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The Secrets behind Moon Rock

Source: NASA
Source: NASA

On 20 July 2019, it will have been exactly 50 years since the first moon landing. This “giant leap for mankind” thrust space travel into the public consciousness. Astronauts from Apollo 11 and other missions collected minerals and rocks from the Moon that enabled new scientific findings.

The work done by the Apollo astronauts was ultimately a service to researchers. Their photos, rock samples and experiments granted the world access to all-new insights. The samples collected from the lunar surface – all Apollo missions were tasked with bringing back a total of 382 kg, including gray moon dust known as regolith – still provide substantial evidence that astronauts really did set foot on the Moon. They have essentially become the rock to quash all conspiracy theories.

“These ‘souvenirs’ have afforded us new insights into our own planet. Analyzing moon rock is like looking back through the history of the solar system,” says geoscientist Matthew Andrew, who is based in California and conducts research for ZEISS into microscopes used to precisely analyze minerals and rocks.

Cameras that stand the test of time

The analysis began with photos. ZEISS employees in Oberkochen designed the wide-angle lens Biogon 5.6/60 specifically for the moon landing. The contrast and clarity of the images taken of the lunar surface had to be just right. The camera featured a glass plate used to create visible markers on the image during exposure. The markers were what made image evaluations possible, thus enabling subsequent size–ratio analyses of objects on the Moon. The most enterprising lens developer was Dr. Erhard Glatzel, who went on to receive multiple accolades. Once their missions were complete, the astronauts left the cameras on the Moon so they could take back as much rock as possible.

Rocks, rocks and more rocks

The astronauts took photos of the rocks and moon craters around the landing spot of the Apollo 11. They saw the craters as impact basins, which ranged in size from microscopic to ones as large as 2,000 kilometers, which had flooded with lava a long time ago. This part of the Moon’s surface comprises a “loose mix of fragments of rock, minerals and glass, which range from being almost invisible to the naked eye to blocks with a diameter of 1 meter,” wrote geologist and mineralogist Wolf von Engelhardt in an article for ZEISS back in 1972.

Since there is no atmosphere or water on the Moon, the craters are not exposed to the processes of weathering or erosion, allowing them to survive over astronomical timescales. The lack of atmosphere also means the rock is exposed to huge differences in temperature, allowing – over those timescales – for the rock to be ground down to a fine powder. Today there is no plate tectonics on the moon like there is on the Earth, and active volcanics with hot lava is a thing of the past.

Moon vs. Earth

On average, rocks on the Moon are older than those on Earth. This analysis also supports the theory of how the Moon came into being: since the moon landing, scientists have assumed that it was created when the Earth collided with another celestial body.

The age of the individual rocks can be determined through radiometric dating. The samples the astronauts brought back are between three and five billion years old, in other words they date back to an early period of the solar system. Lunar rocks also contain less iron, potassium and sodium. Unlike rocks found on Earth, they contain no traces of water whatsoever, which leads researchers to believe that there has never been any water on the Moon. Nevertheless, there are some similarities in the rocks, primarily in terms of the amount of oxygen isotopes and volcanic traces.

Basalts, anorthosites and breccia

The rock samples collected by the astronauts can also be classified in relation to the rocks found on the Earth: lunar basalts, anorthosites and breccia. The basalt rocks are black or gray in color and some contain glass. The lunar anorthosites are rarer and whiter. Like the basalts, they were formed by melting. Then we have the conglomerates, known as lunar breccia, which are rocks that are made of smaller rock fragments and contain a small amount of glass. They were created by colliding comets, meteorites and asteroids.

“Technology has certainly come a long way since then,” says Matthew Andrew. “These days we work with a range of light, electron and X-ray microscopes, which allow us to precisely analyze sections of rock ranging in size from around 10 centimeters to around 30 nanometers in size. Modern microscopes also allow us to fully digitize the results, analyze them with sophisticated image processing algorithms and share them with collaborators throughout the world.” Andrew works with a team to develop new technologies that allow them to look at and examine rocks in new ways. These technologies have a wide range of applications, from looking for fossils, to understanding sedimentary pore structures to characterize the flow of water, gas, oil or nuclear contamination, to understanding the structure, composition and distribution of historical volcanic eruptions.

Microscopic images of a slice of a rock found during the Apollo 12 mission. Source: NASA
Microscopic images of a slice of a rock found during the Apollo 12 mission. Source: NASA

Only with the right microscope

Mineralogists were only able to make findings on Earth similar to those relating to lunar rock because they had the right microscopes for the job. Back in 1972 Wolf von Engelhardt used the ZEISS POL photomicroscope and the standard microscope GFL Pol with an attachment camera.

Back in 1969, when the first samples from the Moon arrived at the space agency, there was a real need for the technology. The “main sample” consisted of rocks, fragments and sand, as well as the “photo-documented sample,” both of which reached the Manned Spacecraft Center in Houston in sealed, airtight crates. A closer inspection was performed in glove boxes behind protective glass. This was to ensure that nothing contaminated the samples. Then it was time for the physical, chemical and biological tests. The ZEISS surgical microscope II was used for some of the tests as it was deployed for surgery at the time. 80 percent of the rock the astronauts brought back with them still has not been analyzed. The rocks are stored in the space agency’s repository.

A lab technician inspects findings brought back by the Apollo 11 mission through glove boxes and behind protective glass. Source: NASA
A lab technician inspects findings brought back by the Apollo 11 mission through glove boxes and behind protective glass. Source: NASA

A trip to Mars

Nowadays, researchers eagerly await the day when man will set foot on Mars. “There’s one thing we all want to know: is there any life in outer space, even if it’s just on a microbiological scale?” says Matthew Andrew. Scientists have discovered compelling evidence to suggest there is water on Mars.

Geologists in particular are eager to analyze rocks from the red planet. We could even make this happen by 2020, by which time the space agency wants to have obtained the first samples. “Analyzing such a sample would be a great honor,” says Andrew. “But I’d be happy just to develop the microscopes used in the examination.”

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