Hey All!
Today we have a very special post: We have the first pictures from the inspection done last week off of the Azores! But first, Challenger is still flying due east thanks to the navigational help of the current correction keeping us on a b-line to the way point. It looks like we are still about 60 km from being able to make an adjustment to the way point that will allow us to get around the dangerous bathymetry to the south and south east of us.
Now to the inspection.
Early Thursday (10/27), the Portuguese Navy vessel shown below set sail from the port of Praia da Vitoria to sail out to the position of the glider to do an ocular inspection.
On board there were scientists from our partners at Teledyne, the Azores and the Canaries. From left to right: Santos Martinho (Hidrográfico Marinha-Portugal), Eduardo Manuel Vieira de Brito (Centro de Estudos do Clima, Meteorologia e Mudanças Globais, CMMG), Christopher Decollibus (Teledyne), Francisco (Centro de Estudos do Clima, Meteorologia e Mudanças Globais, CMMG), Ángela de Manzanos (Plataforma Oceanica de Canarias, Plocan), Francisco.
The seas were pretty rough, but we had people willing to go out in a zodiac to give this brave glider a proper ocular inspection.
Chris DeCollibus described the glider as being so clean it could have just come off the inspection line. This is great news as we had run into a number of problems with gliders being out for as long as Challenger has. With the RU 27 mission, we saw a large amount of biological growth on the exterior of the glider that accounted for a significant degradation in velocity over time (seen in the plot below).
Plot by Dave Aragon of RU27 Vertical Velocity & Pitch. Before Servicing in the Azores, 27's speed decayed at 3.25 cm/s due to biological growth
What caused this reduction in speed is the presence of the goose neck barnacles. When these organisms feed, they spread out their fan like appendages that allow for their filter feeding. When these fans are spread out when the stalk of the barnacle is on a glider, this can cause a large amount of drag which leads to a massive reduction in speed.
Goose neck Barnacles: The main culprit in the degradation of glider velocity
What makes it even more remarkable about the fact that Challenger has withstood any biological growth over the past 130 days at sea is that there is no anti-bio fouling paint. What we believe has allowed Challenger to survive unscathed is the immense difference in temperature and preasure the glider sees everytime it goes from the surface to depth
After concluding that the glider was still in exquisite shape, he was sent back on his way to finish his mission.
With the way the surface currents have a flow due south while the glider is recording currents flowing in a 180˚ difference due north, it is best to keep the way point where it is for now and allow the current correction setting to continue doing an excellent job flying us straight to the east past the numerous sea mounts in the area (seen in the previous post).
Once we get out to the east past Sao Miguel and Santa Maria, we can move the way point potentially to about 36 N 21 W (depending on what the currents are doing) to then allow us to cut down to the south on our way to the finish line.
Lauren Cooney, Antonio Ramos & Nilsen Strandskov