Jupiter Direct - Origins and History

Origins and History

DIRECT's Jupiter vehicle is an "in-line" Space Shuttle-derived launch vehicle. This broad category of Space Shuttle adaptations, postulated since before the first Shuttle launch, removes the winged Space Shuttle Orbiter, moves the liquid main engines to the bottom of the cryogenic tankage (typically proposed to be adapted from the Shuttle external tank), and relocates the payload to above the tankage.

The first official study of the concept was conducted in 1986 by NASA's Marshall Space Flight Center in the aftermath of the Space Shuttle Challenger disaster. It was promoted as one of the alternatives for launching unmanned cargo and would have potentially allowed a restarted lunar program as well. There were, however, no funds available to NASA for building any new vehicles while the Space Shuttle program continued. The idea was shelved and NASA concentrated on fixing and operating the Space Shuttle instead.

DIRECT has a resemblance to the 1991 National Launch System effort. Proposed jointly by NASA and the Department of Defense as an alternative to the Titan IV, the design was based on the same solid rocket boosters and modified external tank, but instead of the reusable Space Shuttle main engine, specified four of the proposed disposable, less expensive Space Transportation Main Engines. The United States Congress did not appropriate funding for the development. A great deal of reference material exists in the public domain regarding NLS.

NASA's Exploration Systems Architecture Study (ESAS) of 2005 included a similar design to the DIRECT proposal using three Space Shuttle Main Engines (SSME). Known as LV-24 in crew launch form, and LV-25 in cargo configuration, the idea was dismissed because it did not have sufficient performance for the proposed lunar program - however the concept was not considered using an Earth departure stage (EDS).

DIRECT's re-exploration of the SDLV idea began in 2006 in frustration with the high cost and delays of Ares I and worries that any similar issues with the giant Ares V might put the whole Constellation Program in jeopardy. An additional goal was to maintain American ability to launch crews to space with as short a gap as possible after the planned retirement of Shuttle.