Sunrise, Sunset

So one morning almost three months ago, Rebecca and I are standing on Cocoa Beach. It’s her first time ever visiting an ocean, and I’ve arranged it that the first time she sees the Atlantic, she’s watching the sun rise over the horizon. It is, all in all, a neat experience.

Flash-forward to two weeks ago. I’m on a business trip to NASA’s Jet Propulsion Laboratory. It’s my fourth trip to California in less than a year, and so I decide that this time I’m going to finally get around to doing something I’ve put off on previous trips — I’m going to watch the sun set on the Pacific. And so I do.

I’m currently helping one of the Space Launch System executives work on an upcoming TEDx talk, using the transcontinental railroad as analogy for the future of human space exploration, playing with themes like public-private partnerships and the fact that, historically, there are almost no new transportation capabilities that do not improve everyday life.

I thought about that as I was standing on the beach in Los Angeles. I, a fairly normal person, had watched the sunrise over one ocean and set over the other two months apart. Just 150 years ago, before the completion of the transcontinental railroad, that was impossible in the United States. Today, if you really wanted to, you could see them both in the same day. On the International Space Station, you see sixteen sunrises and sunsets a day.

We live in a time of miracles and wonders. It’s good to be reminded to wonder at it.

Mars Rocket Yadda Yadda Horses’ Butts


According to an old story that’s circulated the internet for years, the dimensions of the space shuttle’s solid rocket boosters were prescribed by the width of a horse’s rear end.

The story goes from Roman chariots that were made wide enough to accommodate the back end of two war horses to British roads that were built for those chariots and ended up with ruts where their wheels were to Engish wagons that were built wide enough to fit those ruts to trains that were built from the jigs and toolings for those wagon and thus U.S. railroads were all built to the width of a Roman chariot and thus based on the width of two horse’s butts. And then it takes it a step farther to the fact that the shuttle solid rocket boosters were designed to be transported via rail and thus had to fit through a railway tunnel determined by the width of a  train and thus, yadda yadda, horses.

The particulars of the story get some stuff wrong. U.S. railways didn’t originally have a standard gauge, and were built to a variety of widths before being standardized, so there was no particular magic number that they had to be. On the other hand, it’s also worth noting that the original railroad cars were horse-drawn, so there was a more direct connection between the widths of train tracks and horses, so there is some basic truth to the story, even if the particulars aren’t exactly right.

I was thinking about this story again recently because of interesting fact I learned about the Space Launch System rocket I’m honored to support.

The core stage of SLS is 27.6 feet in diameter, because it’s designed to have the same diameter as the space shuttle’s external tank in order to more effectively take advantage of existing manufacturing and launch facilities. We were talking about that at work, and the question came up as to why the shuttle’s external tank had that diameter. We suspected at first it, in turn, had something to do with the facilities left over from the Saturn days, but weren’t able to find the answer anyway.

So I called someone I know who worked on the external tank, and asked him. And the answer has to do with the fact that the shuttle’s solid rocket boosters were to be mounted to the side of the external tank. Given the volatility of the fuels inside the tank, you wanted the attach points to be somewhere on the structure off of the fuel tanks inside it. The length of the solid rocket booster had already been established, and that determined what the length of the external tank would need to be to properly accommodate the attach points. The engineers knew what the volume of the tank had to be in order to hold enough fuel for launch, so once the length was established, the diameter was just a question of division.

Which means that the next time astronauts fly around the moon, they’ll be launched on a vehicle with a diameter determined loosely by the width of horses’ butts.

The Fall of Huntsville

I was excited to see that I was on the schedule to work at the Huntsville Depot Museum today.

After all, today is a major anniversary of one of the most important days in the history of the Depot, to say nothing of the city of Huntsville.

On this date, 150 years ago, at about 6 a.m., we were invaded and conquered.

April 11, 1862. The Battle of Shiloh was fought four days earlier, and, while a Confederate defeat, delayed the Union army from taking Corinth, Miss., and the strategically important Memphis & Charleston and Ohio & Mobile railroads that crossed there.

In the wake of Shiloh, one General Ormsby Mitchel, a former banker, railroad surveyor and noted astronomer before rejoining the army to claim that glory that had eluded him in his younger days, decided that he was going to break the Memphis & Charleston, and in a way far less bloody than Shiloh had been.

As his target, he picked Huntsville, appealing for at least two reasons — it was the eastern headquarters of the M&C, and it was relatively poorly defended. (Huntsville would also be of value in his plan, launched the next day, to capture Chattanooga, but we shan’t go into that.)

Of course, it doesn’t matter how poorly defended a town is if a large group of reinforcements arrive. Working in Mitchel’s favor was the fact that the Confederate army was still very much pre-occupied with the siege of Corinth, but he wanted to leave as little as possible to chance.

The worst thing for him would be for, when someone saw his army coming toward Huntsville, the impending invasion to be reported to Confederate headquarters and reinforcements to be sent. We don’t know exactly what Mitchel did to try to prevent this from happening, but we do know two things — no telegraph asking for reinforcements was sent, and, when Mitchel’s army arrived, the local telegrapher, stationed at the Depot, was given a job with the Union army.

To further take no chances, Mitchel timed things impeccably. Back during the Civil War, war was, in some ways, in fact more, well, civil. Among those ways, you didn’t fight at night. Under the rules of engagement, that would be  downright rude. But what Mitchel did do was to wake his troops during the night, have them get ready and start marching, to time their entry into Huntsville after daybreak, when it was fair game, if a bit surprising.

As he marched into town early that morning, the vastly unnumbered, unreinforced and generally unready defenders gave in without a battle, and Huntsville and its Depot were under Union control.

For those that haven’t visited the Depot, this resulted in one of Huntsville’s more interesting historical curiosities from the Civil War. When Mitchel captured the Depot, he inherited a train of injured Confederate soldiers who had been evacuated from Corinth in the wake of Shiloh. Unable to transport them immediately to a prisoner of war camp in Ohio, Mitchel detained them in the third floor of the Depot, which was used as overnight accommodations for railroad workers. Visitors today to the Depot can still see graffiti there that dates back to that period.

Looking back, there’s a bit of historical irony to Mitchel’s occupation of Huntsville. Concerned about the economic situation, Michel found a quandary — the local Confederate money was already inflating to the point of worthlessness, while the locals were too proud to use Union money. In hopes of stabilizing the local economy, Mitchel requested that the Union army send a shipment of gold that could be introduced into circulation. The gold was captured in transit, and never made its way to Huntsville, causing that part of Mitchel’s plan to fail.

Fast forward 150 years, to the modern day city of Huntsville as the nation undergoes a very challenging financial time. The main stabilizing force in Huntsville’s economy? Money sent in by the U.S. Army.

Apparently, Mitchel had the right idea.