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Author Topic:   The smell of moondust (spent gunpowder)
Robert Pearlman

Posts: 44183
From: Houston, TX
Registered: Nov 1999

posted 01-30-2006 07:41 PM     Click Here to See the Profile for Robert Pearlman   Click Here to Email Robert Pearlman     Edit/Delete Message   Reply w/Quote
NASA Science (audio version)
The Mysterious Smell of Moondust

Moondust. "I wish I could send you some," says Apollo 17 astronaut Gene Cernan. Just a thimbleful scooped fresh off the lunar surface. "It's amazing stuff."

Feel it -- it's soft like snow, yet strangely abrasive.

Taste it -- "not half bad," according to Apollo 16 astronaut John Young.

Sniff it -- "it smells like spent gunpowder," says Cernan.

How do you sniff moondust?

Every Apollo astronaut did it. They couldn't touch their noses to the lunar surface. But, after every moonwalk (or "EVA"), they would tramp the stuff back inside the lander. Moondust was incredibly clingy, sticking to boots, gloves and other exposed surfaces. No matter how hard they tried to brush their suits before re-entering the cabin, some dust (and sometimes a lot of dust) made its way inside.

Once their helmets and gloves were off, the astronauts could feel, smell and even taste the moon.

The experience gave Apollo 17 astronaut Jack Schmitt history's first recorded case of extraterrestrial hay fever. "It's come on pretty fast," he radioed Houston with a congested voice. Years later he recalls, "When I took my helmet off after the first EVA, I had a significant reaction to the dust. My turbinates (cartilage plates in the walls of the nasal chambers) became swollen."

Hours later, the sensation faded. "It was there again after the second and third EVAs, but at much lower levels. I think I was developing some immunity to it."

Other astronauts didn't get the hay fever. Or, at least, "they didn't admit it," laughs Schmitt. "Pilots think if they confess their symptoms, they'll be grounded." Unlike the other astronauts, Schmitt didn't have a test pilot background. He was a geologist and readily admitted to sniffles.

Schmitt says he has sensitive turbinates: "The petrochemicals in Houston used to drive me crazy, and I have to watch out for cigarette smoke." That's why, he believes, other astronauts reacted much less than he did.

But they did react: "It is really a strong smell," radioed Apollo 16 pilot Charlie Duke. "It has that taste -- to me, [of] gunpowder -- and the smell of gunpowder, too." On the next mission, Apollo 17, Gene Cernan remarked, "smells like someone just fired a carbine in here."

Schmitt says, "All of the Apollo astronauts were used to handling guns." So when they said 'moondust smells like burnt gunpowder,' they knew what they were talking about.

To be clear, moondust and gunpowder are not the same thing. Modern smokeless gunpowder is a mixture of nitrocellulose (C6H8(NO2)2O5) and nitroglycerin (C3H5N3O9). These are flammable organic molecules "not found in lunar soil," says Gary Lofgren of the Lunar Sample Laboratory at NASA's Johnson Space Center. Hold a match to moondust -- nothing happens, at least, nothing explosive.

What is moondust made of? Almost half is silicon dioxide glass created by meteoroids hitting the moon. These impacts, which have been going on for billions of years, fuse topsoil into glass and shatter the same into tiny pieces. Moondust is also rich in iron, calcium and magnesium bound up in minerals such as olivine and pyroxene. It's nothing like gunpowder.

So why the smell? No one knows.

ISS astronaut Don Pettit, who has never been to the moon but has an interest in space smells, offers one possibility:

"Picture yourself in a desert on Earth," he says. "What do you smell? Nothing, until it rains. The air is suddenly filled with sweet, peaty odors." Water evaporating from the ground carries molecules to your nose that have been trapped in dry soil for months.

Maybe something similar happens on the moon.

"The moon is like a 4-billion-year-old desert," he says. "It's incredibly dry. When moondust comes in contact with moist air in a lunar module, you get the 'desert rain' effect -- and some lovely odors." (For the record, he counts gunpowder as a lovely odor.)

Gary Lofgren has a related idea: "The gases 'evaporating' from the moondust might come from the solar wind." Unlike Earth, he explains, the moon is exposed to the hot wind of hydrogen, helium and other ions blowing away from the sun. These ions hit the moon's surface and get caught in the dust.

It's a fragile situation. "The ions are easily dislodged by footsteps or dustbrushes, and they would be evaporated by contact with warm air inside the lunar module. Solar wind ions mingling with the cabin's atmosphere would produce who-knows-what odors."

Want to smell the solar wind? Go to the moon.

Schmitt offers yet another idea: The smell, and his reaction to it, could be a sign that moondust is chemically active.

"Consider how moondust is formed," he says. "Meteoroids hit the moon, reducing rocks to jagged dust. It's a process of hammering and smashing." Broken molecules in the dust have "dangling bonds" -- unsatisfied electrical connections that need atomic partners.

Inhale some moondust and what happens? The dangling bonds seek partners in the membranes of your nose. You get congested. You report strange odors. Later, when the all the bonds are partnered-up, these sensations fade.

Another possibility is that moondust "burns" in the lunar lander's oxygen atmosphere. "Oxygen is very reactive," notes Lofgren, "and would readily combine with the dangling chemical bonds of the moondust." The process, called oxidation, is akin to burning. Although it happens too slowly for smoke or flames, the oxidation of moondust might produce an aroma like burnt gunpowder. (Note: Burnt and unburnt gunpowder do not smell the same. Apollo astronauts were specific. Moondust smells like burnt gunpowder.)

Curiously, back on Earth, moondust has no smell. There are hundreds of pounds of moondust at the Lunar Sample Lab in Houston. There, Lofgren has held dusty moon rocks with his own hands. He's sniffed the rocks, sniffed the air, sniffed his hands. "It does not smell like gunpowder," he says.

Were the Apollo crews imagining things? No. Lofgren and others have a better explanation:

Moondust on Earth has been "pacified." All of the samples brought back by Apollo astronauts have been in contact with moist, oxygen-rich air. Any smelly chemical reactions (or evaporations) ended long ago.

This wasn't supposed to happen. Astronauts took special "thermos" containers to the moon to hold the samples in vacuum. But the jagged edges of the dust unexpectedly cut the seals of the containers, allowing oxygen and water vapor to sneak in during the 3-day trip back to Earth. No one can say how much the dust was altered by that exposure.

Schmitt believes "we need to study the dust in situ -- on the moon." Only there can we fully discover its properties: Why does it smell? How does it react with landers, rovers and habitats? What surprises await?

NASA plans to send people back to the moon in 2018, and they'll stay much longer than Apollo astronauts did. The next generation will have more time and better tools to tackle the mystery.

We've only just begun to smell the moondust.

Note: As the story explains, moondust is nothing like modern smokeless gunpowder. It's nothing like old-fashioned "black powder" either: Black powder, an ancient form of gunpowder, is mainly potassium nitrate (75%), a.k.a. "saltpeter," mixed with charcoal (15%) and sulfur (10%). Moondust contains almost none of these ingredients. For example, "the maximum amount of sulfur in moondust we've studied is only 0.2%," says Gary Lofgren of the Lunar Sample Laboratory at NASA's Johnson Space Center. "And the explosive ingredient of black powder, saltpeter, is completely absent."


Posts: 1664
From: Smithfield, Me, USA
Registered: Mar 2005

posted 10-26-2006 07:41 PM     Click Here to See the Profile for MCroft04   Click Here to Email MCroft04     Edit/Delete Message   Reply w/Quote
National Geographic magazine has a short article in the November 2006 issue about Apollo 17 astronauts Eugene Cernan and Harrison Schmitt's claim that moondust smelled like gunpowder.

Schmitt suggested that the "fine lunar powder houses fractured chemical bonds that latch onto receptors in the nose."

Geologists have opinions about everything.

The article also mentions Gary Lofgren of NASA's Astromaterials Curation Lab who some of us met at the AAPG Field Trip to JSC in April which was lead by Schmitt.

Nothing new here but it's always nice to see space exploration highlighted in a respected magazine.

Editor's note: Threads merged.


Posts: 1067
From: Leawood, Kansas USA
Registered: Oct 2003

posted 10-26-2006 10:36 PM     Click Here to See the Profile for fabfivefreddy   Click Here to Email fabfivefreddy     Edit/Delete Message   Reply w/Quote
I think Armstrong and Aldrin thought it smelled like that too. Maybe all the moonwalkers did?


Posts: 769
From: West Midlands, UK
Registered: Jun 2005

posted 10-27-2006 06:18 PM     Click Here to See the Profile for robsouth     Edit/Delete Message   Reply w/Quote
I think Charles Conrad said it smelt like ammonia.


Posts: 623
From: Dublin, Ireland
Registered: Mar 2011

posted 02-20-2017 06:26 PM     Click Here to See the Profile for YankeeClipper   Click Here to Email YankeeClipper     Edit/Delete Message   Reply w/Quote
This is what Buzz Aldrin reported on pp. 26-27 of LIFE Magazine, August 22, 1969:
Inside our suits and helmets we could smell nothing on the surface, but when we got back into Eagle and got our helmets off we could.

Odor is very subjective, but to me there was a distinct smell to the lunar material, pungent like gunpowder or spent cap-pistol caps. We carted a fair amount of lunar dust back inside the vehicle with us, either on our suits and boots or on the conveyor system we used to get boxes and equipment back inside. We noticed the odor right away.


Posts: 191
From: Trinity, FL USA
Registered: Jan 2011

posted 02-21-2017 06:46 PM     Click Here to See the Profile for moonguyron   Click Here to Email moonguyron     Edit/Delete Message   Reply w/Quote
The smell apparently lasted until after splashdown. The following is from conversations with the flight surgeon, Dr. Bill Carpentier, who was quarantined with the astronauts after Apollo 11 and who also took swab samples from the command module interior of Apollo 15.

He mentioned the "gunpower" smell when he visited the inside of the CM on the aircraft carrier after both Apollo 11 and Apollo 15. His job was to take swab samples from designated areas of the spacecraft interior and swab samples from surfaces that had been exposed on the lunar surface. The samples were then used in an attempt to grow cultures. He described the smell as quite pungent and irritating.

As an aside he also mentioned that he (and I am assuming the astronauts would be included here) had to sign a wavier of sorts that he understood and accepted the fact that in the highly remote chance that he or his colleagues developed a virus or "bug" that could not be cured that they understood that it might be possible that they would have to be quarantined "indefinitely."


Posts: 113
Registered: Feb 2014

posted 02-21-2017 09:54 PM     Click Here to See the Profile for Dave_Johnson   Click Here to Email Dave_Johnson     Edit/Delete Message   Reply w/Quote
The smell isn't limited to the moon, either. Astronauts orbiting in the ISS have stated that when they return to the airlock after an EVA, they too smell the fireworks-like odor, perhaps from the atomic oxygen reacting with other materials in space.

Doug Wheelock noted that it smelled like an extinguished match or burnt cookies.


Posts: 2475
From: U.K.
Registered: Jul 2009

posted 02-22-2017 12:41 AM     Click Here to See the Profile for moorouge   Click Here to Email moorouge     Edit/Delete Message   Reply w/Quote
But if the universe started with a "big bang" there would be a gunpowdery smell, wouldn't there?

Ross Sackett

Posts: 18
From: Santa Fe, NM
Registered: Aug 2015

posted 02-24-2017 07:59 AM     Click Here to See the Profile for Ross Sackett   Click Here to Email Ross Sackett     Edit/Delete Message   Reply w/Quote
I think I've experienced exactly the smell that astronauts describe, in two similar circumstances. Back during my early career in archeology while flint knapping, and while roughing out a glass blank making telescope mirrors. Both operations involve pulverizing silicon dioxide, so I'd place a lot of weight on that hypothesis. The scent is pungent and quite distinct. Bang two quartz-containing rocks together and sniff the impact point and you'll know what I mean.


Posts: 928
From: Vancouver, WA, USA
Registered: Feb 2012

posted 02-24-2017 11:01 AM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
Did any of the Navy divers who set up the rafts around the command module report a "gunpowder" like odor when they opened the hatch or when the crew exited? I wonder how long this aroma persisted?

David C

Posts: 1107
From: Lausanne
Registered: Apr 2012

posted 02-24-2017 02:19 PM     Click Here to See the Profile for David C     Edit/Delete Message   Reply w/Quote
I think the divers were reporting different and much stronger aromas.


Posts: 928
From: Vancouver, WA, USA
Registered: Feb 2012

posted 02-24-2017 04:41 PM     Click Here to See the Profile for Headshot   Click Here to Email Headshot     Edit/Delete Message   Reply w/Quote
Good point!


Posts: 623
From: Dublin, Ireland
Registered: Mar 2011

posted 04-18-2017 01:22 PM     Click Here to See the Profile for YankeeClipper   Click Here to Email YankeeClipper     Edit/Delete Message   Reply w/Quote
This is an excerpt from The Sunday Times Magazine interview with Buzz Aldrin, Charlie Duke, and Harrison Schmitt published on Sunday 09 April 2017:
Aldrin was struck by the fineness of the regolith dust.

“Like talcum powder. That’s why I took one of the few photos on the moon of the iconic boot print.”

The dust also got to Duke. He noticed, back inside the lander, that when you rubbed it between your fingers, it felt “oily, like graphite”. He also said it smelt like gunpowder. Other walkers have said the same thing. But when transported back to Earth, it seemed to lose this smell. So does the moon smell? Well, it is possible the regolith emitted an odour on contact with the oxygen in the lander — so maybe yes, the moon smells of gunpowder.


Posts: 623
From: Dublin, Ireland
Registered: Mar 2011

posted 05-29-2017 10:30 AM     Click Here to See the Profile for YankeeClipper   Click Here to Email YankeeClipper     Edit/Delete Message   Reply w/Quote
Excerpt from ALSJ Apollo 15 Post-EVA-1 Activities :
126:16:16 Irwin: There's a funny smell in here.

126:16:17 Scott: Yeah, I think that's a lunar dirt smell. (Pause) Never smelled lunar dirt before, but we got most of it right here with us.

[Jones - "How would you describe the smell of lunar dirt?"]

[Scott - "Like gunpowder."]

[Jones - "That's what most people say."]

[Scott - "I hadn't heard that before we went. I don't think."]

[Jones - "Here, you don't actually describe it as gunpowder."]

[Scott, from a 1996 letter - "I actually whispered it to Jim so that nobody would become alarmed."]

All times are CT (US)

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