A Lunar Itinerary

The hilarious image of the Apollo 11 astronauts’ US Customs form, filled out upon their return to Earth through Pearl Harbor, Hawaii, has been going around the internet again; so I thought I might share one of my favorite little pieces of NASA spaceflight miscellanea: Buzz Aldrin’s travel expenses.

Upon returning to Earth from his history-making trip to the lunar surface, Buzz Aldrin filled out a travel expense voucher to get reimbursed for his “official travel.” It’s a delightfully mundane and hilarious thing, that nonetheless highlights some pretty interesting stuff about the jaw-dropping trip to the moon that he, Neil Armstrong, and Michael Collins undertook fifty-five years ago this summer.

His official itinerary is more detailed than the one provided on the customs form. Here it is in full, with some annotation. All dates are, naturally, in July of 1969:

7-7 | LV: Residence | 0445 | POV
(note: POV means “Privately Owned Vehicle.” Aldrin reported 8 miles for this leg of the journey and was reimbursed 56¢.)
7-7 | AR: EAFB | 0500
(note: EAFB is “Ellington Air Force Base” in Houston)
7-7 | LV: EAFB | 0530 | Gov. Air
7-7 | AR: Cape Kennedy, Fla. | 0800
7-16 | LV: Cape Kennedy, Fla. | 0832 | Gov. Spacecraft
(note: Saturn V serial number SA-506, of course)
7-19 | AR: Moon | 1325
7-21 | LV: Moon | 2400 | Gov. Spacecraft
(note: transfer from NASA LM-5 Eagle to NASA CSM-107 Columbia not listed)
7-24 | AR: Pacific Ocean | 0600
(note: at 13°19′N 169°9′W in the North Pacific, about 920 miles or 1480 km from Honolulu)
7-24 | LV: Pacific Ocean | 0800 | USN Hornett
(note: Aldrin misspelled the name of the US navy aircraft carrier Hornet here.)
7-26 | AR: Hawaii | 0900
(note: Pearl Harbor, to be specific)
7-26 | LV: Hawaii | 1200 | USAF Plane
(note: the particular plane was a C-141B Starlifter designated 66-7958 USAF, which I cannot find a name for.)
7-27 | AR: EAFB | 0100
7-27 | LV: EAFB | 0215 | Gov. Veh.
(note: the Government Vehicle in question was the Mobile Quarantine Facility (MQF), a converted Airstream trailer. They would stay in the MQF for three weeks. Actually, they boarded the MQF on the Hornet; it was then loaded into 66-7958 in Hawaii and unloaded in Houston.)
7-27 | AR: LRL | 0300
(note: LRL is the Lunar Receiving Laboratory, building 37 at Johnson Space Center in Houston.)
A notation beneath this itinerary reads:
Government meals and quarters furnished for all the above dates.

Aldrin also reported 100 miles of “official vicinity travel” at Cape Kennedy for the nine days between his arrival and departure, for which he was reimbursed $10. Another note reads
POV authorized for official vicinity travel at Cape Kennedy, Fla. in leiu [sic] of rental car.
I can’t find any information about what POV this is; he left his personal vehicle in Houston when he flew on a government plane to Florida, so perhaps he owned two cars?

There are three handwritten notes beneath that which I cannot read but claim $8.00 and $19.25, as well as $4.50 of charges that he subtracts from the total; these three are listed in the “subsistence” column. The grand total claimed on this voucher are $33.31 ($279.17 in 2024 dollars), and it was approved by someone named “C.W. Bird.”

I find it so fantastic that a man who went to the moon still had to deal with paperwork once he returned. What a gem was 1960s NASA. A delightful interaction between the sublime moon and the mundane Earth.

Paintings in this post are from a set of NASA images produced before the launch and originally shared in a PopSci article. Here’s some more (click each to enlarge):

The Great Moon War

This innocuous-looking meme came up on a friend’s feed recently, with the caption “I need to know”:

My immediate thought was, “They aren’t, though!” The reality is so much cooler than that, and this joke actually asks a really interesting question with an even cooler answer.

Tidal Locking means that the same side of the Moon always faces the Earth.

So, first of all, yes, the moon is “tidally locked” with Earth, so only one side ever faces us (incidentally, this means that there’s no “Dark Side” of the Moon; only a “far side”). Tidal locking is going to come up later, so remember that. But the mares (MAH-rays)—the dark marks on the moon—are actually cooled lava flows, not craters.

And it’s actually the fact that meteors don’t hit the near side as often that is the reason we can still see the mares at all; there have, at one time or another, probably been such mares on all sides of the moon, but the others got pummeled into oblivion.

Ok, cool, but…what caused the lava flows that made the mares?

They were created when meteors hitting the far side of the moon made a huge enough impact to cause lunar volcanoes on the near side. (And if “lunar volcanoes” isn’t the coolest phrase you have heard this week, you live a pretty exciting life.)

Oh but wait, it gets better. Due to the way the Earth-Moon system works—that is, as mentioned before, that the moon is tidally-locked—there’s a good chance that, if the moon wasn’t there, those meteors would probably have hit Earth instead.

So the mares aren’t the remnants of the Earth-Moon war. They’re the battle scars of the moon taking bullets that were meant for us.

Thanks Moon.


This was originally typed out to a Reddit user who asked the following question. His comment was removed before my reply was complete, but I had already done all the research, so I decided to drop it in anyway.

So you are telling me sanitizer does not remove germs?

Yes, correct. Many studies have shown hand sanitizer to be largely ineffective; alcohol and Triclosan deployed via hand sanitizers allow most dangerous, disease-causing bacteria to survive. The “99.9%” that Purell talks about? That’s largely stuff that’s part of your microbiome and is supposed to be there. The .1% is mostly the stuff you don’t want, but hand sanitizer can’t touch it.

In addition (and probably more frightening), hand sanitizers may encourage antibiotic-resistant strains of bacteria to proliferate, while also giving them a relatively simple transmission vector (namely, your hands).

Triclosan has also been linked to higher rates of allergy diagnosis, meaning that it is actually negatively impacting your immune system.

Finally, Triclosan leeches BPA from clear bottles (like the ones it comes in), receipt paper, and other sources, causing them to be absorbed into your skin much more readily and potentially leading to higher instances of hormone disorders, cancer, heart disease, infertility, and diabetes.

So, no, don’t use hand sanitizer. When you sneeze, use a tissue if you have one, or your upper sleeve (that is to say, elbow) if you don’t.

Stay healthy out there!

Airplane on a Treadmill

by Randall Munroe of xkcd.  Originally posted at blog.xkcd.com; reposted here for language sensitive audiences.


Feynman used to tell a story about a simple lawn-sprinkler physics problem. The nifty thing about the problem was that the answer was immediately obvious, but to some people it was immediately obvious one way and to some it was immediately obvious the other. (For the record, the answer to Feynman problem, which he never tells you in his book, was that the sprinkler doesn’t move at all. Moreover, he only brought it up to start an argument to act as a diversion while he seduced your mother in the other room.)

The airplane/treadmill problem is similar. It contains a basic ambiguity, and people resolve it one of a couple different ways. The tricky thing is, each group thinks the other is making a very simple physics mistake. So you get two groups each condescendingly explaining basic physics and math to the other. This is why, for example, the airplane/treadmill problem is a banned topic on the xkcd forums (along with argument about whether 0.999… = 1).

The problem is as follows:sauropod

Imagine a 747 is sitting on a conveyor belt, as wide and long as a runway. The conveyor belt is designed to exactly match the speed of the wheels, moving in the opposite direction. Can the plane take off?

The practical answer is “yes”. A 747’s engines produce a quarter of a million pounds of thrust. That is, each engine is powerful enough to launch a brachiosaurus straight up (see diagram). With that kind of force, no matter what’s happening to the treadmill and wheels, the plane is going to move forward and take off.

But there’s a problem. Let’s take a look at the statement “The conveyor belt is designed to exactly match the speed of the wheels”. What does that mean?

Well, as I see it, there are three possible interpretations.  Let’s consider each one based on this diagram:


  1. vB=vC: The belt always moves at the same speed as the bottom of the wheel. This is always true if the wheels aren’t sliding, and could simply describe a treadmill with no motor. I haven’t seen many people subscribe to this interpretation.
  2. vC=vW: That is, if the axle is moving forward (relative to the ground, not the treadmill) at 5 m/s, the treadmill moves backward at 5 m/s. This is physically plausible. All it means is that the wheels will spin twice as fast as normal, but that won’t stop the plane from taking off. People who subscribe to this interpretation tend to assume the people who disagree with them think airplanes are powered by their wheels.
  3. vC=vW+vB: What if we hook up a speedometer to the wheel, and make the treadmill spin backward as fast as the speedometer says the plane is going forward? Then the “speedometer speed” would be vW+vB — the relative speed of the wheel over the treadmill. This is, for example, how a car-on–a-treadmill setup would work. This is the assumption that most of the ‘stationary plane’ people subscribe to. The problem with this is that it’s an ill-defined system. For non-slip tires, vB=vC. So vC=vW+vC. If we make vWpositive, there is no value vC can take to make the equation true. (For those stubbornly clinging to vestiges of reality, in a system where the treadmill responds via a PID controller, the result would be the treadmill quickly spinning up to infinity.) So, in this system, the plane cannot have a nonzero speed. (We’ll call this the “JetBlue” scenario.)

But if we push with the engines, what happens? The terms of the problem tell us that the plane cannot have a nonzero speed, but there’s no physical mechanism that would plausibly make this happen. The treadmill could spin the wheels, but the acceleration would destroy them before it stopped the plane. The problem is basically asking “what happens if you take a plane that can’t move and move it?” It might intrigue literary critics, but it’s a poor physics question.

So, people who go with interpretation #3 notice immediately that the plane cannot move and keep trying to condescendingly explain to the #2 crowd that nothing they say changes the basic facts of the problem. The #2 crowd is busy explaining to the #3 crowd that planes aren’t driven by their wheels. Of course, this being the internet, there’s also a #4 crowd loudly arguing that even if the plane was able to move, it couldn’t have been what hit the Pentagon.

All in all, it’s a lovely recipe for an internet argument, and it’s been had too many times. So let’s see if we can avoid that. I suggest posting stories about something that happened to you recently, and post nice things about other peoples’ stories. If you’re desperate to tell me that I’m wrong on the internet, don’t bother. I’ve snuck onto the plane into first class with the #5 crowd and we’re busy finding out how many cocktails they’ll serve while we’re waiting for the treadmill to start. God help us if, after the fourth round of drinks, someone brings up the two envelopes paradox.

Munroe’s website is typically licensed under a Creative Commons Attribution-NonCommercial 2.5 License; that license is assumed here.


Whenever I see videos like this, I always want to know just how MIND-BLOWING!!! they really are.

So I pulled out a piece of paper and a red pen (so I could look like a teacher) and did some math.

  • mathThere are 50 states, but only 12 letters at the end of each. Those twelve letters are: A, S, O, E, N, I, T, Y, D, K, H, and G. (Interestingly, you can spell “STATES” with those letters, though not “UNITED.” But you can spell “INSANITY” and “SEGA”)
  • But it’s not an even distribution; 21 end with A, 5 end with S, and 4 each end with O, E, and N. So 1/3 of all letters account for 76% of the states.
  • Guess which ones he picked to be red? That’s right: A, Y, D, O, S, T, E, I, Y (again), D (again), and N. All but three letters that actually end a state name are colored red.
  • The only three that aren’t red are K, H, and G, which account for 3 states: New YorK, UtaH, and WyominG. K and H are white, and H and G are blue (that’s right, H is both white AND blue).
  • Now is where he engages in some social engineering. You’re most likely to choose the state you live in or a state you’d like to go, and the most populous states have a last letter colored red.
  • Hawaii, California and Florida are popular tourist destinations, and they’re all red. Alaska is an outlier state, which makes it likely to be chosen, and it’s red.
  • But he’s got a problem, because a lot of people have heard of (and live in) New York. Now, people outside the US are pretty likely to just think that New York is just a city, and NOT a state; but that aside, he’s got to try to get you not to pick New York. So he mentions New York and Utah as his examples, which inclines you to NOT CHOOSE THEM. (if he mentioned them, why would you choose them? It wouldn’t be as MIND-BLOWING!!! that way.) He doesn’t mention Wyoming because the odds are probably fairy low that you’d choose that one anyway.

And just like that, you’re all but guaranteed to pick anything but K, H, and G. Which means you’re all but guaranteed to pick a red letter.

Interestingly, this would work if Puerto Rico were a state, but not if Washington DC were a state. It would also work if, like Joey from Friends, you thought New England was a state.