the success nrl achieved in this series of experiments encouraged laboratory scientists to believe that, with a more powerful engine and the addition of upper stages, the viking rocket could be made a vehicle capable of launching an earth satellite. this led to nrl's three-stage project vanguard vehicle which launched the second us satellite. two later rockets in the viking series, vanguard tv0 (renamed from viking 13) and tv1, substantially similar to vikings 8 through 12, were used as suborbital test vehicles during project vanguard, before the first vanguard vehicle became available for test as vanguard tv2, in the fall of 1957.