It is sadly possible to be in the middle of the ocean with no land in sight and not see the ocean, or know when day turns to night. With 24-hour operations aboard the JOIDES Resolution, and most of us splitting each day by working a 12-12 shift, the natural cutoff to a day is missing. The gym doesn’t have windows, most cabins don’t have windows, and some stations in the lab are without natural light. It sounds silly, but one almost needs an alarm or a friend to signal a trip out of the air-conditioning into the hot, sticky air to witness glorious sunsets and sunrises. The ritual Sunday boat drill at least tells us we have come to the end of the week. As much time as drilling into the ocean floor requires, I am still amazed what I can miss if I don’t monitor the camera feed. Time slips away so quickly, but somehow twists back on itself to make it simultaneously feel we have all the time in the world. This intense focus and lack of distractions must somehow wobble time.
First, some perspective on drilling operations at the edge of the Izu-Bonin-Mariana Trench: Picture the tallest building in the U.S.: the One World Trade Center in New York, reaching just under a third of a mile. Stack eight more of them on top of each other and chop off, say, 300 feet –the height of the Statue of Liberty. Once you reach the top, which is equivalent to climbing a little over halfway up Mt. Everest, you will be aiming for one of those safety nets back on the ground that firemen use, and ultimately the small manhole centered beneath the net. To make it harder, let’s fill up that entire space – from the ground to the tiptop of those stacked buildings – with water. Jump onto a boat and tell the captain to stay right above the net that you can no longer see. *Note: there will be strong currents, swells, and wind knocking you around in New York’s new ocean.
Start connecting 100 feet of pipe together (we’ll use PVC pipe the diameter of a small plate for this exercise), and slowly lower it into the water. Do that process 150 more times. Right before you connect that last 50 feet of pipe, though, connect a fiber optic cable to a GoPro that can miraculously withstand nearly 7000 pounds of crushing pressure all around it. Slide the camera down the outside of the pipe almost to its end. The camera feed comes through a monitor so your boat driver can carefully nudge the boat to where the firemen’s net is – hoping to spot the darned thing. You are watching the same scenario on another monitor at the opposite end of the boat, and in charge of lowering that last 50 feet of pipe once the net comes into view. When it does, you must push that wobbly mess of pipe straight into the open hole that is below the middle of the net.
Congratulations! This represents a successful reentry into the hole we had already drilled on the bottom of the seafloor.
That is just one operation on the JOIDES Resolution, which takes about half a day. Placing the net (i.e. reentry cone) and opening the manhole (i.e. borehole) in the first place, can take a week. In our case, we tried to save five days by lowering the reentry cone and casing (pipe to reinforce the top of the hole) and drilled it in all at once. It worked!
Here’s a timeline when drilling in water depths of at least 15,000 ft:
Sending the camera down and back- three hours
Navigating pipe back into the hole- five minutes to an hour
Changing drill bit every 40 hours of drilling (must bring 15,000 ft of pipe to the surface, then send it back down)- 20 hours
Sending instrument to retrieve the cored rocks- an hour
Cleaning out the hole- three hours to a full day
Of course, those timeframes represent operations running smoothly, which they rarely do. Invariably equipment fails, weather rears up, or something like a medical evacuation can stop operations. Our color camera fiber optic cable recently failed, but the crew’s ingenuity meant that although we have a less than spectacular black and white image, the expedition could proceed and we now save several hours deploying the camera.
Cores of sediment can come up every 45 minutes. But hard rock can take three to four hours. Once on board, rocks have to be arranged, imaged, measured, and then cut. A day later the scientists gather together to decide what should be sampled for certain tests, and three to four days later, the chemistry results tell us something about the origin of the rocks.
The first step that truly counts with time, though, is the seismic imagery on which we base our drilling decisions. Interpreting the data can be subjective (I heard one scientist liken it to a “witchy, voodoo process”). Data can be inaccurate, particularly when surveying in complex environments that show topography on or beneath the seafloor. The measurements that help create these images come from knowing the density of particular rocks, and how fast sound travels once bounced off them.
If drilling into new rocks the images are harder to interpret. Furthermore, what may appear as dark layers of hard rock could have sediment in between or actually be cement-like sediment. While drilling requires sediment to “spud in” or begin drilling, this group wants an expeditious route to the rocks. If our interpretation is wrong, we lose a lot of time (though keep the sedimentologists happy). With this operation costing $120,000 a day, we can’t afford to miss our mark. Thanks to our seismic wizards, we’ve been spot on.
Scientific ocean drilling requires numerous steps, repeatedly connecting and disconnecting the same gear, and a complex choreography of teamwork. I suppose time passes normally, but it’s that we’ve been too busy to track it. What’s been collected thus far (a future post) has delighted the science team, so perhaps time won’t feel regular again until they return home to the arduous task of analyzing the samples and writing up the results. Then they’ll probably wish they were back at sea waiting for new rocks to arrive.