Further references to HP-65 calculator in ASTP rendez-vous manual

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These were found by a fellow HP Museum forumite. They are part 1 and part 2 of the Apollo Soyuz Test Project rendez-vous manual and include several references to the HP-65. They are in PDF format.

Part 1

Part 2


HP-65 Apollo Soyuz Test Project checklist binder

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From an auction webpage (sorry, this is all I could find):

This three-ring checklist (6″x8″) was flown used onboard Apollo-Soyuz by Deke Slayton and has extensive pencil notations in his hand. Pristine condition and unique. Fourteen pages plus front and back cover. A ‘Slayton’ Certificate of Authentication is included and states, in part: ‘This checklist book has been on loan for exhibition to the Astronaut Hall of Fame in Titusville, FL and the Air and Space Museum in Huntsville, AL. Ex-Donald ‘Deke’ Slayton Estate Collection.

HP-65 ASTP checklist

HP-65 ASTP checklist

HP-65 ad

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Here’s the classic HP-65 ad about the Apollo-Soyuz mission.



Complete text:

HP-65 in space with Apollo-Soyuz.

The American astronauts calculated critical course-correction maneuvers on their HP-65 programmable hand-held during the rendez-vous of the U.S. and Russian spacecraft.

Twenty-four minutes before the rendezvous in space, the American astronauts corrected their course to place their spacecraft into the same orbit as the Russian craft. Twelve minutes later, they made a second positioning maneuver just prior to braking, and coasted in to linkup.

In both cases, the Apollo astronauts made the course-correction calculations on their HP-65. Had the on-board computer failed, the spacecraft not being in communication with ground stations at the time, the HP-65 would have been the only way to make all the critical calculations. Using complex programs of nearly 1000 steps written by NASA scientists and pre-recorded on magnetic program cards, the astronauts made the calculations automatically, quickly, and with ten-digit accuracy.

The HP-65 also served as a backup for Apollo’s on-board computer for two earlier maneuvers. Its answers provided a confidence-boosting double-check on the coelliptic (85 mile) maneuver, and the terminal phase initiation (22 mile) maneuver, which placed Apollo on an intercept trajectory with the Russian craft.

Periodically throughout their joint mission, the Apollo astronauts also used the HP-65 to calculate how to point a high-gain antenna precisely at an orbiting satellite to assure the best possible ground communications.

The first fully programmable hand-held calculator, the HP-65 automatically steps through lenghty or repetitive calculations. This advanced instrument relieves the user of the need to remember and execute the correct sequence of keystrokes, using programs recorded 100 steps at a time on tiny magnetic cards. Each program consists of any combination of the calculator’s 51 key-stroke functions with branching, logical comparison, and condition skip instructions.

The HP-65 is priced at $795. See it, and the rest of the HP family of professional hand-helds at quality department stores or campus bookstores.

Apollo guidance computer and HP-65

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From www.absoluteastronomy.com, a badly formatted text about the AGC and the HP-65 which I have taken the liberty of correcting:

Dsky user interface

The user interface unit was called the Dsky. Dsky stood for display and keyboard and was usually pronounced dis-key. It had an array of numeric displays and a calculator-style keyboard. Commands were entered numerically, as two-digit numbers: program, verb, and noun. The numerals were green high-voltage electroluminescent seven segment displays. The segments were driven by electromechanical relays, which limited the display update rate (Block II used faster silicon controlled rectifiers). Three 5-digit signed numbers could also be displayed in octal or decimal. These were typically used to display vectors such as space craft attitude or a required velocity change (delta-V). This calculator-style interface was the first of its kind, the prototype for all similar digital control panel interfaces.

The first advanced desktop calculators hit the market in roughly the same time frame, with scientific and then programmable pocket calculators appearing during the following decade. The first programmable handheld calculator, the HP-65, was tried on backup computations aboard the Apollo Command/Service Module in the Apollo-Soyuz Test Project in 1975.

The command module (CM) had two Dskys; one located on the main instrument panel and another located in the lower equipment bay near a sextant used for aligning the inertial guidance platform. Both Dskys were driven by the same AGC. The lunar module (LM) had a single Dsky for its AGC. A Flight Director Attitude Indicator (FDAI), controlled by the AGC, was located above the Dsky on the commander’s console and on the LM.

A standard tool for every crew of NASA astronauts

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From this webpage of http://www.hpmemory.org, several milestones of Hewlett-Packard related to space explorations. A noteworthy quote from this page: “After its introduction in 1974, the HP65, world first fully programmable pocket calculator, became a standard tool for every crew of NASA astronauts.

HP-65 and Apollo-Soyuz

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Press release describing the proposed use of the HP-65 in flight:


“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.

Apollo launch of the Apollo-Soyuz Test Project

Apollo launch of the Apollo-Soyuz Test Project

Soyuz launch of the Apollo Soyuz Test Project

Soyuz launch of the Apollo-Soyuz Test Project

HP-65 in flight

HP-65 in flight