| definition |
- A fundamental feature of the heliosphere is the three dimensional structure of
the interplanetary magnetic field. The magnetic field investigation on Ulysses,
the first space probe to explore the out-of-ecliptic and polar heliosphere,
aims at determining the large scale features and gradients of the field, as
well as the heliolatitude dependence of interplanetary phenomena so far only
observed near the ecliptic plane. The Ulysses magnetometer uses two sensors,
one a Vector Helium Magnetometer, the other a Fluxgate Magnetometer. Onboard
data processing yields measurements of the magnetic field vector with a time
resolution up to 2 vectors/second and a sensitivity of about l0 pT. Since the
switch-on of the instrument in flight on 25 October l990, a steady stream of
observations have been made, indicating that at this phase of the solar cycle
the field is generally disturbed: several shock waves and a large number of
discontinuities have been observed, as well as several periods with apparently
intense wave activity. The paper gives a brief summary of the scientific
objectives of the investigation, followed by a detailed description of the
instrument and its characteristics. Examples of wave bursts, interplanetary
shocks and crossings of the heliospheric current sheet are given to illustrate
the observations made with the instrument.
(Abstract from: A. Balogh et al., Astron. Astrophys. Suppl. Ser. 92, 221-236,
1992)
For more information, see:
http://www.sp.ph.ic.ac.uk/Ulysses/
and
http://ulysses.jpl.nasa.gov/spacecraft/inst_vhm_fgm.html
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