Introduction to WIND
Wind is a spacecraft launched on November 1, 1994 and placed in a halo orbit to observe the unperturbed solar wind that is about to impact the magnetosphere of Earth. Wind, together with a host of other NASA spacecrafts constitute a cooperative scientific satellite project designated the International Solar Terrestrial Physics (ISTP) program that aims at gaining improved understanidng of the phyiscs of solar terrestrial relations. The Wind satellite is specifically designed to study the Solar Wind and its excited sub-atomic particles.
- Provide complete plasma, energetic particle and magnetic field for magnetospheric and ionospheric studies.
- Investigate basic plasma processes occurring in the near-Earth solar wind.
- Provide baseline, 1 AU, ecliptic plane observations for inner and outer heliospheric missions.
WIND carries these instruments:
- Magnetic Field Investigation (MFI)
- Solar Wind Experiment (SWE)
- 3D Plasma Analyzer
- Solar Wind and Suprathermal Ion Composition Studies (SMS)
- Energetic Particle Acceleration, Composition, and Transport (EPACT)
- Transient Gamma-Ray Spectrometer (TGRS)
- KONUS (first Russian instrument to fly on American satellite)
Magnetic Field Investigation (MFI)
The Magnetic Fields Investigation (MFI) will investigate the large-scale structure and fluctuation characteristics of the interplanetary magnetic field, which influence the transport of energy and the acceleration of particles in the solar wind and dynamic processes in the Earth's magnetosphere. The fundamental observations of solar wind magnetic fields are important to the study of the solar wind and magnetosphere coupling process and also to the interpretation of other observational data from WIND. MFI's science objective is to establish the large-scale structure and fluctuation characteristics of the interplanetary magnetic field as functions of time, and through correlative studies to relate them to the dynamics of the magnetosphere.
Solar Wind Experiment (SWE)
The Solar Wind Experiment (SWE) will measure ions and electrons in the solar wind and the foreshock regions (particles whose energies are in the kiloelectronvolt range). From these measurements, the solar wind velocity, density, temperature and heat flux can be deduced. Electron and ion velocity distributions should reveal properties of the following plasmas and their pivotal role in the transfer of mass, momentum, and energy from the Sun to the Earth. Measurements made in the foreshock region will contribute to understanding the structure of the bow shock.
See also the Solar Wind Experiment Homepage.
The 3-D Plasma and Energetic Particle Analyzer investigation will measure ions and electrons in the interplanetary medium with energies including that of the solar wind and the energetic particle range. It will study the particles upstream of the bow shock in the foreshock region and the transient particles emitted by the Sun during solar particle events following solar flares. This experiment will cover the gap between the energy ranges covered by SWE and EPACT.
For more infromation see the 3-D Plasma and Energetic Particle Homepage.
SMS Suprathermal Particle Data
The Solar Wind and Suprathermal Ion Composition Studies (SWICS/MASS/STICS) experiment comprises three major instruments: Solar Wind Ion Composition Spectrometer (SWICS), High Mass Resolution Spectrometer (MASS), and Suprathermal Ion Composition Spectrometer (STICS). This experiment will determine the abundance, composition and differential energy spectra of solar wind ions, and the composition, charge state and 3-D distribution functions of suprathermal ions. These ions and their abundance fluctuations provide information about events on the solar surface and the formation of the solar wind, complementing the EPACT and 3D-PLASMA investigations.
Energetic Particle Acceleration, Composition, and Transport (EPACT)
The Energetic Particle Acceleration, Composition, and Transport (EPACT) investigation will provide a comprehensive study of energetic particle acceleration and transport processes in solar flares, the interplanetary medium, and planetary magnetospheres, as well as the galactic cosmic rays and the anomalous cosmic ray component.
EPACT measurements will determine elemental and isotopic abundances for the minor ions making up the solar wind, with energies in excess of 20keV. This direct sampling of solar matter is a way to study events on the solar surface and the incorporation of solar material into the solar wind. EPACT will also provide information on shocks in the interplanetary medium, which accelerate particles from solar-wind energies to several hundred keV.
The Sun and the Earth emit radio waves that affect particles in the interplanetary plasma and carry some of the energy flowing there. The Radio and Plasma Wave experiment will measure the properties of these waves and other wave modes of the plasma over a wide frequency range. Analyses of these measurements, in coordination with the other onboard plasma, energetic particles, and field measurements, will further the understanding of solar wind and interplanetary plasma processes.
Transient Gamma-Ray Spectrometer (TGRS)
The Transient Gamma-Ray Spectrometer (TGRS) will detect transient gamma-ray burst events and will make the first high-resolution spectroscopic survey of cosmic gamma-ray bursts, and will also make measurements of gamma-ray lines in solar flares.
Cosmic gamma-ray bursts are among the most violent and energetic processes known to exist in nature, characteristically emitting most of their luminosity at gamma-ray wavelengths. The high-resolution spectroscopy of solar flares will contribute to the study of solar flare activities and help in understanding the coupling between the active corona and photosphere.
For additional information see the TGRS Home Page.
The Gamma Ray Burst Studies investigation will perform gamma-ray burst studies similar to the TGRS studies. It will perform event detection and will measure time history and energy spectra. Although KONUS has a lower resolution than TGRS, it has broader area coverage to complement that of TGRS so that, when their data are combined, they provide coverage of the full sky. KONUS is the first Russian instrument to fly on an American satellite since civil space cooperation between the U.S. and Russia was resumed in 1987.
For more info go to NASA's WIND site.