Think back to the Apollo moon missions of the late ’60s and early ’70s and the images they conjure up. Human footprints in the lunar soil. Helmeted astronauts kicking up grey dust beside the lunar module. Spectacular “Earthrise” photographs, and 10,000 computer tapes.
10,000 old computer tapes? Yes. A little-known legacy of U.S. Apollo missions is the monstrous amount of data collected-a torrent of numbers so large that it simply could not be analyzed with the tools of the time.
Now, NASA-led researchers-using off-the-shelf Intel-based machines-have chewed through this trove of 40+ year old lunar data, and are making fresh discoveries about the Moon’s geology.
Most notably, in a paper recently published in Science magazine, Dr. Renee Weber and colleagues have analyzed lunar seismic data and discovered that the Moon has a red-hot and partially molten core. The very center of the Moon is an iron ball with a radius of 150 miles, which is surrounded by a liquid iron shell with a radius of about 205 miles. Think the Moon is cold? Think again.
The discoveries reported by Dr. Weber and her team have been made possible by advances in computing technology that were unimaginable at the time.
“It blows my mind that these data, and the computers originally used to analyze them, literally filled rooms,” Dr. Weber said.
She says that the seismometers the Apollo astronauts left on the Moon kept running for nearly eight years, radioing back 300,000,000 bits of moonquake data every day. Weber says the resulting 630 gigabytes of data-a modest amount today, but far too much to crunch with the mainframes of the day-sat on those 10,000 computer tapes for decades.
“Some of my favorite images of the Apollo program were of scientists hunched over looking at the seismic data-printed on reels of paper,” Weber says.
Using a data technique called “seismogram stacking” the NASA researchers were able to eliminate the “noise” from overlapping seismic data and create a dramatically clearer picture of the Moon’ s deep interior.
“All of my work is done on my standard-issue MacBook Pro, with a 2.66 GHz Intel Core processor which has 8 gigabytes of memory,” says Weber. For the Moon research she just reported in Science, she says she left her Intel-powered machine running overnight to chew through a typical set of moonquake data.
Crunching the old data has revealed some 7,000 moonquakes, more than five times more than Apollo-era scientists thought they had captured.
With its molten interior and quake-rattled surface, the Moon, it turns out, is much more like Earth than we’d ever known before.