Ulysses and Voyager 2


Ulysses

The Ulysses spacecraft will be 2.5 AU (375 million Km) south of Jupiter at the time of impact and will also have a direct line of sight to the impact point. From this position the Ulysses unified radio and plasma wave (URAP) experiment will monitor radio emissions between 1 and 940 KHz, sweeping through the spectrum approximately every 2 minutes. URAP will be able to detect radio emissions down to 10**14 ergs. There are no imaging experiments on Ulysses.

ULYSSES MISSION STATUS

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

                      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 2

Voyager 2 is on its way out of the solar system, 44 AU from Jupiter at the time of the impact. The planetary radio astronomy (PRA) experiment will be monitoring radio emissions in the 1 KHz to 390 KHz range with a detection limit of 10**19 to 10**20 ergs. PRA will sweep through this spectrum every 96 seconds. The Voyager 2 imaging system will not be used.

VOYAGER MISSION STATUS

PUBLIC INFORMATION OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109. TELEPHONE (818) 354-5011

                       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.


[NASA Logo]
Author/Curator:
Dr. David R. Williams, dave.williams@nasa.gov
NSSDCA, Mail Code 690.1
NASA Goddard Space Flight Center
Greenbelt, MD 20771
+1-301-286-1258


NASA Official: Ed Grayzeck, edwin.j.grayzeck@nasa.gov
Last Updated: 08 January 1997, DRW