[meteorite-list] Living Interplanetary Flight Experiment

From: JoshuaTreeMuseum <joshuatreemuseum_at_meteoritecentral.com>
Date: Wed, 1 Jun 2011 23:26:45 -0400
Message-ID: <72407547B72E4781A0A03D6BEF841A28_at_ET>

Living Interplanetary Spaceflight Experiment--or Why Were All the Strange
Creatures on the Shuttle Endeavour?
By David Warmflash | Jun 1, 2011 07:55 AM | 1

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This morning, the world witnessed the safe landing of the space shuttle
Endeavour, after a 16-day mission to the International Space Station. For
those of us inhabiting Earth's more western time zones, we got to watch the
landing last night, with no inconvenience, other than having to divert from
the Colbert Report. While I did not travel to the Kennedy Space Center for
the landing and recovery of the Planetary Society's experiment known as
Shuttle LIFE, my experience was infinitely better than it was the last time
that I had an experiment on a shuttle, when I did go to the Cape to attend
the landing.

This is because the last time for me was on February 1, 2003. I was waiting
for the return of the Columbia, with friends and colleagues, Eran Schenker
and Yael Barr, alongside the very runway where the Endeavour glided to a
touch down this morning. Having developed the Planetary Society's "GOBBSS"
experiment -which came to be known as the "Peace Experiment", since we had
recruited two students, one Israeli, the other Palestinian, to work together
as co-investigators- I anticipated the post-flight analysis of the
biological cultures from GOBBSS, and from two other experiments that Eran
had developed dealing with probiotic microbes. But there was no sonic boom,
no sign of the Columbia. The time to landing clock went into positive time,
and we were directed to return to the bus that would take us back to the
building where we had gathered earlier. Then we learned of the tragic fate
of the seven people who had made up the Columbia's crew, and we no longer
cared about the experiments.

Like the Columbia mission, STS-107, this flight of the Endeavour, STS-134,
was conceived as a mission of science. Shuttle-LIFE is only a tiny part of
the Endeavour science payload; compared to cool-sounding devices like the
alpha magnetic spectrometer, designed to detect anti-matter throughout the
Cosmos, a few 10 microliter test tubes containing microorganisms must sound
positively mundane. Why then did we book passage for our little bugs on the
penultimate flight of NASA's STS program?

To begin, the Planetary Society and all research groups who had flown
experiments packaged by Instrumentation Technology Associates (ITA) for the
STS-107 flight were offered a chance to fly new experiments on STS-134. The
Shuttle-LIFE organisms flew inside an experiment module called CREST-1. LIFE
stands for "Living Interplanetary Flight Experiment". This may sound
strange, since the Endeavour, like all space shuttles, does not fly
interplanetary missions. But Shuttle-LIFE is a precursor to another
experiment -Phobos-LIFE. Conceived and developed earlier, Phobos-LIFE awaits
launch at the end of this year to Phobos, one of the two tiny moons of Mars.
The other is Deimos, Phobos' twin brother in Greek mythology; both were
children of Aphrodite by Aries, the war god, but Mars was his Roman name.
When naming planets, we like using Greek gods by their Roman names, even in
science fiction. That's why Spock's home is called Vulcan, and not
Hephaestus.

Scheduled to be launched by the Russian Federal Space Agency (Roscosmos), a
probe called "Grunt" will depart after the next launch window opens this
December. It will be an unprecedented, 34-month voyage to Phobos and back to
Earth. Sitting inside the probe is an 83-gram discoid canister, the LIFE
biomodule. Like three identical biomodules that were loaded as experimental
controls, the one in the Grunt probe contains 30 sample tubes housing ten
biological species, most of them in triplicate, representing all three of
Earth's domains of life: Archaea, Bacteria, and Eukarya. Additionally, there
is a sample of soil from the Negev desert in Israel whose mixed population
of microorganisms will be studied by Russian microbiologists.

The purpose of Phobos-LIFE is to examine the effects of the space
environment, particularly the radiation, on organisms traveling through
interplanetary space for nearly three years. While many such experiments
have been flown in low Earth orbit, very few have flown through
interplanetary space. Those that have flown in interplanetary space have
done so for relatively short periods.

Most of the meteoroids created from cometary impacts with the Martian crust
that arrive on Earth as "Mars meteorites" take thousands or millions of
years to make the voyage. A famous example is ALH84001, a Mars meteorite
containing features that some scientists believe are fossils of ancient
Martian microorganisms that were trapped inside the rock more than 3.5
billion years ago. A small piece of Martian crust that was ejected into
space by an impact event about 16 million years ago, ALH84001 arrived on
Earth, in Antarctica, only about 13,000 years ago. Between being ejected
from Mars and landing in Antarctica, the rock was just floating about in
space as a meteoroid. This is fairly typical of the forty or so meteorites
that have been found and identified as being from Mars, but these represent
only a tiny fraction of rocks and other Martian material that have traveled
to Earth. Each year, about a ton of material ejected from Mars arrives on
our planet. Most of it has taken a very long time to get here, but a small
fraction of it, about one out of every ten million Mars rocks, has made the
trip in only a year or so.

If any of such fast-transiting rocks carried microbes from Mars during the
Solar System's early years, it is plausible that they may have made it to
Earth, before Earth had a chance to develop its own life. Since Mars is
known to have cooled down earlier than Earth, it is not unreasonable to
think that abiogenesis, the origin of life from non-living matter, could
have occurred first on Mars, allowing Martian microbes to seed Earth, before
Earth had a chance to develop its own life. In a sense, we might be
Martians, or at least descendents of Martian immigrants.

Roughly the size of a basketball, the Grunt probe will serve as an
artificial meteoroid of sorts, simulating -as best we can at this point- a
34-month voyage of microorganisms through interplanetary space. It is a
model of the fast voyage scenario that occurs in that tiny fraction of
ejected Martian material, but if seeding from Mars occurred this tiny
fraction is the key.

It is important that the environment be interplanetary space, since a large
component of the most high energy space radiation is blocked by the
geomagnetosphere, thus protecting samples carried in spacecraft in low
orbits, such as those flown by space shuttles and the international space
station. If organisms from Earth can survive 34 months inside the artificial
meteoroid, it is plausible that other organisms, including organisms that
could have been living on Mars four billion years ago, could survive the
trip too. We know that various microbes can survive the impact effects of a
comet, a small asteroid, or a large meteorite, hitting the Martian crust and
ejecting rocks into space. We also know that organisms a few centimeters
inside a meteoroid would survive entry through Earth's atmosphere.
Therefore, survival of organisms in our artificial meteoroid would make more
plausible the possibility that Earth's biosphere could have developed from a
seeding event.

As the year goes on, you will hear more about Phobos-LIFE, with its ten
species, envoys from Earth's biosphere. Mostly as practice for Phobos-LIFE,
we've included five of the species in Shuttle-LIFE. So let's talk about why
they're on the passenger list for Phobos LIFE in the first place.

Even in the downscaled version of the experiment that we've sent on the
Endeavour flight, all three of Earth's domains of life are represented. From
the bacterial domain, there are two species. One is called Bacillus
subtilis. It is a gold standard organism, both for space flight studies and
for many studies on Earth. Like many types of bacteria, B. subtilis form
spores when placed in an unfavorable environment in which the cells are
dried out and denied nutrients. This ability helps the bacteria to survive
for long periods, and also makes them quite resistant to radiation. B.
subtilis has a long history of space biology missions, beginning in the days
of Apollo, the space program, not the god of music and light. As one of the
organisms flown in early experiments called Biostack 1 and Biostack 2, B.
subtilis even has flown outside of the geomagnetosphere, in the Apollo 16
and Apollo 17 command modules. It also was exposed directly to the space
environment for six years, though in low Earth orbit

The other bacterial species that flew in Shuttle LIFE is Deinococcus
radiodurans. Unlike B. subtilis, D. radiodurans does not form spores, yet it
is even more resistant to radiation. It is able to survive an acute
radiation dose of 5,000 Grays (Gy). This is amazing, since an exposure of 10
Gy would kill the average human. This resistance to radiation, along with an
unusual resistance to desiccation and starvation, is due to various genetic
redundancies. Basically, you could chop up this organism's DNA with
radiation bursts, and it still works just fine, leading some to call D.
radiodurans by a nickname, Conan the Bacterium.

If B. subtilis and D. radiodurans are capable of tolerating radiation
exposures well above what is encountered during a voyage in a meteorite from
Mars to Earth, it is not unreasonable to think that organisms native to Mars
might also have evolved such capabilities long in the past. Mars has no
global magnetic field that would reduce cosmic radiation exposure as Earth's
does. It seems to have had one in the past, but Earth's atmosphere provides
another radiation shield. The Martian atmosphere is much thinner, so more
cosmic radiation gets in, and radiation also comes from radioactive
substances in the crusts of both planets. Thus, Mars would have selected for
organisms with good radiation survivability, and such organisms would have
made good candidates for survival in a meteoroid traveling to Earth. As
models for such theoretical Martians, B. subtilis and D. radiodurans were
placed on the passenger list of Phobos-LIFE and Shuttle-LIFE too.

Members of the domain Archaea tend to be extremophiles, organisms that not
only survive, but thrive, under conditions that we humans would consider to
be extreme. Like bacteria, archaea are single-celled organisms lacking
membrane-bound organelles, but here the similarity ends. One example, which
is included both in Phobos- and Shuttle- LIFE, is Haloarcula marismortui. It
is a salt lover, thriving in high saline environments. Indeed, it is native
to the Dead Sea, as its name in Latin suggests. Studies of certain Mars
meteorites have revealed high salt levels, while studies of Mars itself have
suggested that large amounts of water have flowed on the surface. With an
atmospheric pressure of only 7 millibars, to be in a liquid state and not
evaporate, such bodies of Martian water would have to have been briny, like
having Dead Seas and salty rivers all over the planet. Thus, if life exists
there, it is not unreasonable to think that it may share certain
characteristics with salt-loving microbes such as H. marismortui. That is
why we are sending this organism a long journey through space and why we
also included it in the experiment's precursor, Shuttle-LIFE.

Discovered in 1986 in volcanically heated ocean sediments off the coast of
Italy, Pyrococcus furiosus is a thermophile, a heat lover, thriving in
temperatures from 70 to more than 100 degrees Celsius. We don't think it's
analogous to anything living on Mars, which is a cold planet, but there is a
tiny risk that somewhere in processing the payload, a mistake would cause
the payload to overheat. While it is not thought that the reentry of the
Grunt probe through Earth's atmosphere will expose the payload to very high
temperatures, in the unlikely event that the course of the capsule through
the atmosphere is altered and it does get hotter inside than expected, P.
furiosus will serve as a temperature control. If it is the only LIFE
organism to survive, we'll know that the demise of the other species in the
biomodule cannot be attributed to the space environment. It too is included
in Shuttle-LIFE

Finally, on both Shuttle and Phobos versions of the experiment we've
included a member of the animal kingdom, which is part of the Eukaryotic
domain. Tardigrades, also called water bears, are big compared with LIFE's
other passengers. The samples are a mixture of three tardigrade species. The
body of each organism consists of four segments, each with two legs ending
in claws. Like the archaea, they are extremophiles. Water bears can adapt to
a wide range of temperatures from 150 degrees Celsius down to just a few
degrees above absolute zero. They also are extremely tolerant to radiation.
Who said that cockroaches would be the only animals to survive a nuclear
war? Tardigrades would survive too, and they sure are a lot more lovable.

Images: 1) The diagram of the biomodule with parts labeled is from the
Planetary Society, 2) Image mashup by David Warmflash, 3) Image from Did
Life Come from Another World? by David Warmflash and Benjamin Weiss,
Scientific American, 2005.























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Phil Whitmer

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Received on Wed 01 Jun 2011 11:26:45 PM PDT