Press release describing the proposed use of the HP-65 in flight:
HP-65 IN SPACE
“65 Notes,” July 1975
Volume 2, Number 6, Page 7
PALO ALTO, Calif., July 8 — An 11-oz, $795 pocket calculator that can be programmed like a computer will play an important role in the historic Apollo/Soyuz rendezvous in space July 17.
The Hewlett-Packard HP-65 fully programmable pocket calculator will be used to calculate two critical mid-course correction maneuvers just prior to the linkup of the U.S. Apollo and the Russian Soyuz spacecraft. These maneuvers will take place 12 and 24 minutes after terminal phase initiation (the beginning of the last part of the flight before rendezvous).
The calculator also will be used as a backup for Apollo’s on-board computer for the final maneuvers prior to rendezvous and docking. The first use will be for the coelliptic maneuver (putting both spacecraft into the same orbit) when the vehicles are within approximately 100 miles of each other. The second will be for the terminal phase initiation calculations when Apollo is 22 miles from Soyuz. In both instances, the HP-65 will be used to solve the problems, and its answers will be compared with those of the on-board computer.
In the event of an on-board computer failure, however, the HP-65 will provide the only available solution for the mid-course maneuvers, since the spacecraft will not be in communication with ground stations at that phase of the mission.
A third set of calculations to be performed by the battery-powered HP-65 will allow the astronauts to precisely point Apollo’s high gain antenna at an orbiting satellite to assure proper communications with Earth.
NASA scientists have written programs of up to 1,000 steps and recorded them on tiny magnetic cards (100 steps per card). The astronauts will feed these cards into the HP-65 to automatically perform the critical calculations. In previous space flights, backup maneuver calculations were made manually, using charts. The HP-65 will substantially reduce the time needed to make the complex calculations and improve the quality, accuracy and confidence in resulting solutions.
Two HP-65s will be taken on the space flight, along with four sets of program cards and six spare battery packs.
The HP-65 is not the first HP pocket calculator to venture into space; an earlier model, the HP-35, went along on the Skylab missions.
The HP-65 is a general purpose calculator that can be programmed to go through a step-by-step routine at the touch of a few keys, solving extremely complex, lengthy or repetitive calculations quickly, easily and accurately. Users can write their own programs for the calculator or buy prerecorded program cards from Hewlett-Packard in the fields of finance, mathematics, statistics, electrical engineering, thermodynamics, stress analysis, surveying, medicine, aviation and marine navigation.
Hewlett-Packard pocket calculators are no strangers to adventure. They have served high upon the rugged slopes of Mt. Everest; at the LeMans, France, professional auto races; at the navigator’s station of the sailboat “Courageous” the successful America’s Cup defender; and in the cockpits of Powder Puff Derby aircraft race contestants.
The U. S. spaceship will begin its mission July 15 from Cape Canaveral.