August 15, 2017 | Henry Richter

Explorer 1 Pioneer Corrects Mistakes in Article

Corrections to Article:  “Explorer 1: the First U.S. Satellite” by Elizabeth Howell published August 10 at

by Dr Henry Richter, former Explorer 1 instrument manager

Dr Richter speaks at JPL about the Explorer 1 mission, January 30, 2008. Photo by David Coppedge.

I am glad to see tributes written to the Free World’s first earth satellite as we come up to the 60th anniversary of the launch – which will be January 31, 2018.

The article’s author hits many of the highlights of the launch, but contains a few inaccuracies which I will comment on here. I do not mean to nit-pick, but the record needs some correction. The first line of text says the Explorer satellite (pictured below) was “twice the size of a basketball” although from the figure one can see it was a cylinder about six inches in diameter and about five feet long. It was the Vanguard payload that  was spherical, about twice the size of a basketball. Sputnik was also spherical.

Explorer 1 model with Sputnik 1 behind, California Science Center. Photo by David Coppedge

In the paragraph titled “Behind the Vanguard” she says that the rocket carried Explorer 1. Not the case – it carried the Vanguard satellite. The Explorer 1 was carried on the Army (ABMA/JPL) Juno (Jupiter-C) rocket and was launched January 31, 1958. The first Vanguard was a minimized small sphere, about six inches in diameter, nicknamed “the grapefruit.” It had only a transmitter to establish orbit, and was powered by solar cells. After the explosion of the first Vanguard, it bounced to the side and escaped all the flames.

Three more paragraphs down she talks about the confirmation of successful orbit of Explorer 1. The confirmation was furnished by a small network of receiving stations in Southern California. The first one actually locking on to signals was a JPL-sponsored station operated by a group of radio amateurs from the San Gabriel Valley Radio Club. Based on that data, Dr. Al Hibbs, with us at the Cape then computed the first orbital parameters. I was in the Cape message center on the teletype to the War Room in the Pentagon where Dr. von Braun, Dr. Bill Pickering, and Dr. James van Allen, plus Army brass, were waiting to make the announcement after we were sure of successful  orbit. They then flashed the information to President Eisenhower who was at the Augusta GA golf tournament. Then, von Braun, Pickering, and van Allen went to the press conference at the National Academy of Sciences – where the famous picture of the three of them holding a model of Explorer 1 was taken.

Explorer 1 50th Anniversary display at JPL, 2008. Photo by David Coppedge

Ms. Howell relates that “the satellite detected fewer cosmic rays than expected.” Actually, occasionally the satellite detected no cosmic rays which was worrisome to us. What had gone wrong?  History shows that later we realized that the Geiger counter had stopped sending data because it saturated in the heavy radiation of the magnetically created Van Allen belts.

The last comment is that she states that the satellite was painted white and dark green. Actually, the dark-appearing surface was bare metal and the white stripes were a coating of rokide, a ceramic fused to the metal. Before launch and final design, we ran many calculations and tests to assure that this technique controlled the average temperature to protect the internal electronics.

I will slip in a little promotion. I guess all I can say is that if Ms. Howell had my book America’s Leap into Space – My Time at JPL and the First Explorer Satellites, she might have picked up on these subjects.

Dr Henry Richter, a contributor to Creation-Evolution Headlines, was a key player at NASA/JPL in the early days of the American space program. With a PhD in Chemistry, Physics and Electrical Engineering from Caltech), Dr Richter brings a perspective about science with the wisdom of years of personal involvement. His book America’s Leap Into Space: My Time at JPL and the First Explorer Satellites (2015), chronicles the beginnings of the space program based on his own records and careful research into rare NASA documents, providing unequaled glimpses into events and personnel in the early days of rocketry that only an insider can give. His next book, Spacecraft Earth: A Guide for Passengers, is due out later in 2017. For more about Dr Richter, see his Author Profile.

Dr Henry Richer (2nd from left) receiving award on behalf of JPL with surviving JPL directors, including Bruce Murray, Lew Allen, Ed Stone (at lectern), and Charles Elachi. AIAA meeting, Washington DC, May 2008.

(Visited 697 times, 1 visits today)


  • mikeboll64 says:

    “…the Geiger counter had stopped sending data because it saturated in the heavy radiation of the magnetically created Van Allen belts.”

    How do you suppose the Apollo missions were able to overcome such heavy radiation as they passed through these belts on the way to the moon?

    • Regarding the Apollo astronauts enroute to the moon, since they were travelling at escape velocity, it should have not taken more than a minute or two to transverse the belts. It would take hours or days in the belt to cause body damage.

  • Regarding the Apollo astronauts, I presume they were moving through the VanAllen belts at escape velocity, and did not spend more than a couple minutes transversing the radiation. It would take hours, or days in the belts to get enough radiation to cause body damage.

Leave a Reply