Invited Talk

Carol Raymond, Jet Propulsion Laboratory

Past Experiences and Lessons Learned

Many investigators have years of experience with autonomous systems in extreme environments. Careful design and engineering is crucial for a successful system, however, much can be learned from practical experience. Unanticipated feedbacks have occurred within systems, winds and temperatures have proved more extreme than anticipated, and methods for data retrieval or system deployment have changed with time. Accounts of successes and other experiences from current investigators will prove invaluable in formulating recommendations for future autonomous systems within polar regions and other extreme environments.

The most extreme example of systems that survive hostile conditions for long periods is spacecraft. Talks will address experiences investigators have had with spacecraft that could be pertinent to our problems with autonomous systems on Earth. The challenge will be to identify cost-effective solutions that aerospace engineers have identified that can be transferred to terrestrial applications.

Ocean floor observatories are under development for siting in sea floor boreholes and at active spreading centers such as the Juan de Fuca Ridge (under the NSF RIDGE program). The Juan de Fuca Ridge has been selected for focused development of a comprehensive ridge crest Observatory. Two segments within the ridge have been chosen for focused long-term sea floor instrumentation. The Ocean Seismic Network (OSN) Experiment will emplace a broadband borehole seismometer in a cased borehole paired with a sea floor seismograph at the same location. The borehole has been dubbed B3S2 (BroadBand Borehole Seismic System) and the seafloor and buried broadband system is called BBOBS (BroadBand Ocean Bottom Seismograph).

Anandakrishnan, S., D. Voigt, P. Burkett, R. Henry, B. Long
University of Alabama, Penn State University

ANUBiS; Antarctic Network of Unattended Broadband Seismometers

The goal of the Antarctic Network of Unattended Broadband Seismometers Project is to deploy a network of a dozen seismometers that will record data throughout the year. Four stations will be at existing Automated Geophysical Observatory (AGO) sites in East Antarctica and seven will be at sites in West Antarctica that are powered by wind- and solar-energy. These data will fill a huge lacuna in the global seismic dataset and provide valuable new information about the Antarctic crust and mantle structure.

Ashley, M., J. Storey, and M.Burton
University of New South Wales

Lessons learned from running astronomical instruments at the South Pole

In collaboration with the US Center for Astrophysical Research in Antarctica (CARA), we have designed and deployed a number of astronomical instruments at the South Pole since 1995. These have included tip-tilt mirrors driven by piezo transducers, miniature stirling-cycle coolers, small telescopes (0.5-cm, 30-cm and 60-cm aperture), PC/104 computers, web cameras, and sundry rotating gizmos (chopper motors, gearboxes, etc). We have written reliable software that is able to run autonomously or be controlled and updated remotely.

The Antarctic environment is in many ways more difficult to design for than space: there are large temperature extremes, atmospheric pressure changes, convection, and wind-blown ice crystals to contend with. We have had successes and failures in deploying remotely-operable and autonomous instruments in Antarctica. This talk will describe our design philosophies and the lessons we have learned.

Box, J.E. and K. Steffen
CIRES/University of CO, Boulder

Automatic weather stations in Greenland

Beginning in 1995, a network of automatic weather stations were installed on the Greenland ice sheet as part of NASA's PARCA program. Each year, between 1 and 5 stations were added to the network. As of the 1999 field season, the Greenland Climate Network (GC-Net) consists of 18 stations distributed widely over Greenland's inland ice. The system samples 27 surface climate parameters on minute time-scales, averages, stores, and transmit the hourly data via GOES and ARGOS satellites to ground stations from which the data are retrieved automatically using the internet and posted on a web page (http://cires.colorado.edu/people/steffen.group/aws/main.html). The stations are powered by large battery packs stored in the snow and recharged by solar panels. So far, our success rate has been over 90% for more than 3.5 million hourly averages.

Chadwell, C.D., J. A. Hildebrand, F. N. Spiess, S. Wiggins
Scripps Insitution of Oceanography

Autonomous Sea Floor Geodetic Monitoring using GPS and Acoustic Measurements from an Oceanic Buoy

This is a 3-year project to develop GPS/Acoustic technology that can operated autonomously from a moored buoy. This technology will monitor continuously undersea crustal deformation in a coastal region where the potential for catastrophic events pose a natural hazard.

From top to bottom, the geodesy buoy is comprised of three main assemblies: electronics platform, flotation/exoskeleton frame, and ballast/transducer stinger. The complete package weighs close to 7000 pounds, is 21 feet from top of GPS radome to bottom of the transducer and has a waterline near the middle of the flotation. At the top of the buoy is the electronics platform. It consists of three GPS antennas, housings for batteries and electronics, solar panels, and a radio antenna. Placed 3-1/2 feet above the deck of the buoy on 20 inch diameter tubes are the GPS antennas, housed in radomes, are spaced 7-1/2 feet apart in an triangle/three-spoke configuration. There are three stainless steel weather-resistant, electronic housings. One is used for battery storage, one for data acquisition, recording, and radio transmission electronics, and one for the GPS receiver electronics. They are cabled together via stainless steel conduit.

We will report on the initial test of this system conducted June 1999.

Cobbett, N.
British Antarctic Survey

I will aim to present a poster on the UK Antarctic AGO programme and a new engineering project - Remote Low Power Magnetometers. These experiments operate remotely on the Antarctic plateau between Halley Research Station and the south pole. We are currently operating 5 AGO sites and 2 LPM sites in Antarctica.

Conquest, C. and B. Johns
UNAVCO

UNAVCO Remote Continuous GPS Station Support - Power, Communication, and Data Management

The UNAVCO facility has supported the installation of over 150 continuously operating GPS stations worldwide and currently monitors the operation of 194 stations. These include stations from the NASA Global GPS Network and various NASA and NSF funded regional networks. From supporting these efforts, UNAVCO offers experience in remote, autonomous GPS site design and support to the GPS science community. Areas of design and field experience include year-round solar powered autonomous GPS sites and data relay stations; data telemetry via radio modem, microwave links, cellular and land line telephone modems to internet sites; low power, low cost L1 autonomous TDMA systems for remote, high density applications; automated GPS download software; and power management strategies. Recent efforts of support include facilitating collocation and integration of various sensors including GPS receivers, seismometers, and MetPaks, in cooperation with JPL, IRIS, NOAA, and individual investigators working in Antarctica and other remote locations. UNAVCO and JPL are collaborating on a VSAT demonstration project to test a low power (~20W), environmentally robust remote satellite data retrieval system.

Donnellan, A., B. Luyendyk, T. Rebold, M. Smith, H. Awaya, B. Nesbit, and G. Dace
Jet Propulsion Laboratory, Antarctic Support Associates, Acumen Instruments Corporation

Autonomous GPS Stations in Marie Byrd Land, Antarctica

During the 1998-1999 Antarctic field season, we installed three autonomous GPS stations in Marie Byrd Land, West Antarctica to measure glacio-isostatic rebound and rates of spreading across the West Antarctic Rift System. The systems collect data throughout the entire year and therefore must function during the warm, relatively mild summer, and cold, harsh winters. They are powered by gel cell batteries that are charged by wind and solar power. The system includes dual data logging capability. We log data at 5 minute intervals within the receiver and at 30 second intervals to a serial data logger. We do not require 365 days of continuous data for well determined crustal velocities, but rather long periods (24 hours) of continuous data distributed throughout the year. Therefore, for simplicity, we designed the system to accept occasional data interruptions. The batteries, in addition to supplying power, act as a thermal capacitive heat storage device to help regulate the temperatures within the system. This storage system absorbs the majority of the 10-15 watts of power from the receiver and 5 watts from the data logger which helps to maintain temperature for long periods of time. Power is switched off when the temperature within the system enclosure reaches 50 degrees C and is reconnected at 20 degrees C. If battery voltage drops too low the batteries will freeze. Therefore, we cut the power off when the batteries drop to a low voltage of 12.45V. Power is restored at 13.2V. The temperature and power hysteresis allows for a minimum of several days of data to be collected before system shutdowns. A check of all three stations in late January 1999 indicated that the thermal and power control systems are performing as expected. We plan to implement satellite telemetry to the systems during the 2000-2001 season following a year of development.

Flynn, M. and J. Hines
Ames Research Center

The study of life in extreme environments provides and important context from which we can undertake the search for extraterrestrial life. The NASA Astrobiology program is currently working to develop the capability to conduct in situ long-duration physical, chemical, and biological investigations of extreme environments. Although these systems are being developed to support generic extreme environment research, the initial target for implementation is deep ocean hydrothermal fields.

Currently, the two most likely targets for the search for extraterrestrial life are Mars and Europa. In both cases, the existence of hydrothermal energy sources is widely considered a prerequisite for life. Developing innovative strategies to explore analogous terrestrial ecologies and the life forms they support will provide insights into how and where to explore these planets/moons.

The objective of this program is to develop an integrated instrumentation platform capable of supporting a wide variety of life in extreme environments research. This activity will focus on both the development od specific instrumentation and the infrastructure required to effectively utilize these instruments. The following tasks are being addressed:

Environmental characterization
Sample Targeting
Sample acquisition
Sample analysis
Data acquisition, storage, and transmission
Power generation
Power distribution and storage
Mobility

Hamilton, G. and I. Whillans
Byrd Polar Research Center, The Ohio State University

We are using remote, autonomous systems to understand important glaciological processes related to the mass balance of the Greenland and Antarctic ice sheets. The work builds on our experience of measuring mass balance using very precise GPS surveys (the coffee-can technique).

The system - RASCAL - has been developed for two purposes. The first purpose is to provide control for measurements obtained by satellite radar altimeters, such as NASA's forthcoming ICESat. Satellite laser altimetry offers one of the best opportunities for measuring the large-scale mass balance of ice sheets. Very precise measurements of ice sheet elevation can be obtained routinely over very large areas. Interpreting elevation changes in terms of mass balance is more problematic, however. Transient variations in processes occurring at and near the snow surface, mainly snow accumulation and firn compaction, complicate interpretation of altimetry data.

RASCAL is designed to make continuous measurements of these processes at sites where we are also measuring long-term mass balance using the coffee-can technique. The study will allow us to link short-term variations in snow surface elevations, as measured by laser altimetry, to the long-term rate of ice thickness change. The second purpose of RASCAL is to study processes responsible for spatial variations in snow accumulation rate. Several studies have described large variations in accumulation rate for sites located a few kilometers apart but on different slope gradients. Differences in katabatic wind speed are hypothesized as being important.

We plan to deploy RASCALs at two sites near Byrd Station in West Antarctica, where large differences in slope and accumulation rate are already known. The systems will make continuous measurements of snow surface elevation (accumulation), firn compaction and wind speed. Results from this study will be important for the interpretation of ice core records. RASCAL is designed using off-the-shelf components. The system is based on, and resembles, an AWS. Mounted above the surface on a tower are ultrasonic ranging sensors, air temperature probes and wind speed/direction sensors. A subsurface box attached the tower contains several linear transducers for studying firn compaction by making continuous measurements of the lengths of wires installed at various depths. Thermocouple wires for measuring firn temperature at several depths are installed in an adjacent hole. Initial field tests of RASCAL were conducted at Siple Dome, Antarctica. One system is currently deployed at Summit, Greenland and several new systems will be deployed during the ITASE (International Transantarctic Science Expedition) traverses, beginning this austral summer.

Rall, J.A.R. and J. B. Abshire
NASA Goddard Space Flight Center, Laser Remote Sensing Branch

We have developed a compact, autonomous, ground-based atmospheric lidar instrument to sense Polar Stratospheric Clouds (PSCs) from an Automated Geophysical Observatory (AGO) situated on the Antarctic polar ice sheet. The AGO program is sponsored be the National Science Foundation and the United States Antarctic Program. Each of the six AGO platforms currently installed in Antarctica provides electric power, data storage and a stable thermal environment for up to seven instruments. One lidar instrument has been installed in AGO Platform P1 at 83 degrees south latitude, 129 degrees east longitude, and at a surface elevation of approximately 9,500 ft. The design constraint for our lidar instrument included high altitude/low pressure (600-700 mBar), extreme temperatures (-80C to +30C), extreme humidity, and severe vibration environments due to aircraft and general handling.

Sanders, L., C. Odom, J. Kelley, D. Dasher, S. Read, F. Levno-Chuthlook, A. Orr, W. Splain, and T. Vargo
Los Alamos National Laboratory, Institute of Marine Science, University of Alaska, Fairbanks, Alaska Department of Environmental Conservation, NEWNET Program, University of Alaska, Fairbanks, Battelle Pacific Northwest National Laboratory

Status of Autonomous Transboundary Radiation Monitoring in Alaska

Storey, J.W.V., M.C.B. Ashley and M.G. Burton
University of NSW

The Automated Astrophysical Site Testing Observatory (AASTO) contains a suite of autonomous instruments designed to fully characterise the astronomical potential of remote antarctic sites. These instruments include infrared sky monitors, an acoustic radar and an optical/UV spectrometer. The instruments typically draw less than 7 watts each. Stirling-cycle cooled detectors and highly efficient electronics systems allow unattended operation throughout the long antarctic winter. This talk will describe the instrument design and performance, and present some preliminary results.

Invited talks:

Bill Nesbit, Antarctic Support Associates

The range of options for powering polar autonomous systems includes both passive sources like solar and wind, and active sources like fuel cells, propane and diesel generators. Environment will be the biggest factor in limiting the design of passive systems. Solar power is not a viable option during the dark polar winters, nor is wind an option in still regions such as the Antarctic polar plateau. Diversified power sources (e.g. wind and propane, or wind and solar) are one way to overcome temporal variations in the source strength of passive systems. Restrictions in weight and size might further limit choices for particular applications. In all cases temperature extremes will determine the key design parameters. Battery freezing points depend on the electrolyte mixture and charge level, thus, both must be carefully controlled. Batteries may also outgas acid vapors if overcharged, which can adversely affect other components within the system. To prevent outgassing, the charging system must be regulated with temperature compensation. Finally, a properly designed system needs a mechanism for safely venting exhaust gasses from active systems and batteries without compromising the thermal insulating barrier.

Ray Dibble, Victoria University

On Ross Island, Antarctica, the Mount Erebus Volcano Observatory (MEVO) group, led by Prof P.R. Kyle of New Mexico Tech, operate a seismic telemetry net on the 3800m volcano, powered by solar panels and auxilliary wind generators. The seismic signals are automatically digitised at McMurdo and FTP'd to NMT and VUW each night. Year round operation is achieved with Gel/cell batteries on the Mountain, which have low self discharge rates, and excellent tolerance to complete discharge at temperatures as low as -50 deg C. Part time attention by the Science Technician at McMurdo, and yearly servicing of the equipment on the Mountain enables nearly 70% data recovery. All the equipment components are available off the shelf at low prices, and have withstood the environmental conditions and volcanic gases remarkably well. Some of the batteries have been in service for 15 years, and storm damage is rare. Equipment specifications will be provided, including the conversion of DC powered computer fans to auxilliary wind generators.

Similar techniques have been used to operate a television station at the Crater Rim to monitor the activity in the liquid Lava Lake from 1986 to 1990, and to record the infrasonic signals at the Windless Bight Array, powered by a Radioactive Thermoelectric Generator on loan from NSF.

Henry Awaya , Jet Propulsion Laboratory
Yi-Chien Wu, Jet Propulsion Laboratory

The thermal control of an instrument in the Antarctic poses multiple challenges for the instrument designer/implementer. The Antarctic environment is very harsh by Earth's standards and encompasses temperatures ranging from a balmy 0 degrees centigrade all the way down to -60 or -70 degrees centigrade and with wind conditions ranging from still air to velocities of raging windstorms. The sun is either very low to the horizon or below the horizon. One interesting aspect of Antarctic weather (especially at high elevations) is that the temperature ranges resemble those in the fair latitudes of Mars.

The first instinct is to heavily insulate the instrument to protect it from the potential cold, however, heat from power utilizing instruments and support equipment must be removed to avoid an over heat situation. Thus, the problem of thermally controlling an Antarctic instrument becomes one of balancing the changing environment against the variation incurred within the instrument box.

To construct a thermal model, the environment must be characterized first, and the configuration of the instrument/assembly must be thoroughly understood. The power levels generated within the instrument must be known as a function of time. This model can first be used as a predictor of thermal performance. Pre-application tests can help "tweak" the model. Finally, the model is validated/refined and can be correlated with reality when actual instrument data becomes available.

Cargnelli, J., X. Chen, D. Frank, R. Gopal and P. Rivard
Hydrogenics Corporation

PEM fuel cells

Hydrogenics Corporation has concentrated its efforts on the development of air-breathing PEM fuel cell systems which can be operated under extreme conditions ranging from ñ40 to +40 oC, from 0 to 95% relative humidity and from sea level to 2500 meter elevation. The hybrid system incorporates a PEM fuel cell stack and a thermoelectric generator and offers a unique power source that rivals primary and secondary batteries with respect to cost, performance and reliability. The system is ideal for remote applications in the Antarctic and the Arctic regions or specific missions for military. Hydrogenicsí air-breathing 30W PEM fuel cell system is currently being tested in an environmental chamber for deployment in Antarctic next winter. This paper discusses the primary test results and system characteristics.

Invited Talk:

Gregory Dace, Acumen Instruments Corporation

Autonomous science missions employ data systems to perform many critical tasks. These tasks include data collection, processing, and storage; system monitoring and control; and data retrieval operations. Extreme environments impose unique requirements on data system design that dictate which functions the system must perform and how each function is implemented.

Data requirements vary greatly among experiments being conducted in extreme or polar environments, so data systems should be designed with the expected volume of data in mind. Some systems, such as those for meteorological experiments, collect only a few hundred bytes of data per day (making cost per megabyte only a minor issue), while others (e.g. seismic) collect megabytes per day, requiring the use of low-cost high-capacity storage media.

Deployment in Antarctica can expose systems to extremes in temperature, pressure, and vibration that can adversely affect components. For instance, disk drives are not specified to operate below 0 degrees C, nor do they survive the high altitudes of the polar plateau. Flash memory proves robust in these conditions, but is prohibitively expensive for high capacity systems. Electrostatic discharge (ESD) is another common source of problems in the extremely dry Antarctic conditions. All electrical systems must be built to withstand this harsh environment.

Extreme environments limit data retrieval opportunities. Remote data retrieval is an attractive option, but communications systems are expensive and limited in data bandwidth, making them suitable only for transferring small amounts of data at present. Data compression and/or on-site data reduction can make remote data retrieval practical. Data volume may necessitate archiving data on site for periodic retrieval by field personnel. Systems that archive data for on-site retrieval must provide simple and expedient download mechanisms such as removable media, equipment swapping or high-speed data transfers (e.g. SCSI, Ethernet, FireWire, USB).

Limited development resources (e.g. time and funds) often force compromises in these specifications. As system complexity increases, more failure points are introduced and more resources must be devoted to development and testing. Testing is the most important ingredient for successfully completing a scientific mission in extreme environments, so systems need to be simple enough to provide adequate time for thorough testing and personnel training.

Anandakrishnan, S., D.E. Voigt, P. Burkett, and B. Long
U. Of Alabama, Penn State University

Results of the Anubis deployment

The Anubis (Antarctic Network of Unattended Broadband Seismometers) network was deployed in 98-99. We report on the results of our design and deployment experiences. We used wind and solar energy sources to heat our systems and to power them. We used a '386 CPU single-board computer running the Linux operating system and custom software as the data logging "engine" of our system. Due to the large volume of data, we used a mechanical hard disk to store the data. We report on the status of the system and the lessons learnt during the design phase and the installation phase.

Invited Talk:

Ngoc Hoang, NAL Research Corporation

There is a requirement for a satellite communications system that could supplement, complement or even replace some of the current communications techniques used in polar regions. These include the high data rate NASA Tracking and Data Relay Satellite System (TDRSS), the INMARSAT maritime satellite network, the Argos data relay satellite system, high frequency (HF) radios and some of the old government satellites operating beyond their original design lives. There are shortcomings associated with each of these systems. However, they are the only available options that provide vital voice and data links within the polar regions. For example, HF radios are the best means for on-demand contact between McMurdo and South Pole operations and for communicating with aircraft supporting the station. With these systems, however, blackouts can occur for days due to disturbances in the ionosphere caused by solar activity or due to strong interference from the Earth's magnetic field. Another example is the use of the Argos system for the collections of meteorological data from drifting buoys in the Arctic Ocean or from the Automatic Weather Stations (AWS) and Automated Geophysical Observatories (AGO) in Antarctica. Argos has demonstrated its great potential for the collection of atmospheric data, but it also has many disadvantages including one-way communications, non-continuous temporal coverage, low data transmission rate, long message latency and high cost due to low volume markets. Another example is that a geosynchronous (GEO) satellite will experience orbital inclination over time due to gravitational fields of the sun and the moon if station-keeping corrections are not made. Thus, a GEO satellite at the end of its operating life will tend to drift north-south at an inclination rate of about 0.8 degrees per year allowing direct line-of-sight view of both north and south poles a few hours a day. The National Science Foundation has been taking advantage of these "old" GEO satellites such as ATS-3, LES-9 and GOES-2 to provide a temporarily solution for voice and data communications in the polar regions.

A variety of commercial low-Earth orbit (LEO) satellite communications systems produced by the private sector are now in, or will soon achieve, operational status that may provide solutions for the South Pole Station and other Antarctic and Arctic locations. They will offer considerable research opportunity for autonomous science platforms applications in remote regions including two-way communications, real-time data transmissions, global coverage and reduced costs. They are much closer to Earth; therefore, low-power lightweight transmitters and receivers and omni-antennas can be used. NAL Research Corporation is currently developing a satellite data relay system for remote science platforms utilizing commercial LEO satellite transceivers. The system will allow two-way real-time data collection. In addition, science platforms can be monitored, adjusted and re-calibrated by scientists at their home laboratories or institutions.

 

Reeder, S., B. Johns, C. Meertens, D. Mencin, B. Perin
UNAVCO

TDMA spread-spectrum communications and low-power VSAT systems for GPS remote networks

A new system of low cost, low power GPS receivers has been developed for deployment in dense arrays to monitor volcano deformation, small-scale crustal deformation, structures, and atmospheric water vapor. The system consists of an L1 GPS receiver, radio modem, solar power, data collection and processing components. System development was funded by NASA and NSF. Networks of two to twelve receivers systems have been deployed along the Hayward Fault, California, on Taal Volcano, Philippine Islands, Popocatepetl Volcano, Mexico, Mauna Loa, Hawaii, in Long Valley, California, and will soon be deployed for tide gauge calibration and for a Department of Energy atmospheric water vapor tomography experiment in Oklahoma. A test deployment on Mt. Erebus, Antarctica is also scheduled for the 1999/2000 field season to evaluate performance of this system in extreme cold environments. The current configuration uses an L1 GPS receiver to continuously transmit carrier phase and pseudorange observations at 10 second to 10 Hz rates through a Time Delay Multiple Access (TDMA) radio data modem/repeater network. The system supports multiple redundant data paths with remote stations also serving as repeaters. Initial tests of the system show mm-level baseline repeatability with 24-hour data. An expanded test of the network capability will occur in the fall when a small L1-network will be co-located with a dual frequency GPS receiver streaming data to the UNAVCO Facility using a new, low-power Very Small Aperture Telemetry (VSAT) satellite system for data telemetry. The VSAT remote uses only 20W of power, which is critical for deployment in remote areas lacking reliable infrastructure. The VSAT system test is a joint JPL and UNAVCO demonstration that will begin in early September with a hub located at the UNAVCO Facility and a remote location at Marshall Field, Colorado.

Invited Talk:

Michael Brennan, Northern Power Systems, Inc.

In finalizing an autonomous system the various sub-systems (communications, data acquisition, power) must be put into a physical framework that meets form and fit requirements. These include size, bulk, weight, operator controls, making the pieces work together, managing the thermal environment for the pieces, etc. Heating, cooling, electromagnetic interference, venting, or other problems may arise when a group of electronics are packed into a tight space. Environmental issues such as shock, vibration, splash, spray, or wind must be taken into account when designing the completely integrated unit. The housing of the system must be able to withstand transport, and temperature extremes and high winds within its local environment.

Anderson, P.S.
British Antarctic Survey

Electrostatic Charge Effects during Polar Blizzards: Effects, Mechanism and Solutions

Running sophisticated equipment in polar regions poses many problems to the engineer and instrument scientist. Some effects such as cold, darkness and snow ingress are well documented and have been a personal hazard since the beginning of polar exploration. With the advancement of modern electronic monitoring systems, both manned and automatic, the electrostatic effects of low temperature blowing snow now give an additional extreme environment.

Electrostatic buildup during blizzards can destroy unshielded electronics, especially modern ultra-low power CMOS based loggers, but there is an additional effect of injected radio frequency interference onto signal lines. This is due to continual "micro-sparking" from plastic coated cables onto the inner shield which injects wide band current pulses around the Faraday cage. The mechanism for electrostatic charge transfer is not well understood, but measurements of charge magnitude made the British Antarctic Survey's Halley station (76S 26W) imply that the aquired charge is always negative, and the magnitude is highly dependant on the relative humidity of the blizzard, RHice, and not just on the wind speed (that is, snow transfer) alone as might be expected. A mechanism involving RHice dependant quasi-liquid layers of water on the impacting ice crystals may explain this phenomena.

The dependance of electrostatic charge magnitude on RHice implies that katabatic driven blowing snow, where adiabatic warming maintains the blizzard below saturation, is more prone to static than blizzards driven by coastal synoptic storms. Although shielding is essentially the answer to electrostatic problems, radio communications antennae cannot be protected, and careful attention is needed in the design of such transmitters.

Bahlavouni, A., P. J. Stein, and D. W. Andersen
Scientific Solutions Inc.

Intelligent Sensor Protection System for Polar And Marine Environments

An intelligent sensor protection system has been developed under the U. S. Navy's Small Business Innovation Research Program. Its purpose is to provide a "smart" system to protect sensors during remote unmanned measurements in hostile environments. The first application is to perform solar radiation measurements under Arctic conditions. The sensor protection system consists of an enclosure which houses and protects the sensor. Just before the measurement, the sensor is deployed while clearing of snow and ice build up. After the measurement, the data is stored, and the sensor is brought back within the enclosure for protection. A routine to determine sensor contamination is then executed and the sensor cleaned if necessary. An on-board computer controls all electr-mechanical and logical functions. Eight units were deployed during the year long SHEBA experiment and for the first time provided year long radiation measurement from unmanned site in the Arctic. A working model of the instrument will presented during the talk. Also data from the SHEBA experiment will be presented.

Brennan, M. (invited)
Northern Power Systems, Inc.

Packaging is where the "system" part of system integration comes into any project. My talk will focus on desiging (packaging) environmental enclosures for extreme environments - such as Antarctica and space. While most system designs are fairly consistant in specification, I've found over the years that each system has it's own set of unique attributes (factors) that if overlooked can result in poor performance and even failure. I plan to visit (show slides) several remote autonomous sites and discuss these factors and how they influenced the integration and packaging of each system.

Last modified on 3/11/00 by Maggi Glasscoe (Maggi.Glasscoe@jpl.nasa.gov)