Properties of a Pocket Calculator for Astronauts

[deetee]

Just some thoughts and an lot of subjunctives:

What are the "properties" of a pocket calculator to be useful in a spacecraft when every other computer dies?

* Hardware for space conditions? - Display, keyboard, case, power supply/consumption, battery, ...
* Explicite Software/programs? - Travelling, trajectory calculations, lunar math, spaceship controlling math, ...
* There is some information about calculators in space (HP65, MK-52, AGC) - Which programs did they run?

Thanks for any information and idea.

Regards
deetee

[sa-penguin]

If you read "The Martian" by Andy Weir, there is a section on an LCD exposed to vacuum. It's not nice. I suspect OLED displays would suffer the same fate.

So, if you have a calculator as a backup, it better be decompression - proof. Either LED, or part of a spacesuit Heads Up Display (HUD).

If there's a vacuum inside your suit, you are beyond worrying about a calculator.

[teenix]

Google HP-65 Apollo-Soyuz

Plenty of links

cheers

Tony

[Didier Lachieze]

The perfect pocket calculator for astronauts:



http://spaceflownartifacts.com/flown_sliderules.html

[Maximilian Hohmann]

Hello!

(09-06-2019 07:36 AM)deetee Wrote:  What are the "properties" of a pocket calculator to be useful in a spacecraft when every other computer dies?

The only thing left to calculate for a pocket calculator after every other computer dies, is for how many hours the oxygen left in the cabin is going to keep the crew alive... And honestly, I would not like to know.
And all those trajectory calculations are pretty useless because the thrusters are operarted by electric valves which themselves are controlled by the (deceased) computer. It was already like that 50 years ago on Apollo. The had a simple backup computer for the ascent from the moon with a hardwired trajectory for a rendevouz. But never any control over their engines without at least one functioning computer!

Regards
Max

[pinkman]

(09-06-2019 08:48 AM)sa-penguin Wrote:  If there's a vacuum inside your suit, you are beyond worrying about a calculator.

Except for people on this forum! ?

[pinkman]

(09-06-2019 11:36 AM)Maximilian Hohmann Wrote:  Hello!

(09-06-2019 07:36 AM)deetee Wrote:  What are the "properties" of a pocket calculator to be useful in a spacecraft when every other computer dies?

The only thing left to calculate for a pocket calculator after every other computer dies, is for how many hours the oxygen left in the cabin is going to keep the crew alive... And honestly, I would not like to know.
And all those trajectory calculations are pretty useless because the thrusters are operarted by electric valves which themselves are controlled by the (deceased) computer. It was already like that 50 years ago on Apollo. The had a simple backup computer for the ascent from the moon with a hardwired trajectory for a rendevouz. But never any control over their engines without at least one functioning computer!

Regards
Max

What about this information ?

[toml_12953]

(09-06-2019 11:53 AM)pinkman Wrote:  

(09-06-2019 11:36 AM)Maximilian Hohmann Wrote:  Hello!


The only thing left to calculate for a pocket calculator after every other computer dies, is for how many hours the oxygen left in the cabin is going to keep the crew alive... And honestly, I would not like to know.
And all those trajectory calculations are pretty useless because the thrusters are operarted by electric valves which themselves are controlled by the (deceased) computer. It was already like that 50 years ago on Apollo. The had a simple backup computer for the ascent from the moon with a hardwired trajectory for a rendevouz. But never any control over their engines without at least one functioning computer!

Regards
Max

What about this information ?

Yes, they could compute trajectories with the HP but an on-board computer actually controlled the angles of the thruster nozzles. The control handle wasn't mechanically linked to the nozzles. All it did was send a signal to the computer which then activated the servos to rotate the thruster gimbals. The crew couldn't change the direction of the thrust manually. Without at least one working on-board computer, they couldn't use the results from the handheld calculator. It's like modern transmission dials on cars that are replacing levers. You're not actually changing the gear ratios directly by turning a dial. The computer monitors the position of the dial and sends a signal to the transmission components to do that.

[pinkman]

Thanks! So for sure deetee’s initial question is valid.

[Maximilian Hohmann]

Hello!

(09-06-2019 02:08 PM)toml_12953 Wrote:  The control handle wasn't mechanically linked to the nozzles.

But even if the astronauts would have full manual control over their thrusters, they would not know how to orient them in order to follow their trajectory.
The position of the spacecraft in space as well as it's attitude are measured by gyroscopes and accelerometers that feed their raw signals directly into the computer. We all know that a modern pocket calculator can easily solve the equations involved in this task in real time, but without a connection to the sensors it will be totally useless.

So if a calculator on board a spacecraft should really be able to back-up the onboard computers then it needs to have it's own inertial navigation system built in... And no, the solid state accelerometers (and/or "gyros" as they wrongly call them) that are built into our smartphones are not remotely capable to do that.

At one time Neil Armstrong demanded to get a full manual control over the ascent engine of the Lunar Module. In case they had to fly home from the moon in an emergency situation. But they quickly convinced him that without a way to know where exactly to steer manual control of the engine is as good as no engine at all.

Regards
Max

[Gene222]

(09-06-2019 11:53 AM)pinkman Wrote:  

(09-06-2019 11:36 AM)Maximilian Hohmann Wrote:  Hello!


The only thing left to calculate for a pocket calculator after every other computer dies, is for how many hours the oxygen left in the cabin is going to keep the crew alive... And honestly, I would not like to know.
And all those trajectory calculations are pretty useless because the thrusters are operarted by electric valves which themselves are controlled by the (deceased) computer. It was already like that 50 years ago on Apollo. The had a simple backup computer for the ascent from the moon with a hardwired trajectory for a rendevouz. But never any control over their engines without at least one functioning computer!

Regards
Max

What about this information ?

Nice photos of the HP-41C with a keyboard overlay. Too bad the photos don't show what module was used or what programs were used, as requested by the OP.

[Thomas Okken]

(09-06-2019 11:26 PM)Gene222 Wrote:  

(09-06-2019 11:53 AM)pinkman Wrote:  What about this information ?

Nice photos of the HP-41C with a keyboard overlay. Too bad the photos don't show what module was used or what programs were used, as requested by the OP.

This was covered in HP Key Notes V5N1.

Quote:Two calculators were set up for the flight. Each HP·41C was outfitted with four Memory Modules, giving each the memory to handle more than 2000 program lines. The flight suit pouches for the calculators also held extra Memory Modules, extra batteries, and a card reader and magnetic cards containing the programs, just in case they had to be reloaded in flight.

For the first shuttle flight, one Hp·41C was dedicated to the Center of Gravity program, and one to the Acquisition of
tI Signal program. These programs were loaded into the calculators shortly before launch. The Center of Gravity program was used before reentry into the earth's atmo- sphere 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 Continuous Memory, the calculator did not have to be on during the whole flight.

[Mark Power]

The older version of the Smithsonian page has more details and a picture of the HP-41 on the flight deck of the shuttle.

http://web.archive.org/web/2000062100375...wlett-.htm

[Ángel Martin]

To my knowledge those programs have never surfaced so there's no records of them anywhere, is that correct? I see a great opportunity for SlideRule here ! ;-)

Somehow I seem to remember that the Time Module was developed to meet a NASA request, but from the description above the calculators didn't have it. Perhaps it was used in a subsequent mission then.

[EdS2]

Here's a 1600px version of the photo of Sally Ride with three HP calculators, in space, on the Shuttle:
https://i.pinimg.com/originals/8d/be/58/...abf8d3.jpg

[Thomas Okken]

(09-11-2019 05:04 AM)Ángel Martin Wrote:  To my knowledge those programs have never surfaced so there's no records of them anywhere, is that correct? I see a great opportunity for SlideRule here ! ;-)

Somehow I seem to remember that the Time Module was developed to meet a NASA request, but from the description above the calculators didn't have it. Perhaps it was used in a subsequent mission then.

This is mentioned in the link in Mark's post, just before yours:

Quote:The HP-41C also contained a clock, which allowed astronauts to set alarms and schedule experiments. (The clock was not available to consumers at the time of the first Shuttle launches, but NASA obtained pre-production modules that plugged into the calculators. Hewlett-Packard later offered these as an option.)

[Druzyek]

Quote:And all those trajectory calculations are pretty useless because the thrusters are operarted by electric valves which themselves are controlled by the (deceased) computer.

So was the reasoning for having the calculator backup that the computer might partially malfunction and still have control of the thrusters even if it couldn't calculate trajectory any more?

[Gene222]

(09-11-2019 05:04 AM)Ángel Martin Wrote:  To my knowledge those programs have never surfaced so there's no records of them anywhere, is that correct? I see a great opportunity for SlideRule here ! ;-)

Somehow I seem to remember that the Time Module was developed to meet a NASA request, but from the description above the calculators didn't have it. Perhaps it was used in a subsequent mission then.

I found this article Flight-critical calculator which contained a link to Introduction to Orbital Flight Planning June 1981. This workbook was designed for students in the area of space flight planning, who after training may serve as flight planner aids at NASA. This workbook does not contain calculator programs (except for a HP67 Kepler program), but seems to be a training manual for students to calculate and write their own orbital flight programs.

[Gene222]

(09-11-2019 05:04 AM)Ángel Martin Wrote:  To my knowledge those programs have never surfaced so there's no records of them anywhere, is that correct? I see a great opportunity for SlideRule here ! ;-)

Somehow I seem to remember that the Time Module was developed to meet a NASA request, but from the description above the calculators didn't have it. Perhaps it was used in a subsequent mission then.

There is an old forum message entitled "HP41 and Space Shuttle" by Rupert on 12 Oct 1999 about trying to find the HP 41 software used by Shuttle astronauts. (I can't create a working link to this archived post.) One HP Museum member said he spent several years tracking down HP 41 shuttle software (see post number 5) and has some HP 67 and HP 41 programs for calculating satellite and orbit adjustments, but he did not post those programs. He mentioned that he does know someone that has copies of the shuttle programs. So, some of the shuttle programs are out there - somewhere.

[Added] The same poster mentioned that the astronauts had to buy their own calculators and write their own programs, presumably on the HP 41. This does not seem so far fetched as NASA flight planning aids had to write their own orbital flight programs as shown in the Introduction to Orbital Flight Planning workbook in the previous post.

[Gene222]

There is another archived post entitled "HP-41 in Space - Shuttle Training Manual" and posted by Bill (Smithville, NJ) on 24 Apr 2007 in the HP Forum Archive 17. He obtained a copy of the "Hewlett-Packard 41 Calculator/Shuttle Portable Onboard Computer Training Manual", which was a 45 page manual dated November 1985. The manual covers both the HP-41 and the Grid Computer. He said a lot of it covers pretty basic HP-41 operating procedures.

He noted that the manual included a brief description of six Space Shuttle programs:
Center of Gravity
Orbit
Alarm/Hex
Landing
Proximity Operations
Tail

And, he said "Now for the real teaser - They refer you to the 'HP-41 Flight Procedures Handbook' for details on each program." He was unable to find this second manual.

That second manual is listed on the August 1988 Johnson Space Center Document Index as document number 18778, entitled HP-41 COMPUTER FLIGHT PROCEDURES HANDBOOK, dated 12-07-84, by D. A. Lamar. Unfortunately, I cannot find this document on the NASA Technical Report Server.