Today was a big day! We've officially sealed the habitat, and are now locked in one gigantic hyperbaric chamber. We're actually only at 20 feet of pressure now, instead of our usual 46ish. This means it's getting easier to whistle, among other things. I know there's a bit of confusion about the whole process of decompression, so I'm just gonna take a little walk though our day today. First it may help to have an idea of what decompression means, and what saturation means!
On any dive when you go below certain depths, the pressure increases. On the surface we are subjected to one atmosphere of pressure. At 46 feet, we are subject to 2.5 atmospheres of pressure because the water around us is way more dense than air. This means that more air can be compressed into the same volume of space. So when we breathe here, we are breathing in 2.5 the amount of air on the surface, even if it is the same volume. Make sense?
When the gases are compressed within our bodies at this depth, we are thought of as saturated, which is okay as long as we stay under pressure. However, were we to go to the surface quickly and relieve that pressure, all of those compressed gases would suddenly decompress and expand in our blood and tissues. This is known as decompression sickness, or the bends, and can cause problems ranging from disorientation, dizziness, joint pain, and ultimately death. This is why we go through the process of safe decompression. Decompression is the slow lowering of pressure, so that the gases have time to slowly expand and leave our bodies before we exit the habitat. It requires the use of a hyperbaric chamber, in which we can control the level of pressure to a fine degree of accuracy. This is where Aquarius comes in.
On any dive when you go below certain depths, the pressure increases. On the surface we are subjected to one atmosphere of pressure. At 46 feet, we are subject to 2.5 atmospheres of pressure because the water around us is way more dense than air. This means that more air can be compressed into the same volume of space. So when we breathe here, we are breathing in 2.5 the amount of air on the surface, even if it is the same volume. Make sense?
When the gases are compressed within our bodies at this depth, we are thought of as saturated, which is okay as long as we stay under pressure. However, were we to go to the surface quickly and relieve that pressure, all of those compressed gases would suddenly decompress and expand in our blood and tissues. This is known as decompression sickness, or the bends, and can cause problems ranging from disorientation, dizziness, joint pain, and ultimately death. This is why we go through the process of safe decompression. Decompression is the slow lowering of pressure, so that the gases have time to slowly expand and leave our bodies before we exit the habitat. It requires the use of a hyperbaric chamber, in which we can control the level of pressure to a fine degree of accuracy. This is where Aquarius comes in.
The decompression process begins with a standard change of the CO2 scrubbers, so that we have enough for the entire duration of enclosure within the habitat. We then prepared the door for closing and sealing. Since the sonars we were running require cables to run outside into the water, we had to remove those first. It was quite sad, seeing our tools being put away... but they'll be back up soon for the remainder of the mission and I will control them from topside!
Once the door was cleared, it's important to ensure a good seal on the gigantic steel vault door. We add grease to the o-ring, to help prevent a seal being broken. We then have to go throughout the habitat and open any closed or sealed containers! Just like our bodies, any gases kept within a container will expand as the pressure releases, and could cause little explosions of things like ziploc bags and jars. Once we determined that the habitat was properly prepared, Mark, Ryan, and Jason (the dive medical technician who is decompressing with us to make sure we're okay) gave it a final look over around 3:45 PM, and we go into our bunks for oxygen treatment. At 4 PM, the steel vault door was sealed shut and hammered into place. It was final, we were getting ready to head to the surface!
We begin the decompression process by breathing 100% oxygen for a total of 60 minutes. This aids in the offgassing process, and can speed things up. The masks felt like they were relics of the cold war and were not the most comfortable, but worth it for the safety! It helped that we threw a movie onto Fabien's mini-projector and watched it while we had to remain motionless in bed breathing oxygen!
Oxygen treatment finished, we were now free to move around the cabin. Which, since the wet porch is sealed off, is considerably smaller. I have to say I feel more like a sardine now than ever!
As part of a fun little side experiment, we put a little air into a glove at 46 feet of pressure, and placed it beside the pressure gauge. I've been taking a picture as the pressure has been dropping to see how it changes! The small amount of air placed inside the glove at 2.5 atmospheres has now blown the glove up quite a bit in the lack of pressure. We'll see what it looks like in the morning!
As part of a fun little side experiment, we put a little air into a glove at 46 feet of pressure, and placed it beside the pressure gauge. I've been taking a picture as the pressure has been dropping to see how it changes! The small amount of air placed inside the glove at 2.5 atmospheres has now blown the glove up quite a bit in the lack of pressure. We'll see what it looks like in the morning!
Despite the fact that we are now sealed off from it, the ocean never ceases to surprise us. Tonight we got a fantastic view of two reef sharks coming by the habitat to eat some of the fish in the area! Kip got an amazing video that not only included the sharks, but also our favorite grouper Sylvia doing some eating. All in the same frames! Can't wait to link that for you guys, it was really something to see.
The pressure is still dropping in here, as we slowly ascend to surface levels. In the morning, we will be ready to repressurize the habitat so that when we open it, it will not flood with water. We will then quickly enter the water, and begin a slow ascent to the surface, just as if it were a normal dive. At that point, my journey as an aquanaut will have come to an end. As I've said before, it's a bittersweet feeling, however I am ready to feel the sun. Besides, there's still over 15 days left in the mission, and I plan to be around for as many of them as I can. Not only to continue running the experiments, but also to help the new aquanauts Liz and Grace with their work!
It was really amazing to share this experience with all of you readers, and though my words are inadequate to truly describe this journey, I'm glad you were along to read it. I plan to continue from the surface, but I will likely not be posting daily updates anymore!
For one last time from underwater on Mission 31 and the Medina Aquarius Reef Base... until tomorrow,
- Aubree Zenone, Aquanaut
The pressure is still dropping in here, as we slowly ascend to surface levels. In the morning, we will be ready to repressurize the habitat so that when we open it, it will not flood with water. We will then quickly enter the water, and begin a slow ascent to the surface, just as if it were a normal dive. At that point, my journey as an aquanaut will have come to an end. As I've said before, it's a bittersweet feeling, however I am ready to feel the sun. Besides, there's still over 15 days left in the mission, and I plan to be around for as many of them as I can. Not only to continue running the experiments, but also to help the new aquanauts Liz and Grace with their work!
It was really amazing to share this experience with all of you readers, and though my words are inadequate to truly describe this journey, I'm glad you were along to read it. I plan to continue from the surface, but I will likely not be posting daily updates anymore!
For one last time from underwater on Mission 31 and the Medina Aquarius Reef Base... until tomorrow,
- Aubree Zenone, Aquanaut
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