Outer space is known to be
unfriendly to biology, but it has been hard to determine just how long it takes
for life and life-related compounds to be negatively affected. A new research
project plans to monitor samples of organic compounds and living organisms as
they orbit the Earth in a small satellite.
The hope is that this will give
astrobiology researchers vital data about chemical evolution in the early
cosmos, and about the survival of life
that may be transported between the planets.
Above the protection of our planet's
atmosphere and magnetic field, a myriad of particles and high-energy rays await
the intrepid space traveler. This
onslaught includes heavy ions, protons, electrons, gamma rays, X-rays and
UV light. Life in this region of space also must cope with the effects of a
lower-gravity environment.
"In the lab, researchers can
duplicate certain aspects of this, but the combined radiation environment in
space is very complex," says Tony Ricco from NASA's Ames Research
Center.
The Organism/ORganics Exposure to
Orbital Stresses (O/OREOS) nano-satellite will test how life and the components
of life respond to this complexity. Ricco is a member of an engineering team in
the NASA/Ames Small Satellite Division that is building the satellite. O/OREOS
will carry selected organisms and organic compounds up into space and directly
monitor the changes induced by the radiation and microgravity of the final
frontier.
Because of its simple, inexpensive
design, O/OREOS may be just a taste of what's to come.
Astrobiology in Real Time
Space-based biology experiments
similar to O/OREOS have been performed before. Samples either have been flown
in a return capsule, such as the BIOPAN experiments, or placed outside the
International Space Station on platforms, such as with the EXPOSE facility. In
these experiments, the samples are brought back to Earth to be analyzed after
their exposure in space. In contrast, O/OREOS samples will
"The only thing that comes down
in our case is data," says David Squires, the mission's project manager.
Over the course of the 6-month
mission, onboard instruments will check whether chemical changes are uniform in
time or perhaps correlated with other phenomena such as solar activity.
O/OREOS is similar in design to
other nano-satellites that have flown, including GeneSat, which tracked the
reaction of bacteria to microgravity, and PharmaSat, which is poised
to launch on May 7 and will track how yeast behaves in space. The cargo on
those experiments weren't exposed to the full array of space conditions,
however, like in the O/OREOS experiment.
The 5-kilogram O/OREOS has a modular
design made up of three 10-centimeter cubes. One of these cubes acts as the
"brains" (radio and telemetry), while two other cubes carry the
scientific payload.
Microbes in Space
The first cube will carry
experiments to study how two types of microbes cope with the space
environment. One microbe is a common, fast-growing bacteria, Bacillus
subtilis, which holds the record for surviving in space for the longest
duration (6 years on a NASA satellite). The other is a slow-growing microbe, Halorubrum
chaoviatoris, which thrives in the sort of briny
water that may exist below the surface of Mars or on Jupiter's moon Europa.
Both of these "bugs" have
been studied before in space, so the team has a rough idea of what to expect,
says project scientist Pascale Ehrenfreund, who currently works from the Space
Policy Institute at George Washington University.
The bacteria will be launched as
dried spores and revived at different times during the mission with a
nutrient-filled fluid.
O/OREOS will be in a low-Earth orbit
(at an altitude of 650 kilometers) where its samples will experience 1/10,000th
the gravity on Earth. This could affect how microbes get food and how their
waste is carried away, says Wayne Nicholson, a science team member from the
Kennedy Space Center and the University of Florida.
The radiation dose will be around 30
rads per day (which is roughly 30,000 times more than on a single
intercontinental airplane flight). The growth rate and metabolism of the
bacteria will be tracked by measuring the color of a metabolic indicator dye
and via total light absorption.
To test if the bacteria are capable
of adapting to life in space, mutant varieties of the two species will also be
flown on O/OREOS, according to science team member Rocco Mancinelli of NASA
Ames.
Cassie Conley, NASA's Planetary
Protection Officer and the program scientist for the O/OREOS project, explains
that learning about the evolutionary potential of microbes in space is
important, because it could help us avoid contaminating other worlds with our
biology.
Molecules in Space
The second cube will carry an
experiment designed to measure space effects on four biologically important
compounds. The list of molecular passengers includes an amino acid (a building
block of proteins) and a polycyclic
aromatic hydrocarbon (the most abundant organic species in space).
The compounds will be placed in four
different micro-environments that will simulate conditions in interplanetary
space, on the Moon, on Mars and in the outer solar system. Each sub-sample will
be monitored through measurements of the UV and visible light that they absorb.
"The really cool thing is we
measure every day, so we can for the first time give quantitative information about
the day-by-day degradation of organic compounds," says science team member
Richard Quinn of NASA Ames.
The survival rate of these molecules
will help determine whether some of Earth's biochemistry might have been
performed in space and later delivered by meteorites. Another science team
member from NASA Ames, Andy Mattioda, says the data may also help in deciding
which molecules are good biomarkers that can signal the existence of past or
present life on another world.
Piggybacking
Launch of the nano-satellite is
planned for February 2010 from Kodiak Island, Alaska. O/OREOS is small and
light, so it will be able to piggyback on another spacecraft's launch vehicle.
This makes it a bargain, at a cost of just $2 million.
"We can do lots more of these,"
says John Hines, who helped lead the engineering team.
And there may be a lot more of these
nano-satellites on the way. In 2008, NASA's Astrobiology Science and Technology
Instrument Development program established a small payloads initiative, which
seeks quick-turnaround science experiments that can fit on nano-satellites or
as external attachments to larger space vehicles. The program selected O/OREOS
as the first demonstration flight.
NASA also wants to develop similar
satellites through its Stand-Alone Mission of Opportunity Notice.
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