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Theme 4 | Maximizing Science from Returned Samples

M. Darby Dyar

by M. Darby Dyar

Kennedy-Schelkunoff Professor of Astronomy, Mount Holyoke College

When I was a little girl, I watched in awe with my family as the grainy images of the Apollo astronauts walking and hopping around on the surface of the Moon appeared on our black and white television. I had special reason to be interested because my father had helped build the fuel and oxidizer tanks on the Apollo landers.

Another exciting part of the space missions was the splashdown landings, when the lunar capsules returned the astronauts to Earth in a very dramatic way. Aircraft carriers were positioned in the ocean in the approximate areas of touch-down, and television sometimes captured the capsules as they leapt out of the sky toward the ocean. There were always a few moments of concern as the tiny lunar modules bobbed in the sea awaiting rescue from helicopters and the nearby carriers. But how proud we felt with the hatch popped open and the first astronaut waved for the cameras! It was a time of great optimism in this country, and tremendous pride in our space program. Little did I think then that all these years later, I’d be working with samples brought back by those brave astronauts, and pondering new human exploration throughout our solar system.

Retrieval of the Apollo 13 capsule.

Retrieval of the Apollo 13 capsule. Credit

Of course, the capsules brought back more than men – each mission retrieved a cooler-full of samples. Between 1969 and 1972, six Apollo missions brought back 382 kilograms (842 pounds) of lunar rocks, core samples, pebbles, sand and dust from the lunar surface. The six space flights returned 2200 separate samples from six different exploration sites on the Moon. In addition, three automated Soviet spacecraft returned important samples totaling 300 grams (approximately 3/4 pound) from three other lunar sites.

The first Apollo 11 sample return container back on Earth. http://history.nasa.gov/SP-4223/ch13.htm; NASA photo S69-39984

The first Apollo 11 sample return container back on Earth. Credit

But samples from the Apollo missions are not the only extraterrestrial samples we have to study. The constant rain of meteors on the Earth’s surface means that we have a surprising supply of samples from other places in our solar system. Meteorites have been found in many locations on Earth that came from the Moon and Mars; other groups of meteorites are believed to have come from specific asteroids. NASA’s Stardust mission brought back tiny fragments of material for the tail of comet Wild 2, while the Japanese Hayabusa mission returned more than 1500 particles of asteroid dust from asteroid 25143 Itokawa. In 2016, NASA will launch the OSIRIS-REx mission to return samples from the asteroid Bennu.

Dust samples in aerogel collected by NASA's Startdust mission. http://stardust.jpl.nasa.gov/images/5trackposter.jpg

Dust samples in aerogel collected by NASA’s Startdust mission. Credit

Meteorites and missions have brought us a wealth of precious extraterrestrial material for study, but it’s a highly limited resource and presents special challenges to modern geochemical analyses. For example, the Hayabusa samples are mostly smaller than 10 microns across (human hair ranges between 17 and 180 microns across). Our scientists in Theme 4 will be working to understand the amount of oxygen present when these very small samples formed.

Samples returned from asteroid 25143 Itokawa by the Hayabusa mission

Samples returned from asteroid 25143 Itokawa by the Hayabusa mission

In this project, we will develop techniques to analyze extraterrestrial samples using two sophisticated instruments. We will use the synchrotron at the National Synchrotron Light Source II in Brookhaven, New York, and state of the art transmission electron microscope at the Naval Research Laboratory. Students, post-docs, and faculty will work together to develop new techniques to allow successful and accurate measurements of a variety of geological materials. Once developed, these new tools will be applied to the study of Apollo lunar samples, meteorites from Mars and asteroids, and returned samples from the Stardust and Hayabusa missions. While some of these samples have previously been studied with more “macroscopic” methods, the newly developed techniques for nano-analysis should give us a better understanding of how oxygen evolved on the parent bodies, or sources, of these rocks.

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