Living in the Universe

Space Germs Get Mean

Fourth Week of October 2007

Today I’d like to catch up with a story from a couple of weeks ago based on a paper published in the Proceedings of the National Academy of Sciences. That’s normally a fairly serious and stodgy journal, but this story has the plot of a scary B movie. Germs go into orbit on a spaceship and come back stronger and deadlier than ever. Yes, it really happened. The germ was salmonella, best known as a culprit in food poisoning.

The trip? Space Shuttle mission STS-115 back in September, 2006. The reason salmonella were sent into orbit? Scientists wanted to see how space travel affects germs so they took some along, carefully wrapped for the ride. The result? Mice that were fed the space germs were three times likelier to get sick and died more quickly than mice fed identical germs that remained behind on Earth. Cheryl Nickerson, a team member for the experiment and an associate professor at the Center for Infectious Diseases and Vaccinology at Arizona State University, said, “Whenever humans go, microbes go. You can’t sterilize humans. Wherever we go, under the oceans or orbiting the Earth, the microbes go with us, and it’s important that we understand how they’re going to change.”

Learning about how germs change also has the positive potential to novel new countermeasures for infectious diseases. So the researchers placed identical strains of salmonella in containers and sent one into space on the shuttle while the second was kept on Earth under similar temperature conditions. Mice were given varying oral doses of the salmonella and then watched. After three weeks, forty percent of the mice given Earth-bound salmonella were still alive, compared with only ten percent of those dosed with the germs in space, and the researchers found that the amount of bacteria it took to kill half the mice was three times larger for normal salmonella than the space germs. When looked at in detail, the researchers found that a hundred and sixty-seven genes had changed in the salmonella that went into space.

Why? Members of the research team simply don’t know, but they think it’s a force called fluid sheer. According to Nickerson, “Being cultured in microgravity means the force of the liquid passing over the cells is low. Those cells are responding not to microgravity but indirectly to microgravity in the low fluid sheer effects. There are areas in the body which are low sheer such as the gastrointestinal tract where obviously salmonella finds itself. So it’s clear this is an environment not just relevant to spaceflight but to conditions here on Earth, including in the infected host.” She said it’s an example of a response to a changed environment. These bugs can sense where they are by changes in their environment. The minute they sense a different environment, they change their genetic machinery so they can survive.

Obviously this result has enormous implications for astrobiology. If microbes can indulge in this kind of genetic adaptation to what’s considered an extremely hostile environment in space, then potentially their survival ability in very harsh situations is greater. So this degree of adaptation to space environment is another positive indication that microbes could travel through space, seeding life between planets. This idea is called panspermia, and the main objection to it has been the long time taken for space rocks with microbes to travel between solar system and the hazard of the space environment. In biology, it seems that duress can spur survival. Maybe we would never want to run into the kind of germs that are mean enough to thrive in outer space.

Bookmark It

Hide Sites

The Great Lakes of Titan

Third Week of October 2007

This week’s news comes from the outer reaches of the solar system. JPL released some newly assembled radar images from the Cassini spacecraft that provide the best view so far of the hydrocarbon lakes and seas on the north pole of Saturn’s moon Titan. Another new radar image reveals that the south polar region also has lakes. These images give new insights into the cycling of hydrocarbons on Titan, which are in some ways analogous to the water cycle on Earth. Titan is a uniquely active environment in the solar system, along with Io as another example with its active volcanoes. Titan is the only moon known with a significant, substantial atmosphere. Scientists think that it might in some ways resemble aspects of the early Earth and provide clues of how precursor molecules for the origin of life were formed.

The images that we’re seeing now were sent back from an October 2 flyby where the primary goal was the hunt for lakes at the south pole. The new mosaic has been stitched together from radar images from seven Titan flybys over the past eighteen months and it shows a north pole pitted with giant lakes and seas, at least one of which is larger than Lake Superior. About half of Titan’s north polar region has been mapped by Cassini’s radar instrument, and about fifteen percent of that region is covered with what scientists interpret as liquid hydrocarbon lakes. The lakes and seas are very common at the high northern latitudes of Titan, which is mired in the depths of winter now. Scientists say that it rains methane and ethane there, filling in the lakes and seas. These liquids then carve meandering rivers and channels on the moon’s surface.

Now Cassini is moving into unknown territory, the south pole of Titan. One of the mission specialists said, “We wanted to see if there are more lakes present, and sure enough there they are, three little lakes smiling back at us.” Titan is indeed the land of lakes and seas, and it will be interesting to see the differences between the north and south polar regions. Scientists have made progress in understanding how these lakes have formed. On Earth, lakes fill low spots or are created when local topography intersects a groundwater table. Mission specialists now think that the depressions containing the lakes on Titan may have formed by volcanism or a type of erosion called karstic on the surface, leaving a depression where the liquids can accumulate. Karstic lakes are common on the Earth. For example, Minnesota and central Florida have hundreds of lakes like this.
The lakes observed on Titan appear to be in varying stages of fullness suggesting their involvement in a complex hydrologic system akin to the Earth’s water cycle, and that really does make Titan unique amongst the extraterrestrial bodies of the solar system. The lakes seen so far vary in size from the smallest that can be observed, about a kilometer square, to greater than a hundred thousand square kilometers which is slightly larger than the great lakes in the Midwest U.S. Of the four hundred observed lakes, seventy percent of their area is taken by large seas. These flybys will continue, and they will continue to pencil in our view of this strange world. Titan’s nitrogen atmosphere, its geography, and its complex weathering are familiar, but the chemistry is completely different.

Another story this week from Cassini involves the surprising moon Enceladus, which was shown to have jets of fine icy particles spraying up. Members of the imaging team have used two years worth of data from the geologically active moon to find the sources of the most prominent jets sprouting from the moon’s surface. They compared these surface source locations to hotspots that had been previously detected in 2005. They found that almost all the jets appear to come from four prominent tiger stripe fractures in the moon’s active south polar region, and in almost every case in the hottest areas detected by Cassini’s infrared spectrometer.

This is the first time that these visible icy jets have been tied to the tiger stripes. Scientists suspect that these jets collectively feed a plume that towers thousands of kilometers above the moon. This is the first proof, however, that makes a causal connection between the jets and unusual heat radiating from the fractures. All the measured jets fell on a fracture, but not all jets fell on a previously discovered hotspot, and so the team concluded there are other hotspots to be found. The possibility suggested by the imaging team is that the jets may erupt from pockets of liquid water. That, together with the unusually warm temperatures and organic material detected by Cassini in the vapor accompanying the ice particles, pushes this small Saturn moon into the spotlight as a potential habitable zone object, but what happens beneath the surface to power the jets remains a mystery.

Carolyn Porco, lead of the imaging team on Cassini, says, “These are findings with tremendously exciting implications. To say that I’m eager to get to the bottom of it would be a cosmic understatement. Do the jets derive from near surface liquid water or not, and if not then how far down is the liquid water that we all suspect resides within this moon? Personally, I’d like to know the answer yesterday.” Me too, but patience is required. The next opportunity for answering these questions will not be until March 2008, when Cassini dips low again over Enceladus and flies through the plume. Astronomers will be waiting anxiously for this moment to learn more about the most intriguing small moon in the Solar System.

Bookmark It

Hide Sites

SETI Gets New Ears

Second Week of October 2007

This week saw a landmark in the search for intelligent life in the universe. At Hat Creek, California, astronomers switched on the first elements of a large new array of radio telescopes that will extend the investigation of unnatural signals from the universe that we think might come from intelligent aliens. The facility is called the Allen Telescope Array, named after one of the founder members of Microsoft who provided twenty-five million in seed money, which is actually pin money for such a multibillionaire. Paul Allen is of course the “poor cousin” of Bill Gates.

When it’s complete the Allen Array will consist of three hundred and fifty dishes or antennae, each twenty feet in diameter. Using them as if they were one dish, radio astronomers will be able to map vast areas of sky very cheaply and very efficiently. It will extend the search for extraterrestrial radio signals by a factor of a thousand to include a million nearby stars over the next twenty years. This week only forty two of the antennae go online. They are mass-produced from molds and have very inexpensive telecommunications technology. Seth Shostak, the Chief Astronomer at the SETI institute, said, “It’s like cutting the ribbon on the Nina, the Pinta, and the Santa Maria,” and he pointed out that this is the first radio telescope ever designed specifically for the extraterrestrial quest. Most previous surveys have been done with existing radio telescopes, squeezed into time for their conventional radio astronomy programs or piggybacking astronomy programs.

The telescope is a joint project between Paul Allen and the Radio Astronomy Lab at UC Berkeley. Mr. Allen said in an interview published this week, “If they do find something, they’re going to call me up first and say that we have a signal. So far, the phone hasn’t rung.” Allen describes himself as a child of the fifties, which was the golden age of space exploration and science fiction. He first got interested in supporting the Search for Extraterrestrial Intelligence after talking to Carl Sagan about twelve years ago. When the idea came to build a radio telescope array on the cheap, Mr. Allen was intrigued. “If you know anything about me,” he said in the same interview, “you know I’m a real enthusiast for new, unconventional approaches to things.”

It’ll take another three years and forty-one million dollars more, depending on the price of aluminum, to complete the array. The complete array will be useful not just for science but also as a practice for a truly giant telescope called the Square Kilometer Array, which would have a combined receiving area of a square kilometer and an effective resolution of a telescope a thousand kilometers across. The main advantage of the Allen Array for normal radio astronomy is the ability to observe the sky in large swaths over and over again in a single night. In principle, the array can map the entire sky in day and a night and do it again the next day, and that’s never been possible before.

The previous radio search for extraterrestrial signals was called Project Phoenix and it finished three years ago and checked only seven hundred and fifty stars. Dr. Shostak says, “While that might sound a lot, it doesn’t impress anyone who knows how many stars there are in the galaxy.” Indeed, there are some two hundred billion stars in the galaxy, and we already know that a significant fraction of them have planets. Estimates of the number of intelligent civilizations in the galaxy range from one, or none if you don’t think we’re going to amount to much, to the millions.

Shostak has calculated that a full Allen Array would be able to detect a signal from as far away as five hundred light years, and that’s only a few more times powerful than what we can now send by our own Arecibo Radio Telescope. Arecibo is the world’s largest telescope, although it’s in danger of being shut down right now. It translates to the million stars which is a promising number. Shostak, who has a wit about him, described the expanded search as looking for a needle in the proverbial haystack with a shovel instead of a spoon. Anyone who’s out there broadcasting would also have to be broadcasting right at Earth, but an advanced civilization would be able to tell there was life here because of the oxygen in our atmosphere.

The first thing the new telescope will do is survey a strip across the center of the galaxy, where there are several billion stars in the field of view, but they will be very far away, ten to fifty thousand light years, so any signal would have to be huge to be detected. But who are we to say what the transmission power of an unknown galactic civilization will be? Either way, it’s a very promising new step in the search for extraterrestrial life in the universe using radio technology. And perhaps, a major advance in answering the profound question: are we alone?

Bookmark It

Hide Sites

Fifty Years in Space

First Week of October 2007

This weekend is a momentous anniversary in the history of space, not just in the history of space but in the history of humankind and human civilization. Fifty years ago, the fourth of October 1957, the first artificial satellite was launched: Sputnik, a new moon. Those people who were alive in that moment knew that it wasn’t a wondrous sight. It wasn’t a brave new dawn. It was the incipient rise of fear and paranoia in the United States because it was the agent of the Cold War.

Sputnik was an unassuming little device, a simple metal sphere weighing about a hundred and eighty pounds and not even two feet wide, made of highly polished aluminum to better reflect sunlight and be visible from the Earth. The Russians put two radio transmitters with whiskery antennas on it beeping signature frequencies that ham radio operators could pick up to confirm the achievement. The Russians clearly intended Sputnik to be a statement of their technological prowess and its profound military implications to put bombs in space, but even they didn’t quite anticipate the frenzied response that it caused in this country.

Various commentators have described how the United States was flung into a frenzy by the launch of Sputnik, and of course it took a couple of years before the United States recovered in the space race. John Kennedy was just a junior senator from Massachusetts with no particular interest in space at the time Sputnik was launched. Yuri Gagarin, John Glenn, and Neil Armstrong were test pilots with no idea eventually they would be landmark people in the race to space. When news about Sputnik’s launch reached Alabama where Werner von Braun was working, he was beside himself because he knew that his adopted country could have beaten the Russians into orbit if the Pentagon had allowed him to work with the Jupiter-C missile that he had been testing.

To make matters worse, the first American attempts to go into space were mostly disastrous. Finally, in January 1958, the Americans launched Explorer I, boosted into orbit with a multistage version of Mr. von Braun’s Jupiter-C, but by then the Russians had already put a dog Laika into orbit, which was a forerunner of human spaceflight. The race was on. It was an incredible wake up call.

In a recent piece in the New York Times, John Noble Wilford asked, “What would have happened, one of the might-have-beens of history, if America had deployed the first satellite?” It’s likely that there wouldn’t have been an Apollo program, but once Sputnik was launched, there was no stopping the momentum of the space race. Many people still remember the ringing words of John Kennedy committing the United States in less than a decade to land on the Moon. The quote was “This goal, before the decade is out, of landing a man on the Moon and returning him safely to Earth.” The space race was phenomenally short in its peak phase barely twelve years from the wake up call to that first walk on the moon, but what an amazing ride it was.

As an aside, we know that there’s roughly a quarter of the general public that don’t believe the moon landings actually happened, think that they were faked, a fraud by the government. Of the moon landings, three are sharply etched in memory. The Apollo 8 astronauts, the first to reach the Moon and leave the Earth and look back on it from behind. That date, December 1968, not coincidentally was the start of the environmental movement. Then Apollo 11, the first steps on the Moon. And finally, near the end, when the attention was already waning amongst the public, Apollo 13, a failure of a mission but a real drama that involved everyone in the risks of space.

So what’s happened since then? We haven’t been to the Moon for a very long time. Space science definitely benefited. The 70s and 80s were times when we explored the solar system. Carl Sagan wrote, “Of this golden age of planetary exploration, in all the history of mankind there will only be one generation that will be the first to explore the solar system. One generation for which in childhood the planets are distant and indistinct disks moving through the night sky and for which in old age the planets are places, diverse new worlds in the course of exploration.” It seems like we’ve only taken our baby steps.

The relevance to astrobiology is obvious. Humans are smart and have been capable of great things for thousands of years, but leaving our planet is a very, very young endeavor, barely fifty years old. It’s impossible to tell what the next fifty or a hundred years will hold. Space visionary science fiction writers have been impatient at the slow progress in the last few decades, but let’s listen to Apollo 11 astronaut Neil Armstrong, a man of few words. “I think we’ll always be in space. It’ll take us longer to do new things than the advocates would like, and in some case it will take external factors or forces which we cannot control and can’t anticipate that will cause things or not to happen. We were privileged,” he says, speaking of his own generation of astronauts, “to live in that thin slice of history when we changed how man looks at himself and what he might become and where he might go.”

The space race is young. Only a few hundred people have left the Earth, but we imagine that in centuries ahead, it will become a routine thing spreading through the population. And that point will have been reached, we think, by many creatures on many planets out there in the universe. So being at this special point in time and commemorating fifty years in space is interesting, because it’s the beginning of a very long journey.

Bookmark It

Hide Sites