Editor's Note: Journalist and crew member Kathryn Eident is traveling on board the RV Atlantis on a monthlong voyage to sample and study nitrogen fixation in the eastern tropical Pacific Ocean, among other research projects. This is the seventh and final blog post detailing this voyage of discovery for ScientificAmerican.com. But the next leg of the cruise begins now: a deep water exploration of undersea volcanism.

RV ATLANTIS, OFF THE COAST OF CHILE—On a hot, windy day in late January, a group of 28 scientists stood on a pier in northern Chile, luggage in hand, scientific equipment packedin cases and storage vans beside them. Many of them were tired andstressed; the 24-hour journey from the US to Chile had been fraught with delays, lost luggage and missing equipment.

Now, as the RV Atlantis slowly approached the dock to tie up, the group had to prepare for a month-long voyage into the Eastern Tropical South Pacific (ETSP). They were searching for traces of nitrogen in the water column, and for the organisms that could break its tough triple bond into usable biomass.

Over the next month, the group worked tirelessly to gather as much data as possible, sailing over thousands of miles of ocean, gathering liter upon liter of water samples as they went. Working in shifts 24-hours-a-day, the scientists gathered thousands of samples that once processed, might provide a window into the complicated process of nitrogen fixation in both this piece of ocean and on a global scale.

Each member of the nearly 30-person team contributed an important piece to the puzzle of nitrogen fixation throughout the voyage. Some dragged nets and found trichodesmium, the organism best known for its nitrogen-fixing prowess. Others identified each tricho species, then prepared to take home. Still others seeded water with various nutrients hoping to find the elusive combination that makes life possible in this otherwise barren stretch of water. And they measured the presence of nitrogen itself, filtering liter upon liter of water to quantify a vital nutrient source.

Thirty-three days later, the ship returned to a port in northern Chile. With samples safely stored, bags re-packed and the vans closed up, the science party disembarked.  Ironically, the trip ended much like it began--fraught with travel delays and missing equipment as the party tried to fly out of the earthquake-torn country. But while the scientists fret about getting themselves home, the bulk of the samples will remain on the ship, to be retrieved when the Atlantis docks in San Diego come April, returning a six-month stint in international waters.

While the voyage at sea is over, the work is just beginning for this group of scientists. There are hours---months--of analyses to be done at home in the lab. And despite the enormous volume of samples they have, there is still more data to be collected. Many of this group will return to the ETSP in the spring of 2011 to do it all over again.

In the meantime, the RV Atlantis prepares itself for yet another month-long expedition. This time, the ship will venture north and west of the Galapagos Islands to study volcanic eruptions and magma flows along the Galapagos Spreading Center. Together with Chief Scientist John Sinton (University of Hawaii), a group of 21 scientists will dive to the seafloor to take video and samples of lava with the submarine Alvin. They’ll map the region with the autonomous vehicle, Sentry, and they’ll gather rocks in an attempt to understand global volcanic processes along mid-ocean ridges. The next leg promises to be exciting, so be sure to check in!