Rosebud
May 28, 2002
by Lonny Lippsett

As Alvin descended to the seafloor today, two of its thrusters conked out. It required a quick decision.

There was no danger to the sub or anyone in it. But Alvin was not as nimble as it normally is. The plan had been to spend the first part of the day looking for the elusive “Rose Garden” vent site. And then the sub would return to the newly found, and still unnamed vent site. But with less maneuverability, Alvin could not cover as much ground.

In Alvin’s sphere, Susan Humphris, Craig McLean and Pilot BLee Williams decided to go first to the new site and map and photograph it thoroughly. Alvin flew back and forth over the new vent site, like a lawnmower mowing a lawn, until it had gathered enough high-resolution photographs to create a photomosaic of the entire field.

“Alvin has many back-ups so that it can still keep going—but there’s a limit, and we approached that limit,” Williams said. “We were probably at 50 to 75 percent capability. It was harder to maintain a straight course. We actually did very well with what we had.”

The new vent field is about 60m by 40m. The fresh lava suggests that the site is very young, and many of the animals dwelling amid the warm hydrothermal fluids wafting out of seafloor cracks are also very young. Some of the tubeworms, which can grow up to 2 m long, are only 2 cm. The scientists named it “Rosebud,” because it could well grow into something like the Rose Garden. (“Rosebud” is also a key word in a famous movie called “Citizen Kane,” but that’s another story.)

Tomorrow, Alvin will try one last time to find Rose Garden. But the Rose Garden that scientists first saw in 1979 and last saw in 1990 may no longer look as it did then. A seafloor eruption since 1990 may have overrun it with lava—like Pompeii after Mount Vesuvius erupted. It may be gone, or may look so different that we might not be able to recognize it.

Why can’t we just return to the spot on a seafloor map where previous scientists found Rose Garden, you ask? There are no signposts on the seafloor, and we see no markers from previous visits to guide us. We cannot directly use Global Positioning Satellites (GPS). Satellites use electromagnetic waves, and these do not penetrate water. Today, we use Global Positioning Satellite to position our ship Atlantis on the surface. But then Atlantis must use sound waves to locate our transponders on the seafloor. (See “Oceanographic Tools-Navigation” under “Deeper Discovery”)

When Rose Garden was last visited in 1990, Alvin did not even use transponders to locate Rose Garden. The crew then was incredibly lucky. They landed almost right on it and found it in 8 minutes. Before then, GPS was not as available or as accurate as it is now. So any location for Rose Garden plotted then is only approximate.

“We need to be absolutely sure we’re in the right place,” Susan said. “When you’re in Alvin you can see perhaps 30 feet out of the porthole. We have covered a lot of ground, but there’s a lot of seafloor in between. These vent sites are not that big, it’s easy to miss them.”

What about Alvin’s thrusters? “Unless the scientists decide they’ve had enough for this cruise, we’ll find a way to fix them overnight,” said BLee, casting a glance at Susan “Have you had enough, Susan?”

She gave him a tired, but no-nonsense look.

“We’ll fix ‘em,” BLee said, casting a sly glance at Susan.

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