Tag Archives: spaceflight

Fellow Travelers

“The radio signals of the satellite [Sputnik II] were followed and recorded on tape frequently by Mr. C. Newton Kraus, an outstanding radio amateur of Touisset Point, R.I. He had followed Sputnik I signals for the three weeks that the transmitters continued to function.”

―Charles H. Smiley, The First Artificial Earth Satellites, August 1958.

On October 4, 1957 the Soviet Union launched the first artificial Earth satellite which was called Sputnik I. The word Sputnik simply means “satellite” or, more generally, “fellow traveler.” The quotes from Prof. Charles Smiley, director of Ladd Observatory, are from a report published in The Hinterlands, the Bulletin of the Western Rhode Island Civic Historical Society. He describes how Sputnik I could be seen from all parts of the Earth and reports on the local observations of it: “In Rhode Island, between October 12 and November 27, it was observed at Ladd Observatory of Brown University on 13 different passages for a total of 33.2 minutes.” The observed positions and motion were plotted on a star map.

Observations of Sputnik I
Observations of the Sputnik I rocket body from southeastern New England. October 12-17, 1957.

The satellite itself was only 22 inches in diameter and would have been difficult to see from the ground. Instead, they were observing the rocket that launched the satellite which also entered orbit. The second stage of the rocket was 92 feet long and 9.7 feet in diameter. Sunlight reflecting off the rocket body was much easier to see. Notice that observers in Providence RI, Nantucket MA, and Mansfield CT saw the rocket in a slightly different position against the background stars due to parallax.

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Flight-critical calculator

“In addition to helping the crew organize its time, the second HP-41 computer was kept ready for flight-critical, deorbit-burn calculations. Once during each orbit around the Earth, the shuttle has an opportunity to land at one of six contingency locations. During a routine flight, Mission Control supplies the shuttle crew with deorbit-burn information. Should the shuttle encounter an emergency, however, the astronauts would rely on the HP-41 for these calculations.”

―”HP-41’s Again Aboard Columbia.” HP Key Notes, March-May 1982.

HP-41 advertisement
Hewlett Packard advertisement, 1982.

To prepare an orbiting Space Shuttle for re-entry through the Earth’s atmosphere it is critical that the spacecraft be “balanced” by taking into account the mass of the fuel left in the tanks at the end of a mission. An astronaut would use a handheld computer or programmable calculator to determine how many minutes and seconds of fuel to burn to get the center of gravity correct for a smooth descent and landing. The “personal computing system” used for this was made by Hewlett Packard in the 1980s. NASA donated one of these, a model HP-41CV, to Ladd Observatory after the retirement of the Shuttle program.

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