RISC DISC 2/RISC_DISC_2.iso/resources/nasa/shoemaker/info/planetaryimagingreports894

Text File | 1995-05-03 | 5.5 KB | 111 lines

Shoemaker-Levy Imaging Reports from: GALILEO, ULYSSES and VOYAGER

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109.



GALILEO MISSION STATUS    August 1, 1994

     The Galileo spacecraft captured an extensive range of data on the impacts
of the fragments of Comet Shoemaker-Levy 9 on Jupiter July 16 through 22.
Because of its position 240 million kilometers (150 million miles) from Jupiter
and in the direction of the impact sites on the planet's night side, Galileo
was able to make unique direct observations of the impact events which were not
visible from Earth.

     The data from Galileo's science instruments were stored on the
spacecraft's onboard tape recorder.  Science teams are now carefully evaluating
data stored on tape to select portions to be transmitted to Earth starting in
August.

     The spacecraft's photopolarimeter-radiometer has already obtained and
transmitted light-intensity readings from the impacts of comet fragments H, L
and Q on Jupiter's far side.  The B impact did not produce a significant
indication; data from fragment P was recorded on tape for later playback.

     Engineering telemetry indicated that Galileo's computer directed the
imaging system, the near-infrared spectrometer, the ultraviolet spectrometer
and plasma wave instrument to observe the impacts as planned.  The camera
observed the fragment D, E, K, N, V and W events, the infrared instrument the
C, F, G and R impacts.  Their observations are stored on tape, intended for
gradual transmission to Earth beginning this month and continuing through
January 1995.

     The spacecraft continues to operate normally, spinning at about 3 rpm and
transmitting at 10 bits per second to ground stations of the NASA/JPL Deep
Space Network. Galileo is about 640 million kilometers (400 million miles) from
Earth, so that a command takes 36 minutes to reach Galileo, and the response
another 36 minutes to return.  The spacecraft will reach Jupiter on December 7,
1995, when its probe will descend into the Jovian atmosphere and the orbiter
spacecraft will begin two years of observation and measurement of the planet,
its moons and magnetosphere.




ULYSSES MISSION STATUS   August 1, 1994

     The Ulysses spacecraft -- currently exploring high latitude regions over
the sun's southern pole -- has climbed to 75.5 degrees south of the sun's
equator and is in the midst of its primary mission to examine the complex
forces at work in these regions of space.

     Ulysses was in a position to observe the impacts of comet Shoemaker-Levy 9
during mid-July.  At the time Ulysses had a direct line of sight to the impact
region at 74.5 degrees south of the sun's equator.  The spacecraft was about
375 million kilometers (230 million miles) below the ecliptic plane in which
the planets orbit and 795 million kilometers (490 million miles) from Jupiter.
Ulysses' unified radio and plasma wave experiment was reconfigured to provide
the highest level of sensitivity for detecting very low frequency radio waves
of less than 1 megahertz that might have been generated by the comet impacts.

     Data from the impact of fragment A on July 16 through the collision of
fragment Q on July 20 have been processed and analyzed, but no clear evidence
of changes in radio frequencies has been detected.  Jupiter normally has
considerable activity at these frequencies.  Members of the Ulysses radio
science team will continue to watch for the more subtle or long-term effects of
the comet collisions, but they do not anticipate much new information in the
aftermath of the event.

     All spacecraft operations and science experiments continue to go well.
Ground controllers are carrying out routine data-gathering activities and
experiment readjustments as needed.  The European Space Agency's tracking
facility at Kourou, French Guiana, has been modified and brought on-line to
help provide 24-hour coverage of Ulysses now that it is moving into the
sun-Earth region where the spacecraft's axial boom is illuminated by the sun.
This illumination causes uneven heating of the boom which, in turn, causes a
slight wobble of the spacecraft.  Shortly after launch, Ulysses went through a
period of wobbling that was finally controlled by an onboard control system
that is used to maneuver and keep the spacecraft pointing at Earth. Ground
controllers must be in constant contact with the spacecraft to carry out this
technique, allowing the onboard system to detect and reduce unwanted motion.

     Today Ulysses is traveling at a velocity of about 74,000 kilometers per
hour (46,000 miles per hour) with respect to the sun.




VOYAGER MISSION STATUS   August 1, 1994

     Both the Voyager 1 and 2 spacecraft are healthy and they are continuing to
take data on fields and particles in interplanetary space.

     The Voyager 2 spacecraft used two of its scientific instruments to look at
the impacts of Comet Shoemaker-Levy 9 fragments as they impacted Jupiter July
16-22.  Both the ultraviolet spectrometer and the planetary radio astronomy
experiments were used in the observations.  Neither instrument detected any UV
emission or radio signals during the impacts.  The spacecraft began its
observations of Jupiter on July 8 and will continue to observe the planet until
August 17.  At the time of the comet impacts, Voyager 2 was 6.1 billion
kilometers (3.7 billion miles) from Jupiter.

     Voyager 1 is currently 8.4 billion kilometers (5.2 billion miles) from
Earth. Voyager 2 is 6.4 billion kilometers (4 billion miles) from Earth.

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