Luca Parmitano, an astronaut from the European Space Agency, placed some of them in a speed-rotating centrifuge to simulate the gravity of Mars or Earth. Other samples were familiar with the free-floating environment of space. More control experiments were performed on the ground.
Within 21 days, the bacteria were killed and the samples returned to Earth for examination.
Two out of three bacterial species had disappointing results. S. desiccabilis has twice doubled the rare earth elements extracted from the basal, even in a zero gravity environment.
“We were shocked,” Dr. Cockell said, explaining that without gravity there is no convection that normally carries bacterial waste and renews food around cells.
“It can then be hypothesized that microgravity will stop microminating microbes or stress them so much that they will not be biominated,” he said. “Actually, we haven’t seen any impact.”
The results were even better for the lower gravity of Mars.
Payam Rasoulnia, a PhD student at the University of Finland in Tampere who studied the biomass of rare earth elements, described the results of the BioRock experiment as interesting, but noted that the yields are “very low even in ground experiments”.
Dr. Cockell said BioRock was not designed to optimize mining. “We’re really looking at the basic process that underlies biominization,” he said. “But it’s certainly not a demonstration of commercial mining.”