The newly formed Advanced Research Projects Agency (ARPA), which was put in charge of development of the launcher, sided with the ABMA design. Their only concern was that the new engines might be a risk, suggesting that more moderate upgrades of existing engines be used instead. ABMA quickly adapted the design to use eight engines developed from the Jupiter's S-3D as the H-1, as opposed to four of the proposed E-1 of the original design. ARPA was satisfied, and started funding development of both the booster at ABMA and the new H-1 engines at Rocketdyne. Contracts were tendered in October 1958 and work proceeded quickly; the first test-firing of the H-1 occurred in December and a mock-up of the booster had already been completed. Originally known as Super-Jupiter, the design became the Juno V during development, and on February 3 an ARPA memorandum officially renamed the project Saturn.