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Jellyplants on Mars
NASA Science News
Scientists are creating a new breed of glowing plants --part mustard and
part jellyfish-- to help humans explore Mars.
June 1, 2001 -- The first colonists on Mars probably won't be humans.
More likely, they'll be plants. And the prototypes of these leafy
pioneers are under development right now.
As part of a proposed mission that could put plants on Mars as soon as
2007, University of Florida professor Rob Ferl is bioengineering tiny
mustard plants. He's not altering these plants so that they can adapt
more easily to Martian conditions. Instead, he's adding reporter genes:
part plant, part glowing jellyfish -- so that these diminutive explorers
can send messages back to Earth about how they are faring on another
The plants can be genetically wired to glow with a soft green aura when
they encounter problems. Within a garden grouping, some plants could
report (by glowing) low oxygen levels, while others might signal low
water or, say, the wrong mix of nutrients in the soil.
"Just like humans, plants must learn how to adapt to any new
environment," Ferl says. On Mars they would encounter extreme
temperatures, low air pressure, exposure to harsh ultraviolet light, and
generally inadequate soil. "We are using genetics to create plants that
can give us data we can use to help them survive."
Learning to grow plants on Mars will be an important precursor to humans
living there. Future explorers will need oxygen, food, and purified
water -- items too costly to ferry from Earth to Mars on a regular
basis. But plants can help provide those essentials inexpensively and
locally as part of a self-contained "bioregenerative" life support
Bioregenerative life support means humans, plants, and microbes working
together in a renewable system. Humans consume oxygen and produce carbon
dioxide. Plants take carbon dioxide and turn it back into breathable
air. Human waste (after processing by suitable microbes in bioreactor
tanks) can provide nutrients for growing plants, which will, in turn,
produce food for people.
Such life support systems on Mars will probably involve growing crop
plants in Martian soil within specially designed greenhouses, says
Andrew Schuerger, a manager of Mars projects with Dynamac Corporation at
the NASA's Kennedy Space Center.
Ferl, Schuerger, and Chris McKay of NASA's Ames Research Center want to
test the greenhouse concept by sending bioengineered plants to Mars on
board a small NASA spacecraft -- a "Mars Scout." They envision a seed-
bearing lander that would scoop up a portion of Martian soil, add
buffers and nutrients, then germinate the seeds to grow within a
Thriving plants won't glow at all. They'll look like normal mustard. But
plants struggling to survive will emit a soft green light, a signal to
researchers that something is amiss. A camera onboard the lander would
record the telltale glows and then relay the signal back to Earth. No
humans are required on the scene -- a big advantage for such a far away
The plants' designer genes consist of two parts: a sensor side to detect
stress and a reporter side to trigger the glow.
The sensor side of the gene comes from the plant itself -- Arabidopsis
thaliana, a member of the mustard family also known as thale cress. Ferl
and his colleagues picked Arabidopsis because three attributes suit it
well for a Mars mission: Its maximum height is about 6 inches, so it can
fit inside a small greenhouse, its life cycle is only six weeks, and its
entire genome has been mapped. (For these same reasons Arabidopsis
plants are already orbiting Earth on board the International Space
Station as part of an independent experiment to learn how plants react
to free fall.)
The reporter side of the gene comes from Aequorea victoria, a jellyfish
common along the Pacific coast of North America. Aequorea live about six
months, grow to 5 or 10 cm, and can glow soft-green along the rim of
their bell-shaped bodies. Scientists aren't sure why they glow --
Aequorea victoria do not flash at each other in the dark, nor do they
glow continuously. But the touch of a human hand, for example, can
stimulate the jellyfish to "light up."
Right above: An overhead flash reveals the outlines of Aequorea
victoria. The blue glow is reflected light, not bioluminescence. Credit:
C.E. Mills. Right below: True bioluminescence around at the rim of the
jellyfish. The light produced by Aequorea is actually bluish in color,
but in a living jellyfish it is emitted via a coupled molecule known as
GFP, or green fluorescent protein, which causes the emitted light to
appear green to us.
Once the sensor and the reporter gene fragments are stitched together,
Ferl uses a bacteria to move the newly-constructed gene into the plant.
Because plants are sessile -- that is, they can't get up and walk away
from stressful situations -- they can survive only by adapting to
whatever their environment offers. So, they've developed an exquisite
variety of sensing mechanisms to monitor their surroundings and trigger
appropriate responses to stressors. By adding phosphorescent reporters
to those sensors, Ferl says, "we can learn not just whether the plant is
surviving, but whether it's struggling to survive, and whether it's
surviving because it's mounting specific responses to the Mars
Ferl offers this example of an adaptive response to hard times: Here on
Earth when plants are flooded by water, they have access to less oxygen.
The plants respond by changing their metabolism to generate energy
anaerobically (without oxygen) -- a less efficient pathway, but one that
is available to them. On Mars plants might adopt the same response to
survive in the thin oxygen-poor atmosphere.
Water on Mars will also be very scarce, and plants will need to conserve
every bit. The leaves of all plants contain stomata, little holes that
let gas molecules in and out. Plants have the ability to open and close
stomata as conditions demand. "One can imagine plants [living on the
surface of Mars in the distant future] that might adapt by means of
fewer stomata in their leaves: that means fewer opportunities for water
vapor to leave, and maybe that would be a positive adaptation," says
The first wave of Martian plants envisioned by Ferl and his colleagues
would sprout inside a very small and protected greenhouse. We don't know
exactly how big it's going to be," says Schuerger, "but we're shooting
to fit a foot print of about 10 inches by 10 inches, and weighing about
15 to 20 pounds." The greenhouse, he expects, could hold as many as 20
to 30 plants. "We can grow a single plant," he says, "in one or two
grams of soil, in a tiny glass or steel or Teflon container."
The plants might also be exposed to Martian light, which could be piped
into the greenhouse (inside the lander) through fiber optics, and to a
moisture-added, oxygen-enhanced version of the Martian atmosphere. But
the project's primary goal is determining whether plants can thrive in
Martian soil -- an experiment best done on Mars itself!
As important as it is to know whether plants can actually grow on the
Red Planet, this project also has a philosophical purpose, says Chris
McKay, the principal investigator of the proposed Scout mission. "It
will be a symbolic step," he says, "of life from Earth, leaving Earth,
and growing somewhere else." And when this little plant grows on Mars,
he believes, it's going to be a major awakening of our interest in our
future in space.