Sunday, December 5, 2021

How the shuttles’ DNA is preserved on the moon

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With NASA’s retired space shuttle program on the way out, how is its DNA preserved on the moon? Research out of Oxford has shed new light on this technological legacy.

Bacteria that thrive on asteroid debris for microbial support could be growing inside the space shuttle Atlantis. After a three-and-a-half-year mission, the space shuttle’s final landing was in Florida, not Florida. Before that, the shuttles launched from Cape Canaveral in Florida — where microbial spores survived, grew, and sustained their colonies for 17 months in the cold, dry, sunless environment of Cape Canaveral Air Force Station.

“You get conditions similar to living under conditions of just below absolute zero (-273.4 Celsius, -372.1 F),” said Mohamed Zakri, a molecular biologist at Oxford University who led a team of researchers that sequenced the DNA of thousands of plasmids from samples of the shuttle’s plasmids. “We could see them maintain their identity as they put in their own phosphate-containing molecules and mix them with bacteria from the plasmids,” Zakri said. (Plasmids are small communities of cells that join together to form whole organisms).

The researchers detected more than just DNA. They found a cellular response that is typical of life on Earth: a cellular message system known as a mitochondrial chimera. As some cells turn to phosphates to grow and multiply, others turn to sugars to help meet their metabolic needs. The signal system in the mitochondria splits the natural sugars into their derivatives, and then throws a wrench in that molecular process to redirect the synthetic mixtures into channels, compartments, and circuits of the cell.

This chimera response is a highly specific response: Whereas the genetic map of bacteria on Earth is essentially an uncodified script, the genetic map of the shuttles’ live bacteria grew like a book that the cell’s DNA could reinterpret and rewrite, “as you might as well imagine a rule book that could reinvent the wheel,” Zakri said. In this twist of genetic self-correcting, the study showed, not one of the more than 300 microbial genes is “fixed” in one specific place in the shuttle’s engineered bacteria. In other words, the shuttles’ microbiomes are remarkably flexible and uncertain, and they display multiple sets of complex interactions among living cells, or aplasia, as Zakri puts it. The fact that the shuttle’s plasmids match those of microbial critters on Earth is thus kind of nice, because these bacteria could interact, and perhaps improve, these latter two systems, on our behalf.

But, having pieced together the shuttle’s microbial DNA, Zakri now has something else to add: All those molecules his team found inside the shuttles could also potentially hold the DNA of biological spacecraft that the space shuttle carried to orbit. “What you are now effectively seeing is the DNA of spacecraft on a voyage around the sun. It’s very exciting to think about what the future may be for space flight — what will the astronauts grow on the spacecraft, could they help maintain the image of space through growing them onboard,” Zakri said.

Other Planetary Risks

Human contact with other planets is one of the biggest reasons we have a mission to the moon in the first place. But with NASA’s mission out of the picture, and with missions like the Orion spacecraft — essentially a space capsule that can carry astronauts to the International Space Station and back — and the Space Launch System rocket, making regular Mars trips a possibility, humanity is headed in a new direction. Scientists are always being asked: Have we tested ourselves?

But Stephen Willey, a biogeochemist at the University of California at Irvine who was not involved in the study, said the team of researchers behind this study offer a valuable perspective on a very different era. “This showed for the first time that the shuttle’s own molecular products is being preserved by the shuttle’s own plasmids. This study highlights how important the shuttle really was to the biogeochemical program that allowed us to do the so-called space-time protoplanetary assembly with the likes of Voyager 1,” Willey said.

Willey said he was surprised to find that the shuttle has continued to support itself long after the mission ended, and that it is ready to support itself to new destinations now. “This is really a credit to all the hard work by the myriad men and women who worked to keep the shuttles going. It is a testament to their dedication, their humanity, and their ability to see these important projects through to the end,” he said.

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