Sciency Words: Silicosis

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Today’s post is part of a special series here on Planet Pailly called Sciency Words. Every Friday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together. Today’s word is:


What’s the scariest thing about the Moon? Moondust.

My10 MoondustI’m glad you asked, Mr. Moon!

  • First, moondust gets all over your spacesuit. During the Apollo missions, astronauts found it was practically impossible to get all the dust off their spaceboots and spacesuits, possibly due to a sort of static cling effect. So astronauts wound up tracking a lot of this stuff back into the lunar lander.
  • Next, it gets in your air supply. Once all that moondust got into the lander, the Moon’s low gravity meant dust particles could drift about in the air a lot longer than they would on Earth—just waiting for someone to breathe them in.
  • Finally, it gets in your lungs. Roughly half of moondust is composed of fine grains of silicon dioxide. Essentially, moondust has the consistency of powdered glass. You don’t want that in your lungs.

On Earth, the inhalation of silica dust can cause a respiratory disease called silicosis. Symptoms include coughing, shortness of breath, and swelling or inflammation of the lungs. Those most at risk include miners and quarry workers, as well as anyone working in the glass manufacturing industry.

At least one astronaut reported experiencing silicosis-like symptoms while on the Moon. Future Moon missions and possible lunar settlements will likely involve longer-term exposure and higher risks of respiratory diseases.

So while this may sound like an odd piece of advise, given that the Moon is airless, please be careful about the air you breathe on the Moon.

P.S.: Silicosis or similar respiratory conditions will also be problematic for Mars missions. The surface of Mars is covered in iron oxide dust (a.k.a. rust). I for one don’t want to breathe in flecks of rust any more than I want to inhale powdered glass. Martian soil may also contain other as-yet-unidentified chemicals that could be hazardous to human health.


Silicosis from MedLine Plus.

Don’t Breathe the Moondust from NASA Science.

The Mysterious Smell of Moondust from NASA Science.

Occupational Health: Lunar Lung Disease from Environmental Health Perspectives.

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Today’s post is part of Moon month for the 2015 Mission to the Solar System. Click here for more about this series.

We Choose to Go to the Moon Again

My06 Stuff on the Moon

Humanity will return to the Moon… eventually. We have a long list of reasons to do so. The most commonly cited reason is, of course, the mining of helium-3.

In nuclear fusion reactions, helium-3 can be used as a carbon-free, radiation-free fuel. So that would be awesome for the environment. Nuclear fusion also promises to generate more usable energy by far than any other currently available technology, thus solving the world’s energy crisis.

Although helium-3 is rare on Earth, it’s relatively common on the Moon. Once we establish lunar mining facilities, we could send this fuel back to Earth or use it to power spacecraft for further exploration of the Solar System.

But is this really the best reason to return to the Moon?

How Difficult Will This Be?

While helium-3 is more common on the Moon than on Earth, that doesn’t mean it’s easy to get. Lunar mining operations would have to sift through hundreds of metric tons of rock, heating that rock to temperatures in excess of 600 degrees Celsius, just to obtain a teeny-tiny sample of helium-3.

When you consider the total amount of energy needed to extract usable quantities of helium-3, combined with the cost of sending that helium-3 back to Earth, as well as the costs associated with shuttling astronauts and equipment to and from the Moon’s surface, you might find that you’re not getting much of a return on your investment.

Do We Really Need Helium-3?

At this time, nuclear fusion remains a promising but highly experimental technology. In theory, helium-3 is the idea fuel, but other fuels like hydrogen-2 could also work (although the fusion of hydrogen-2 nuclei would produce radiation in the form of free neutrons).

Since we can get hydrogen-2 right here on Earth, it may make more economic sense to use that instead.

The Future of Helium-3

In a more distant, Sci-Fi future, it’s a pretty safe bet that helium-3 will become a major energy source. Planetary economies will depend on it. Wars will be fought over it. Labor-class men and women will don spacesuit and go mining for it.

But I’m not convinced that this will be humanity’s top reason for returning to the Moon. Not when there are so many other, more achievable goals for our next Moon mission.

So what do you think will be the motivating factor when we finally do return to the Moon?


Could Helium-3 Really Solve Earth’s Energy Problems? from io9.

How Nuclear Fusion Reactors Work from How Stuff Works.

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Today’s post is part of Moon month for the 2015 Mission to the Solar System. Click here to learn more about this series.

Ice Skating in Shackleton Crater

There’s one thing I’ve always wanted to do: go ice-skating on the Moon. It’s a dream I’m sure we’ve all had at some point. The best place to make that dream become a reality is Shackleton Crater… maybe.

Shackleton Crater is a lunar cold trap situated at the Moon’s geographic south pole. The exact pinpoint location of the pole lies on the crater’s outer rim. And the inside of the crater contains water ice, or at least some scientists think so.

In the mid-1990’s, a space probe named Clementine beamed radio waves into Shackleton. The radio waves bounced back in a manner that could be interpreted as a reflection off water ice… or possibly reflections off exceptionally rough, rocky terrain.

Later, analysis of data from NASA’s Lunar Prospector and Lunar Reconaissance Orbiter revealed a higher than average concentration of hydrogen in Shackleton Crater and other nearby craters. Since hydrogen is part of the water molecule, this could be more evidence of water ice. Or it could be evidence of some other hydrogen-containing molecule.

In 2009, NASA’s LCROSS Mission made headlines for “bombing the Moon.” A large projectile crashed into Cabaeus Crater, not far from Shackleton, and the resulting debris plume was observed to contain, among other things, particles of water ice which must have lain buried underground for billions of years.

Although a lot remains open to interpretation, the pattern of evidence seems to suggest that water ice is spread throughout the Moon’s polar regions, with Shackleton Crater possibly containing one of the largest deposits.

But before we start lacing up our ice skates, we should note a few things. Any ice in Shackleton is likely buried under layers of rock, similar to what was observed in Cabaeus. Also, we might only be talking about a few hundred gallons spread thinly over an area of several hundred square kilometers.

My05 Shackleton Ice Skating

Fortunately, my dreams of one day ice skating on Mars seem far more realistic.


The Mystery of Shackleton Crater from Air & Space.

Evidence for Water Ice near the Lunar Poles from The Journal of Geophysical Research.

An Explanation of Bright Areas Inside Shackleton Crater at Lunar South Pole Other Than Water Ice Deposits from the 2013 Lunar and Planetary Science Conference.

LCROSS Impact Data Indicates Water on Moon from NASA.

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Today’s post is part of Moon month for the 2015 Mission to the Solar System. Click here for more about this series.


Sciency Words: Cold Trap

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Today’s post is part of a special series here on Planet Pailly called Sciency Words. Every Friday, we take a look at a new and interesting scientific term to help us all expand our scientific vocabularies together. Today’s word is:


My04 Lunar Water 1The Moon has a lot in common with the planet Mercury, and just like Mercury, the Moon has trouble retaining its volatiles.

Water is a volatile, meaning it’ll spontaneously evaporate or sublimate at relatively low temperatures and/or pressures. Without the protection of an atmosphere or a magnetic field, volatiles like water tend to be swept off into space by the solar wind.

The only way the Moon can hold on to its water is to keep it well hidden from the Sun’s heat. Regions of the Moon (or Mercury) that are dark enough and therefore cold enough to retain water ice are informally known as cold traps.

The Moon’s best cold traps lie near its south pole, within the basins of large craters that remain in perpetual shadow, never seeing the Sun. Temperatures there hover around 100 Kelvin (a.k.a.: -170 degrees Celsius or -280 degrees Fahrenheit or simply “@&%$, that’s cold!”).

Similar craters exist near the Moon’s north pole, but they’re generally smaller and shallower and might not serve as effective cold traps.

My04 Lunar Water 2But just because the Moon has cold traps, that doesn’t prove it has water ice. On Monday, we’ll go exploring one of the Moon’s most famous and controversial cold traps: Shackleton Crater. Feel free to bring your ice skates, but I can’t guarantee you’ll get to use them.

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Today’s post is part of Moon month for the 2015 Mission to the Solar System. Click here for more about this series.



Sciency Words: DSKY

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Continuing with the 2015 Mission to the Solar System, we now come to the Moon (Earth’s moon, in case there’s any confusion). The most important fact about the Moon is that human being have actually been there, so for this week’s edition of Sciency Words, let’s look at a term that was closely tied to the Moon Landings:


Pronounced “dis-key,” this term is an acronym for “display and keyboard,” and it served as the main computer interface for astronauts during the Apollo Missions. And I cannot emphasize this enough: DSKY was not exactly “user-friendly.”

Apollo astronauts issued commands to their guidance computer by entering a “verb” followed by a “noun.” The computer would then perform the indicated verb on or with the indicated noun. Verbs included things like “display” or “enable” or “initiate.” Nouns could be parts of the spacecraft, countdowns, preprogrammed maneuvers, etc.

That seems simple enough until you see the interface itself. It’s just a number pad with a few extra buttons (note the two on the left labeled “verb” and “noun”).

My01 AGC_user_interface
You can land on the Moon using just nineteen buttons… assuming you know which buttons to push.

This system is not even a little bit intuitive. Turns out every noun and verb had specific two-digit numbers assigned to it. How did astronauts know which number combinations to use? They had to memorize them.

As user-unfriendly as it may seem, DSKY actually simplified the Apollo Missions by reducing the total number of keystrokes required to operate the guidance computer. If you’re trying to land on the Moon, would you want to type out “please perform landing and breaking phase” or would you rather just hit six buttons: “verb-5-0, noun-6-3”?

In fact, Apollo astronauts reported that DSKY was surprisingly easy to use. One astronaut compared it to playing the piano. Once you familiarize yourself with the keys, your fingers just know what to do.

But that’s only true after you’ve learned the interface. You need training. A lot of training. I’m willing to bet even experienced pilots from NASA’s Space Shuttle Program would not necessarily be able to figure out how to use the DSKY interface from the Apollo Missions.

This is one of my biggest pet peeves in science fiction: characters sitting down at unfamiliar control panels and somehow instantly knowing how to use them.

But maybe I’m wrong about this. Maybe computers on spacecraft will become more user-friendly over time (based on my research, that has not yet been the case). So what do you think? If we ever build something like the starship Enterprise, how easy or difficult will it be to learn the user interface?


Apollo Flight Journal from NASA History Division.

Computers Aboard the Apollo Spacecraft from Computers in Spaceflight: The NASA Experience.