And a Couple More

Researchers considered X-ray photographs important for understanding the problems of the solar atmosphere, which led to the "X-ray mapping of the sun" experiment. Instruments on sounding rockets had obtained similar photographs of the sun, but the excessive motion of the vehicle had greatly complicated measurements. NASA installed a small pinhole camera in one of the upper bug-eye camera bays on the X-15 in January 1962. This experiment flew above 150,000 feet several times between March 1962 and September 1963.[78]

The "electron-distribution determination" experiment measured electron distribution in the upper atmosphere using radiofrequency techniques. These measurements of the ionosphere D-layer (often as low as 50 miles) were important for investigators seeking to gain a basic understanding of the ionosphere. Since the temporal variation of the electron distribution was important, a series of flights was desirable; however, there appears to be no record indicating that the experiment actually flew or acquired any useful data.[79]