Archive for July 22nd, 2011

Roads go ever ever on…

Friday, July 22nd, 2011

"Far over the misty mountains cold (North Atlantic waters)
To dungeons deep and caverns old
(1000m depths)
We must away ere break of day
To seek the pale enchanted gold"
(shores of the Canarys)

Hey all!

I liked the quote that Antonio included in the previous blog entry from J.R.R. Tolkien's Lord of the Rings, so I figured I'd include a quote from The Hobbit.

Challenger 1 is currently staring into the face of an eddy. Like an alluring siren, its currents beckon to us, desiring to reel us in and interfere with our quest. Our muscles and batteries are sore, eyes and oil pump fatigued...the call of the eddy is ever so enticing. But Challenger 1 will not give in, in this moment our glider wings, perseverance, and mettle will cut through the lure of the eddy like a blade through evil; Challenger 1's blunt face deflecting the pull of the currents like a shield against the blows of a mythical hydra.

Our plan is to navigate to the west of the eddy, where we can safely sail for the time being. The overlay for both pictures is sea surface temperature, which has been showing a warming trend reflected in the sub surface data collected by Challenger 1.  In the second picture below, we see that the thermocline has been getting deeper this is a good sign since over the past couple days we have been having a couple pretty important discussions, one of which is on battery life.

 

As we have mentioned in earlier posts, keeping an eye on the batteries is crucial as the battery life of the gliders are shortened when in colder waters such as the far North Atlantic or the Antarctic Ocean.  Since deployment, there has been a bit of unease amongst everyone working on this project from TWR, Iceland, The Canaries, and Rutgers over whether or not our hopes of making it all of the way from Iceland to the Canaries were too ambitious.   But after long discussion it seems we may just have enough. Ruben Marrero, an electronics engineer from PLOCAN who has been at Rutgers for a few weeks came up with a plot that was matched by Lauren Cooney's (Teledyne Webb Research) saying that based off of an estimation of having 718 Amp hours total, ~610 Amp hours left which should give us enough juice to fly until the end of January.  With this estimate based off of our current conditions, it looks like we will be cutting it very close.  We may need to continue looking for ways to conserve battery power to ensure we have enough for the final leg of our journey

 

So far Challenger 1 has gone ~600km of the estimated 4000km it will take to get to the Canaries

Another issue that has been a topic of discussion lately has been bio-fouling.  During the 27 mission, biological growth caused an incredulous reduction in speed until it was cleaned near the Azores.  The most recent talks however have been about whether the bio will be as effective in slowing down Challenger as it was with 27.  Throughout her mission, Scarlet was only flying to about 200 meters due to the grade of her pump.  Now Challenger 1 is class of glider called 'Deep Glider' as it's pump allows it to go down to over 1000m!  The pressure and temperature difference that Challenger goes through as he goes from nearly the surface to 1000m depths is so great, it is theorized that we should slow, if not prevent the growth from occurring.  The debate against this comes form our friends down under at the University of Western Australia who have flown long endurance missions off their coast and have also suffered.  They, however first flew shallow for some time before going deep.  It will be interesting to see if Challenger will be be immune to the biological growth.

By Antonio Ramos ULPGC

By Antonio Ramos ULPGC

The two graphs above come our good friend Antonio at University Las Palmas at Gran Canaria where he calculated how long it took 27 to get bogged down by the bio fouling.  In the first image, he shows that it took us 115 days at sea for the biology to slow us down.  This was through the months of April-August when the North Atlantic is warming with the effects of the summer months and in turn being incredibly productive biologically.  The second graph, shows it takes a little longer to be slowed to 10% speed, 143 days.  We think it took longer for the second bout of growth since it occurred during the months of August-November when the waters begin to cool and become less active.

Gooseneck Barnacle- the main culprit of the bio-fouling that slowed 27's progress

 

 

 

 

 

 

 

 

 

 

 

 

Barnacles and other biological growth seen during the recovery of RU27 "Scarlet" off of Spain

The picture above shows some gooseneck barnacles which will likely be the most common bio fouling we will see flying through the North Atlantic.  With the necks of the barnacles growing out from the hull of the glider, plus the feather-like projections, a large amount of drag is produced as the glider flies through the water column thus severely reducing speed (a lot like opening the flaps on the wings of an air plane to reduce speed).  The effects of these and other little critters will definitely be watched with critical eyes as we go further along our journey.  With Scarlet, we didn't see these effects until about 50 days into the mission.  I think with the waters being much colder where we deployed Challenger we may have bought ourselves some more time.

Seen above, Challenger continues to fly a very smooth path through the water column while keeping a pretty steady vertical velocity of ~20 cm/s.  We also continue to push the records of this glider as over the past few days we came very close to breaking speed records for this mission by recording .46m/hr (our standing record is .47m/hr).  Recently however the effects of the eddy we discussed at the beginning of this post have slowed us a bit as it brings a head current to the glider.

Looking at the satellite imagery of what is going on meteorologically above us, it seems we are now also seeing the effects of our 9th storm since deployment exactly 1 month ago.  It has been a long battle so far for Challenger 1 and there is still much to come!

 

Nilsen & Oliver