HP 41 used on Shuttle at Air & Space Museum


I live in the metropolitan DC area and recently visited the Smithsonian National Air and Space Museum. It has an exhibit entitled 'Beyond The Limits' which depicts the role of computers in the development of aviation and space flight. An HP 35 (version 2) hangs near the entrance to the exhibit. Further in the exhibit, there is a display of an HP 41CV used aboard several Space Shuttle missions. The following links are pictures of this exhibit:



Apparently the usual 41 case has been replaced by something more NASA'ish. It's also interesting that the 41 has a translucent keyboard overlay (which in retrospect seems like a great idea) and color coded sticky labels. Also, there is a picture (which hangs below the 41) of astronaut Sally Ride taken aboard the Space Shuttle Challenger with a 41 next to her.

Just curious if anyone has come across information about the programs the astronauts used on the 41's? Also, I'm wondering if there are any other 'physical' museums that display Hewlett Packard calculators?



I know the HP engineer that went to Houston to teach the astronauts how to use the 41. I've asked him about it but I haven't gotten many details from him yet. Also Richard Nelson once told me that he had copies of the programs that the astronauts used. I've asked him for copies of them but so far he hasn't had time to find them. He did say that they were relatively crudely written but that's understandable since the 41 usage was something that the astronauts did on their own and was not an offical NASA project. That "unoffical" status lead to the astronauts writng their own programs instead of professional programmmers writing them.

Also you may have heard the story that the 41s that they used were standard 41s that were bought at a local Houston office supply store and were not procured through NASA. I was told by both the HP engineer and by Richard Nelson that that story is true. The engineer did say that they had to use the NiCad battery packs since alkaline batteries were not permitted for space use. That was the only change from the standard out-of-box configuration.

What kind of markings and/or property tags are on the two 41s that you saw? It looks like there's a property tag on the top of the second one. I have two HP 41s that I bought at KCS that have NASA and KCS property tags and I was wondering about their usage.



In case there was some confusion, the display at the Air and Space Museum has only 1 HP 41CV. The two pictures are the same calculator but from different angles. The 41 did not have any modules installed (only the port covers). It did have what looked like a silver property tag on the top.


One other change made to the hp-41s was that the small door on the side for the ac adapter was glued in place. rdb.


More information about the modifications made to the 41s which went into space can be found in HP Key Notes, May-Aug 1981, Vol. 5, No. 2, Page 14 at the bottom of the page.



If you look at the HP advertisement section, there are two HP advertisements about the 41 and the space shuttle. If you zoom in on one about getting the "free Module", it says " The HP-41 handheld computer was chosen by NASA as a regular member of the Space Shuttle ????. If need be, it can help land the Space Shuttle without help of mission control. And until April 30, ...." Sorry could not make out the word I put ???? in for above. That is what I thought I remember they could or would use it for. Hope it helps!


Two of the HP-key note issues (Jan-April 1981 Vol. 5, No. 1 and March - May 1982 Vol. 6 No. 2) describe the HP-41C's that were used aboard the Columbia. There are also a few pictures showing them in use. One article described that the HP-41C was used to calculate deorbit-burn information, should data coming from mission control be interrupted or during an emergency. Two other programs helped balance Columbia prior to re-entry and another to pin-point Earth observation sites. The 41C's did not take place of the larger on board computers, but complemented them with personal computer convenience. The time module was also mentioned, as well as the HPIL peripherals. The other article described how the 41's were tested at white sands New Mexico (for shock, vibration and outgassing). As a result of the tests, certain modifications (which were not described) were made to certify them for flight. Special flight pouches with extra memory modules (each 41C had four mem. modules), extra batteries, a card reader and cards were used. For the first shuttle flight, one HP41C was dedicated to the center of gravity program (balance) and the other to acquisition of signal."The center of gravity program was used before reentry into the earth's atmosphere to compute the shuttle's present center of gravity and the amount of fuel to be burned in each tank to reach the required center of gravity for reentry. This center of gravity program was termed "flight critical" by NASA and necessitated extensive pre-launch testing of the calculators".

"The other program, the Acquisition of signal program, ran continually in the second calculator, starting at launch, so it could display at any time the next ground station that columbia could contact, when it would be in contact, the duration of that contact, and which frequency (UHF or S-band) could be used. And thanks to the continuous memory, the calculator did not have to be on during the whole flight". The article also mentioned that HP might make custom ROM modules for NASA to eliminate the need for memory modules


Another 'physical' museum (nice distinction, that) is the 'Deutsche Museum', Munich, Germany, where you can find an HP-41CX model displayed in the Department of Information Science (unless they have had it removed, my last visit was in the early nineties of the last millennium...:-).

Klaus (Cococollector)


Hi Klaus,

What was the subject of the 41CX display in Germany?


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