Comment by danso
12 years ago
Besides the great photo and backstory, I liked this snippet:
> She was all of 31 when the Apollo 11 lunar module landed on the moon, running her code. (Apollo 11 was able to land at all only because she designed the software robustly enough to handle buffer overflows and cycle-stealing.)
You could read that paragraph in several ways. Back then, accomplishing something like that at 31 seems precocious. Today, in the hype about 18-year-olds becoming millionare-startup founders, she sounds like a late bloomer of a programmer.
Considering she didn't learn how to program a computer until her 20s, and there were no shoulders of giants (sorry, frameworks and operating systems) to stand upon, I'd say it's a more impressive feat.
And no Internet, no Stackoverflow, no "common knowledge".
Incredible.
More detail on the cycle-stealing bit, which caused an alarm during the Apollo 11 lunar descent, which the AGC's priority scheduling allowed it to recover from: http://en.wikipedia.org/wiki/Apollo_Guidance_Computer#PGNCS_...
Some years ago, there was a video about the moon landing in Washington DC airport (it was at a Smithsonian exhibit or store or some such). It included video of the control room when the alarm went off during descent. There was silence and blank faces - nobody knew what to do.
But by the time the alarm went off the second time on descent, it was completely different. Someone - whoever was in overall charge - called a role (something like "descent control officer") and that person responded "go", all within one second.
But, yes, it wasn't a problem because the priority scheduling recovered from this problem, and that recovery was a really big deal.
> Some years ago, there was a video about the moon landing in Washington DC airport (it was at a Smithsonian exhibit or store or some such). It included video of the control room when the alarm went off during descent. There was silence and blank faces - nobody knew what to do.
You have to be careful interpreting something like that. Without the backstory, you run the risk of projecting your own emotions onto the events.
Mission Control was actually not very worried about the program alarms. According to Gene Kranz in his memoirs, the white team had been fed a program alarm during a pre-flight simulation. In fact, it was the last simulation they ran through before launch, so it was fresh in their minds.
During the simulation, Mission Control incorrectly called an abort. During the debrief, the instructors told them that the program alarm was non-fatal, and they should have continued to a lunar landing.
During the actual lunar landing, Mission Control was astonished to run into the same scenario. It was like running through the simulation a second time.
> But by the time the alarm went off the second time on descent, it was completely different. Someone - whoever was in overall charge - called a role (something like "descent control officer") and that person responded "go", all within one second.
Neil Armstrong did have to ask twice, but he did get a response from Mission Control on the first alarm. Mission Control did not ignore the first alarm.
The delay was caused by having to consult a list of fatal and non-fatal program alarms. Once they had that list, it was easy to call a Go on subsequent program alarms. However, they couldn't just give a Go to the first alarm without checking the list.
Armstrong and Aldrin hadn't participated in that earlier simulation, so they were probably a lot more worried than Mission Control was!
Here is the transcript with references to Kranz's book: http://www.hq.nasa.gov/alsj/a11/a11.landing.html
Steve Bales with feedback from Jack Garman (Gar-Flash).
The amazing thing is that Garman was the only one to have a quick reference of the various error (numeric) codes.
Wasn't that the same alarm that was randomly thrown at the astronaughts in training and they made the wrong choice then and learned to make the right choice on the moon?
I will look up the story in Kranz's autobiography when I get home tonight.
I do believe it was. The Simsups threw a 1201 alarm at them, and the controllers got confused, and Kranz called an abort. Afterwards, they told him, "It wasn't an abort, you should have continued the landing...I thought you guys had it, but then you went off the rails and called for an abort...You violated the fundamental rule of Mission Control: You must have two cues before aborting. You called for an abort with only one! " As a result, one of the controllers went more into depth on program alarm codes, and they put a rule in dealing with which alarm codes would be grounds for an abort. Neither 1201 nor 1202 were on that list. They saw both those alarm codes during Eagle's descent, and were able to say, "We're Go on this alarm...we're still Go, same type, it's a Go." And the rest was history.
Here's another great photo (http://i.imgur.com/2jJZwBZ.jpg) which was posted on the TIL thread a few days ago (http://www.reddit.com/r/todayilearned/comments/2oskna/til_th...).
See, I see this and the other photo of her as conveying the message, "You don't have to look like the stereotypical 'NASA nerd,' the white guy with the white button-down shirt and the pocket protector full of pens, in order to make a contribution. Some of the biggest contributions were made by people who didn't fall into that stereotype."
At least she didn't make a fucking app.
She made an app that landed spaceships?
Feats of engineering, while technically within the definition of "application" like virtually every other artifact of deliberate human action, rarely actually get described as such.