4 Solar and Fundamental Physics
In Collaboration with J. W. Armstrong
4.1 Principles of Heliospheric Observations
Radio science (RS) observations can probe the inner heliosphere and the solar wind on spatial scales inaccessible to in-situ observations. The first use of the deep space network (DSN) for heliospheric research was a spectral broadening experiment as the line-of-sight (LOS) of the Mariner 4 spacecraft passed within 0.6 degrees (deg) of the Sun. An open-loop receiver (see Chapter 5 ) was used to record the pre-detection electric field data. In 1968, Goldstein (1969) duplicated the experiment during the superior conjunction of Pioneer 6. Table 4.1 summarizes observable quantities and their relevance to heliospheric investigation goals. Appendix 4A describes solar corona observation methodology using Mars Express data for illustration.
Table 4.1 Radio science observables relevant to heliospheric studies.
| Observation | Relevance | Comment |
|---|---|---|
Phase scintillation
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Intensity fluctuations
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