Diving to an Underwater Volcano – NSF Cruise AT26-17A, Day 8-10

Bad news, followed by good news, followed by disaster, followed by insanely good luck, followed by bad luck, followed by a fighting chance. That about sums up the past two days and brings us up to now.

Bad news first. In the week we’ve been out here, Alvin has been able to dive only twice. From a passenger standpoint the weather is beautiful. Blue skies, sunshine, t-shirt and shorts on deck. Calm seas spread out across earth’s round dais and the sky so blue and flat, the sun’s orb so perfectly hung that the whole world appears as if through a tilt-shift lens. The Thompson (our sister ship) appears in the distance, bobbing on the horizon like a Battleship game piece. Sadly, it isn’t the weather you are experiencing that counts, but the weather that you might experience from which decisions are made.

The potential loss of life with the Alvin means that the probability of weather must be considered both during launch and recovery operations. Foul weather, or more accurately the threat of foul weather has prevented Alvin from diving twice and an electronic error prevented it from diving yesterday. Most of the experiments on the cruise rely on Alvin’s manipulators to perform. And since our CTD has been down, that left Woods Hole’s Sentry and ASU’s Sensorbots as the only two exceptions on this cruise. This emphasizes the importance of our success. Unfortunately, we’ve faced considerable setbacks, starting with a microscopic soldering error deep inside one of our boards. It wasn’t repairable at sea and forced us to go to plan B early on.

Now, the good news. Realizing the soldering error we moved to our backup electronics. Our guys on the beach (meaning our lab at ASU), scrambled to finalize some computer code for the backup plan. Their hard work, combined with Greg’s final insight into the memory writing subroutines and we had it working. That much has been true since day 3.

Now the disaster. After waiting our turn for the winch, which was busy dropping cameras with acoustic release-beacons for Alvin to play with on the bottom the following day (which never ended up happening as explained above) we got on deck with our modems at 4am. The plan was to do a short 200 meter drop and back. Looking back, I should have known something was wrong because the upward facing modem blinked off  a few moments earlier than it should have less than 2 meters underwater. At that point there was nothing to do but control the winch and wait for the modems to return. When they did come up, the top housing was flooded with sea water, battery acid and some sort of congealed yellow material resembling gobs of hardened chicken fat.

Understand that the housings were specifically Alvin Dive Certified with a pressure test record down to 2-kilometers depth, which was obtained on each housings at some expense. Needless to say, we were crushed and likely everything inside was too. High pressure saltwater and powered electronics don’t mix. Think dropping your $100,000 computer (you’ve got one of those, right?) into the toilet, for an hour, add salt, and extreme pressure, and you’d know what we were thinking when it came out on deck.

Now for the insanely good luck. Triage in main science begins with getting the modem housing open. Since seawater rushed into the housing at potentially 200 meters, you can’t just open it because the remaining air inside is still under pressure. “But won’t the water just get out the same way it got in?” you ask. No, because holding in water is not the same as keeping it out. Think about how your car door only opens outward. Anyway, the flooded housing was opened as slowly as possible but it still had enough pop to explode in my hands. Breaking some screws and scaring the pants off Greg. If we had gone to 1.5 kilometers the housing would have blown my hand off, a hole in the sink and still had enough oomph to go through the hull.

Once we got the electronics out we followed standard, “electronics rescue procedures at sea”. Boards are scrubbed with a brush in alcohol and deionized water, then hot air dried as you examine them for any corrosion. Let me cut to the chase. The boards still worked! A miracle! Only, it wasn’t…

And now, bad luck. As we continued to run and test the boards, I resealed the housings with fresh o-rings and grease. In doing so I found the flaw that led to our housing failure; The origin of the problem was that when the housing is screwed shut, the boards could catch on a surface and release pressure on an o-ring while the system was at atmospheric pressure. If this particular o-ring releases from its groove then the high-pressure salt water will push it right through into the can. So we did a pressure test of the now re-sealed empty housings down to 500 meters and they held as they were intended to do. It seemed like we were a go. But, and here’s the thing about salt water corrosion, it continues even once you’re dry. By the time we were ready to deploy again, the boards ceased functioning.

Finally, the fighting chance. WHOI electronics engineer, Al Duester, has a kit (and a mind for electronics) like no other. Back-ups of back-ups of back-ups of things he might need, ad infinitum. From resistors to oscilloscopes he’s like a turtle – he carries it all on his back. I wouldn’t say it to his face but when it hits the fan, “Let the Dues loose!” So Al gave us a back-up computer of a type similar to the one we lost. The beach team has written new code for it since it required different library files and Greg is busy as I’ve ever seen him soldering new connections and overcoming wiring issues.

Everyone who reads this to the end, pray for us.

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