Saturday, October 24, 2009

Its good to be wrong (in moderation)

After two weeks of dives, I finally found a new vantage point to get a clear shot of Nereus being lifted outboard on the ship’s crane.

A picture that tells more than one story. On the right hand side of this map is where I had THOUGHT Nereus should search for hydrothermal activity on the seafloor on its latest dive – the dark red circles show how wrong I was – strong hydrothermal signals are coloured yellow, green and blue. At the top of the page and all down the left side are the EXTRA lines that got added. The ones at the top were ones I had pre-planned in case things didn’t start well (note to self: all those red circles show that I was wrong again!) but down the left hand side is where we finally struck gold… or sulfide… of whatever it is down there that remains to be investigated in Leg 2.. Since each of these lines is only 1600m long and spaced 600m apart we really SHOULD be getting close by now. Shouldn’t we?
Position at 08h00 EST (Launch of Nereus 021)
Lat: 18° 33’N Long: 081° 43’W
Water depth: 4650m

If you read the previous blog you’ll remember it ended: “But don't hold your breath - no part of the expedition has been quite that predicatable yet!”

When Nereus came came back Friday night, with one thruster hanging on by its cables and only a subset of the data I had hoped we would collect, I asked that we turn the vehicle around as fast as possible and send it back for a short and simple dive next day that would at least confirm we were searching in the right place.

While it was easy for me, as chief scientist, to say that’s what I wanted to happen, it was Andy and his team who had to stay up past 1am that night running repairs… …and the same guys who were up again just four hours later to conduct the extensive tests needed for Nereus prior to re-launch.

So down the vehicle went, right after breakfast, running the shortest mission possible that I thought was guaranteed to pay off. By 10am Nereus was at the seafloor and by midday it had seen some great hydrothermal signals. Wonderful!

Then it drove around in clean, hydrothermal-free ocean water for another 4 hours. Hmmmm…. And those “clean” waters were in the center of my survey areas, the strong signals were along the western-most flank i.e. not anywhere near where they “should” be. Hmmmmm again…. I went back to the map. I was SURE that I knew that the vents had to be along the ridge we were searching because, obviously, there was no way they could be even deeper, on the deep valley floor at around 5000m. Unless they were, and my judgements to that point were all wrong…

By the third Hmmmm it is always good to question whether you really know what you are talking about or whether it is time to think again. And if everything you predicted in science came out just so, how would you learn anything new? So I don’t mind being wrong too – so long as I doesn’t happen too often. Specially not if it leads to discovery of something nobody has ever seen before… But I digress….

In the “old days” of vent exploration by AUV (since we have only been doing this for about 5 years, that means any time up until about a month ago) the only thing to do when you are chief scientist in a situation like yesterday is to:

a) confess to the engineers that your interpretations were quite wrong
b) compliment them that their new machine is working quite beautifully
c) then add that, even so, since the AUV is working in quite the wrong place, you would now like them to abort the whole mission and start over, elsewhere.

(PS: I’ve found that it’s best if you do remember to say “please”, at that last point…)

But welcome to the future…

In keeping with our NASA funding (how often can a space scientist ask if they can have their rocket fetched back so they can re-program and launch again?) our Nereus team pulled off their most cunning new trick, yet, yesterday afternoon. After listening to my problem and discussing with me what the proposed mission plan SHOULD have been, they simply reprogrammed our submarine while it was driving around on the seafloor, using signals beamed down from the ship via sound waves.

No kidding!

It was during the first dive of this cruise that I had seen little snippets of data coming up from the sub via the same technique and I remember Louis remarking to me: “We think this could be extremely useful in the future… …but it may take us some time to work out how to use it to full advantage.” Make that two weeks, apparently.

During the 2nd half of yesterday’s survey (the part that was sent down AFTER the sub was launched), Nereus not only doubled the size of the area of seafloor investigated but, about an hour before its batteries finally ran out of power, it flew directly over the core of a rising hydrothermal plume some 700m up above the very deep seabed down at around 5000m depth. Our map of the plume-sensing data shows us a clear bulls-eye to aim for, with weaker signals on all sides in a survey that means we now have our source tracked to a fraction of 1 kilometer squared.
I think!

Given that I didn’t know where we would end up within 2000 square kilometers of seafloor when we started work, just two weeks ago, that’s not bad. And of course, we’re not done yet. We heard last night that our Leg 2 scientists are already in port in Grand Cayman, awaiting our arrival. But we plan one last dive, starting Sunday, before we head for dry land.

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