Nakamura disagreed; he foresaw a day when future researchers could unlock new insights in the old data. So, in the early 1990s, he sought support from NASA to preserve the tapes he saved from Galveston. NASA, again citing a tight budget, turned him down, but the Japanese Aerospace Exploration Agency eventually gave Nakamura a grant to condense about 9,000 tapes into just 80 cassettes. These data, which include a full record of the passive seismic experiments as well as everything from the last 19 months of the project, remain the most complete record of raw ALSEP data in existence.
Without seeing the missing data, it’s impossible to say how valuable they might be. But the ALSEP data we do have offer some hints.
When lunar seismic data were first collected and analyzed in the 1970s, researchers like Nakamura interpreted them by eye, holding the jagged lines of seismograms over a light table. “During the mission, all we had was a big computer with 24 kilobytes of memory — a very small fraction of what you have on your cell phone,” Nakamura says.
Recently, he and other researchers have reanalyzed the data with great success. One of those researchers, Renee Weber, a lunar and planetary scientist at NASA’s Marshall Space Flight Center, detected hundreds of new moonquakes in the old data. She and her colleagues then studied how these quakes reverberated through the moon’s interior to probe its structure. In 2011, they published a paper in Science presenting a new look at the moon’s core.
Weber thinks more discoveries will follow as scientists bring increasingly sophisticated analytical techniques to bear on the ALSEP data. “It’s invaluable,” she says.
Because no one has returned to the moon since the Apollo program, many young researchers like Weber began to seek out data for the other ALSEP experiments, only to realize how much was missing. But nobody made a serious effort to figure out what happened, or find the tapes, until Nagihara stumbled onto the mystery while searching for Langseth’s raw heat-flow data.
Fueled by curiosity and concern, he and two dozen other scientists officially formed the ALSEP Data Recovery Focus Group in 2010. NASA gave the group, chaired by Nagihara, its blessing and provided funds to help the team hunt down and archive the lost tapes, as well as make the existing ALSEP data more accessible to today’s researchers.