Press Release

Three days on Galileo – November 26-28 1999

By SpaceRef Editor
November 26, 1999
Filed under

Galileo wraps up its encounter with the Jupiter system on Friday, just a
few short hours after passing within a few hundred kilometers of Io’s south
pole. Friday’s activities include one observation by the Solid-State
Imaging camera (SSI), one by the Extreme Ultraviolet Spectrometer (EUV),
and the continuation of the Fields and Particles low resolution survey of
the Jovian magnetosphere.

Playback of the data stored on the spacecraft’s onboard tape recorder
during the last few days is initiated today at 4:30 pm PST-SCET (5:05 pm
PST-ERT, see Note 1). The next few days see the return of observations
performed by the Near-Infrared Mapping Spectrometer (NIMS) and Fields and
Particles Instruments. Data return is interrupted once. On Sunday
morning, the spacecraft performs a standard gyroscope performance test.

Friday’s SSI observation captures Amalthea, one of Jupiter’s minor moons.
The observation will provide the best resolution ever of the moon at 3.7
kilometers (2.3 miles) per picture element. Later in the day, the Extreme
Ultraviolet Spectrometer (EUV) obtains data by looking at the Io torus.
The Io torus is a doughnut-shaped region with its inner edge bounded by
Io’s orbit. It is a region of intense plasma and radiation activity, in
which there are strong magnetic and electric fields. Similar observations
have been performed during Galileo’s previous encounters, and the data set
will allow scientists to examine long term variations in the torus’ size
and shape, with the goal of understanding energy transfer between the torus
and the overal Jovian magnetosphere.

NIMS returns the first observation on the playback schedule. The
observation was designed to capture information on surface properties near
a hot spot called Tiermes. The remaining observation on this week’s is the
first portion of a 49 minute recording by the Fields and Particles
instruments made as the spacecraft flew closest to Io. The recording
contains measurements describing the plasma, dust, and electric and
magnetic fields surrounding Io. The primary purpose of this observation is
to determine if Io possesses its own internally-generated magnetic field,
similar to both the Earth and to another Galilean satellite, Ganymede.

Come back on Monday, November 29, for the return of This Week on Galileo.

Note 1. Pacific Standard Time (PST) is 8 hours behind Greenwich Meridian
Time (GMT). The time when an event occurs at the spacecraft is known as
Spacecraft Event Time (SCET). The time at which radio signals reach Earth
indicating that an event has occured is known as Earth Received Time (ERT).
Currently, it takes Galileo’s radio signals 35 minutes to travel between
the spacecraft and Earth

For more information on the Galileo spacecraft and its mission to Jupiter,
please visit the Galileo home page at one of the following URL’s:

SpaceRef staff editor.