|February 2, 2007
Resolution. John Kerr was up at dawn and on the cell phone with Nigel Jones going over possibilities for why the new disconnect boards were not functioning. After a few rounds the problem was isolated to one particular chip. John then began methodically testing that chip and found one of the eight tiny solder connections to be non-contacting. When he re-soldered that the system came up. With this resolved we completed the checkout of the E-stop system with the batteries (now fully charged) back in the loop. John then powered up SIOP (the system basic Input-Output onboard interface computer) and was able to interrogate the various sub-systems and their associated sensors. The batteries were online and giving good readings and, following entry of the local GPS coordinates which Vickie Siegel collected outside the lab, the IMU portion of the guidance system came up with a proper alignment.
Above: Vickie Siegel doing final checkout on the 100m sonar array
Above: John Kerr (SAS) interrogating the bot with the microRAPTOR real-time interface tool from the lab.
Above: Screen capture from microRAPTOR showing both batteries online and charged (a very good thing indeed, considering where we were on Tuesday !).
Above: Vickie Siegel and John Kerr with DEPTHX at 10pm on February 2. We are now about one day from being fully operational, assuming no more field glitches.
At this point we continued with routine assembly tasks until 10pm. Marcus Gary meanwhile had completed installation of ceiling vent fans in the lab. Although seemingly unnecessary given the cold temperatures we’ve been experiencing the past few days, it will be required once the normal hot weather returns.
In all, a very good day. Barring any unforeseen problems we should have the bot close to complete assembly by late tomorrow and ready for transport to cenote La Pilita on Sunday, where we will begin the first true exploration field tests in a truly unexplored environment.
February 3, 2007
We made rapid progress today, despite the ever-increasing bad weather (from the same arctic front that dropped temperatures in Colorado far below zero - project microbiologist John Spear wrote by email indicating that it reached -25F in Golden, but here in Tamaulipas it came as a steady cold downpour).
Above: John Kerr carefully loading Battery Pod 1 into DEPTHX. Each of the two Lithium-Ion battery stacks contains the energy equivalent of 6 lbs of TNT.
Above: Vickie Siegel works on the water sampler sub-system of the biology payload for DEPTHX.
Both onboard battery systems were successfully brought online today and after a complete change of all canister and cable connection orings we loaded the two Li-ion packs into the bot (see photo). It is difficult to explain the care and attention that one must pay to such a high energy source, but the following energy conversion may be of help: each battery pack in DEPTHX carries the energy equivalent of 6 pounds of TNT. Having loaded all of the main computer and electronics pressure housings we turned our attention to the science package, where changes had to be made to place the water collection containers in an easily accessable outboard location so that they could be removed at the conclusion of a science mission without disassembling the entire probe sub-payload. By 10pm we had all systems installed and had confirmation of hardware powerup and software communications with the main cPCI computer pod, the guidance unit, velocity logger, environmental sensor suite, depth sensors, batteries, science package, and the 200m obstacle avoidance sonar array. Only the motor controllers and 100 m sonar arrays remain to be tested in the morning before the bot is fully operational. Marcus Gary left basecamp around 3pm to pick up the Carnegie-Mellon portion of the crew at the Tampico airport. They arrived just before midnight. The rain is coming down hard now.
February 4, 2007
February 4, 2007
Today was an extremely busy day. With our crew now expanded to eight we held a team meeting at 8am and divided up the tasks for the day. Our crew contingent as of today includes:
- Dave Wettergreen (CMU), George Kantor (CMU), Nathaniel Fairfield (CMU), Dom Jonak (CMU)
- Marcus Gary (UT Austin)
- Vickie Siegel (SAS), John Kerr (SAS), Bill Stone (SAS)
Following final checkout of the electronics pods and software communications interfaces we rolled the bot out of the “garage” and began loading the four orange syntactic flotation blocks (see photos).
Above: Left to right: Alejandro Davila (owner of Rancho la Azufrosa), Nathaniel Fairfield, Marcus Gary, and Vickie Siegel look on as DEPTHX gets its final software verification.
Above: Nathaniel Fairfield (left) and John Kerr load the syntactic foam flotation blocks.
Above: the conditions we were working under.
Above: Marcus Gary ably drives the bot to cenote La Pilita, a 4 wheel drive journey of about a kilometer which we successfully completed in about 30 minutes.
The syntactic is a special glass-sphere-filled foam that remains nominally incompressible down to a kilometer depth underwater. We use this to make the vehicle initially precisely neutrally buoyant (neither sinking nor floating). The entire operation was complicated by the strong, steady dounpour as the unusual weather persisted.
Once the syntactic was bolted down Marcus Gary drove the bot to cenote La Pilita where the first true exploration field tests would begin tomorrow. Divers Jim Bowden, Ann Kristovich and others have made initial reconnaissance descents that indicate that La Pilita seems to have a bottom at around 100m, but very little else is known because of the reduced visibility and limited range of diving lights
Thus, the geometry remains unknown as does the potential presence of passages that extend off the entrance shaft. Because of this, we have prepared a safety tether for the initial descents that includes a fiber optic communications line and a 1500 kg test dyneema retrieval line. The entire umbilical measures only 3mm in diameter. However, because of the potential for line snags we planned to feed the safety tether through a high pulley suspended over the center of the cenote.
|Above: Vickie Siegel scales a few phone poles to install a high line support for the vehicle safety tether at cenote La Pilita.
To enable this Vickie Siegel used Yosemite style aid climbing equipment to scale a series of telephone poles that had been installed for lighting around La Pilita some years ago. Once the high anchor points were in place the pulley was drawn up through a central second pulley at the mid point of the horizontal high line over the cenote.