Marker Droppers

A primary part of the 2004 mission is to drop markers into targets underwater. A pull-type 30V pulse solenoid is used to accomplish this task. The solenoid is housed in a waterproof chamber with two aluminum end caps. A two pin Subconn low profile series connector links the solenoid to the electronics tube. Two stainless steel balls are housed in the bottom end cap, with the magnetic shaft of the solenoid holding the balls in place. When the solenoid is activated, the shaft retracts, breaking the magnetic bond that holds the balls in the end cap. The balls fall from the end cap and travel downwards to the targets. The Solenoid is the only device aside from the thrusters that use the raw 30V battery supply supplied by the lithium polymer batteries. The solenoid draws considerable amperage; however the solenoid is only activated for about 1/10 of a second. The DAC digital output pins are used to activate the solenoid. When the computer finds it favorable to drop the markers, the DAC outputs a +5V signal to a Crydom relay. The relay device closes the circuit to the solenoid, allowing +30V to travel across the solenoid.