The Plasma-Mag investigation will contribute to both the source and structure of the slow solar wind and the heating of the corona. The mechanisms for heating the solar corona to temperatures that are much hotter than the photosphere are not well understood. Waves in the solar wind almost certainly undergo a turbulent cascade to heat the wind at small scales, but our current descriptions of this are mostly phenomenological. More generally, the coupling between magnetic and electric fluctuations and particle distribution functions is a fundamental plasma interaction, important in a wide variety of contexts, but difficult to study directly. The improved time resolution of Triana/Plasma-Mag provides an opportunity to determine the mechanism by which small-scale fluctuations dissipate in plasmas. A time resolution of less than 1second will provide information to determine how the plasma responds to the simultaneously measured magnetic fields.
Triana would also provide a monitor of the solar wind in addition to any other spacecraft that may still be available at the time of its launch. This would allow the detailed study of the non-radial correlation with solar wind fluctuations. This study was begun with earlier spacecraft such as the Explorers, IMP, and ISEE, but new opportunities would now be available. For example, if WIND or a STEREO spacecraft were measuring the solar wind at a variety of positions away from L-1, this would provide correlation at multiple baselines. These measurements would help to determine the symmetry of the fluctuations in the wind that in turn determine the way in which energetic particles propagate in the heliosphere. This basic understanding is also central to determining how, for example, solar events affect the Earth and its near-space environment, and thus is important for determining the effects of solar activity on spacecraft and manned space flights.
The Plasma-Mag instruments will measure the magnetic field and the velocity distribution functions of the electron, proton, and alpha components of the solar wind with higher time resolution than existing spacecraft.
The three Plasma-Mag instruments (Faraday cup, magnetometer, and electron spectrometer) will obtain 3-dimensional measurements of the velocity distribution functions of protons, helium ions, and electrons, and the interplanetary magnetic field. The data can be collected with high temporal resolution because Triana is a fixed orientation spacecraft that permits the solar wind ions and electrons to strike the Faraday cup continuously. The data collected by Plasma-Mag will provide early warning of solar events that may cause damage to power generation, communications, and other satellites. Together, the Plasma-Mag suite of instruments will provide a 1-hour warning to the appropriate agencies that safeguard electrical equipment on Earth and satellites in Earth orbit. Present plans include routinely providing the data to NOAA with typically only a 5-minute data processing delay from detection of an event at the Triana spacecraft position to the time that it is delivered. Monitoring of the solar weather has become a mandatory function of government due to the growth of civilian and military satellite communications. Plasma-Mag will add to, or replace, the first generation space-weather monitors, such as WIND, IMP-8, and ACE.