"I'd like to introduce to you today to the bacterium GFAJ-1."
A team of NASA-funded researchers has discovered a bacterium that can live and
grow without phosphate salt, an essential building block for life as we know it.
The bacterium, from the toxic and briny Mono Lake in California, was also shown
to sustain itself and grow on the toxic chemical, arsenic. This is the first
microorganism known to thrive this way and will change how scientists search for
life in space.
"I’ve led a team that has discovered a microbe that can substitute arsenic for
phosphorus in its major biomolecules, but let me step back for a minute. All
life that we know of requires carbon, hydrogen, nitrogen, oxygen, phosphorus and
sulfur and it uses those six elements in some of the critical pieces I think
we’re all familiar with including: DNA and RNA or the information technology of
the cell, the proteins which are the molecular machines and the lipids which
separates you from everything else. And so, we‘ve discovered an organism which
can substitute one element for another in these major biomolecules."
"With respect to space exploration, this is a very interesting result again
because the implication is that we still don’t know everything there is to know
about what would make a habitable environment on another planet, or a satellite
of another planet; we have to increasingly broaden our perspective. So, perhaps
arsenic is not an essential component for habitability or for life, but it may
be one that can be tolerated."
Until now, astronomers and scientists have believed that, without phosphates,
life couldn’t exist anywhere else in the universe. Discovery of this
arsenic-eating bacterium tells scientists they need to re-examine how and where
"There is really no way we can get there before the December launch window, so
what we’d like to do now is take that off the table and let John and his team do
a little bit of planning over the next several days, first part of next week,
and analyze the overall plan and the workflow between now, as we go forward, so
we’re setting the next launch date tentative around Feb. 3. "
After reviewing the progress of repairs that have delayed Discovery's launch,
program managers are now targeting the shuttle’s liftoff for no earlier than
Feb.3. Shuttle managers determined that more tests and analyses are needed
before proceeding with the STS-133 mission to the International Space Station.
"We’ve hit a point where there is no obvious answer as to what occurred. What
that means is that we have to take the next step. And, we have to look in
greater detail, to understand what types of stresses you can put on these
stringers during the assembly process, see how they could line up, and add
stress to that stringer. And, we have to do that through a demonstration;
analysis is not going to get us there."
At issue: cracks on two 21-foot-long, U-shaped aluminum brackets, called
stringers, on the shuttle's external tank. The cracks have been fixed and the
stringers re-covered with foam.
If Discovery proves ready to go on Feb. 3, liftoff from the Kennedy Space Center
would come at 1:34 a.