington, D.C.
- end -
This archive was generated by hypermail 2.1.2 : Thu Nov 07 2002 - 05:35:58 PST