MBARI Ridges 2005 Expedition
Juan de Fuca Leg: August 7–18, 2005
Gorda Leg: August 22–September 2, 2005
August 29 update posted by Jim Head
Tiburon dive 890 - Sediment sampling in Escanaba Trough - East transect
This is our "mission control" center on the ship--the ROV control room. Scientists spend about 10 hours a day in this room, directing the ROV science camera and watching and discussing the geologic features we see. The ROV pilots spend about 14 hours a day in here (in rotating 1-hour watches), since they must be present fly the vehicle, even during the ROV descent and ascent. The ROV pilot (in this case, Buzz Scott) is in the center; the copilot is in the foreground.
The primary goal for me on this very exciting scientific cruise is to understand how volcanoes work when they erupt under water. When lava erupts in the deep sea, the immense pressure of the overlying water keeps the lava from “exploding” as it reaches the seafloor and its gas comes out. In Hawaii, we are used to seeing the beautiful “fire fountain” eruptions, but these are believed to be very rare in the deep sea. The same is true on the surface of the planet Venus, where space probes have shown that the surface pressure is very high--about the same pressures that we find when we are diving about a kilometer or so deep in the Earth’s ocean. So by studying the seafloor eruptions and rocks here on Earth, on the Juan de Fuca Ridge, we can also learn about how volcanoes erupt on the planet Venus.
It is also interesting to compare how we explore the seafloor with how we explore the other planets. My first job was working in the Apollo Lunar Exploration Program, where I was involved in the geological training of the astronauts, selection of landing sites, and mission operations. Back then, we spent a lot time taking the astronauts on geological field trips and training them in classes to recognize the key rocks, minerals and geological features. Then, when they landed on the Moon and started exploring, they were well-prepared to make useful observations and select the most important samples to bring back to Earth.
During the time that the astronauts were on the Moon, we were in Mission Control, and we could watch their activities in detail from a TV camera that was mounted on the lunar rover. This camera was controlled from Earth, so when the Astronauts stopped driving and got off the rover, we could follow them around with the camera and listen as they made observations and collected samples. If they had questions or wanted to show us something very exciting, we could discuss specific things with them. Because the Moon is so close to the Earth, the delay in radio communications is very short and not really noticeable.
When we explore Mars, the story is different. Because Mars is so much farther away from the Earth than is the Moon, radio signals take many minutes to travel from Mars to Earth. This makes it impossible to communicate directly and effectively with remote vehicles such as the Mars Exploration Rovers Spirit and Opportunity, which are currently operating on the surface of Mars. It is a very weird experience when you watch spacecraft land on Mars: As you watch the telemetry (the stream of radio signals informing you of the status of the descending lander) at the estimated time of landing, you can tell whether the spacecraft has crashed or is ok. But because of the signal delay, you are still seeing readings about the craft's “health” that were sent a few minutes before the actual landing. Eventually, after a successful landing, the rover will go through a sequence of pre-programmed steps and observations that were stored in its computer memory. After the observations and pictures are recorded, they are sent back to Mission Control, for analysis by the ground crew of Earth-bound scientists. The scientists then review the data and write a plan for the next day. This plan is sent up and stored on the rover's computers, to be executed later on the surface of Mars. So this type of exploration is very exciting, but remote and indirect.
Left image: This image of the surface of Mars shows a row of lava cones and adjacent lava flows (rough, darker areas) that formed from an ancient volcanic eruption. The individual volcanic cones are a few tens of meters to about 100 m across. The arrangement of the eruption sites is very similar to linear eruption vents at mid-ocean ridges such as the Gorda Ridge on Earth, although the tectonic setting is very different. THEMIS themal image courtesy of: NASA. Right image: We collected samples from this small spatter cone, where lava may have bubbled up from beneath the surrounding lava crust. Similar formations may occur on other planets.
On seafloor exploration cruises such as this one, we have the best of all worlds for geological exploration. We sit on the ship R/V Western Flyer in a mission control room just like those in Houston. But in our case, we can communicate directly and instantaneously with the ocean floor (even though it is 3400 meters, or about 30 football field lengths, below us). We send control commands and receive video through the long cable that connects us to ROV Tiburon, which typically flies about a meter above the ocean floor below us. There are about 8 people in the control room and each has a specific job, with a pilot and co-pilot flying the Tiburon and running the sampling arm while a group of scientists control the science camera, take frame grabs, do and do navigation. Another scientist takes notes and makes records of the samples we collect, while the chief scientist directs the operations and narrates the dive on the video tape.
The exciting part for me is that you get to work side by side with the ROV pilot and co-pilot, and also get the benefit of the knowledge and opinions of a large number of your scientific colleagues. There is a real sense of teamwork between the scientists, engineers, and pilots, and a shared sense of exploration of the frontier of the sea floor. And of course, being able to solve complex scientific and engineering problems immediately, as they occur, means that the amount of productive scientific observations and sampling that we can do is maximized. We don’t have to wait a day to see where we have been, but rather we know immediately, and even though we are more than three kilometers away from the ocean floor, we can study an unusual rock formation and take a sample to bring home that night. When ROV Tiburon comes back up to the ship after the day's dive, we can examine the samples and we can refit the ROV with slightly different equipment for the coming day’s exploration.
When I sit in the lead scientist’s seat in "Mission Control" on the ship, I feel like I am exploring the surface of another planet, together with my scientific and engineering colleagues, and making new and very exciting observations about the frontier of the ocean floor. This frontier, Earth's “inner space,” is still virtually unexplored by humans and is almost as unknown as the “outer space” where send our spacecraft.
Left image: Animals such as this huge (almost 1-meter-wide) brisingid sea star would not seem out of place in a science fiction movie. However, in this case, we humans are the aliens, sending our exploratory robots into their dark, watery realm. Right image: Rob Zierenberg (manning the science camera) and Dave Clague peer into the video monitors in the ROV control room, examining deep-sea lavas and discussing their origins.