Luna 2 also crash land on the Moon in exactly the same way. Crash landing proved useful even after soft landing was mastered. NASA used crash landings to test whether Moon craters contained ice by crashing space probes into craters and testing the debris that got thrown out. The satellite's impact made it the first man-made object to land on another celestial body. "Luna 2" carried 5 different instruments to conduct various tests while it was on its way to the Moon. The scintillation counters would be used to measure any ionizing radiation; the Cherenkov radiation detectors would be measuring for electromagnetic
Dynamics of the celestial spheres individual unmoved mover would be required to insure each individual motion in the heavens. While stipulating that the number of spheres, and thus gods, is subject to revision by astronomers, he estimated the total as 47 or 55, depending on whether one followed the model of Eudoxus or Callippus. In "On the Heavens", Aristotle presented an alternate view of eternal circular motion as moving itself, in the manner of Plato's world-soul, which lent support to three principles of celestial motion: an internal soul, an external unmoved mover, and the celestial material (aether). In his "Planetary Hypotheses", Ptolemy (c.90–168) rejected the