Helen Vaughn Michel
Helen Vaughn Michel. Courtesy Ernest Orlando Lawrence Berkeley National Laboratory.
Helen Vaughn Michel (b. 1932) pioneered the use of high-tech chemical instruments for studying archaeological artifacts. With her powerful tools, she pinpointed the geographic origin of the clay in ancient pottery—a clue to who made it and to the history of ancient trade and communication. Michel was also on the research team that uncovered what caused the mass extinction of the dinosaurs 65 million years ago. She detected chemical traces of the massive asteroid collision that sealed the dinosaurs’ fate.
Michel was born in Phoenix, Arizona, where her father was a state legislator. When she was in the sixth grade, her parents bought her a chemistry set for a dollar. She loved the smells she could create with it. A few years later the family moved to Berkeley, California, where she got even more interested in chemistry after seeing one of her teachers give a chemistry demonstration that went awry, ending in an explosion. That bang convinced her that chemistry was the life for her. She was further encouraged by her high school chemistry teacher and went on to study chemistry at the University of California at Berkeley.
While in college, she took a part-time job at the UC Berkeley Radiation Laboratory as an assistant in nuclear chemistry and, upon her graduation, accepted a higher-ranking, full-time position at the lab. There she met and married Maynard Michel, also a nuclear chemist. Except for a year of graduate study at Indiana University in 1955–1956, she spent her whole career working at the lab, now known as the Lawrence Berkeley National Laboratory.
For many years Michel did typical work in nuclear chemistry, investigating how protons and neutrons are put together inside the nuclei of atoms and what happens inside the nuclei during radioactive decay. In the late 1960s, however, she began using nuclear chemistry to tell the age of archaeological artifacts, an emerging field at the time. She made headlines in 1977 when she was asked to analyze a brass plate found in San Francisco in 1936. The plate had an inscription stating that it had been left by 16th-century explorer Sir Francis Drake and claiming the California coast for Queen Elizabeth I. Michel was able to show that the plate was made in the late 1800s or early 1900s—a fake.
Michel was also involved in one of the biggest science news stories of our time, the hypothesis put forth in 1980 that a giant asteroid hit the earth 65 million years ago, explaining the extinction of the dinosaurs. Scientists hypothesized that the impact of the asteroid sent so much dust and debris from the earth’s surface and the shattered asteroid into the atmosphere that the earth was shrouded in darkness for an extended period. Extreme cold and lack of sunlight killed off almost all vegetation and led ultimately to starvation among all species, including the dinosaurs. The hypothesis was based on the discovery of a 65-million-year-old layer of rock found in Italy. The layer was rich in the element iridium, rare on earth but common in asteroids. If the hypothesis were true, and the dust eventually settled over the earth’s surface, then 65-million-year-old iridium layers would exist around the world, and all they would have the same chemical composition, having come from the same asteroid. Michel was part of the team that helped show that both of these predictions were true.
The chief analytical technique used in this research was neutron activation analysis (NAA). In NAA samples are bombarded by neutrons, causing the elements present to form radioactive isotopes. Since the radioactive emissions and radioactive decay paths for the isotopes of each element were by then well known, the emission spectra of the radioactive samples were used to determine the identity and concentrations of the elements in the various samples.
Now in retirement, Michel and her husband devote their time to growing and breeding orchids.