Jacques van Oene
November 29th 04, 10:16 PM
Ulysses Status Report - November 2004
29 Nov 2004 14:21
Mission Status
The spacecraft and its scientific payload are in good health. Solar
Conjunction operations began on 23 August, with the actual Conjunction (the
ninth in the 14-year history of the mission) occurring on 1 September. At
such times, the alignment of the spacecraft, Sun, and Earth is such that the
radio communication ray-path passes close to the Sun, causing degradation to
the signal.
The spacecraft and its scientific payload are in good health. Solar
Conjunction operations began on 23 August, with the actual Conjunction (the
ninth in the 14-year history of the mission) occurring on 1 September. At
such times, the alignment of the spacecraft, Sun, and Earth is such that the
radio communication ray-path passes close to the Sun, causing degradation to
the signal.
As a result of the poor link margins, the possible data rates were lower
than usual, although actual data losses were kept to a minimum. Routine
operations commenced once again on 8 September, with a return to normal data
recovery.
Following the approval by SPC at its February 2004 meeting to extend
spacecraft operations until March 2008, steps have been initiated to extend
the ESA-NASA Memorandum of Understanding for Ulysses accordingly. The
current MOU is valid until the end of the year.
Operations and Archive
All science operations during the reporting period have been nominal.
Payload operations are being conducted according to the pre-determined
power-sharing plan. A core set of instruments providing the key science
measurements is being operated continuously, together with one or more
discretionary instruments depending on the thermal conditions and available
power. In accordance with cost-saving measures agreed at the time of the
2003 Senior Review at NASA, as of 1 October 2004, the baseline telemetry
coverage via the DSN will be reduced from 70 hrs per week to 35 hrs per week
on average. Normal coverage will resume in November 2006 to support the 3rd
set of polar passes. The ESA Ulysses archive is accessible via the World
Wide Web at URL: http://helio.esa.int/ulysses.
Science Highlights
Following the interesting Jupiter Distant Encounter earlier this year, the
scientific focus of the mission has returned to the Sun and the evolution of
the solar wind in the approach to activity minimum. As the spacecraft heads
further south, it is expected to encounter relatively stable solar wind
stream structures that co-rotate with the Sun, similar to those seen in
1992/93. A major difference, however, will be the polarity of the Sun's
magnetic field that underwent a reversal during the recent solar maximum
period.
Another topic of continuing interest, and one to which Ulysses is making
unique contributions, is the study of so-called "inner-source" pick-up ions.
In contrast to pick-up ions of interstellar origin that are created through
ionisation of neutral interstellar gas that penetrates the heliosphere, the
precise origin of the inner-source ions remains uncertain. Among the
possible candidates are neutral solar wind atoms that are implanted in, and
subsequently released from, dust grains close to the Sun. The composition of
the inner source is certainly not cometary in nature, making Sun-grazing
comets an unlikely progenitor. Ulysses measurements have demonstrated
clearly that the population of inner-source ions extends out as far as the
orbit of Jupiter, suggesting that several different sources may be
contributing. In addition to the intrinsic interest in these ions, they also
form a potentially important seed population for injection into shock
acceleration processes that give rise to fluxes of energetic particles of
non-solar origin found throughout the heliosphere.
--
--------------
Jacques :-)
www.spacepatches.info
29 Nov 2004 14:21
Mission Status
The spacecraft and its scientific payload are in good health. Solar
Conjunction operations began on 23 August, with the actual Conjunction (the
ninth in the 14-year history of the mission) occurring on 1 September. At
such times, the alignment of the spacecraft, Sun, and Earth is such that the
radio communication ray-path passes close to the Sun, causing degradation to
the signal.
The spacecraft and its scientific payload are in good health. Solar
Conjunction operations began on 23 August, with the actual Conjunction (the
ninth in the 14-year history of the mission) occurring on 1 September. At
such times, the alignment of the spacecraft, Sun, and Earth is such that the
radio communication ray-path passes close to the Sun, causing degradation to
the signal.
As a result of the poor link margins, the possible data rates were lower
than usual, although actual data losses were kept to a minimum. Routine
operations commenced once again on 8 September, with a return to normal data
recovery.
Following the approval by SPC at its February 2004 meeting to extend
spacecraft operations until March 2008, steps have been initiated to extend
the ESA-NASA Memorandum of Understanding for Ulysses accordingly. The
current MOU is valid until the end of the year.
Operations and Archive
All science operations during the reporting period have been nominal.
Payload operations are being conducted according to the pre-determined
power-sharing plan. A core set of instruments providing the key science
measurements is being operated continuously, together with one or more
discretionary instruments depending on the thermal conditions and available
power. In accordance with cost-saving measures agreed at the time of the
2003 Senior Review at NASA, as of 1 October 2004, the baseline telemetry
coverage via the DSN will be reduced from 70 hrs per week to 35 hrs per week
on average. Normal coverage will resume in November 2006 to support the 3rd
set of polar passes. The ESA Ulysses archive is accessible via the World
Wide Web at URL: http://helio.esa.int/ulysses.
Science Highlights
Following the interesting Jupiter Distant Encounter earlier this year, the
scientific focus of the mission has returned to the Sun and the evolution of
the solar wind in the approach to activity minimum. As the spacecraft heads
further south, it is expected to encounter relatively stable solar wind
stream structures that co-rotate with the Sun, similar to those seen in
1992/93. A major difference, however, will be the polarity of the Sun's
magnetic field that underwent a reversal during the recent solar maximum
period.
Another topic of continuing interest, and one to which Ulysses is making
unique contributions, is the study of so-called "inner-source" pick-up ions.
In contrast to pick-up ions of interstellar origin that are created through
ionisation of neutral interstellar gas that penetrates the heliosphere, the
precise origin of the inner-source ions remains uncertain. Among the
possible candidates are neutral solar wind atoms that are implanted in, and
subsequently released from, dust grains close to the Sun. The composition of
the inner source is certainly not cometary in nature, making Sun-grazing
comets an unlikely progenitor. Ulysses measurements have demonstrated
clearly that the population of inner-source ions extends out as far as the
orbit of Jupiter, suggesting that several different sources may be
contributing. In addition to the intrinsic interest in these ions, they also
form a potentially important seed population for injection into shock
acceleration processes that give rise to fluxes of energetic particles of
non-solar origin found throughout the heliosphere.
--
--------------
Jacques :-)
www.spacepatches.info