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ONERcalled enzymes help reactions happen
fast enough to be useful. The team doesn’t
have alternative enzymes to go with its
membranes and genetic material, though.
“We have backbones we’re making,
and we’re going to have base pairs, but
the problem is we don’t have an enzyme
that will replicate it because the backbone
chemistry is not the same,” says Williams.
“We really have to start at a more basic
chemical level and try to work forward
as far as we can.”
LOOKING FOR ALIEN LIFE
“A lot of this is going to be exploratory
science,” says Butch. “I think it’s a really
cool idea for just pushing the boundaries
of what our assumptions about the transi-
tion from chemistry to biology actually
looks like.” In other words, no synthetic
alien organism is going to crawl out of the
test tube.
“I don’t think that we’re going to dis-
cover the origin of life in the next three
years or that we’re going to figure out
exactly how life could develop [on other
worlds] in nonpolar solvents in the next
three years,” says Bracher. “What this proj-
ect is really about is starting to figure out
how the rules of the game might change
from life as we know it in water to some
new form of life that works in oil and non-
polar solvents, whether here on Earth or
on distant planets.”
What that will tell us, Bracher and his
colleagues hope, is whether the precursors
of biochemistry might be able to take shape
in an ocean made of something other than
water. If the answer is yes, then that means
our current search for life has a huge
blind spot.
“Our problem with looking for life is
that we are looking for our life, largely.
‘Follow the water’ might find some life,
but it might not find other kinds of life,”
says Williams. By demonstrating that at
least basic biochemistry can arise in other
liquids, the team may help open new habit-
able zones, or at least keep some interesting
places from being ruled out.
The results could provide useful ideas
about not only where, but how to look
for life as we don’t know it. For instance,
Earth’s atmosphere
is rich in oxygen
because plants
and cyanobacte-
ria release it as a
product of pho-
tosynthesis. If
Bracher and his
team can identify
potential molecular
building blocks for alien
cells, they might also be able to predict
which chemicals those cells breathe out
into the atmosphere of their home world.
In 2005, astrobiologist Chris McKay
worked out how organisms on Titan might
metabolize acetylene or ethane, and real-
ized that they’d leave a noticeable signature
in Titan’s atmosphere — which, it turns
out, may actually be present, though the
evidence isn’t yet clear. The Cassini and
Huygens probes observed both the lack
of an ethane layer around the moon and
a lack of acetylene on its surface, though
both were expected. The depletion of these
substances could be due to a “biological
sink” — life consuming them and leading
to their absence.
This kind of research can guide how we
comb through the reams of data already
in hand from missions like Cassini, says
Lunine. “No one’s really looked through
the data very carefully for them, so one can
go back now, seeing that they have these
interesting properties, and really try to dig
through the data to see if it’s actually there,”
he says.
Ultimately, tinkering with alien bio-
chemistry is a step into the unknown, and
although the team has some ideas about
what to expect, they’re also prepared for
surprises along the way.
“My expectation is that a lot of things
that we think are challenges to life will turn
out to not be, and things we don’t realize
are difficulties will all of a sudden [turn out
to] be incredibly hard,” says Travisano. “It
will be interesting what doesn’t work and
what does. Expect surprises.”^ D
Kiona N. Smith is a science and technology
journalist, science history blogger, and science
correspondent for Ars Technica.
While Titan is a major focus of the search
for life in the solar system, there are other
icy worlds where life might thrive: Europa,
Iapetus, Enceladus, and Triton are among
the candidates that could host life.
TRITON
EUROPA
IAPETUS
ENCELADUS
OUT THERE