Date: August 18, 2010

Title: Lunar Dust and Dreams

Podcaster: NASA Lunar Science Institute

Organization: NASA Lunar Science Institute (NLSI)

LADEE mission (Lunar Atmosphere and Dust Environment Explorer)

Description: Dust on Earth can be a nuisance, but on the Moon tiny particles of dust can have a big impact, on both humans and equipment. Nancy Atkinson talks with with Dr. William Farrell, a space plasma physicist who studies the dynamic interaction of solar charged particles with the lunar surface. He also leads NASA’s lunar DREAM team (Dynamic Response of the Environment At the Moon)

Bio: The NLSI brings together leading lunar scientists from around the world to further NASA lunar science and exploration.

Nancy Atkinson is a science journalist and is the Senior Editor for Universe Today

Today’s sponsor: This episode of “365 Days of Astronomy” is sponsored by John Sandlin because a little astronomy illuminates the darkest nights.

Transcript:

Voice: You are listening to the NASA Lunar Science Institute podcast which highlights the latest news information of the Moon, on the Moon and from the Moon. It is produced from the NASA Lunar Science Institute at the Ames Research Center in Moffett Field, California.

Nancy Atkinson: Dust on Earth can be a nuisance, but on the Moon tiny particles of dust can have a big impact, on both humans and equipment. Hi, this is Nancy Atkinson for the NASA Lunar Science Institute. There’s a lot we can learn from a little lunar dust. It is intriguing stuff, but it could also be hazardous to your health. Recently, I had the chance to meet with Dr. William Farrell, a space plasma physicist who, among other things, studies the dynamic interaction of solar charged particles with the lunar surface. He also leads NASA’s lunar DREAM team – no, not a basketball team, but a group of scientists that specializes in studying the lunar environment, and they are trying to put a full-court press on understanding the intricacies of the Moon.

William Farrell: I work with a larger team that is part of NASA’s Lunar Science Institute, and what we really study is the dust, and not just the dust but the environment the dust is in. It turns out the Moon is constantly being impacted by little impactors called micrometeoroids and of course on occasion it gets impacted by even bigger objects. And of course ejecta from those micrometeoroids can lift and loft dust but there is sort of this new thinking — and actually it’s not really that new, it probably started in the days of Apollo but has blossomed a lot recently in terms of understanding how the moon behaves as it is exposed to the solar wind. It turns out the Moon gets charged, and because of this surface charging, there are some people think this surface charging can lift and loft dust. So there may be this sort of naturally created dusty exosphere about the Moon. And there is some anecdotal evidence for this. For example the astronauts when they were in the command module saw this twilight as they were passing from the night side into the day side and this twilight was kind of unexplained and some people have thought this lofted dust up to maybe 10’s to 100 km altitude. So it is kind of amazing, actually that you can loft dust up that high. And of course Surveyor when it landed saw a kind of twilight or horizon glow. So these are kind of bits and pieces coming together and telling us that there may be a more active dusty exosphere at the Moon than people have thought.

And what is really interesting, at kind of the microscopic and even the atomic level, the moon is more active than people think. It is not a stagnant or a place where nothing is happening. In fact the surface percolates with atoms that are out gassed and dust is sort of part of that environmental process. So there maybe dust transport that is just a natural part of the environment.

Nancy: So what are some of the things that you have learned so far about lunar dust?

Farrell: What we have learned so far is that, really, our team has spent a lot of time trying to model this dusty atmosphere, this dusty exosphere, primarily because in early 2013 there will be a spacecraft called LADDEE that is there to study the exosphere including the neutral gasses on the Moon and also the dust environment and our team has done a lot of work to support the LADEE team, particularly by building models of what the dusty exosphere should look like; how it would appear in a UV spectrometer like that flying on LADDEE; how it might appear in a dust detector like that flown by Mihaly Horanyi at the University of Colorado. So we’re really trying to support that to get more fundamental information about this dusty exosphere and kind of help frame their expectations.

Nancy: So, for future both robotic and human missions to the Moon, how does dust affect those missions.
Farrell: That’s a good question. In some sense there are really two types – at least this is how I kind of partition things in my mind – there are two types of dust. There’s sort of natural dust environment, a natural transport created by either impact ejecta or electrostatic fields, which is kind a lower density dust. But we know that when humans start running around and human systems start roving they are goingt o kick up dust and I refer to that as anthropogenic created dust! Kind of a fancy name for just the dust you kick around. You’re basically playing in the dirt! You know when your kids are playing in the sandbox, and you can tell them that it is anthropogenic dust you are playing in, and they are going to look at you like you are crazy. But it is that kind of thing that happens when humans get involved and start kicking it up. And that actually has its own set of problems because the dust on the Moon is unweathered – well I should take that back. It is weathered because micrometeoroids come in and impact it and create these particles called glutenates, very sharp objects. But it is not weathered the same way here on Earth where wind and rain erodes those glutenates to make rounded edge. These glutenates are very sharp and jagged. The problem that you have is that if these get into the human breathable atmosphere environment, it can be a silicosis hazard, and that can be pretty nasty stuff. During some of the Apollo missions, they were only there for a short period of time but they complained of eyes and nose irritation, partly because they were donning their spacesuits in their breathable environment. Basically they were running around out in the dirt and came in and they took their spacesuits off in the same air you and I are breathing in. So that’s kind of nasty way of dealing with this problem, so they had dust all over the place on some of these missions. Different missions reported different amounts of irritation. But if you are going to have a lunar base there and people there for long periods of time, the best hing is to isolate the dust from the humans. So they are coming up with schemes where the suits never comes inside the habitat, and they have a suit-lock, so in some ssense you climb into your suit and your suit is always on the outside and you climb in through the back. Those kinds of approaches are being considered because bringing that suit inside just injects too many particles into the breathable atmosphere. So exploration has been thinking about this quite a bit.

Nancy: On the Lunar RATS where the suit is on the outside, that is part of the reason of why they put that there?

Farrell. Absolutely, that’s right. You climb into the suit, like a bat-suit of something, you climb in the back. The suit if a vessel and you just don’t bring it in. You might have to clean it, and that might be an issue at some point, but that actually solves a lot of problems. But Exploration has actually been working hard – there’s an Exploration technology development program and part of that emphasizes dust and people have been coming up with mitigation strategies as well, so there are groups out there thinking about this. But it is a problem. You do not want this in your breathable atmosphere.

Back in the late 20’s there was a Hawk’s Nest Tunnel being built, I think in West Virginia and at that point they were milling through quartz and so it was unweathered quartz that people were breathing and the silicoses situation was really bad, and people got really sick. Some were acute. Silicosis is an autoimmune response, so people responded to it differently so some got actually sick and some had a longer term issue. So it’s just nasty stuff – just keep it out of the atmosphere. But it’s one of those things you don’t think about here on Earth, but you have to deal with it up there.

Nancy: Can you tell me about the project you work on called DREAM?

Farrell: Sure. DREAM is really short for Dynamic Response of the Environment At the Moon. And what it really is, out team is studying the lunar environment as a whole. Dust is really a part of that environment and it is telling us something about the environment when dust starts transporting. But really what we are studying is how the sun and its energy affects the Moon. It is almost like space weather at the Moon. And so as it turns out the Moon really is a sort of immersed in energy coming from the Sun. There is solar wind plasma, there are energetic particles during solar storms and in particular the solar win plasma can charge up the Moon, so that there is surface charging and there are some people who thing that actually creates some dust transport from that surface charging where dust lifts in regions where there are strong electric fields. So we work on those kinds of problems with our institute.

Voice: To find out more about this topic, visit our website at www.lunarscience.nasa.gov. Any opinions expressed are the individuals and do not necessarily reflect the opinion of NASA or the NASA Lunar Science Institute. This podcast is produced for educational purposes only. On behalf of the NASA Lunar Science Institute, thanks for listening.

End of podcast:

365 Days of Astronomy
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