Category: Challenger Mission (Page 16 of 37)

Hey All!

So just about a week ago, Challenger crossed the EEZ of the British Overseas Territory of St Helena

St Helena is a volcanic island along our path that is a territory maintained by the UK.  It stretches just 10 miles across and out of its population of roughly 4,000 people, we have been able to find a man willing to help us out!

In the northwest sector of the island, along the shores of the cities of Jamestown and Ruperts, there looks like there is significant boat activity.  One of these boats will be setting sail within the next month equipped with means of communication back to the COOL room where we will provide shore support as our volunteers sail out to Challenger inspect her and scrape off the suspected biological growth we suspect has been causing our technical issues.

Over the past few weeks, Dave has been hard at work with Scott adjusting the gains and settings on our flight parameters, tweaking and adjusting ever so slightly until they were able to trim our heading error down to a fraction of what it was.  However, due to what ever has grabbed hold of the glider we are no longer able to use the currents calculated by the glider for navigation.  As it turns out, the algorithm that is used to create these vectors is meant for use on a clean glider and does not account for drag.  So, as barnacles grow and create drag, the algorithm can mistake this as a head current.

With the latest numbers, Challenger has been flying between 10 and 11 km/day. Being just 250 km from the western shores, that leaves us just 25 days from the island.

Although we are almost there, there is an obstacle in the way; one last seamount.  Just 35 km to the south west, we are trying for some evasive maneuvers by moving the way point a bit to the east to allow us to fly to the south of the sea mount.

Looking forward, based of the latest calculations, Challenger has roughly 150 days of battery left based off a energy usage of 2.5 Ah/day which was what we maintained before and after the siesta back in May. If after the cleaning, we are able to maintain 20 km/day Challenger will be able to make easy work (relatively) of the transit from St Helena to Ascension Island.  There we can easily get a technician and fresh batteries out to prepare the glider for the next voyage.

To the North, Silbo has been doing a fascinating job as a drifter following the North Atlantic Gyre.

He has been drifting over 25 km a day over the past month and heading right for the Caribbean.  Now just ~80 km from the EEZ of Barbados and ~450 km from the eastern shore, Silbo seems dead set on hitting his finish line and taking a break even without the ability to control his movements.

The forecast even seems to be in our favor as tomorrow the surface currents seem to shift from North/NorthEast to more North West, further towards the Caribbean.  In the coming weeks a recovery mission may need to be planned as Silbo moves further towards shore.

Force Wind Sea & Honor

Hey All,

For two years now, Silbo has sailed the North Atlantic providing us with valuable, never before seen data while pushing the limits of what aquatic rotobics can achieve.   After being left to the will of the surface currents just over a month ago, he has continued to drift to the west now just 800 km from the northern shore of French Guiana and 950 from Barbados.

To the south, Challenger is continuing to fly towards St Helena, forcing her way through the eastward current.

In the myocean dataset, there is a strong surface current flowing to the North East in the <300m portion of the water column with the lower portion deviating a bit with less intensity.  However with this map the entire region is flowing away from St Helena with sparse option on an ideal path to get to our destination

The Hycom doesn’t look too promising either, as it has the currents flowing consistently due north with little variation throughout the water column.  These currents could only be a little more useful than myocean as the angle we are flying into would be less of a fight.

Finally, the glider team has been working together a budget over the past week continuing to weigh our options for a St Helena recovery.

Force Wind Sea & Honor

Hey All,

I just wanted to leave everyone with a quick recap of what has happened over the past few days:

Our team of pilots and technicians from RU and TWR have been working hard analyzing the steering data from Challenger trying to get her to fly better.  Last week, she started spinning occasionally on her dives and so we have been working to try and diagnose the problem and apply a fix.

We have also officially decided that we will recover in St Helena.  With Challenger just 480 km from the northern shore, Tina Chip and Dave have continued contact with the travel agencies that are familiar with the island.  Through here we have been able to confirm that we are able to get to the island by flying into Cape Town South Africa and taking a 5 day ride abord the RMS St Helena.  Today we also received confirmation that we will be able to get a new set of lithium batteries shipped to where we will need them in order to re launch Challenger after the recovery operation.  Chip was even able to secure us a ~40 ft sailboat as long as we are able to get to the island before the end of August.

To the north, Silbo continues to drift, now just 900 km from French Guiana as our friends up at TWR continue to try and find a way to rescue our brave little droid.  Sunday the 23 marks the 2 year anniversary since Silbo was deployed up in Iceland at the beginning of his journey.

Force Wind Sea & Honor

Hey All,

Today I finally made some progress, creating a map of the RTOFS data at depth, allowing us to see the sub surface currents that dictate the forces behind Challenger’s movements.

This now lands us with 3 road maps, all providing us with a various views into the depths of the oceans.

In the image above, HyCOM (the bulkier vectors), RTOFS (blue vectors) and myocean (red vectors) all show a strong flow to the north at depth (300m is shown) with various tendencies following depending on which model you refer to.  Seeing this consistency is  remarkable, however Challenger’s depth average currents are in disagreement, showing a current flowing strong to the south east, following the trend seen since we left the South African Shelf of an overall flow to the east.

It is possible that this is simply due to a lack of data fueling the models as there is a large gap in the locations of the drifters in the area.  Speaking with Antonio today, he provided us with a very interesting theory.  Pointing out that since we left the shelf and started flying deep, we have seen currents flowing in some way to the east, Antonio suggested that this may be a replenishment of the upwelling zone that covers most of the western coast of Africa.  The logic behind the theory is that the water coming up to the surface does flow from the west to the east sub surface before rising up along the shelf.  It could be possible that this is the eastward flow Challenger has been seeing.

We also hypothesize that this flow will be broken up by the line of sea mounts that lay ahead of us:

But getting to this line has become an issue.

As I have mentioned previously, Challenger has been performing sub par since we have regained contact after the no coms from May 15-25.  Since then the glider has been much more sporadic in her flying and much slower as well. Because of this, our testing continues as we try and diagnose the problem and see what we have to work with and from there extrapolating the data to see what our options are over the next few months.

From our daily glider meeting, we made a time line of tests to run on the next three surfacings.  For the surfacing that occurred just moments ago, we increased the data being pulled from the sbd files during file transfer to confirm that by flying in low power mode, the science computer is fully turning on and off as we think. This is an important question for us to determine how much battery power we have to work with. Chip also told Challenger to collect data on both the down and up casts on the CTD that way we can confirm it is working properly after our 10 days at the surface. Finally, we increased the pitch angle to 30˚ in an attempt to increase our velocity.

For tomorrow’s surfacing, we plan on turning the CTD completely off to get a better feel on how much power the increased pitch angle will actually draw over a 3 yo segment.  And then on the following segment,  we will increase the pitch further to an angle of 35˚ to see what effects that has on our speed and battery power. This issue has become more daunting as we get a better handle on the velocities Challenger has been hitting along with the remaining battery power.  With our decrease in speed and the projected further rate of decay, it is looking like it may take us upwards of 145 days to reach Ascension.  With only having roughly 180 days of battery left, there are some big decisions headed our way.

Finally the last alteration we made was that we added a new way point to Challengers repertoire.  Over the past day, the currents had rotated a bit to the south east, resulting in a flow that was contradicting our attempt at progress in nearly the opposite direction.  So after a discussion with Scott, we moved the way point a bit to the south, hoping to cause less of a struggle against the current, but also to keep our options open.

We are just about 600 km from St Helena.  So as we continue our tests to asses the state of our glider, we figured it would be wise to keep this island in mind as a last resort if it turns out that it is too risky to push onwards. From there, we may even do a short mission as we did with Silbo’s run from the Azores to the Canary Islands, taking Challenger with a pack of alkaline batteries (much more easily transported than lithiums) and continuing our flight to Ascension.

In other news, Silbo is continuing to drift at the surface as we weigh our options for a recovery mission for the poor guy

Since blowing his weight and becoming a drifter on May 19, Silbo has made roughly 100 km progress westward.  Now just 1280 km from Barbados, we can only hope he can continue to drift towards the islands where it will be much easier to conduct an emergency rescue.

Force Wind Sea & Honor