It's human nature to clean for company more thoroughly than one would for oneself, but nowhere is this truth taken to greater extremes than at the Johnson Space Center. NASA's setting new standards of cleanliness in its labs that handle samples returning from space. And their efforts are laying the groundwork for samples that might some day contain evidence of extraterrestrial life from Mars, Europa, and other points little known.
Welcome to the Advanced Curation Laboratory, where the guests could entirely change our view of the Solar System. And please, check your plastics at the door.
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| TECH WEDNESDAY | |
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| The first array of collectors for Genesis is assembled in Class 10 cleanroom.
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| Collectors from the Genesis spacecraft returned to Earth in 2003 will be removed from the spacecraft and archived, or distributed for analysis by the scientific community, under extremely clean conditions.
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|  | TODAY'S DISCUSSION | | |
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Where we stop straightening up at Lysol and a Dustbuster, the Advanced Curation Team (ACT) start with oxygen plasma and radiation bombardment. The guest room in this new twist on Southern hospitality includes a pressurized "glovebox" containing a robotic arm, and the whole lab's water and nitrogen "air" are ultrapure.
Before a mission leaves Earth, NASA scrubs its landing probes down to make sure they don't bring microbes from here to new worlds or back. But they must clean carefully to make sure equipment surfaces aren't marred so that they provide microscopic nooks and abrasions in which contaminants might stow away. That's not an easy task according to Judith Allton, a Principal Scientist employed by Lockheed Martin Space Operations, a contractor to NASA at the Johnson Space Center.
"The sterilants react with aluminum surfaces, causing pitting which makes it difficult to clean off microbes and traces of dead microbes," she said.
Even the Galileo Space Probe, which was never sterilized because it wasn't intended to be a lander, is set for a death spiral into Jupiter lest it accidentally crash into Europa or one of the planet's other moons one day. And the Office of Planetary Protection strives to make sure extraterrestrial microbes don't run loose on Earth -- even though some argue that our planet is dusted with new DNA from deep space regularly. But the Advanced Curation Laboratory faces the unusual challenge of meeting those two goals simultaneously -- not just to safeguard terrestrial and alien health, but also to ensure scientific accuracy.
"We're trying to keep clean so that trace materials can be detected and sampled without messing up someone's future experiments," explains curator Allton, who started working with Moon rocks in 1974. Trace materials, in her book, don't include just the obvious problems like flecks of skin and airborne bacteria, but also seemingly benign plastics that are part of even the most sterile Intel microchip facility or Pfizer pharmaceutical laboratory. That's not because alien life might eat through plastics, as exotic creatures do on Earth (and which proved to be a dramatic plot point in the "Andromeda Strain.")
The reason for her plastic phobia is more mundane, but a striking example of how careful ACT and other Astromaterial divisions must be: polymers in most synthetics come from refining crude oil, which is itself dead dinosaur and plant material. Such complex and volatile molecules can give a false reading of evidence for life.
"The chip factories are very clean, but not contained in the biohazard sense. The pharmaceutical industry is a leader in containment sample handling and sterility, but they use a lot of plastics. The best of both these industries needs to be adapted for extraterrestrial sample handling," Allton says.
The demands of NASA's missions can push Allton and her colleagues to what might appear to be excesses. The
Clean Team, of which Allton is also a member, recently tore out its floor because tests indicated that a few stray organic molecules were rising from it. The painted metal panels topped with high-pressure laminate tiles, which Allton says "looked like Formica," are currently being replaced with "all-metal floor panels (electroless nickel plated onto aluminum) using no adhesives in the installation process," explains Allton. Upgrades to the Genesis room are due for completion this year, and Allton expects the new arrangement will eliminate worries of airborne molecular organics from the floors.
"All plastics and pliable sealants outgas," or shed parts of themselves into the air, she notes. "But some are worse than others."
Some of the very tools of the clean room trade, like absorbing materials and many particulate filters, outgas organic molecules or shed particles. "Right now this is a chicken and egg problem," Allton says.
Even seals can present problems. They often require elastomers – stretchable polymers – which outgas organic molecules. Without an elastomer, you have to keep seal surfaces exceptionally clean, but that's difficult in a dusty planetary environment, and Earth's neighbors are often layered with dust. There were even fears that the Apollo spacecraft would sink into a lunar face composed of something like talcum power, and just last year Mars swallowed itself in obscuring dust storms.
The Genesis mission is set to bring its cargo of solar wind samples back in 2004. But why would a solar wind sampler have to worry about organic contamination? Images of
come to mind – spores floating in the interplanetary medium, hanging on even a million miles from Earth, where the planet's magnetic field no longer provides an umbrella to protect against radiation. But even the most ardent believers in panspermia expect any such endurance to rely upon sheltering in rocks, and if by some slim chance the probe crossed paths with a rock, Genesis would face a personal Armageddon. Its delicate sensors would simply be broken. The real danger back on Earth is that organic compounds could mask the mission's quarry – elements and atomic isotopes freshly released by the sun, including building block elements of life like carbon and oxygen.
Water too is treated with suspicion in the curatorial labs at the Johnson Space Center. "It has to be pure to hundred of parts per trillion," Allton says. "We have to tap it off of a flowing line. I couldn't put some in a bottle and send it to you because the water would eventually react with the container." The lab's water is bombarded with ultraviolet light to kill bacteria and blast them to particles, and ion exchangers chemically pull out some impurities while .04 micron pleated filters remove the rest.
In future lab designs, air purity in the event of an accident will be maintained by enveloping pressure fields around each other. Pressure drops steadily as one moves from the outer chamber towards the second to innermost chamber, with the next to last chamber at neutral pressure. The innermost container, however, is filled with nitrogen at higher pressure again. This way an outer hull breach would cause chemical contaminants to fly away from the sample, and pressure differences would ensure that an inner chamber failure will be mitigated by channeling possible biological contaminants through a special filtering system.
Next Page: Cleaner Scientists
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