Monica Martinez paged through a book detailing the mineralogy of the moon last year, her confusion growing as she flipped back and forth through the sulfides section.

The only one listed as present on the moon was iron sulfide, a semiconductor that is found in lithium-ion batteries.

But that couldn’t be right.

Just a few days ago, she had found calcium sulfide — a compound often used as a base for luminescent materials — in a sample of lunar dust collected during Apollo 17, the last human mission to the moon in December 1972.

Did she just find a new compound on the moon? Maybe the book wasn’t up to date, thought Martinez, then a junior at the University of Houston studying mechanical engineering.

She did more research. The presence of calcium sulfide had never been documented.

This was big.

“I was like, ‘OK, that means I found it.’ It was surreal really,” Martinez, now 23, said. “Somehow, a year afterwards, I still can’t believe it. As an undergrad, it’s very odd.”

A year has passed since her discovery, but Martinez’s work on the sample is just beginning. She is still running tests on the sample, looking for other unusual elements. And she plans to publish a journal article about the finding soon, alongside Jim Meen, a research associate professor in UH’s Department of Chemistry who is overseeing Martinez’s work.

Meen acquired the lunar sample from a former student who now works at Jacobs Aerospace, a company that often gets contracts for work from NASA. Though Martinez is studying mechanical engineering — seemingly unrelated to the study of lunar rocks — she had worked on research with Meen and had proved herself smart and capable.

Meen had plans to study resource utilization on the moon — breaking down the moon’s ice to oxygen and hydrogen for use as life support and rocket fuel — but first wanted to understand what was in the dust coating the surface.

It’s especially important given what the Apollo astronauts of the 1960s and 1970s discovered. During the Apollo 17 mission, for example, the dust was so sharp and abrasive it wore through multiple layers of astronaut Harrison Schmitt’s boot, which was made of a material similar to Kevlar, according to a 2008 Science Daily article. Apollo astronauts also reported symptoms similar to hay fever after breathing in the dust and difficulty moving the spacesuits’ joints after dust found its way inside.

Meen had no idea what they would find in the lunar dust. And he had a much more visceral reaction to Martinez’s finding.

“I thought something you probably can’t print in the paper: It begins with holy,” Meen said. “It was astonishing.”

Calcium sulfide is incredibly rare on Earth, Meen said, and it requires high temperatures to form, indicating that the moon was once subjected to those temperatures.

In a way, Martinez’s find makes sense. Apollo 17 landed at Taurus-Littrow, in part to look for proof of volcanic activity on the moon. Astronaut and geologist Schmitt discovered that it was there, in fact, spotting orange soil in the region.

Still, nearly 50 years have passed since Schmitt and fellow astronaut Gene Cernan brought these and other samples back from the moon. And calcium sulfide has just now been found.

Meen attributes this to a lack of study on lunar dust.

“The bigger pieces (of rock) have been looked at in better detail, but the really fine stuff needs to be looked at in detail as well,” Meen said. “People used to see this as just a bunch of dust — that the rest of the dust is just dust, and it isn’t.”

Martinez’s discovery could offer insight into why the dust might have been so problematic and whether the moon could be mined for resources such as oxygen and hydrogen.

If NASA really wants to return to the moon to stay, she added that more studies need to be done on the lunar dust.

“If we actually do want to build a base on the moon and use its resources, we need to look at the big picture,” Martinez said.

NASA is working to put Americans back on the moon by 2024 — a directive handed down by President Donald Trump’s administration this spring that accelerated the landing timeline by four years. The goal, eventually, is to have humans constantly living and working on the moon in the coming years, where they can practice techniques for living and working on Mars.

But the project, dubbed Artemis, is facing funding hurdles.

NASA Administrator Jim Bridenstine has said that putting humans on the moon by 2024 will take up to $30 billion over the next five years. But a full budget plan for the project will not be ready for Congress until February — almost a full year after the accelerated timeline announcement.

So far, the Trump administration has requested only $1.6 billion from Congress for Artemis — primarily to fund development of a lunar lander. That amount has not yet been approved.

Martinez already has presented the findings to the Lunar and Planetary Science Conference this year, publishing a paper through it as well. She’s unsure when the larger paper might be published.

In the mean time, Martinez’s work has her questioning what she wants to do when she graduates next fall. A move toward the aerospace industry, maybe even NASA itself, seems much more exciting given her recent work.

“I always knew the aerospace field was something I could go into, and I remember my aunts, when they first realized I was going to be a mechanical engineer, said I should go work for NASA,” Martinez said. “But through this research I realized I could actually go into aerospace, and I feel like now that’s a very serious alternative for me. As of right now, I know I really like doing research, and I really want to do a master’s (degree), maybe get a Ph.D.”

alex.stuckey@chron.com