Editing Explorer 1 (section)

== Science payload ==
[[File:1958-02-03 First US Satellite Launched.ogv|thumb|upright=1.0|right|thumbtime=3|[[Universal Newsreel]] about the satellite]]

The Explorer 1 payload consisted of the Iowa [[Cosmic ray|Cosmic Ray]] Instrument without a [[tape recorder|tape data recorder]] which was not modified in time to make it onto the spacecraft. The real-time data received on the ground was therefore very sparse and puzzling showing normal counting rates and no counts at all. The later [[Explorer 3]] mission, which included a tape data recorder in the payload, provided the additional data for confirmation of the earlier Explorer 1 data.

The scientific instrumentation of Explorer 1 was designed and built under the direction of Dr. [[James Van Allen]] of the [[University of Iowa]] containing:<ref name="data sheet">{{cite web |url=https://www.nasa.gov/history/sputnik/expinfo.html |title=Explorer-I and Jupiter-C |publisher=NASA |access-date=30 July 2024}} {{PD-notice}}</ref>

* Anton 314 omnidirectional [[Geiger–Müller tube]], designed by Dr. [[George H. Ludwig]] of Iowa's Cosmic Ray Laboratory, to detect [[cosmic ray]]s. It could detect protons with E>30 MeV and electrons with E>3 MeV. Most of the time the instrument was saturated;<ref name="cosmic ray detector">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1958-001A-01 |title=Cosmic-Ray Detector |publisher=NASA |date=14 May 2020 |access-date=12 February 2021}} {{PD-notice}}</ref>

* Five temperature sensors (one internal, three external and one on the nose cone);

* Acoustic detector (crystal [[transducer]] and solid-state [[amplifier]]) to detect [[micrometeoroid|micrometeorite]] ([[cosmic dust]]) impacts. It responded to micrometeorite impacts on the spacecraft skin in such a way that each impact would be a function of mass and velocity. Its effective area was 0.075 m<sup>2</sup> and the average threshold sensitivity was 2.5{{e|−3}} g cm/s;<ref name="micrometeorite detector">{{cite web |url=https://nssdc.gsfc.nasa.gov/nmc/experiment/display.action?id=1958-001A-02 |title=Micrometeorite Detector |publisher=NASA |date=28 October 2022 |access-date=30 July 2024}} {{PD-notice}}</ref><ref name="manring">{{cite journal |last=Manring |first=Edward R. |date=January 1959 |title=Micrometeorite Measurements from 1958 Alpha and Gamma Satellites |url=https://ui.adsabs.harvard.edu/abs/1959P%26SS....1...27M/abstract |journal=Planetary and Space Science |volume=1 |issue=1 |pages=27–31 |bibcode=1959P&SS....1...27M |doi=10.1016/0032-0633(59)90019-4}}</ref>

* Wire grid detector, also to detect micrometeorite impacts. It consisted of 12 parallel connected cards mounted in a fiberglass supporting ring. Each card was wound with two layers of enameled [[Cupronickel|nickel alloy]] wire with a diameter of 17 [[Micrometre|μm]] (21 μm with the enamel insulation included) in such way that a total area of {{cvt|1|xx|1|cm}} was completely covered. If a [[micrometeorite]] of about 10 μm impacted, it would fracture the wire, destroy the electrical connection, and thus record the event.<ref name="micrometeorite detector"/><ref name="manring"/>