Delta 1913 was a three-stage Delta 1000-series configuration with the MB-3-powered extended long-tank first stage, nine Castor II strap-on motors, the 2.44-metre AJ10-118F second-stage and fairing arrangement, and a TE-M-364-3 solid third stage. Its sole flight successfully launched Explorer 49, the Radio Astronomy Explorer B spacecraft, into a high lunar-distance orbit in June 1973.