Scope
This document summarizes the experience of the 2002-2003 AGO field service team. It includes observations and suggestions for the future plus some of the notable events.
Also attached are:
· documents prepared by RPSC staff which provide logistic, inventory and other detailed information.
· Sample plots from the field
· Field Photographs
These documents should provide a useful reference for future field teams.
The mission of the AGO Service Team this season was to implement a new power control, thermal and data transfer strategy at three AGO locations: AGO-1, AGO-2 and AGO-5.
The change in strategy can be summarized as follows:
· Power: new power control system which ends reliance on propane/TEG and uses only solar power. At one site (AGO-1) we also implemented a wind power system.
· Data: switch from reliance on data archived to hard disk and retrieved once per year to continuous near real time data transfer via Iridium modem/satellite connection
· Thermal: switch from heating entire AGO building to placing all instrumentation and electronics within one 19” rack, then heavily insulating and warming that.
Three people went into the field this year:
* Rick Sterling (SSL/UC Berkeley)– PI representative and responsible for the power system conversion.
* Tim Chevalier (Stanford) - responsible for science instrumentation evaluation and checkout; iridium transmitter and insulation installations.
* Erik Barnes (AGO-2), Brian Johnson (AGO-1, AGO-5) – RSPSC staff from Field Safety and Training Program. Responsible for camp coordination, infrastructure maintenance and communication with McMurdo.
While the divisions of responsibility were fairly clear, we worked together as needed and teamed up when it made sense for more than one person to do a job. Camp maintenance, cooking, cleaning, setting up, etc was informally shared among all the team.
Mid December – We flew to South Pole for staging to the first AGO location, AGO-2.
Late December – Carried out work at AGO-2. In addition to the expected tasks, we raised the hut. Christmas in the field.
New Years - Completed AGO-2 work and returned to South Pole for New Years Eve. Spent couple days there.
Early January – Worked at AGO-1. Installed two wind turbines in addition to the other work.
Mid January – Worked at AGO-5. Less to do and procedures down pat. Completed necessary work in three days.
Late January – Tim flew to NZ. Rick stayed to wrap up project. He went into field on January 28 to investigate problem at AGO-1 where data output stopped on Jan 15. Rick departed McMurdo for NZ the next day, January 29.
TRANSPORTATION
We needed two flights for each of the AGO station put-ins. We left each site with one flight. Maximum payload including passengers and cargo (ACL) is approximately 2000 pounds. This number is somewhat flexible and dependent on flight length and fueling plans. We used 300 pounds as the standard weight per person with gear and that seems a fairly accurate estimate.
Depending on the amount of equipment that needs to go into sites, it may be possible at times to have one put-in flight. That will require reductions in food and communication equipment weights but that should be viable.
This site was very low and it was necessary to raise the hut. The hut raising turned into an adventure due to the cranking mechanisms breaking. When the near miss occurred we immediately discussed and implemented safety measures. However Tim and Erik deserve much credit for carrying on and completing a task which had been proven to be dangerous. A “near miss” report was submitted and a copy is included with this document set. It is important that the recommendations from that report are implemented before the next AGO lifting is attempted. Essential elements include new and stronger cranks, fail-safes, and detailed written procedure.
The TEG at this site worked well for heating the hut. We left the TEG with 24V battery in place so that the next team should only have to turn on the ignition switch.
POWER, DATA ACQUISITION, ETC.
We removed the old power control and data control unit. The hard disks are being shipped back to U Md. for possible data retrieval.
We dug battery pits over six feet deep to bury the nickel-cadmium batteries. We measured 14 degrees (celsius) difference in snow temperature between the top and bottom of the pit.
The new power control chassis was installed, wired to solar panels and new batteries. Iridium transmitter installed on roof. Data Acquisition Watchdog and Modem chassis installed.
SCIENCE
All science instruments and electronics powered up immediately after being powered with +28V.
The searchcoil magnetometer initially appeared to not be working properly. Tim checked and improved connections and shielding. Observed strong response from instrument to HF communication. Seems to be working now.
Fluxgate magnetometer needed adjustment.
Before Adjustment: H = +08.820 D = 0.0 Z = 22.850 (but turned OFF)
After Adjustment: H = +09.140 D = +00.854 Z = -25.080
Other instruments appeared ok.
Current measurements as follows (+28Volts) :
DAU – 190 mA
Iridium – 90 mA
All Sky Camera – 95 mA
Mag Fluxgate – 145 mA
LF-HF - 40 mA
Riometer - 160 mA
Mag Search Coil – 70 mA
VLF – 350 mA
Electronics were all placed within one insulated 19” rack. Heating is provided by one 7.5 watt heater operating off the 12 volt battery control unit as long as battery is at 10.5 volts or higher.
Data flow to Maryland lost during the last night at the site. Power cycling made no difference. LED on front panel indicated there was power to the modem. We replaced the DAW/modem chassis with chassis intended for P5. This unit was coming in from outdoors and initially cycled the +5V switched power on and off. After it warmed up in the hut, it worked OK. The problem was subsequently identified as a temperature-related fault in the DAW power circuit, which will be repaired at all sites in the next servicing season.
Visited January 2 – 13
Hut did not need raising. Very little accumulation.
One window is cracked. It might be good to take a replacement piece of glass next season and be prepared to fix. The windows are double paned and quality manufacture and design.
TEG would not start. We used the “black cat” catalytic heaters which are very adequate. Using two of them the temperature of the hut can be raised to 65 – 70F in about a day. After that we frequently only needed to run one of the heaters. Prudence is needed since the heaters can burn clothing or other items which are left in contact with the heater surface.
Installed wind turbines over two days. Tilt-up mast design worked well. There is a diversion resistive load within the hut. Each wind generator immediately started generating 2 – 3 amps (12V). Wind battery was the highest charge and powering the load.
Wind at 10 – 25 knots per hour for 90% of the time during our visit.
Solar panels in good shape. Solar control system installed
without problem.
Fluxgate Magnetometer Settings:
Initial Bias Settings: H = +7.221 D = zero/off Z = -28.940
Left H and D as above. Reduced Z bias setting by 220 nT
Final settings are:
H = +7.221
D = zero/off Z = -28.830
All instruments appear to be working and within spec.
We removed the small VLF antenna which was left standing within the larger VLF antenna.
AGO-5
Visited January 13 – 16
INFRASTRUCTURE
This site needs some maintenance/repair. The interior has been saturated with propane and the mattresses and carpets should be removed and replaced. In addition there is a crack in the bottom of the hut and after the hut is warmed up, there is a continual saturation of the floor/carpet. The washers and bolts which were used to mount the solar panels have rusted badly and led to significant rust stains on the walls.
In summary the following should be done:
· remove mattresses and accessible carpet squares
· seal the crack in the bottom of the hut with fiberglass repair materials
· determine source of moisture in the hut and resolve
· install new mattresses and carpet squares
· replace existing washers/bolts with stainless steel
· wash and paint walls where washers/bolts from solar panels have left bad stain
Ice invasion at door because of poor door seal.
Next visit should allow one or two days for fix up and repair.
TEG does not work. We used the “black cats” but it was still unpleasant with propane smell and saturated floor.
POWER SYSTEM
We removed the old data control unit and
power control system. The hard
disks are being shipped back to U Md for possible data retrieval.
· Replaced one broken solar panel. It appears to have been broken due to a mishap involving the hinged storm window. The long hinges have been removed to prevent this from recurring.
SCIENCE INSTRUMENTS
· We removed the VLF receiver and associated electronics. This is intended to become a engineering model for testing and comparision at Stanford.
· The All Sky Camera does not work even though all the cards were replaced with new units. The optical assembly needs to be retrograded. A proper carrying case should be provided to the next team which visists the site.
· Other instruments working okay.
AGO-1
After working for 10days data stopped being received from AGO-1. A trip to the field was arranged to investigate and fix if possible. At the site, the temperature inside the thermally enclosed rack was tested. With the temperature in the hut at –20C, temperature inside the rack was +5C even with no +28V output. The source of the communciation failure turned out to be with the dc converter. It was not possible to fix, so the unit was brought out for further analysis and correction. The batteries, wind turbines and solar panels were all doing fine, making it doubly frustrating to see failure of something that should be reliable.
AGO-5
Data was being received through Sunday Fe bruary 9. It has not been received since then. Prior to that, there were fairly frequent interruptions in the data transmission. The data would usually resume after 2.5 hours or some multiple of that, suggesting that the data acquisition watchdog was generating a reset which enabled recovery.
AGO-2
This site is working fine.
Checkout of the failed DAW/Modem control chassis from AGO-2 indicates the failure was caused by a bad solder joint at a power connection point.
The essential plan seems sound. For the most part, the sensors and science electronics seems to be rugged and working well. Regarding the specific changes:
· Thermal Enclosure - Preliminary results indicate that the small thermal enclosure will enable a good working temperature for the electronics.
· Data Transfer via Iridium - While there are fairly frequent communication drops with the Iridium modem/satellite connection, experience seems to validate this as a viable method of sending 15 – 20 MB per day.
· Solar Power System - The solar panels are reliable and rugged and should provide ample power for summer power needs.
· Wind Power - The wind turbines performed well while they could be observed and when visited later. It will take more testing to determine how they perform over time and through the winter.
· Smaller service team – This worked fine. We were fortunate to have very good and hard working staff from FSTP.
· Power Conversion – limited success. Some design modifications and more thorough testing including thermal testing is needed.
Following are additional suggestions for consideration:
· Insure adequate housekeeping information (voltages, currents, temperatures) to assist in trouble-shooting
· Transmit some of the housekeeping information via ARGOS
· Continue servicing AGO stations with three people (two from science/engineering; one camp coordinator)
· Continue servicing AGO stations utilizing only Twin Otter
· Implement much more duration and thermal testing of the electronics before the service season.
Overall it appears the science equipment is rugged and in decent working order. Although it will take some more time, it still seems viable to successfully complete the transition to a new way of servicing and operating the AGOs.