The Voyager-1 spacecraft was launched on September 5, 1977
and subsequently encountered Jupiter on March 5, 1979, Saturn
on November 12, 1980 and the heliospheric termination shock on
December 16, 2004. The space craft crossed into Interstellar Space
on August 25, 2012.
The Voyager-2 spacecraft was launched on August 20, 1977 and
subsequently encountered Jupiter on July 9, 1979, Saturn on August 25, 1981,
Uranus on January 24, 1986, Neptune on August 25, 1989 and the
heliospheric termination shock on August 30, 2007. Voyager-2
is now traveling out of the Solar System in the "heliopause crossing"
phasae of its interstellar mission.
Both space craft are now traveling out of the Solar System with the mission objective of
extending NASA's exploration of the solar system beyond the neighborhood of the outer planets to the outer
limits of the Sun's sphere of influence and beyond.
A detailed description of Voyager's past and current mission can be found
at the Jet Propulsion Laboratory's
Voyager Project Home Page.
The principal scientific objectives
of the Voyager Cosmic Ray Subsystem experiment are:
To accomplish these objectives CRS makes the following measurements:
- To measure the flow patterns of energetic solar and
galactic particles separately in the inter-planetary field.
To interpret this measurement, simultaneous determination
of the energy spectrum, radial gradient, distribution, and
streaming parameters is required for each nuclear species
and over as wide an energy range as is practicable.
- To measure the energy spectra, and isotopic composition of
galactic and solar cosmic rays from the lowest practical
energies up to ~800 MeV/nucleon and (by use of objective
1) to unfold the primary flare and interstellar spectrum.
- To measure the time variations of the differential energy
spectra of electrons, hydrogen and helium nuclei over the
corresponding energy intervals. During flare events, to
obtain time histories; during quiet times, to relate gross
time variations to those near earth thus deducing a
spatial gradient for galactic cosmic rays.
- To study the energy spectra, time variations and spatial
gradients associated with recurrent and non-flare
associated interplanetary proton and helium streams and to
define the related solar or inter-planetary acceleration
- To provide information on the energetic particle
distribution surrounding Jupiter and Saturn.
- To try to determine the extent of the solar cavity, the
energetic particle phenomena occurring at this interface
and the cosmic ray density in nearby interstellar space.
- Galactic cosmic ray protons and Solar proton intensities in
the energy range 1.8 - 200 MeV
- Galactic cosmic ray helium and Solar helium intensities in
the energy range 1.8 - 500 MeV/nucleon
- Galactic and Solar electron intensities in the energy range
0.2- 13.0 MeV
- Li,Be,B,C,N,O,F,Ne intensities and their isotopic composition
in the energy range 6 MeV/nuc - 200 MeV/nuc
- Integral flux of IONS > 70 MeV