HP calculators and space exploration


I just put up a blog about the use of HP calculators in relation to space exploration. This intersects two topics that are of high interest to me.

I just put it up yesterday so it's still a bit rough around the edges. References to sources will be included, so no need to flame me about this.

I read earlier last week a post, in this forum, of a guy working in the space program and discussing the HP-42S so that's why there's already a pic of the 42 in there.

It's a safe bet to assume that all HP calculators over the years were used in the space program. I am aiming for documented use here and pictures if possible.

Here's the link: http://hpinspace.wordpress.com/

Edited: 17 July 2009, 12:04 p.m.


That's a pretty good web page. If you want I could give you a little more anecdotal detail on what I used the 42S for, and more importantly, why it was such a valuable tool at the time.


I'd be very grateful.


I sent you an email message. I put together a short document in Word (or PDF if you want) and I have a photo of the 42s. I also have a couple other photos of HP's in space, one with Sally Ride, one of the HP41 in a museum. I found these on the internet some time ago. If you respond to the email I will send it all.


Got it and answered back.


Yes please, more details are welcome.

- Pauli


There was a picture I believe in USA today showing the crew of STS 107 (final Columbia Flight) with a HP48 floating in front of them. I cannot find this pic in any NASA archives. I have a photocopy somewhere...I'll try to find it.



Found an image in Time:




Very appreciated.



So the last HP calculator used in space was the HP 48?


Unless someone can provide additional information...


And one of the G series judging by the colours.

If they take one up on every Shuttle, I wonder how many they have and what will happen to them in "the gap"?



Thank you for your interesting work. Just a short note: I saw that you used one of my pictures (the 42S picture, copyright fjk.ch). This is not really a problem as the picture is used on a HP related site, but often, my pictures are used on eBay to advertise HP calculators. I think that's a real problem because then the picture does not show the actual item (and normally, the seller gives no hint about that fact). That's why I normally put the copyright notice on my pictures.



Hello Juergen, thanks for the heads up. As I wrote earlier, I intend to properly credit all texts and pictures. I had the idea for this blog this week-end and threw it quickly together.

The blog is not intended for a commercial purpose and no ads will ever be placed in it.

Because I'm going camping for the next few days, proper credits will not be placed until next week-end at least.

Edited: 19 July 2009, 2:03 p.m.


That's OK for me, as the site hosts interesting information for the HP community. Enjoy your vacation, as I currently do in South of France :-)

Best Regards,


Great Blog - good to see one central location about the HP calculators and space.

As to the HP-41, I have a copy of NASA document HP41/SPOC 2102, dated November 1985, titled:

Hewlett-Packard 41 Calculator/Shuttle Portable Onboard Computer Training Manual.

This manual covers both the HP-41 and the Shuttle Portable Onboard Computer (SPOC) which is a GRID computer. Sections in the manual are:

Section 1: Introduction
Section 2: HP-41
Section 3: HP-41 Mode Control
Section 4: HP-41 Display & Keyboard
Section 5: HP-41 Program Loading
This section covers using the Digital Cassette Drive to load
programs. No metion is given of using a card reader.

Section 6: HP-41 Flight Programs
Brief overview of each of the Shuttle flight programs used
by the HP-41 calculator.

Programs are:
Center of Gravity
Proximity Operations

NOTE: THe Alarm/Hex program makes use of a special Module,
which looks a lot like the Card Reader (in size).
This module is "HP-41 Tone Amplifier".

Section 7: Shuttle Portable Onboard Computer
Section 8: Shuttle Portable Onboard Computer Flight Programs

Programs are:
Launch Time Update
State Vector Update
Set Grennwich Mean Time
World Map
Orbital Refueling System
Crew Controlled Free Drift

Appendix A: Reverse Polish Notation
Appendix B: HP-41 Maintenance and Service
Appendix C: HP-41 Troubleshooting
Appendix D: HP-41 Error and Status Messages
Appendix E: HP-41 Function Index
Appendix F: HP-41 Calculator

Following is quote from manual:

"Because the HP-41 is being used by the crew as a program monitoring device rather than a programming tool, programming aspects of the calculator will not be covered in the training manual."

Interesting that cassette tape rather than cards were used.

Another quote:

"However, the HP-41 and SPOC Flight Procedure Handbooks shoud be referred to for detailed information concering the latest set of programs."


"For deatails on each program, refer to the HP-41 Flight Procedure Handbook."

I haven't been able to locate a copy of the Flight Procedure Handbooks.

Another quote:

"The large capacity HP-41CVs are flown onboard the Space Shuttle and the lesser HP-41Cs, formerly flown, are now used for training at the Shuttle Mission Simulator (SMS). The SMS HP-41s, however, have had their memories expanded top make them equivalent to HP-CVs."

So both HV-41C and HP-41C have flown.

The Training manual is only 45 pages long and doessn't give a lot of info but does help to complete the picture of HP-41 in space.



I hope I haven't missed anymore of these few isolated posts.

Thanks again!


Doing some searches, I found the following link:

Judith Resnick Material

This is archival material at the University of Akron in Ohio.

Go down to Box 3 on the web page and you'll find:

"HP-41 Computer Handbook: Basic Flight Operations Directorate"

Judith Resnick was one of the Astronauts who was on the Challenger.

Maybe someone who lives close to Akron could review the archives at Akron and see what this handbook is.



Thanks Bill. I'll be sure to look this up!



On the use of the Hp-65 during the Apollo-Soyuz space mission (aka ASTP):

- The HP-65 was used in both normal calculation for approach and positioning and also in case of onboard system failures.

- IIRC this is documented in the ASTP CSM RENDEZ-VOUS BOOK (June 1975): I have to dig out my copy.

- The Rendezvous book gives the input for the programs but does not provide the listings.

- Source for this document should be published by the NASA archives as I believe it is declassified.

I'll try to find it out. However, will have to check the copyright status and am not sure of the way/confitions it can be published.

...all this info to be crosschecked because this is rocket science which I do not claim to be an expert in :-)

All the best!


Edited: 25 July 2009, 8:08 a.m.


Bonjour Étienne,

I just found your post!

Is there anyone in here who is a REAL rocket scientist?

In fact, there are some true rocket scientists in here. This is humbling...

Edited: 7 Aug 2009, 8:16 p.m.


Here's another page I 'stumbled' into today which mentions the usage of the HP65:




Thanks Tom.

I missed a few isolated posts like this one regarding my pet project.

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