Apollo Software

[hp41cx]

http://www.vox.com/2015/5/30/8689481/mar...o-software

[Don Shepherd]

Thanks HP41. Wow, what a story.

[Bill (Smithville NJ)]

Thanks for the link.

A number of years ago, I attended a talk at the Trenton Computer Festival about the Apollo Guidance Computer. I can't remember the name of the person who gave the talk. He had one of the computer modules and described how the system was developed and worked in actual flight. A very interesting talk.

For some simulation fun:

AGC Simulator

Virtual AGC

Bill
Smithville, NJ

[Karl-Ludwig Butte]

Thanks for sharing the link to the article.

For all those who want to know more about the Apollo Guidance Computer will find this book interesting:

O'Brian, Frank: "The Apollo Guidance Computer - Architecture and Operation",
2010, Springer, published in association with Praxis Publishing Ltd., Chichester, UK
ISBN: 978-1-4419-0876-6

Best regards

Karl

[Massimo Gnerucci]

Anybody interested in the Apollo 11 Flight Plan Re-Issue?

[Don Shepherd]

(08-21-2016 10:42 AM)Karl-Ludwig Butte Wrote:  Thanks for sharing the link to the article.

For all those who want to know more about the Apollo Guidance Computer will find this book interesting:

O'Brian, Frank: "The Apollo Guidance Computer - Architecture and Operation",
2010, Springer, published in association with Praxis Publishing Ltd., Chichester, UK
ISBN: 978-1-4419-0876-6

Best regards

Karl

Thanks Karl. That is a good book, I agree. It explains the workings of the AGC in extensive detail.

Another good book is "Digital Apollo" by David Mindell. It focuses more on how the AGC came to be, how it was designed and built, rather than how it operates.

Here is an interesting quote from this book, especially in light of the recent computer problems with Delta Airlines:

"The space shuttle flies with five redundant computers. Any fully digital airliner has a minimum of three. Apollo had only one. It never failed in flight".

Of course, Apollo really had two identical guidance computers, one in the command module and one in the LM. What a marvel of engineering.

[Maximilian Hohmann]

(08-21-2016 05:18 PM)Don Shepherd Wrote:  It never failed in flight.

But it would, if the flight had lasted longer. The Apollo guidance computers were designed for a total life of 2000 hours only. The initial concept even included some degree of in-flight serviceability by supplying the astronauts with tools and spare PCBs. This was only dropped after the prototype computers all exceeded their design life in the laboratory.

Interestingly, Margaret Hamilton, portrayed in the link above as the master mind behind the Apollo Guidance Computer, hardly gets any mention in the excellent book "Digital Apollo". I wonder which recollection comes closer to the actual historic facts?

Regards
Max

[Don Shepherd]

(08-22-2016 10:47 AM)Maximilian Hohmann Wrote:  

(08-21-2016 05:18 PM)Don Shepherd Wrote:  

Interestingly, Margaret Hamilton, portrayed in the link above as the master mind behind the Apollo Guidance Computer, hardly gets any mention in the excellent book "Digital Apollo". I wonder which recollection comes closer to the actual historic facts?

It looks like she may have been a manager of programmers, as opposed to being a programmer herself. Perhaps she did write some of that code, I don't know.

One thing puzzled me about the statement of one of the AGC programmers. He said his code is still on the moon and, not surprisingly, he felt really good about that. Not to take anything away from him--those folks truly achieved something great--but isn't the only thing remaining on the moon the lower, descent stage of the LM, and wasn't the LM AGC in the ascent stage? Wouldn't it have to have been to navigate the LM back to rendezvous with the command module? And after rendezvous, wasn't the ascent stage jettisoned and it would impact the moon and be destroyed? So the AGC would be destroyed too?

I just don't remember the specifics of the Apollo procedures.

[rprosperi]

(08-22-2016 11:57 PM)Don Shepherd Wrote:  One thing puzzled me about the statement of one of the AGC programmers. He said his code is still on the moon and, not surprisingly, he felt really good about that. Not to take anything away from him--those folks truly achieved something great--but isn't the only thing remaining on the moon the lower, descent stage of the LM, and wasn't the LM AGC in the ascent stage? Wouldn't it have to have been to navigate the LM back to rendezvous with the command module? And after rendezvous, wasn't the ascent stage jettisoned and it would impact the moon and be destroyed? So the AGC would be destroyed too?

That is all correct, I'm pretty sure the AGC was in the ascent stage. But bottom line, his code really is still on the moon, though the hardware around it may be a bit (pun intended) worse for the wear.

[Don Shepherd]

(08-23-2016 01:31 AM)rprosperi Wrote:  That is all correct, I'm pretty sure the AGC was in the ascent stage. But bottom line, his code really is still on the moon, though the hardware around it may be a bit (pun intended) worse for the wear.

Thanks Bob. It would be interesting if a future mission to the moon would bring back some of the artifacts from the Apollo missions that were left on the moon, especially to see how the daily lunar temperature extremes affected them. There must be some great Hasselblad cameras up there!

[rprosperi]

(08-23-2016 09:17 AM)Don Shepherd Wrote:  Thanks Bob. It would be interesting if a future mission to the moon would bring back some of the artifacts from the Apollo missions that were left on the moon, especially to see how the daily lunar temperature extremes affected them. There must be some great Hasselblad cameras up there!

I've wondered about the exact same thing many times. Now that the STS missions are actually being planned, it seems that a mission to the Moon, to retrieve some artifacts, would be an ideal early mission to validate and tune the equipment, systems and software, but I've little doubt this would be cost-prohibitive. But as you say, some of those artifacts would be truly prized and valuable items.

And you can imagine the descriptions on eBay - "Hasselblad Video camera: Only used for 2 days, stored 50 years in a smoke-free environment." And "Vintage Guidance Computer: One of the earliest computers used for Lunar trajectory calculations. Some small dings and scratches, but appears to have genuine gold on the contacts and connectors. No power cord available so I can't test it, so being sold as-is."

[Ron Ross]

Not sure that NASA would retrieve its own equipment after implementing its own internal bureaucracy (although who could stop them, or the Chinese or Russians, or whomever was at the site), as these locations are now considered by NASA as static museums and are to be circumvented or traveled around by a wide margin ie not even allowed to walk into or fly over the area.
.
http://sservi.nasa.gov/articles/nasa-set...ing-sites/
.
Or WHAT ARE THEY HIDING???
.
Just a bit of trivia FYI.

[Don Shepherd]

(08-23-2016 01:31 PM)Ron Ross Wrote:  http://sservi.nasa.gov/articles/nasa-set...ing-sites/

Thanks for that site link, Ron. Very interesting.

But I have to wonder how "enforceable" these NASA guidelines would be. Does anyone really "own" things that were abandoned over 40 years ago, especially things located someplace other than planet earth? NASA does not own the Apollo landing sites. Nor does the United States.

Someday somebody will visit there again (probably not in my lifetime, unfortunately).

Very interesting considerations.

[rprosperi]

(08-23-2016 01:31 PM)Ron Ross Wrote:  .
http://sservi.nasa.gov/articles/nasa-set...ing-sites/

VERY interesting trivia indeed, thanks for posting Ron.

Although I get the point, and agree these sites should be preserved, it seems rather unenforceable, so much so that it almost seems to temp other teams to even try.

But the good news for future eBayers here is it would appear Apollo 12, 14, 15 and 16 sites are fair game. Which is the strangest part of this whole thing. If NASA is gonna throw down the gauntlet about preserving these sites on the moon, it's rather silly to only claim 2 should be preserved.... though maybe they know something the rest of us don't (continuing to feed the conspiracy theorists among us).

Apollo remains an infinitely fascinating and proud accomplishment. Though many years ago I thought all there was to say and learn had been said and read, I'm happy that new info continues to emerge regularly. I'll be reading Digital Apollo soon.

[BobVA]

(08-23-2016 09:17 AM)Don Shepherd Wrote:  ...It would be interesting if a future mission to the moon would bring back some of the artifacts from the Apollo missions that were left on the moon, especially to see how the daily lunar temperature extremes affected them. There must be some great Hasselblad cameras up there!

Done! [Sort of] :-)

Apollo 12 returned several pieces of hardware from the Surveyor III lander, which had been on the lunar surface for about two years. Summary here and the NASA analysis report on the returned Surveyor television camera here.

One funny story from Wikipedia - Astronaut Alan Bean smuggled a self-timer for the Hassleblad camera onto the mission. He wanted to take a picture of himself and Pete Conrad next to the Surveyor, presumably baffling the ground crew as to how the photo was taken. Sadly they misplaced the timer and didn't pull off the stunt.

[twdeckard]

Don't forgot all the stuff Andy brought back

https://www.youtube.com/shared?ci=cCJp2eOsYS8

[Jeff O.]

(08-23-2016 01:28 PM)rprosperi Wrote:  ... Now that the STS missions are actually being planned, it seems that a mission to the Moon...

Bob,
It's hard to keep up with all of the “next generation” plans that NASA has put out over the years, but do you mean SLS missions? STS (Space Transportation System) was the space shuttle program. SLS is the Space Launch System, the system which is currently under development. Of course the SLS replaced the Constellation program which was proposed in 2005 to allow a return to the moon by 2020, and then cancelled in 2010.

[Jeff O.]

(08-24-2016 03:06 AM)twdeckard Wrote:  Don't forgot all the stuff Andy brought back

https://www.youtube.com/shared?ci=cCJp2eOsYS8

I was thinking of that movie when reading the prior posts in this thread. I didn't realize it was that long ago.

Andy should have had Barney on his team, based on his extensive experience as "The Reluctant Astronaut."

[rprosperi]

(08-24-2016 01:22 PM)Jeff O. Wrote:  ... but do you mean SLS missions? STS (Space Transportation System) was the space shuttle program. SLS is the Space Launch System, the system which is currently under development. Of course the SLS replaced the Constellation program which was proposed in 2005 to allow a return to the moon by 2020, and then cancelled in 2010.

Yes, I did mean SLS, my careless mistake... I've been watching SRB and main motor tests (youtube and many other places) and SLS progress actually appears to be on schedule with first (unmanned) flight next year. Exciting stuff!

[Jeff O.]

(08-24-2016 02:04 PM)rprosperi Wrote:  Yes, I did mean SLS, my careless mistake... I've been watching SRB and main motor tests (youtube and many other places) and SLS progress actually appears to be on schedule with first (unmanned) flight next year. Exciting stuff!

I hope the progress continues. Still hoping to see humans on Mars in my lifetime. (Which is kind of obvious, since if it is not in my lifetime, I wont see it.)