Properties of a Pocket Calculator for Astronauts

[deetee]

Thanks for sharing this lot of knowledge and thoughts - which I want to summarize (please complete):

HARDWARE:

• Display: LED/OLED displays seem to be very resistant (operating temperatures from -40 to +85 Celsius) and better than LCD displays. I remember Mark Watney's dying laptop on Mars but I also saw Sandra Bullock's LCD wrist watch working well in Earth's orbit. Apollo's AGC worked with 7 segment LED displays (5 digits).
• Keyboard: Less and big keys - simple to understand/operate
• Case: Plastic/Metal? Velcro strips?
• Clock/Time Module: for alarms, timers, ...
• Interface: Serial? - display signals
  

SOFTWARE:

• Acquisition and display of signals
• Time/Alarm/Timer/Stopwatch
• Oxygen calculations
• Center of gravity (What for?)
• Orbit calculations (Kepler's equation)
• Landing, Reentry calculations
• Trajectories
• Proximity Operations
• Tail - course deviation calculations
• Payload arm operations
  

I'm looking now for more details to this kind of software. In Gene222's link to "Introduction to Orbital Flight Planning" are a lot of HP-specific programs. But I saw that this is not easy to follow and deeper knowledge in Physics and Math is required. Is there some "Space Flight Theory and Math for Dummies"?

Regards
deetee

[teenix]

(09-06-2019 02:08 PM)toml_12953 Wrote:  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.

Just wondering if that changed with later Apollo missions.

A poor lens to look through at history I know, but the Apollo 13 movie showed the astronauts having to do a corridor burn manually with the computer powered down. I didn't see them grabbing for the HP's though :-) Hollywood fantasy maybe?

cheers

Tony

[Maximilian Hohmann]

Hello!

(09-12-2019 09:46 AM)teenix Wrote:  A poor lens to look through at history I know, but the Apollo 13 movie showed the astronauts having to do a corridor burn manually with the computer powered down. I didn't see them grabbing for the HP's though :-) Hollywood fantasy maybe?

The only Apollo mission that carried a pocket calculator (HP-65) on board was the Apollo-Soyuz-Test-Project in 1975. Apollo 13 was in 1970. The invention of the programmable scientific pocket calculator had not yet happened then ;-)

And no, Apollo 13 did not perform any major burns without a computer. They were all done using the computer (and engines) of the lunar module. Only the final two small alignment burns (one for the correct re-entry trajectory and the other one to make sure that the radio-isotope-generator on board the lunar module would fall into the ocean) were done manually by visual alignment. See for example here: https://spectrum.ieee.org/tech-history/s...ion-part-3

Regards
Max

NB: An astronaut in space costs in the order of a million Dollars or Euros a day. Using a pocket calculator instead of some efficient, dedicated equipment would mean an incredible waste of money. My taxes! So please do not give pocket calculators to astronauts :-)

[Gene222]

There a 6:47 minute youtube vidoe clip of What is the Space Shuttle landing like? This does not have anything to do with the OP topic, but I found it interesting. At 1:17 minutes into the video, it shows the cockpit instrumentation, which appears to be all computer controlled.

[Maximilian Hohmann]

Hello!

(09-12-2019 04:50 PM)Gene222 Wrote:  ...At 1:17 minutes into the video, it shows the cockpit instrumentation, which appears to be all computer controlled.

It must be, because flying a powerless aircraft from orbit (speed 8000m/s) to a gliding landing at a fixed point is way, way, way beyond the capabilites of the humand mind, no matter how much experience or training one has accumulated. The same applies to landing on the moon. And because these tasks require permanent real-time computation a pocket calculator is no use at all.

The flight simulator program X-Plane (https://www.x-plane.com/) contains a simulation of the complete Space-Shuttle de-orbit and landing sequence. Takes close to 30 minutes but is a real eye-opener...

Regards
Max

[Gene222]

(09-12-2019 06:50 AM)deetee Wrote:  I'm looking now for more details to this kind of software. In Gene222's link to "Introduction to Orbital Flight Planning" are a lot of HP-specific programs. But I saw that this is not easy to follow and deeper knowledge in Physics and Math is required. Is there some "Space Flight Theory and Math for Dummies"?

I am not very knowledgeable on the subject, but you might want to read NASA's Basics of Space Flight, and then take a look at Orbital Mechanics by Robert A. Braeunig. NASA's Basics of Space Flight does not include any formula's. It just explains the concepts of space flight and orbital mechanics. It was designed primarily as a quick training guide for mission operations people. Some of the animations don't work. Braeunig's Orbital Mechanics includes the formula's and explains the math. More importantly, it includes many examples on how to solve various problems. Braeunig's Orbital Mechanics is part of his Rocket & Space Technology web site. Braeunig found information on this subject to be either too simplistic to be very helpful, or too advanced for those who lacked advanced math and science skills. So, he created a web site on the Basics of Space Flight for space enthusiasts like himself.

[SlideRule]

Perhaps: Space Flight for Beginners (kindle edition) by Andrew Motes
From the Author:
"I taught Astrodynamics at the U.S. Air Force Academy from 1980 to 1982. I loved it but hated all the books on the subject. I'd read a chapter then say to myself, "I can sum that up in one paragraph and two equations!" I never understood why technical authors have to make technical subjects so difficult. This one short book sums up all the technical books I've ever read on the subject; and it does it in simple language that describes the concepts using intuition based on everyday experience."

or: Space Mathematics:Math Problems Based on Space Science (kindle edition) by Bernice Kastner
"Created by NASA for high school students interested in space science, this collection of worked problems covers a broad range of subjects, including mathematical aspects of NASA missions, computation and measurement, algebra, geometry, probability and statistics, exponential and logarithmic functions, trigonometry, matrix algebra, conic sections, and calculus. In addition to enhancing mathematical knowledge and skills, these problems promote an appreciation of aerospace technology and offer valuable insights into the practical uses of secondary school mathematics by professional scientists and engineers.
Geared toward high school students and teachers, this volume also serves as a fine review for undergraduate science and engineering majors. Numerous figures illuminate the text, and an appendix explores the advanced topic of gravitational forces and the conic section trajectories."

or: Spaceflight Theories: A beginners guide to rocket and space sciences (kindle edition) by Raymond T. Hill
"When people say it isn’t exactly rocket science what do they mean? Well for the uninitiated it’s seemingly a jumble of complex maths, physics and engineering. The question I have always asked is how complex is it to understand and can it be presented in a more accessible level for the lay reader?"

or: It's ONLY Rocket Science: An Introduction in Plain English (kindle edition) by Lucy Rogers
"Most amateur astronomers – and many of those with similar interests but who are not currently practising observers – have only a sketchy understanding of space flight. This book provides an introduction to its mechanics. The beauty of this book, written by an engineer who is also an accomplished science writer, is that it covers the subject comprehensively, and yet is almost entirely descriptive and non-mathematical. It deals with all aspects of space flight, from how to leave the Earth (including the design of the rocket, mission planning, navigation and communication), to life in space and the effects of weightlessness. The book also includes sections describing how an amateur can track satellites and understand their orbital parameters."

BEST!
SlideRule

[Gene222]

(09-12-2019 06:50 AM)deetee Wrote:  I'm looking now for more details to this kind of software.

Here an excerpt from the STS-4 Mission Report about the early use of the HP-41 CAP alert program. Although it talks about fixing the problems with the program, it shows how the program was used. [Added 9/15/19] The second excerpt is about the roller world map, which includes a discussion of the use of the HP-41 AOS/LOS and MET (mission elapse time) programs. [Added 9/15/19] The third excerpt is from The Christian Science Monitor which discussed the operation of the HP-41 AOS/LOS and Deorbit programs. The last excerpt is from STS-4 Space Shuttle transcript discussion about the HP-41 AOS/LOS and HP-41 CAP alert programs

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STS-4 Orbiter Mission Report Supplement, November 1982, pp A-27 thru A-28, Document ID: 20160013499, from NASA Technical Reports Server [the public version].

4.2.10.6 HP-41 Calculator.- Four HP-41 calculator-type computers and a card reader were carried onboard. Three had CAP alert programs and the other carried an AOS/LOS program as well as a stopwatch and countdown alarm function. The large number of CAP alerts utilized in the planned mission required breaking them down into three load segments. One segment was preloaded into each of the CAP alert units to avoid having to use the card reader or real-time loads. Both the card reader and printed alert lists were available in case one of the calculators had to be replaced.

Each day's activities were stored with a MET time tag. An alarm sounded as each event came due. The purpose was to relieve the crew of clockwatching and allow them to concentrate on any particular task without fear of missing a time critical event. This worked very well in training, but did not work well in flight for two reasons. First, the alarm tone was too faint to be heard from more than several feet away in Columbia. Second, the timer module stopped on numerous occasions. The concept of using audible and visual aids as a means of improving crew efficiency on-orbit was demonstrated during training. Once the crew incorporated these tools into their procedures, it became very difficult to do without them on-orbit. It is unlikely that the computer tone volume will be increased. However, an external tone booster should be very simple to build. Just as a point of interest, the crew did try using an HIU to put this tone on the SMS intercom. The SMS would not pick up the computer frequencies even though it did work on the CFES. This was not evaluated in flight.

How the crew assures themselves that the alert program time function can be relied upon is equally as important as and potentially more difficult to solve than the tone volume issue.

The nature of the HP computer timer problem has not been identified. The crew believes the on-orbit problem was the same as encountered several times during SMS training. Prior to flight, this behavior had been attributed to specific timer modules since this problem could not be repeated in the office. In flight, all three alert program calculators stopped at least once, although the AOS/LOS unit ran the entire mission. In retrospect, the crew has never seen the AOS/LOS program halt, only the alert program. Therefore, procedural error or EMI (electromagnetic interference) are the current candidates.

Even without these two problems, the HP computer utility would still have been compromised because of the massive CAP changes which were invoked. These could have been entered manually had the time been provided, however, a much more versatile solution would be to uplink this from the ground. Eventually, a basic Orbiter capability should be the ability to update both summary and detail CAP's automatically on-orbit. In fact, it should even allow execution directly from the CRT using it as a master checklist. The cost savings which may be realized by replacing printed pages with magnetic tape just might pay for itself as well as enhance the operations era capabilities.

This is a fundamental crew tool which should be permanently implemented in the Orbiter DPS (data processing system). As an interim measure, increased volume on the tone and a fix for the program halts is required.

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4.2.10.5 World Map.- The roller world map was used throughout the flight. It was the only display that allowed looking ahead to which ground stations would be crossed and over what part of the world the spacecraft would fly. This information is essential for planning.

The map is cumbersome to use at best. First, the AOS/LOS program must be exited in the HP-41 calculator and the MET (mission elapsed time) program called, this taking several minutes. The longitude of the ascending mode and minutes past the ascending mode are then calculated in the MET program. The event timer is set to the time past the ascending mode and counting up. The roller map is then adjusted to put the ascending mode at the right place. The AOS/LOS (acquisition of signal/loss of signal) program must then be recalled to get the AOS/LOS displays {several minutes). This process must be repeated every couple of orbits to keep the map current.

A substantial portion of the STS-4 mission activity was tied to the spacecraft's position over the earth and its relative attitude. The crew should be able to quickly determine their position and attitude with respect to the earth to efficiently execute the flight plan and provide the essential flexibility necessary for them to capitalize on their unique vantage point. This capability will always be paramount in achieving productive use of man in space.

Until TDRSS (tracking data and relay satellite system) becomes routine, the crew will require a big picture of the communications capability which is also ground-track dependent. Today, the best way to do this is with the world map.

Today's operations display shows a pictorial antenna pattern which has little utility. If this operations display were replaced by an electronic world map, it would be the most useful display in the spacecraft. Since knowledge of earth relative position and attitude is essential for good flight planning, a display should be immediately developed which provides the current position, future ground track, major earth features, relative spacecraft attitude and day/night terminators.

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Exploring space with the help of a hand computer, The Christian Science Monitor, March 24, 1982, by Robert C. Cowen

As they move around Earth ... they constantly lose and re-establish communication with Houston. One of their two hand-held computers keeps track of their position. When they are out of contact, it locates the next relay station. It tells the astronauts when they will be within its range and which radio frequency to use. Once contact is established, the computer tells how long it can be maintained.

Should something happen to force the astronauts to decide to make an emergency landing when out of touch with mission control, the little computer can pick a landing site and figure the timing of the retrorocket burn needed to bring Columbia in.

There are six designated landing sites. At least one of these is available during each orbit. In selecting the right site, the computer takes account of the requirements that the site be within 995 miles cross-range of Columbia's orbit path and be in daylight at the time of landing. The computer then picks the site based on the mission's elapsed time and of Columbia's velocity and position. This is a task for the little computer that the National Aeronautics and Space Administration (NASA) has designated as ''flight-critical.''

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PAD Mission Control Houston, 2 days 7 hours 6 minutes, Mission Elapsed Time. Columbia is on orbit number 37, and we're about to pass within range of the tracking station at Botswana in southern Africa. Crew is running just a few minutes behind the timeline and should be finishing up their meal about now.
STS-4 AIR/GROUND TRANSCRIPT t107j 6/29/82 GMT 181:21:22 PAGE 2
Primarily some housekeeping activities related at the end of they are [their] day, their only about an hour away from the beginning of their scheduled sleep period. They have a fuel cell purge to do, and some documentation and then a little bit of other work before they can turn in this evening and attempts are being made to have their activities wrapped up through …
CAPCOM …Botswana for 4 1/2 minutes.
SPACECRAFT Hi there.
CAPCOM T. K. your loud and clear. I’ve got a bottom-sun attitude to read up to you, if your ready to copy.
SPACECRAFT Be with you in about 10 seconds.
CAPCOM Okay.
SPACECRAFT Okay, l’m all yours.
CAPCOM Roger T. K. we'd like you to maneuver to bottom-sun, and the attitude is roll 310.4, pitch 233.0, and yaw 58.8, would like you to use DAP Alpha 1 for both the maneuver and the attitude hold, it's about an 8 minute maneuver, and we’d like to be in bottom-sun before sunrise, that comes up in about 20 minutes, over.
SPACECRAFT Okay, I copy, be in bottom-sun at sunrise and the attitude is 310.4, 233.0, 58.8, using DAP Alpha 1, and we're on our way.
CAPCOM Okay, copy that.
END OF TAPE
STS-4 AIR/GROUND TRANSCRIPT t108j 6/29/82 GMT 181:22:10 PAGE 1
SPACECRAFT Okay George, that's started, anything else?
CAPCOM Roger TK I've got a couple of tag-up items for you. First one we'd like to know if you’re still using your HP AOS LOS program? If we start messing with the flight plan we may need that, over.
SPACECRAFT I have been using the calculators just as we said we would. The AOS LOS I've been using for that and for map updates and it has done rather well, you know it’s got a power, I figure if it's within the nearest minute, that's fine. But it does that for us. The prompting programs, well we've sort of altered the days enough so that the prompting programs haven't had a good workout, but I've had a number of instances of that program's timer halting. I'm going to switch to the other calculator tonight and try tomorrow. But, that's sort of where I stand on those.
CAPCOM Okay, we copy that.