Mission Day 4
Nerina Holden (Surface-based team leader) 12 August 99: 8pm

The day of logistic's and help.

Today was our first rendezvous with the Aquanauts. Because the Habitat area is not a particularly good site for our coral work 9 (too deep, not enough of the right corals), only Uli, CC and Daryl went out to visit. Ania and I stayed back at the lab to finish processing our coral samples.

CC needed to meet up with Tom to do an underwater light study that would require two dives, with Uli as his dive buddy. Nadav was to be Tom's buddy and the rendezvous time for the first dive was set for 10:30. Greg Buck, our skipper for the day, helped us prepare our gear, everything was packed onto the PISCES, lunch was safely stowed in the cool box, sun protection was applied and everything was ready to go at 8:45am. Then the phone rang; there was a problem at the Habitat. A technical hitch was preventing the Aquanauts from filling their SCUBA tanks. The surface team was asked to wait for the OK before leaving shore, which we got a few hours later. PISCES headed out at noon and the new rendezvous was set for 1 pm.

CC's work with Tom was expected to take a long time, so we wanted to dive using Nitrox. Diving on Nitrox means that you can have more time on a dive. Nitrogen is the main limiting factor determining the length of a dive, so if the amount of nitrogen absorbed by the diver is reduced, he/she can have more time in the water. For a Nitrox dive the SCUBA tanks are filled with a gas mixture that has more oxygen and less nitrogen than ambient air. CC and Tom would use today as a practice dive for their work, it wouldn't take as long as the real thing. An added bonus for the divers today was that they could pop up into the Habitat's wet porch and talk to the Aqunauts.

CC and Tom's work was to film a "contrast target" at different distances, using an underwater camera, through 4 different filters (red, green, blue, and UV). Results from this project will help us to understand how marine animals see things in water, and how animals' eyes are adapted to underwater environments. Knowledge gained from this study may potentially lead to the design of better underwater artificial visual systems. The dive went well and they returned to PISCES with more coral samples and some fish. These were collected by the other Aquanauts and left at the Habitat's wet porch for pick-up at the end of the dive.

CC had not seen the Habitat before; here are his impressions,

"I was impressed by the setting of Aquarius. It allows tremendous bottom time for divers. For example, I would have loved to stay and do more work, if I could stay in the water longer. Other than that, the schooling fish (more than a thousand!) I saw today near the habitat area also impressed me, because this reminds me how complex fish behavior can be."

After the dive, more work was to be done at Conch Reef to help us understand how things appear underwater. Uli and Daryl took light measurements from PISCES, down through the water column, while Justin was doing the same across the water column at the Habitat. This was planned to ensure that both sets of measurements were done under similar weather conditions. As you can imagine, this required lots of communication from PISCES to the Habitat by radio to ensure everything was simultaneous.

All in all, an exhausting but successful day. The rest of the surface team are back in the lab. I will join them now to work the new coral samples that were brought back today. We were hoping for an early night, but it looks like it will be another long one to finish up the lab work.