From 1969 to 1974, Dr. Brett was chief of the geochemistry branch at NASA's Lyndon B. Johnson Space Center in Houston. In July 1969, he was among a select four scientists present for the opening of a sealed box containing the first moon rocks from the initial Apollo lunar mission.
The moon rocks were eagerly awaited as clues to help unravel the mysteries of the universe, and they drew wide interest from a public steeped in song, legend and myth about the moon — the dominant object in Earth’s nighttime sky.
“By learning about the moon, we learn much more about the Earth at present, by putting its past in context,” Dr. Brett said at a 2005 ceremony where he received the Mineralogical Society of America’s medal of distinguished public service.
But, he added, “We still have not answered many questions about the moon.”
Among those unanswered questions remained one of astronomy’s most basic and frequently asked: How did the moon come into existence?
He was among those who wanted to know whether the moon rocks could provide an answer. Not entirely, it turned out, but they may have helped.
Three theories on the origin of the moon had been debated before that first lunar mission, New York Times reporter John Noble Wilford wrote in his book “We Reach the Moon,” published shortly after the first lunar landing.
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“The first theory held that the moon was torn from the earth by a fission process,” Wilford wrote. “The second was that the moon was formed at the same time as the earth as a sort of twin planet. The third was that the moon was unrelated to the earth and was captured by earth’s gravity.”
Wilford quoted Dr. Brett: “All three theories have weaknesses. The composition of the returned lunar samples makes it difficult to derive them from anything like the composition of the earth’s mantle. This, therefore, makes the fission theory extremely unlikely. And if the moon was formed as an identical twin planet with the same composition as the earth’s mantle, the same argument applies against that theory. The capture theory presents difficulties in celestial mechanics and is regarded as statistically fairly improbable.”
So, concluded Dr. Brett, “It seems much easier to explain the nonexistence of the moon than its existence.”
Since the end of the Apollo lunar missions, the studies of moon rocks have continued in laboratories around the world.
The prevailing theory now on the moon’s origin, said Everett Gibson, an emeritus NASA scientist who worked on the lunar samples, is that it was formed from a major impact on Earth, early in its existence, of another large astronomical object.
Peter Robin Brett was born in Adelaide, Australia, on Jan. 30, 1935. His father was a manager at a wool company. He graduated from the University of Adelaide with a degree in geology in 1956 and received a doctorate in geology and geochemistry at Harvard University in 1963.
He came to Washington in the mid-1960s as a scientist with the U.S. Geological Survey. He returned to USGS after leaving NASA in 1974. Later he studied undersea sulfur hot springs for the National Science Foundation and the biological extinction of the dinosaurs following the crash of a meteor into Mexico’s Yucatán Peninsula 65 million years ago.
For five years before he retired from federal service in 2003, Dr. Brett was a part-time administrative judge for geology-related cases before the Nuclear Regulatory Commission.
His first marriage, to Abigail Trafford, a former health editor for The Washington Post, ended in divorce. Survivors include his wife of 33 years, Jill Davidson Brett of Washington; two daughters from his first marriage, Abigail Miller of Portland, Maine, and Victoria Brett of Northampton, Mass.; two stepsons, Timothy Merrill of Los Angeles and William Merrill of Madison, Wis.; a sister; and four grandchildren.
When the lunar samples were first brought to Earth, they were kept for a period in a quarantined and sterile environment, lest they contain or exude a noxious substance that might be harmful in Earth’s atmosphere.
Dr. Brett doubted the necessity of this precaution, which he demonstrated, he said, by becoming the first man on earth to lick a moon rock.
What did it taste like?
“A dirty potato,” he answered.
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