a second time, this time at 80% rated thrust, for Trans Lunar Injection (TLI). Unlike the S-IVB, which propelled the Apollo Spacecraft and its three-man crew in a forward-facing motion, the EDS would have fired its onboard rocket with the crew facing the EDS. This "eyeballs out" type of flying would be similar to the flight profile of the proposed, but never flown Manned Venus Flyby, from the cancelled Apollo Applications Program of the late 1960s. When TLI was completed and the EDS was shut down for the last time, it would then have been jettisoned to fly into a heliocentric orbit, or in a manner similar to that employed by NASA from Apollo 13 to Apollo 17, it may have been deliberately crashed into the lunar surface to help scientists calibrate sensitive seismometers placed on the lunar surface by either astronauts on lunar sortie flights or by uncrewed robotic probes. Space Launch System When the Ares program was cancelled in favor of the Space Launch System, the EDS was considered as a second stage for the Block 1B SLS. This version of the stage would have been about long and equipped with one to three J-2X engines. Technological development of the J-2X was expected to take considerably more time, so the EDS was dropped in favor of the Exploration Upper Stage, which will use the much lower-thrust but already-developed RL10. According to NASA, the J-2X will be overpowered for the Artemis program; its development has been put on hold (though not abandoned) until stages capable of transferring heavy payloads to Mars are required (expected in the 2030s). References Ares (rocket family) Rocket stages Space Launch System