Editing Explorer 1 (section)

== Results ==
Explorer 1 changed [[Rotation|rotation axis]] after launch. The elongated body of the spacecraft had been designed to spin about its long (least-inertia) axis but refused to do so, and instead started [[precession|precessing]] due to energy [[dissipation]] from flexible structural elements. Later it was understood that on general grounds, the body ends up in the spin state that minimizes the kinetic rotational energy for a fixed angular momentum (this being the maximal-inertia axis). This motivated the first further development of the [[List of things named after Leonhard Euler|Eulerian]] theory of rigid body dynamics after nearly 200 years – to address this kind of momentum-preserving energy dissipation.<ref>{{cite journal |last=Efroimsky |first=Michael |date=August 2001 |title=Relaxation of wobbling asteroids and comets – theoretical problems, perspectives of experimental observation |journal=Planetary and Space Science |volume=49 |issue=9 |pages=937–955 |doi=10.1016/S0032-0633(01)00051-4 |bibcode=2001P&SS...49..937E |arxiv=astro-ph/9911072 |citeseerx=10.1.1.256.6140 |s2cid=14114765}}</ref><ref>{{cite journal |last=Efroimsky |first=Michael |date=March 2002 |title=Euler, Jacobi, and missions to comets and asteroids |journal=Advances in Space Research |volume=29 |issue=5 |pages=725–734 |doi=10.1016/S0273-1177(02)00017-0 |arxiv=astro-ph/0112054 |bibcode=2002AdSpR..29..725E |citeseerx=10.1.1.192.380 |s2cid=1110286}}</ref>

Sometimes the instrumentation reported the expected cosmic ray count (approximately 30 counts per second) but other times it would show a peculiar zero counts per second. The University of Iowa (under James Van Allen) observed that all of the zero counts per second reports were from an altitude of more than {{cvt|2000|km}} over [[South America]], while passes at {{cvt|500|km}} would show the expected level of cosmic rays. Later, after Explorer 3, it was concluded that the original Geiger counter had been overwhelmed ("saturated") by strong radiation coming from a belt of charged particles trapped in space by the Earth's magnetic field. This belt of charged particles is now known as the [[Van Allen radiation belt]]. The discovery was considered to be one of the outstanding discoveries of the International Geophysical Year.

The acoustic micrometeorite detector detected 145 impacts of cosmic dust in 78,750 seconds. This calculates to an average impact rate of 8.0<sup>−3</sup> impacts per second per square meter, or 29 impacts per hour per square meter, over the twelve-day period.<ref name="dubin">{{cite journal |last=Dubin |first=Maurice |date=January 1960 |title=IGY Micrometeorite Measurements |journal=Space Research – Proceedings of the First International Space Science Symposium |volume=1 |issue=1 |pages=1042–1058 |bibcode=1960spre.conf.1042D |url=https://apps.dtic.mil/sti/pdfs/ADA285101.pdf |access-date=2023-02-09}}</ref>