Northwestern scientist uses laser to study lunar soil

Funded by NASA, professor’s research will help humans return to the moon

The Romantic poet William Blake once wrote you can “see a world in a grain of sand.”  At Northwestern University’s Integrated Laboratories for Earth and Planetary Sciences, a single grain may reveal worlds beyond our own.

Hunched over a powerful microscope, Professor Steve Jacobsen studied a grain of lunar soil.

 “Oh, look,” he said. “You can see the green color already. This is the well-known green glass collected during the Apollo 15 mission.”

He’s on a NASA mission of his own:  to study lunar soil, known as regolith, so the space agency knows how to build on the moon.

“One of the reasons they called me is because I’m a mineralogist,” Jacobsen said. “I know a lot about the type of minerals and the composition of minerals that occur on the Earth and Moon.”

Alongside his doctoral students, he’s examining samples of simulated lunar soil.  

“We’re classifying their composition and their grain size using primarily Raman spectroscopy,” said Laura Gardner, a Northwestern University graduate student.

It’s part of NASA’s Artemis mission, the goal of which is to re-establish a human presence on the Moon, and eventually build a permanent base on the lunar surface.

But before they can build, they must know about the soil on which they’d be building.

“If you want to go to the moon over and over again back to the same place, the first thing you need is a landing pad,” Jacobsen said. “This is the best place to practice.”

Regolith is a fine powder made up of shattered moon rock. Its sharp edges can be rough on astronauts and their equipment. It’s also an uncertain surface for construction. Jacobsen said the first thing NASA needs is a landing pad built on the regolith.

“If you put a spacecraft down on the surface of the moon, you’re going to sandblast everything around the campsite,” he said.

Jacobsen designed a special device, which uses lasers, computers, and a microscope to unlock the mystery of simulated lunar soil.

“We’re going to look at individual grains of this sediment, of this regolith under high magnification, to take a ramen spectrum at specific points,” Gardner said.

Raman spectroscopy is a technique that measures how the vibrations of molecules alter laser light. The specific way in which the light is changed allows scientists to identify the exact substances they’re examining. 

“The way we tell ‘what’s what’ is by looking at a lot of peaks on a plot that our system generates and once you get to know what each of those peaks means, you can figure out what minerals you’re looking at,” Gardner said.

With the analysis of each grain, they’re creating a library of lunar soil profiles. The information will eventually guide the building process on the moon.

“Doing this here on Earth is actually relatively straightforward – as complicated as it looks – what’s going to be complicated is shrinking this down to about the size of a shoebox and putting it on a spaceship,” Jacobsen said.

Since it’s incredibly expensive to bring raw materials from earth to the moon, any lunar outpost will likely have to be built – in large part — from lunar soil, which will be fed into a 3D printers to make the building blocks of a basecamp.

“Just as the first bricks on the Earth were made from earth’s soil, the first bricks on the moon will be made from lunar soil, but to get there, we have to develop all of that engineering,” Jacobsen said.

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