Astronomy and Space
Explorer 20, also known Ionosphere Explorer-A, IE-A, S-48, TOPSI and Topside Explorer, was a NASA satellite launched as part of Explorer program. Its purpose was two-fold: long-term investigation of the ionosphere from above, and in situ investigation of ion concentrations and temperatures.
Evidence of water on Mars found by Mars Reconnaissance Orbiter.
Eridanus (constellation).
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