Moonshot programming

This iconic image shows Margaret Hamilton standing next to a printout of the flight software that she and her team wrote to control the Apollo Guidance Computer. I recently discovered that the code has been made available via a scan of the printouts, later re-typed as code, and uploaded to GitHub. The code is written in assembly, which consists of individual instructions to load, calculate, and act on data values. Today we use compilers so we can write code in higher-level languages that are easily understandable by humans, but at the time compilers were still pretty new, and the available memory was so limited that they wanted humans to do the optimization at the individual instruction level. Wow!

Here’s an example excerpt from the code. Even if you don’t know AGC assembly (I don’t), it’s possible to follow along due to the excellent comments.

I’m in awe of how this massive software engineering project would have proceeded (How did they test it? And without modern version control… did they use periodic printouts in case they found a mistake and wanted to roll back?) What an inspiring project!

Browsing the open issues on the project, they seem dedicated to increasing the quality of the content by carefully proofreading it against the original scans of the code printouts. What a labor of love :) But what a wonderful piece of programming history!

Why it’s called ascorbic acid

Recently I came across this fascinating discussion of the mystery that scurvy posed: a painful and ultimately fatal disease for which the cause was unknown. Was it caused by bacteria? Something in food? Food preservation processes? Overwork? It was a major issue for sailors in the British Royal Navy, including Captain Scott:

Scott and Scurvy

But what makes this an especially captivating story is not how the cause was found, but instead how it was subsequently LOST, impacting many people’s lives for the worse, before being rediscovered. Go read the link above to find out more!

While reading it myself, I came across the word “antiscorbutic” to describe a property of lemons – that they could help prevent scurvy. Anti-scorbutic. Theories even developed that some foods could be “scorbutic” – actively causing scurvy.

And in the end when vitamin C was isolated and demonstrated to conclusively eradicate scurvy (which we now conceive of rather circularly as a lack of vitamin C), it now makes perfect sense that it should also go by the name ascorbic acid: an acid that prevents scurvy. Nice!

Also of interest: the reason we suffer when we don’t ingest enough vitamin C is that our bodies can’t produce it internally but it’s needed for a variety of life maintenance procedures. It turns out that humans are in the minority on this: most animals can manufacture their own vitamin C. We, and guinea pigs and bats and a few others, cannot.

How Phoenix got its name

Recently I discovered how Phoenix, Arizona, got its name. In ancient times, people living in the area dug a bunch of canals (135 miles of them!) to direct water from the Salt River to the plains where they were growing crops. In 1867, the area was colonized by white settlers who also dug canals and named the town Swilling’s Mill (after founder Jack Swilling). Darrell Duppa suggested the name Phoenix, “inasmuch as the new town would spring from the ruins of a former civilization.” I think this is pretty cool – a recognition (however subtle) that history didn’t begin when white pioneers reached an area.

Black in Oregon

I took some time to investigate the history of blacks in Oregon, and what I found was eye-opening. In 1844, the then-territory of Oregon passed a law banning slavery. To modern eyes this may seem quite progressive, until you read the rest of the law and it becomes clear that this was not a statement about the ills and injustice of slavery, but rather an effort to rid the state of black people. In addition to banning slavery, the law also prohibited blacks from entering the state. Those who entered anyway could be whipped “upon his or her bare back not less than twenty nor more than thirty-nine stripes”, every six months until they left. The law was repealed the next year, but other “exclusion bills” followed.

In 1857, Oregon joined the United States and became the only state to do so with a clause in its state constitution to specifically exclude blacks. The Oregon Constitution banned slavery and prevented blacks from legally residing in the state, or owning property, voting, etc. Oregon also rescinded (took back) its ratification of the 14th amendment (which gave all native-born Americans citizenship, including blacks) in 1869 and voted against the 15h amendment (to give blacks voting rights) in 1869. It did not ratify the 15th amendment until 1959 (!) and the 14th in 1973 (!!).

Oregon continues to have a small black population – about 2%. That rarity can create its own problems. I found this very thought-provoking:

“Because exclusion policies served to keep minority numbers low, racial discrimination has not been evident to white Oregonians and many outsiders… Perhaps that is why Oregonians have a special problem with race-blindness: it tends to afflict most those who are unaccustomed to seeing themselves in racial terms.” from Race, Politics, and Denial: Why Oregon Forgot to Ratify the Fourteenth Amendment by Cheryl A. Brooks (2005)

And maybe this contributes to not only ignorance, but also violence. Given the recent murder of George Floyd, it was chilling to come across this passage:

“One such case occurred in 1985, when Lloyd Stevenson, a black man, was killed by a policeman using a choke hold. Neither of the two officers involved was disciplined. The case took a bizarre and controversial turn when on the day of Stevenson’s funeral, two police officers sold t-shirts to fellow officers bearing the slogan “Don’t Choke ‘Em, Smoke ‘Em.” They were fired but were eventually reinstated with back pay.” from Blacks in Oregon by Darrell Milner (2019)

There is so much more to learn and so much more to do. And of course it is not just about Oregon. I am grieving for this history and for our present day. Unlike a virus that jumped species and attacked us from the outside, racism is something that we created. We did it to ourselves. That makes us responsible. And that also means it is an opportunity, because we control our actions and how we want the future to be. We get to choose.

The mysterious Goodyear blimp

On a recent drive across the desert from California to Arizona, I decided to stop and see the Blythe airport. I had flown over it, but never landed and visited. To my delight, as I rolled up in my car, I discovered that the Goodyear blimp had just landed!

I had never seen it that close before. This one is Wingfoot Two (I later discovered that there are three in the current fleet). I talked briefly with one of the ground support staff and learned that the blimp was stopping in Blythe overnight on its way to Vegas to attend (and record/broadcast) a golf match. In this picture, the blimp is attached to a mobile mast on the right, and a tiny wheel at its aft end is touching the ground as they maneuver the blimp to its desired position. (Click the image to enlarge)

Later when I was back at a computer, I wanted to find out more about these blimps and how they work. Apparently Goodyear got into the lighter-than-air business in 1898, and in 1925 they flew the first blimp that used helium. Mostly they seem to have been used for advertising, and not just for their own tires. Some blimps have lighted panels on their sides where they can spell words or scroll messages; in 1966 they added the “Skytacular” which was in 4 colors and had animations; now they have “Eaglevision” which uses high-res LEDs and can show video :). I’ve never seen one in operation scrolling messages!

In WWII, they were used for patrolling the ocean (escorting navy convoys). I don’t know if they had any weapons.

In 1955, the blimp became the “first aerial platform to provide a live TV picture”… for the Rose Parade! :)

The Goodyear blimps use helium, which has about the same lifting force as hydrogen, but with the added benefit of not being explosive. The infamous Hindenburg disaster occurred when the (German) Hindenburg, which was also designed for use with helium, was instead filled with hydrogen, apparently because the U.S. was monopolizing helium for its own use, and helium had become correspondingly expensive internationally. The Hindenburg had 97 people onboard when it ignited in 1937 (36 died).

We actually have stunning real footage of the Hindenburg coming in to land and blowing up (!).

What Goodyear flies now is not technically a blimp (!) (“blimp” = no rigid structure) but instead a “semi-rigid airship” or “zeppelin”. (The Hindenburg was a third type of airship: fully rigid). However, Goodyear still encourages the use of the term “blimp.” Its max speed is 73 mph (not bad!), and it seats up to 14 people. Today’s Goodyear blimps are 246 feet long, compared with 804 feet (!) for the Hindenburg.

On my way back to California a few days later, I saw the blimp AGAIN, this time cruising eastward and following Interstate 10. It was less than 1000′ above the ground, which seemed curious to me. Fare you well, semi-rigid airship! :)

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