Log In


Reset Password
News Education Local News Nation & World New Mexico

Scientists measure how moon reflects light

BOULDER (AP) – From the moon to Earth and now into the hands of two Boulder scientists, dust collected decades ago is being studied to better interpret the ways sunlight is reflected from the lunar surface.

Samples of lunar dust from both the Apollo 11 and 14 missions were quietly hand-delivered in the spring to the National Institute of Standards and Technology, where for at least the next year two scientists will be highly invested in unlocking its mysteries.

“I’m especially excited about having this in my lab and in my hands, actually, because I grew up in the ’60s,” said Edward Garboczi, a NIST fellow. “I watched Gemini and Apollo, and my parents let me stay up late the night that Neil Armstrong set foot on the moon.

“I always wanted to be an astronaut, and I didn’t get to be, so this is as close as I’ll ever get to the moon.”

Garboczi’s partner in the moon dust analysis is Ann Chiaramonti Debay, a NIST materials research engineer. She was born in the late 1970s, so she doesn’t have the same memories as Garboczi. But she’s just as excited.

“When Ed called me and asked if I wanted to work on moon dust with him, I basically hung up the phone and literally ran to his office to talk to him about it,” Chiaramonti Debay said.

She glanced down at the glass jar holding sample 14163, about 1 gram of dust ferried back from the lunar highlands by the Apollo 14 mission in 1971.

Garboczi, a soft-spoken man who admits that near-sightedness ended his dreams of perhaps being in the space shoes of Armstrong, confided a fantasy.

“I want to put the (moon) soil on the floor and take a step and say: ‘That’s one small step for Ed.’”

Measuring how light scatters

The NIST scientists have joined Jay Goguen, a research scientist at the Jet Propulsion Laboratory in Pasadena, California., in his efforts working with NASA to interpret measurements of how light scatters from the surface of the moon.

Their piece of the project is using powerful X-ray instruments and electron microscopes to analyze and produce three-dimensional mathematical models of the shapes that make up the lunar regolith, the aluminosilicate soil of the moon accumulated through the impact of countless meteorites smashing into the lunar surface.

“It is a grass-roots initiative from us, not a directed project from NASA,” said Goguen, who works in the JPL’s Comets, Asteroids and Satellites Group. “Our goal is to use these actual lunar soil particles as the ‘ground truth’ to relate what is measured through telescopes and from spacecraft to the physical state of a planet’s surface. To me, this is the holy grail of planetary astronomy.”

Accurate calculations of light’s reflectivity off the moon are much more possible for scientists if they have a better understanding of the actual shape of the particles off which the light is reflecting.

“If it’s all covered with little ball bearings, or all covered with little cubes, it makes a big difference in what you can tell from it,” Garboczi said.

But, of course, it’s not ball bearings, or perfect little cubes.

“The moon dust is really interesting, actually,” Chiaramonti Debay said. “Some of them are perfect spheres, like Dippin’ Dots, and it’s sort of the same physical process they use to make Dippin’ Dots ice cream that happens on the moon, where an asteroid comes in and impacts and melts the regolith. That (regolith) flies in the air and it’s so cold, and it’s in vacuum, and there’s very little gravity on the moon. So as soon as they melt, they form perfectly spherical particles, they solidify and they fall.”

However, she added, “In the lunar soil we see a huge, large variety of different particle sizes and shape morphologies, and the perfect spheres are just one type of many.”

Particles range in size from 100 micrometers down to 100 nanometers in size. And to think you know what you need to know about the soil, without putting it under their instruments, the scientists said, is like looking at a sandbox and thinking you already know everything about the sand.

The work they are doing is groundbreaking.

“Lots of people have looked at lunar regolith and taken images of it over the years for various reasons,” Chiaramonti Debay said. “There have even been studies cataloging the various particle shapes and morphologies that are present in the soils from the different regions on the moon where they were collected. But no one has ever gone through the detailed process of making a mathematical model that fully describes the shapes.”

Once mathematical models are produced at NIST, they can then be used in simulations – experiments modeled on computers – to help better understand and interpret the experimental data that is collected.

A special safe

Garboczi will not, of course, be spreading any of the soil on his laboratory floor to stage his own moonwalk.

The two samples, when not within his or his colleague’s eyesight, are kept in a locked safe.

“We have safes at NIST that have precious metals like platinum in them, but they can’t be in that kind of safe, because then if a thief targeted precious metal, they might get the soil, too. They had to get a separate safe for just the soil.

“Everybody who tries to touch it, they go through me. That’s part of the custodial agreement.”

The security around the dust doesn’t end there. Small plastic cocktail straws on which Garboczi spreads a sample, before mounting it under a layer of epoxy and playing it in his X-ray machine, will ultimately all be shipped back to NASA.

“They want everything,” he said. “They want to account for every particle. To me, all I hear is, ‘Be extra careful.”’

Chiaramonti said that level of care extends even to preserving any and all laboratory materials that come into contact with the moon dust.

“We take our roles as custodians of this very seriously, and I don’t want to take a paper towel that has moon dust on it and throw it in my trash,” she said. “The little plastic pipettes I use to drop it, I keep separated by which type of moon dust it is in a Ziploc bag, and then I’ll send everything back.

“I don’t know what they’re going to do with it at that point, but at least I feel like I fulfilled my role as a dutiful custodian on this material.”

Garboczi and Chiaramonti Debay both exhibit a palpable glow of excitement as they discuss their work. Garboczi appears similarly animated when he mentions his many years doing similar work with materials as familiar as concrete.

“NIST has for five years had a shape metrology project, a very large project for how to measure shape for facial recognition for particles, for biological cells, so my work has been one part of that project. I’ve been doing particle shape stuff for 15 years, so this is just a really nice application of that,” he said.

Their excitement hasn’t been infectious with everyone.

“My daughter is 4½ years old,” Chiaramonti Debay said. “She’s learning about the Earth and moon at school, so I printed up some pictures that I took, and she was very nonplussed. My husband tried to explain to her that there’s not that many people in the world whose mom has touched the moon.

“I think she thought they would look very different than they do. Maybe when she’s a little older, she’ll be able to appreciate really what it took to get this back to Earth.”

Meanwhile, Garboczi admits he has daydreamed about some other unusual soils on which he might one day be able to work his magic.

“I’d like to get some Martian soil,” he confided. “I’ve got some Martian simulated soil in my lab. But I haven’t worked on it yet.”



Reader Comments