One of the things that my mother always says to me when I tell her I'm about doing anything remotely dangerous is "Michael, BE CAREFUL!"

Despite my repeated attempts to assure her that "Extreme 2004" refers only to the fact that the environmental conditions at hydrothermal vents are extreme, she repeats these words of wisdom every time I call home. So, in an effort to reassure my mother one final time that R/V Atlantis and her crew are, in fact, focused on safety, first and foremost, I'd like to discuss today's activities.

This morning at 10:20, we mustered in the main laboratory for a fire drill. Fire at sea can be a very serious issue, and so the crew of Atlantis practices as though this were real. I'll let Chief Mate Mitzi Crane (the Safety Goddess, my "Mom" at sea) tell you about what we did ...

So, Mitzi, why do we do these fire drills?

"Why we practice and pretend ... so we know how our equipment works, its limitations, and ours. And to make things seem as real as possible so that in the time of a real emergency we make a professional response."

Mitzi, it seems like some of these situations are a little 'extreme'. What's up with that?

"Do we always think up worst-case scenarios? No, but we do let our imaginations wander. The United States Coast Guard (USCG) rules and Safety of Life at Sea International Standards (SOLAS) require that we demo and instruct our crew, using our fire and safety equipment, in approximately a two-to three-month rotation."

I see that we're using two types of fire extinguishers. Can you tell me why?

"Why are we using CO2 extinguishers on the swimming pool and dry chemical extinguishers on the Christmas tree? CO2 is a cryogenic gas. It is never a good idea to rapidly decrease the temperature of warm steel lest we make it brittle, and so we aim at something that won't be hurt by chilling it. We thought the pool could use a temperature drop!

Also, CO2 is not usually recommended for use outside where the wind can blow away the cooling gas. Dry chemical extinguishers come out like powder and what better way to illustrate that than show the powder against a dark object. This would be the portable extinguisher of choice to put out a Christmas tree fire. So for each type of fire, we choose the extinguishing agent best suited for the job.

I don't recommend that anyone decorate the Christmas tree this way or chill things off with CO2 extinguishers -- a freezing burn is a very big danger from cryogenic gases/liquids."

Mitzi, how would the crew handle a large fire?

"The hose teams demonstrate the teamwork needed if we were to face a bigger fire out here. Since seawater is readily available, we use it in our fixed-fire main system. The drawback of using seawater is that it is not intended for electrical fires (CO2 can be used on them), and it adds a lot of weight to the ship, which has a negative effect on our stability. Foam would be the suppression agent of choice for a fuel fire as it lays down a blanket, which helps to cool and smother a fire."

Mitzi, I see we've deployed orange smoking buoys in the water. Why?

"The orange buoy smoke canisters have expired. They are a type of distress signal. We carry two attached to the life rings on either side of the bridge wings. These are attached in a manner to let go rapidly in the event of a man overboard situation."

How do you measure whether a cruise has been successful?

"A good trip for me is one where I didn't have to call MAS (Medical Advisory Service). This is a group of doctors standing by in Maryland to assist us in diagnosis and treatment of medical emergencies. Although we are in the Pacific Ocean, we do have a real staff of doctors available to consult. We have a fairly well stocked hospital on the officer's deck. And, although we practice responding to emergencies, we spend even more time practicing prevention. We really do want all who sail with us to disembark having only good memories of their cruise."

So, there you have it Mom! Out here, safety always comes first and Mitzi Crane and the crew of Atlantis make sure that the scientists always remember that. Mitzi also gave me one final message for my Mom back on shore:

"Don't worry about Michael, Mrs. League, I am 'Mom' for everyone out here. While it's your Mom's mission to guard your welfare at home, it's mine to guard the safety and welfare of all here on board. (And your Mom can probably attest that it's a thankless job)."

It's our last dive, and Dr. Craig Cary and Ky Hacker are taking the plunge with Pilot Bruce Strickrott. Ho hum. Not! The word from the bottom is surprise! They've come down into a snowstorm the likes of which neither Bruce nor Craig has ever seen -- and they've logged a lot of dives between them. To Ky, it's all new, but it's new to Bruce and Craig, too.

Expedition Leader Pat Hickey gives the credit to Frosty, the Styrofoam snowman who's riding Alvin today for shrinking purposes. "Frosty brought the snow," says Pat.

In the evening, everyone gathers around the video screen in the computer lab to see what they're talking about. It's marine snow, of course -- not the flaky crystals they're getting back home in Connecticut, the frosty kind. Marine snow is a host of organisms, dead and alive, floating through the water. Because they are mostly the same color, they dot the water like snowflakes dot the sky.

"So it was really coming down?" I comment to Bruce that night at the post-dive meeting.

"No," he says. "It was really coming up."

While snow above the surface comes down by force of gravity, snow at the vents gets thrown up by the force of the flow coming out of the vents. The snow made it hard to see -- like passing through the blast from a snowblower -- but, amid it, the observers could see giant Riftia pachyptila and gathered sulfide from the chimneys nearby.

Unexpected discoveries are all part of the exploration process for the Extreme 2004 scientists. Over and over we are reminded how little we know, how unknown the ocean is, and how unpredictable the vents are. Areas that were enormously active a year or two ago (during other Extreme dives) have quieted down or nearly died out now. New vents have opened up and are spewing out the chemicals that give rise to new life.

While Craig was down below checking out what was new at 13º north, I was on Atlantis talking to other people in the Biocomplexity Group in an effort to understand the work they're doing and how the Extreme 2004 cruise fits into their process.

"Can you give me a timeline?" I asked Co-Principal Investigator Alison Murray.

She did. It's a complex one. The Metagenome Project has been in the works for years.

The plan began to become reality in 2002, when the Extreme 2002 dives brought up Alvinella samples from the area where we are now. Craig Cary and Barbara Campbell extracted DNA from the cells of those worms.

Barbara began to make a library of the DNA fragments. Once the procedure was in place, robots were "hired" and programmed to do the library-making work.

Dr. Joe Grzymski explains what happens next: "The whole pool of DNA is chopped up. It's like putting it in a shotgun and shooting it out." (In fact, it's called a shotgun library.)

The shotgun is cloned into E. coli bacteria, which allows the DNA to grow into colonies. Colonies of a certain size are picked by the robots. The number of colonies picked is the number of DNA sequences that will be performed.

These colonies were BLASTed. This means that they were compared with all of the data that had already been sequenced and placed in the public domain by anyone.

This step is the first one in the bioinformatics aspect of the project, in which computer programming is written that helps biologists sort and group their data. It is the creation of Alison Murray and Mihailo Kaplarevic, along with Dr. Guang Gao, another co-principal investigator who is not on this cruise. A total of 210,000 clones were picked in this gene-finding step.

"The computer links DNA, joining like and like sequences," Alison explains.

After the BLAST, the computer tells whether or not the gene fragment has the predicted protein in it. "An assemblage of predicted proteins give us how the organisms deal with their environments," says Joe.

"We have organisms. We know their environment. So we compare them to lots of other organisms and what they do, to figure out what this one is doing," adds Joe.

The result is a hypothetical organism (one that represents a group, something like the "typical American teen") that might metabolize (convert energy) in one of three possible ways. We put all these possibilities on a microarray, which shows us which way it uses. There could be ten ways of dealing with sulfur, for example, but only one at a time is working. The microarray can tell us which one it is.

The next step, then, is to design the right sort of microarray to produce the information desired. These microarrays produce different colors based on what's showing up, or, as the scientists say, "lighting up." What lights up is what's active in the gene under a given circumstance. And it is these lit up circles -- gene fragments -- that will provide new information about Alvinella and the vent environment.