On 29 May 2009, DIRECT spokesperson Stephen Metschan gave a presentation to the 28th Annual International Space Development Conference in Orlando, Florida entitled, "Direct 3.0: Landing Twice the Mass on the Moon at Half the Cost." In April 2009, following NASA trade studies comparing use of the Space Shuttle Main Engine (SSME) to the originally planned RS-68 engine for Ares V, the DIRECT Team announced that future DIRECT proposals would recommend SSME as the core-stage engine. The engine change was due to concerns that the ablatively-cooled RS-68 would not survive the intense heat produced by the nearby exhaust plumes of the Space Shuttle SRBs. DIRECT asserts that the higher cost of the regeneratively cooled SSME will be offset by the time and money saved by not human-rating the RS-68. Similarly, for the upper stage, the DIRECT Team recommended using six of the flight-proven RL10B-2 engine.