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|NatureInterface > No.02 > P038-041||[Japanese]|
Ecological Research on Whales with Sensors
Professor, Chiba Institute of Technology
Nature Interface (NI): Your research group made the WEOS (Whale Ecology Observation Satellite). In 1997, the WEOS was chosen as a small satellite for piggyback launch with NASDA's ADEOS-II (Advanced Earth Observing Satellite-II), by an H-II A Launch Vehicle Flight. Global-range investigation of whale ecology may be realized soon. Why did you think you wanted to investigate whales?
Prof. Hayashi (H): We had launched several rockets every year to investigate atmosphere and the ionospheric layer. But the apparatus became complicated and expensive, so we decided to collect the rocket payload by separating it from the falling vehicle and dropping it onto the sea.
We used the LORAN-C (Long-Range Navigation System-C) for the collection of the position data, since there wasn't a GPS (Global Positioning System) yet. I was also on the ship for collection of the payload. At that time, I wondered if we would be able to apply this technology to saving lives.
My idea was this: send the information about the latitude and longitude from the buoy of the point where someone was shipwrecked to GMS (Geostational Meteorological Satellite: "Himawari"). Then, the information would be sent to a center for meteorological satellite communication at the Japan Meteorological Agency at Hatoyama Town, Saitama Prefecture. If there is a ship in the vicinity of the wrecked ship that can be sent to the site of the shipwreck, this would be the fastest way to effect a rescue. I proposed this idea at various places, but it's not realized yet.
Later, I got the idea of using this system for whales. There are whaling and antiwhaling opinions, but the objective of our investigation is just to obtain scientific data.
NI: How do you investigate whales?
H: We investigate the position of whales using the GPS. As Fig. 1 shows, the WEOS (Whale Ecology Observation Satellite; Fig. 2) circles a polar orbit. Transmitters called probes are installed on whales, and data on the positions of the whales, the depth to which the whales dived, and the sea temperature at places where the whales are located, are stored in the probes's memories.
Whales surface every several minutes for respiration, and the data stored in the probes are sent to the WEOS together with each identification code and recorded at that time. The control center at the Chiba Institute of Technology retrieves the data by sending a command signal to the WEOS each time the WEOS passes over the control center. Then researchers analyze the data, and learn about the ecology of whales.
NI: What were the impressions of students who worked on the manufacture of the WEOS?
H: Since the range of this theme is wide, about seven to ten students studying electronics, electrical engineering, mechanical engineering, and industrial design study this theme for their graduation theses every year. The objective of this study is very clear, so the students enjoy and are greatly interested in the research.
Of course, the satellite is assembled at a professional manufacturing corporation, but the students are happy to do the basic experiments needed for making the satellite system.
To reduce the budget for developing a satellite is most important as an activity in a university. In the field of space development, however, high reliability is required for satellite parts. Parts called "high-reliability components" are usually used, about which people can obtain such data as where, how, and by whom the part was made at any time. But such components are quite costly. So we decided to use the parts for consumer electronics after careful selection and tests: their quality is guaranteed only for use under the standard atmospheric pressure, which is 1 atm (1013.25 hPa).
It was necesary for us to determine if the product we were adapting for parts would bear the shock of launching and of space radiation. We often went to JAERI Takasaki (Japan Atomic Energy Research Institute in Takasaki) for experiments using radiation.
As for the development of the probe, we also went to an organization which has a large pressure-tank for underwater experiments
NI: What were your new findings?
H: We learned a great deal about the ecology of whales from Mr. Seiji Osumi at the Institute of Cetacean Research. There were many people who helped us. We are planning to realize the attachment of a probe to a whale in a minimally invasive way. We needed to control the pressure of an airgun with which the pin enters, so that it does not go deeper than the blubber, and so that the whale won't be injured.
For this objective, we collected basic data on how much the gas pressure or the weight of the pin should be, by analyzing the thickness and features of the skin of each of the whale species.
It's quite hard to get the skin of whales, but whales sometimes make stranding.
When a sperm whale went aground at Shizuoka Prefecture in Central Japan last year, I heard on TV at night that the whale would be scrapped on the following day. So I rushed to Tokyo Station, and went to Shizuoka by the first bullet train the following morning. In this way, I got the skin of that whale.
At first, I heard it would be good to shoot a light pin with high speed. But this method didn't work: the pins rebounded or bent.
We came to understand that the proper weight was necessary. We attached an iron shaft on the tail of a pin. The shaft was designed to go away as the pin attached on the skin.
Baird's beaked whales dive to the depth of 1000 m (0.6 mi), and their skin is hard, probably so that they can bear high water pressure. Therefore, we thought it would be difficult get the pin to attach, but in fact it was easy, once we weighted the pin a little.
In contrast, we thought it would be easy to get the pin to stick into the skin of minkes, because their skin is soft. But actually, it was not very easy. Minkes dive to the depth of only 100 m (0.06 mi), so they don't need to bear heavy water pressure, and yet it's important for them to not let their skin be bitten by enemies.
These issues were quite interesting for me. People only thought about catching whales before, and never thought about the quality of their skin.
These issues were discovered through drop tests of a pin done by the students of the Department of Mechanical Engineering. The influence and availability of the pins were observed by attaching them into bottlenose dolphins for a two month period. We didn't find any problems in this experiment. For this we had the help of Mr. Akio Tobayama, of Kamogawa Sea World.
NI: What kind of data do you hope to obtain through this investigation?
H: We plan to install a GPS receiver (for monitoring the latitude and longitude), a water temperature sensor (for measuring seawater temperatures), a pressure gauge (for measuring depths of diving), a geomagnetic sensor (for monitoring the directions of the whales' movement), and a sound pressure sensor (for monitoring their clucks) on the probe.
We haven't yet decided whether we should install all these sensors the first time, but I want the data on the whales' migration patterns, diving depths, and temperatures at least. There is little data on how many meters whales dive.
I also want data on the whales' clucks and other sounds in the future.
We haven't done anything yet, so it may be strange to talk about our future big dreams. But I want to observe various kinds of whales in the Northern and Southern Hemispheres in the future, if possible.
Many researchers tell me that they want us to investigate blue whales. But I think it's better to start with minkes or sperm whales, which are abundant around Japan.
I heard there are many things that are unknown about the sea itself, such as the relationship between water depth and temperature and salt concentrations.
We may be able to learn a great deal about the environment in the sea.
NI: On how many whales are you planning to install the probes?
H: Whale researchers tell us that they want to install probes on whales from various groups, because they want to know how groups communicate.
So, it would be best if we could install the probes on many whales.
We are now investigating our installation method. I heard that if you stop the engine of your ship, the whales sometimes come closer to you. Mr. Hiroya Minakuchi, a photographer of whales, and Mr. Nagaoka, who was once a harpooner for a whale catcher, and who works for ships doing whale watching in Muroto, will help us determine how to get close enough to whales to be able to attach our probes. (Note: Muroto is a city in Kochi Prefecture, southwestern Japan.)
NI: How will the data obtained be utilized?
H: Once we get the data, I think many people will request it. I want to decide how the data will be utilized after getting the data, with input from others.
NI: What is the schedule for the project?
H: The satellite was planned to be launched as a piggyback payload of a H2A rocket, which was supposed to be launched in November 2001. But as you know, there were several problems on the rocket and the satellite will be launched in winter of next year, February or March, 2002.
NI: Your project is quite interesting. We hope it will be successful.
H: Thank you very much.
(Cooperation: Chiba Institute of Technology)
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