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Feb.
6, 2009: If you saw a mushroom growing in your
bathroom, you'd probably bring out the heavy artillery.
– Mr. Clean, astride a Howitzer
Even
in space, someone has to clean the bathroom. Good housekeeping
is essential when you're living in the close quarters of a
tightly-sealed spaceship for months at a time. To make this
possible, NASA scientists have developed a tricorder-like
device called "LOCAD-PTS" that can track down microscopic
bacteria and fungi. It helps astronauts do their chores--no
Howitzer required.
"The crew of the space station works hard to keep things
clean," says Norm Wainwright, principal investigator
for LOCAD-PTS (Lab-On-A-Chip Application Development Portable
Test System) at the Marshall Space Flight Center. "Our
instrument tells them where to focus their efforts."
Above: The International Space Station. [more]
Strange,
but true: LOCAD works using enzymes from the immune system
of a horseshoe
crab. Astronauts swab a surface with a high-tech Q-tip,
insert a sample into the LOCAD device, and crab-chemistry
does the rest. In less than 15 minutes, the LOCAD test system
tells the crew if they've got some cleaning to do.
During
March to May 2007, astronaut Sunita "Suni" Williams
proved LOCAD's adeptness at detecting gram negative bacteria
in the space station's Node 1 and US Lab.
In
June and September 2008, a station crew tested a second type
of LOCAD cartridge, designed to detect fungi. First, they
tested Node 1 and found it virtually fungi-free.
That
sounds like great news, but it didn't help the LOCAD scientists
prove the abilities of the new cartridge.
So
just a couple of weeks ago, astronaut Sandy Magnus decided
to play hard ball. She thought of a place that would surely
be a fungi factory – the spot where crewmembers put their
feet to brace themselves while working on their laptops.
Wrong.
Clean.
A
determined fungi-finder, Magnus tried another location. She
went to the "gym," where station astronauts ride
a modified exercise bike and a treadmill to combat the muscle
weakening effects of microgravity. To keep themselves from
floating up off the bicycle seat while pedaling, the sweaty
space cyclers hold onto hand brackets.
You
guessed it -- fungi are thoroughly enamored with an oft-sweaty
surface. LOCAD ratted out some hand bracket fungi.
"The
fungi posed no immediate health concern to the crew,"
says Maule, LOCAD-PTS project scientist. "But Magnus
called to Houston to say, 'Tomorrow I'm going to give those
brackets a good cleaning.' That's just what we want -- the
intuitive reaction 'I need to clean that.'"
Above:
Astronaut Greg Chamitoff swabs for fungi on Aug. 20, 2008.
[Larger image]
In
years to come, spacecraft cleanliness will be a critical issue
for another reason: "One of the key scientific goals
for NASA's future Constellation missions beyond low Earth
orbit will be to prepare to search for life on Mars,"
says Maule.
All
humans carry stowaway microbes around with them on their skin,
microbes that shouldn't be allowed to contaminate Mars samples.
On the other hand, they don't want to bring unwanted alien
life forms back into the spacecraft.
"The
crew will need a way to monitor themselves before and after
EVA [extra-vehicular activity]," says Maule. "LOCAD
is ideal for that purpose. We've used it successfully during
EVA tests on the ground."
The
LOCAD team has also conducted several tests in the US Quest
airlock, the conduit from the interior cabin to the outside
of the space station where the crew "camps out"
overnight and depressurizes before venturing outside. LOCAD
proved the airlock to be pretty clean in general, but showed
that the handle to the airlock entrance harbored gram negative
bacteria. Bacteria on a surface like the airlock handle would
be a concern if crew members were about to embark on a sample
collecting excursion on Mars.
It
would seem that finding fungi onboard the ISS is just the
beginning for LOCAD. There are chores to be done ... and the
whole solar system awaits.
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Author: Dauna Coulter
| Editor: Dr.
Tony Phillips | Credit: Science@NASA
more
information |
LOCAD
Home Page
Space
Station Tricorder (Science@NASA)
Preventing
Sick Spaceships (Science@NASA)
Lab
on a Chip Works! (Science@NASA)
Crabs
Give Blood for Space Travel (Science@NASA)
LOCAD
Personnel:
- Mike
Effinger of NASA's Marshall Space Flight Center is
the LOCAD project manager.
- Norm
Wainwright, principal investigator for LOCAD-PTS,
is also director of research and development at Charles
River Laboratories in Charleston, SC.
- Jake
Maule is the principal investigator for LOCAD Exploration,
and LOCAD-PTS project scientist, based at British
Aerospace Systems.
Appendix
In
closed quarters like your home and the space station,
microorganisms can not only present a human health risk
-- they can even attack electronics, causing corrosion.
Fungi can soil air and water filters too. But LOCAD
finds fungi and germs before they have a chance to multiply
and do their dirty work.
Astronauts
gather samples for testing by swiping surfaces with
a small, dry swab. Then they flush sterile water through
the swab, converting the sample into liquid form, and
place a few drops into the LOCAD PTS. The system yields
its answer less than 15 minutes later, while standard
methods of culturing can take several days and may require
return to Earth for further analysis.
Oddly
enough, to sniff out trouble in a hurry, LOCAD enlists
the help of creatures whose ancestors were crawling
around in the ocean 300 million years ago -- horseshoe
crabs. No, there are no armor-clad hordes of horseshoe
crabs scuttling around under the astronauts' feet scarfing
up germs and fungi. But the hearty horseshoe crabs,
according to project scientist Jake Maule, do have a
"very primitive but extremely sensitive immune
system" that helps detect the presence of unwanted
microbes.
“We
use an enzyme cascade from that immune system. One part
of the horseshoe crab’s enzyme cascade is activated
by endotoxin -- a cell wall component of gram negative
bacteria. Another part of the horseshoe crab's enzyme
cascade is specifically activated by glucan, a cell
wall component of fungi."
(The
creatures are not harmed in any way and are released
after some of their blood is extracted for enzyme harvesting.)
More
information about horseshoe crabs: #1,
#2.
NASA's
Future: US
Space Exploration Policy |
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