[meteorite-list] Living Interplanetary Flight Experiment

[JoshuaTreeMuseum]

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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