majority of the buoys was to be recovered. However, the use of radar reflectors posed a secur- ity problem since the pip received from the reflectors could not be differentiated from that received from any other object, such as a submarine. Thus any ship or aircraft making radar contact would also have to make visual contact in order to identify the target positively. This visual contact would not always be feasible because the search aircraft or ships would have to pe diverted from their primary mission for such identification. To partially overcomethis ob- jection, the numberof buoys was reduced to about thirty so that the Navy Task Force could keep track of this relatively small number and forewarn units searching the area. Planning within the task force was undertaken on this basis, and the somewhatincreased security risk was considered acceptable by the Task Force Commander.* As additional aids for the location and identification of the buoys, each one was equipped with an alphabet signal flag, and the staff over a short section was wrapped with paper with a reflective surface such as used in billboard advertising. 2.3.3 Operational Success Of the 19 buoys placed, 12 were recovered by the USS O’Bannon. One buoy was picked up by another ship to the west of Eniwetok (10° 41’ N latitude and 158° 42’ E longitude) on 13 November, and the collected sample was returned to the laboratory. One buoy was reported to be lodged on the reef at Eniwetok and could have been recovered, but was not. The averageset of the buoys was 286° with a drift of 0.70 knot. This is compared with an estimate of 270° for the set and 0.75 knot for the drift (see Appendix D for observed set and drift of the buoys). As a result of the error in estimated position, the search for the first buoy was undertaken to the south of the actual position. The search began about 0400 on 2 November, and the first buoy was not recovered until 1810 that day. Once the first buoy had been recovered, the lapse of time between picking up the remaining buoys was not generally so great. Sea anchors for buoys 17, 18, 19, 2, and 5 were missing when the buoys were recovered. These buoys had been in the water for the longest time, and it is believed that the iss of the sea anchors resulted from the chafing of the line. The poor percentage of recoverY of buoys 1 through 8 is attributed to the probable loss of their sea anchors. The use of wire or satisfactory thimbles and shackles should prevent similar difficulties in future operations. It is believed that the percentage of recovery of sea stations in this test definitely establishes the operational feasibility of their use in the collection of fall-out. It is recommendedthat a coded signaling beam be used on each buoy in future operations to assure positive identification of these free-floating sea stations and to eliminate any inter- ference with the security patrol. Such a device should operate on a unique frequency band, be undetectable by the task force security vessels, and not respond to any common radar frequencies. The British Air Sea Rescue beacon satisfies these requirements. It weighs very little and can be easily installed on a small buoy. Special portable receivers, which will home on any one of a group of signals coming from a concentrated area, are available for these beacons. These receivers have a range of about 65 miles when used aboard an aircraft flying at 10,000 ft and a range of 3 to 10 miles when used aboard a surface craft. 166° *On M-6 day, instructions were received from the Office of the Commander-in-Chief, Pacific Fleet, that use of the buoys imposed unacceptable limitations on security from submarine penetration and that the area out to 75 miles from the shot island must be kept clear of the buoys. This directive eliminated all but 19 of the buoys and reduced the placementof stations to that area downwind of the predicted upper air winds, i.e., on two 90° arcs, one at 100 miles and the other at 150 miles to the northeast of the atoll. 17