With the launch of the first scientific instrument into space. (USA's first satellite after the success of Sputnik and Mutnik by the USSR)
Sixty years ago, on January 31, 1958, the Explorer 1 was launched a loft a Juno-1 (a modified Jupiter-C) rocket.
The Juno name derived from Von Braun wishing to make the satellite launch vehicle appear less weapon like.
The Rocket has the lettering system designed to fool the soviets.
Here is the key
The test base was in Huntsville, Alabama, giving HUNTSVILE, with duplicated letters dropped: H was used for 1, U for 2, ..., E for 9 and X for 0. For example, the Jupiter-C modified to launch Explorer 1 had "UE" painted on the side, indicating it was S/N 29 (U→2, E→9)
The sequence of manufacture of the rockets (which are not necessarily launched in order) was considered a military secret
So really this marks the start of the era of space exploration for the United States, exactly 60 years ago today
Explorer I was a thirty pound satellite that carried instruments to measure temperatures, and micrometeorite impacts, along with an experiment designed by James A. Van Allen to measure the density of electrons and ions in space.
Explorer 1 was given Satellite Catalog Number 4, and the Harvard designation 1958 Alpha 1, the forerunner to the modern International Designator
The measurements made by Van Allen's experiment led to an unexpected and then startling discovery of two earth-encircling belts of high energy electrons and ions trapped in the magnetosphere. Now known as the Van Allen Radiation belts, the regions are located in the inner magnetosphere, beyond low Earth orbit.
Explorer I ceased transmitting on February 28, 1958, but remained in orbit until March of 1970.
The scientific instrumentation of Explorer 1 was designed and built under the direction of Dr. James Van Allen of the University of Iowacontaining
Anton 314 omni-directional Geiger-Müller tube, Most of the time the instrument was saturated.
Five temperature sensors (one internal, three external and one on the nose cone);
Acoustic detector (crystal transducer and solid-state amplifier) to detect micrometeorite (cosmic dust) impacts.
Wire grid detector, also to detect micrometeorite impacts. If a micrometeorite of about 10 µm impacted, it would fracture the wire, destroy the electrical connection, and thus record the event
And all this on a night where we get the anniversary marked by the second full moon of the month, which only happens once in a blue moon, and for some lucky people a lunar eclipse!!!