A student’s lunar breakthrough
Research on moon water challenges long-held beliefs
It’s long been accepted that the moon is dry. No oceans wash its Swiss cheese surface, and lunar rocks and soil samples collected by Apollo astronauts 40 years ago bolstered the case the moon was an arid place.
But a paper published yesterday challenges that notion, based on findings from a research project by Westwood native Thomas Weinreich, who spent the summer after his freshman year at Brown University sorting through thousands of grains of moon dust.
Weinreich was not strictly following orders when, on his own, he slightly expanded his research mission. He had been asked to pick out round, orange glass particles from lunar soil samples taken from the moon during Apollo 17, almost two decades before he was born. As he became more familiar with looking at the dust under the microscope, he also began to use his tweezers to sift out something else that caught his attention, a handful of tiny crystals with black flecks.
Yesterday, the end result of Weinreich’s painstaking summer task was announced: a paper published online by Science, a top journal, that shows that parts of the moon’s interior are as wet as the upper mantle of the Earth, the layer beneath the crust.
It is the latest finding in “the new era of lunar water,’’ in which people are beginning to rethink beliefs about how wet the moon is and even how our closest neighbor came about in the first place, said Benjamin Weiss, an associate professor of planetary sciences at MIT.
“I think this is extremely important, and I think the most important issue is what does it mean for the origins of the moon,’’ said Weiss, who was not involved in the research. “It makes you wonder how many other bodies we’ve inferred to be dry in the solar system are, in fact, dry.’’
People have long been fascinated by the possibility that water exists on other planets, because it is crucial for life as we know it. To planetary scientists, the presence of water provides important clues about how planets formed.
The son of a Brown scientist, Weinreich said in an interview that he was always interested in science and math, but that a chemistry class at Westwood High School captivated him. Now a 20-year-old junior majoring in chemical physics, Weinreich said it was exhilarating to play a role in such an important finding.
“It’s interesting to be doing something that has this air of excitement,’’ he said.
The idea that the moon was dry and has been for billions of years is part of the widely accepted theory of how it formed 4.5 billion years ago: A collision between the nascent Earth and an object about the size of Mars ejected molten debris that coalesced into the moon. Because of the heat generated in the collision, any lunar water would have evaporated, the thinking goes.
But about five years ago, Alberto Saal, an associate professor of geological sciences at Brown who until then had been studying the composition of the Earth’s interior, decided with collaborators to look for traces of water or other volatile chemicals in glass particles formed during the moon’s volcanic eruptions. He wrote an application to NASA requesting approval to study samples taken from the moon.
Colleagues laughed at his naivete, he recalls, and NASA twice rejected his request.
“They said, ‘We know there is no need,’ and that [made] me a little bit upset,’’ Saal said. He persisted and finally got NASA to change its mind.
It turned out he was right after all. From those samples, Saal and colleagues published a provocative 2008 paper in Nature that found traces of water still present in beadlike glass particles. Based on a model, they predicted there was much more water than that in the moon’s interior. The assertion set off debate in the scientific community, and “we got hammered’’ with criticism, Saal said.
When he met a particularly bright student in his freshman seminar on volcanoes, he asked him if he would like a research job that summer. That student, Weinreich, agreed, and Saal started him off sorting out samples taken on Earth and preparing them for analysis.
“I thought that would take the whole summer; one month later, he comes and it’s done,’’ Saal said. “I said, ‘No, it’s not possible.’ . . . He is working at a level I have not seen.’’
So Saal gave Weinreich a precious vial of lunar soil and asked him to pick out the orange particles.
“It was definitely a little bit nerve-racking, knowing that if I made a mistake there wasn’t really any way to get those things back,’’ Weinreich said.
But he began the task and used his growing expertise to set aside interesting anomalies, like a handful of crystals with black specks to show his adviser.
Saal was instantly excited. The crystals Weinreich found, called olivine, had formed a kind of armor around a drop of molten rock from the early life of the moon.
That meant that if there was water or other volatile material that had come from the moon’s interior, it could be found by analyzing the speck.
Weinreich carefully polished the samples, and they were sent to Erik Hauri, a staff scientist at the Carnegie Institution of Washington and an expert with a very precise instrument that could aim a narrow beam of charged atoms at a sample and then analyze the composition of what was removed.
Together with a collaborator at Case Western Reserve University, they found amounts of water equivalent to that found in parts of the Earth’s mantle, just as predicted.
Now, the scientists plan to analyze more samples from more spots on the moon. In recent years, satellites have discovered ice on the moon’s surface, and the scientists hope that it will be possible in the future to determine whether that ice was deposited there by comets, as has been thought, or whether it came from the moon itself.
Weinreich, meanwhile, is headed this summer to a laboratory at the Santa Fe Institute.
He is not sure what he will be working on, but he thinks he might dip his toe in a new field, biology.
Carolyn Y. Johnson can be reached at email@example.com.