Fig. 1. Scientists clustered around Argo II for a briefing from chief Argo pilot, Will Sellers. Photo by Monte Basgall.
One digital black and white still camera, a sensitive device synchronized to two strobe lights, makes high resolution images that can be assembled into larger "mosaics" that provide unprecedented details of usually inaccessible geology.
A 15-foot-long, rectangular, tubular frame packed with cameras, lights, sensors, and electronics, Argo II is also towed behind Atlantis by a cable tether that provides power and communications. But Argo has more pin-point maneuverability. Carrying three video and two still cameras, it needs to maneuver to give scientists back in the control room a picture window view of ocean bottoms and underwater mountain slopes.
Link: Argo II
For more information on the Argo II, check out the Woods Hole Oceanographic Institution page: http://www.whoi.edu/home/marine/argo_main.html
To get these views, Argo II has front and rear water jet thrusters that can pivot to keep the vehicle facing forward. Like DSL-120, it can also be "flown" higher or lower by reeling in or letting out it's cable tether. However its pilots must do more than operate a winch. Because it operates only 8-10 meters from the features it is photographing, it must be gently guided along slopes and cliff faces at a crawling speed.
That requires delicate coordination of cable, thrusters and the ship's own nimble navigation system, which also uses thrusters. In fact, Argo-II navigators can use a computer linkup to maneuver Atlantis itself from their aft control room, under watchful scrutiny of crew members on the ship's bridge.
Meanwhile, scientists will intensify their round the clock control room watches to keep tabs on all the images and other data that Argo provides.
To learn more about the vehicles:
DSL-120 | Argo II | Alvin