外文翻譯--支持美國(guó)航天局地球科學(xué)事業(yè)的下一代海洋觀測(cè)浮標(biāo)（英文）

1、Reprint courtesy of Ars Hermeneutica, Ltd. http://ArsHermeneutica.org Paper appeared in Sea Technology, 40, pp. 37-43 (May 1999). The Next Generation Ocean Observing Buoy in Support of NASA’s Earth Science Enterprise

2、 By James D. Irish Walter Paul Woods Hole Oceanographic Institution, Woods Hole, MA J. N. Shaumeyer Carl C. Gaither, III, Jackson and Tull, Seabrook, MD and John M. Borden Wavix, Incorporated, Rockville, MD Intr

3、oduction The Woods Hole Oceanographic Institution (WHOI) and Jackson and Tull (J&T) are developing an improved moored instrumented buoy system in support of NASA's Earth Science Enterprise. This new d

4、esign utilizes WHOI's oceanographic experiences with buoys, moorings, and sensing systems, and J& T's expertise with aerospace telemetry and computer systems. The buoy system includes capability for

5、 a full suite of meteorological sensors, water temperature, conductivity (salinity), bio-optical sensors and radiometers at several depths and an acoustic Doppler current profiler (ADCP) for currents. The sys

6、tem is capable of deployment on continental shelf regions worldwide for ocean science studies, including ocean color satellite ground truth validation. It uses the new generation of Low Earth Orbiting (LEO

7、) communication satellites for two- way, high throughput command and data telemetry. Buoy Structure These new NASA buoy systems are constructed from steel and aluminum with a foam flotation collar. Steel, used fo

8、r low cost and simplicity of construction, was hot dip galvanized and painted for protection against corrosion. Some old steel guard buoys (submarine net floats with towers added) are still in use after 20 years,

9、so life should not be a problem. Also, making the base from heavy steel bar stock eliminated the need to add zinc or lead weights for ballast as in aluminum buoys. The buoy’s tower is made of 6061-T6 aluminum fo

10、r light weight, and electrically isolated from the steel base by plastic shoulder washers. Mounted on the tower are a radar reflector, Coast Guard approved flashing light, telemetry antennas, meteorology sensors

11、, solar panels, and an ARGOS locator beacon antenna. One solar panel can be swung up to gain access to the instrumentation well in the center of the buoy. The well is 24” in diameter and about 45” deep to provid

12、e space for the batteries, solar panel regulators, power distribution system, the data processing and storage system, telemetry system, and backup ARGOS buoy locator. Access to the buoy’s watertight electronics we

13、ll is through a hatch in the top. The large diameter allows a person to lean into the well to work on batteries in the bottom Mounting the electronics for easy servicing has always been a problem. In similar but s

14、maller GLOBEC (GLOBal ocean ECosystems dynamics) buoys, the batteries and electronics are screwed to bars on the side of the electronics well. Bending over the smaller well and working on the components was d

15、ifficult. In this new buoy, the electronics are mounted on racks that slide down four split guide tubes welded to the inside of the well. A hard rubber “spring” and pin at the top of each tube hold the racks in p

16、lace. Lifting the electronics and batteries out of the buoy for servicing is still difficult. . The new buoy system undergoing tests off the WHOI dock. The foam flotation collar is the basic buoy hull. On top

17、 of the tower the satellite receiving antenna (on right) and transmitting antenna (on left) are mounted as far apart as possible. Flotation Collar A Surlyn foam flotation collar (Gilman Corporation) provides the

18、buoyancy for the buoy. In GLOBEC (our first experience with this technology) the buoys were made with about 2000 pounds Reprint courtesy of Ars Hermeneutica, Ltd. http://ArsHermeneutica.org The Next Generation Oce

19、an Observing Buoy in Support of NASA's Earth Science Enterprise page 3 of 5 not doing too badly. The two panels 90° from the sun supplied 1.0 amps each, and the one in the shade supplied 0.75 amps. The

20、refore, the “256 Watt” solar panel array was actually supplying about 80 Watts into the battery. That day, the solar panels delivered 42 ampere-hours (about 550 Watt hours) to the batteries. These numbers nee

21、d to be scaled by the sun angle and daylight time. Also, in colder weather solar panels and batteries perform less efficiently. A regulator is necessary to prevent overcharging of the gel cell batteries. If ov

22、ercharged they release hydrogen gas, which can form an explosive environment in the buoy well. We also mount a catalytic cell to convert the hydrogen and any oxygen in the buoy into water that is absorbed by desi

23、ccants. There is a voltage drop across the blocking diodes on the batteries, so the power at the instrumentation runs about 1/3 volt below the battery voltage. We generally design power systems with a safety f

24、actor of two to account for temperature and battery inefficiencies, and the systems have supplied the necessary power. The new system had an additional problem because the computer was continuously pow

25、ered and additional circuits were on for diagnostic purposes, so that the solar system could only keep up during long summer months with little cloud cover. An internal power controlling clock which powers down th

26、e computer has allowed PC/104 systems to be successfully used in the past, and will be added to this system in the future. Mooring The mooring is a taut, compliant link between the buoy and anchor. In shallow wat

27、er depths (40 to 100 m), this mooring must accommodate the greater than 6 m heave excursions of the buoy due to waves and tides, and the horizontal displacement due to currents. This is possible with comp

28、liant elastic mooring elements. Four to six one- inch diameter NATSYN rubber elastomeric elements (terminated and assembled by Buoy Technology, Inc.) form the tether. Each element is stretched about 100% with

29、 100 lbs tension, resulting in a very soft spring response. The tether length is selected to provide sufficient stretch for the particular deployment conditions. Stretch often exceeds 100% in severe weather

30、 and high current events. The positive experience gained with the elastic tethers in GLOBEC was used to develop the elastic mooring for the NASA buoy. Schematic configuration for a shallow water deployment of

31、the system. A tether operates at significantly lower tensions levels than the all chain or cable mooring. The elastic tether eliminates the large shock loads of conventional moorings. The low tensions incre

32、ase the life of these moorings due to reduced wear in the mooring hardware, which in return can reduce the weight of hardware required while increasing service life. Deployments have exceeded 12 months without fai

33、lure. The constant tension on the bottom of the buoy reduces buoy motion for improved scientific observations. A new feature of this mooring is electrically connecting a sensor package near the sea floor with the

34、 surface buoy. A coil-cord assembly (like a rugged telephone handset cable) is spiraled around one of the elastic elements. (The coil-cords were developed at WHOI for the SSAR drifting buoy program, part of t

35、he GAMOT project to measure global warming of the oceans. Coil-cord assemblies have survived 6 million stretch cycles in lab tests and long deployments inside rubber stretch hoses without failure.) They are con

36、structed of a central braided strength member, heavily insulated #18 AWG conductors spiraled around the core, and a thick outer extruded rubber jacket. The 0.7 inch thick cable is spiraled around a steel mandrel,

37、and autoclaved to vulcanize the initially uncured rubber jacket in its spiraled shape. The jacket provides torsional and flexural rigidity and retraction. Retraction is the ability of the coil- cords to contract t