Post Reply 
Properties of a Pocket Calculator for Astronauts
09-14-2019, 08:58 PM (This post was last modified: 09-20-2019 11:41 PM by Gene222.)
Post: #28
RE: Properties of a Pocket Calculator for Astronauts
(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


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]. 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.

--------------------------------- 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.


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.''


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.
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.
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.
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.
Find all posts by this user
Quote this message in a reply
Post Reply 

Messages In This Thread
RE: Properties of a Pocket Calculator for Astronauts - Gene222 - 09-14-2019 08:58 PM

User(s) browsing this thread: 1 Guest(s)