Ocean-sensor project reaches milestone

Scientists seeking to deploy an armada of 3,000 robotic probes to take the pulse of Earth’s oceans are halfway to their goal.

SENSORS AWAY. Instrument-laden Argo probes drift with ocean currents and transmit data to researchers every 10 days. Scripps Institution of Oceanography

As of Nov. 30, 2004 oceanographers had launched 1,516 of the sensor-laden Argo floats, says project director John Gould of the Scripps Institution of Oceanography in La Jolla, Calif.