Urgently needed cargo was hauled by air to Enewetak as described above. However, most equipment, supplies and materials traveled by surface, either in ships of the Military Sealift Command or by barge. Shipping by surface obviously required considerable time, even more so because of the lead time required to deliver the cargo to the staging area well in advance of the loading time. Hazardous cargo (acids, flammable liquids, compressed gases, radiation sources, ete.) required special handling. In many cases, it could not be shipped on passenger aircraft. When possible, such cargo was sent by ship or barge. Supplies urgently needed were sent by air, but with difficulty if there was need to avoid passenger-carrying flights. Communications On-AtolL A dial telephone system was the principal means of communication on Enewetak Island. During a part of the operation, it was possible also to dial Ursula over a radiotelephone link. A network of five Very High Frequency (VHF) radio nets received great use and was immensely important to all project activities. These nets were the only means of communicating with boats underway between islands, work parties on islands other than Enewetak and Ursula, and with the helicopters. A great deal of traffic was also passed over these nets between individuals and offices on Enewetak and Ursula. It is probably safe to say the project could not have been completed on schedule had it not been for the timely coordination that the radio nets made possible. Off-Atoll. A communications center, operated by the USAF element, was the main link with the outside world. There were several High Frequency (HF) radioteletype and three radiotelephone circuits between Enewetak and Hawaii (about 2,000 miles distant) where they connected with military and commercial circuits to mainland U.S. The quality of the voice circuits varied considerably due to vagaries of HF propagation and ranged from very good to impossible. Competition for use of the voice circuits was keen during business hours. However, personal calls were permitted during off hours if no official traffic was waiting. A secondary, quasi-official capability existed in the Military Affiliate Radio System (MARS) stations. Personnel were able to contact their families by HF radio link from Enewetak to some amateur radio operator in the mainland who would complete the call over commercial telephone, i.e., a phone-patch. The only cost was for any tolls between the receiving station and the caller's destination. Although each atoll occupant was limited to one three-minute call per week, this service was of incaleulable value to morale and helped solve or avert many personal problems. The MARSstations were augmented by ham radios on both Enewetak Island and Ursula. Operators of these ham stations generously donated their time in setting up phone patches to families back home. The more conventional form of routine communication was, of course, through the mail Though not fast, it generally functioned reasonably well, even though Enewetak was, literally, outside the U.S. Occasionally, delays were encountered in customs when shipping articles to the U.S. from Enewetak. SATCOM. The ATS~1 satellite was used as a special ERSP programmatic communication link. Three days each week, key ERSP personnel converged at a radio terminal in the ERSP office trailer to exchange information with their home team counterparts. This was done by means of a radio satellite that enabled a direct link between the home DOE office in Las Vegas and the ERSP office trailer at Enewetak via the satellite relay station. A telephone bridge network from Las Vegas to DRI, EG&G, EIC and other laboratories allowed the home teams in those locations to listen and participate in discussion with personnel on Enewetak. 21