抄録
Ecology of many species of whales are not knownbecauseof their wide scope of activities.We are
building a new system to reveal their migration pattern and living style in the sea. This system is
composed of three segments: a dedicated small satellite in a polar orbit of 1000km high, probes at
tached to many whales in various oceanic regions, and a ground station for tracking, telemetry and
command of the satellite.
In each probe a GPS receiver for obtaining the position on the sea surface, and several sensors
(pressure, temperature,geomagnetic field and acoustic signal) to detect the environment under the sea
are installed. When the whale surfaces these data are sent by UHF band telemetry transmitter to the
satellite. The satellite stores the data in a memory after the reception. When the satellite enters in the
visible rangeof the groundstation, it sendsout a command signalinVHFband, and the storeddata in
the satellite are transmitted to the ground station in L-band telemetry. The electric power needed for
the probeoperation will be generated by utilizing the motion of whale,in whichAGSsystem devel
opedby Seiko-Epson Co. for a wristwatch will be applied. Ecological data of whaleswith individual
identification code will be retrieved on the ground. This system is in a process of construction in the
Chiba Institute of Technology, expecting the launch of the satellite in 1998-1999.
To realize this system attachment of probes to whales is indispensable. Based on fundamental
studies on the attachment, application of a small harpoon shot by an airgun is most promising.To
achieve a long term (l-2years) observation, attachment to a livingbodyshouldbe as gentleas possile.
To attain tight fixing of the probe a set of barb plane strips madeof Ti-Ni shape memory alloy is
attached at the top of the harpoon, whose phase transition temperature is chosen to be30°C, and the
shape in the higher temperature is so designed as to bea quarter circle, by which the pressure of the
barbagainst the fascia is reduced andthis fact will beeffective to avoidthe necrosis. Usage of a kind
of medicineto avoid infection, and a proper surface treatmentof the harpoon material for improving
the affinity withliving tissues are alsoconsidered. Sincethe thermal timeresponse of thebarbis very
important fordefining the attachment procedure, thethermal time constant of barb plate is calculated
basedon the configuration underdesign, and a practical operational scheme is proposed.
