Artist's impression of HOPE-X. Photo: NASDA

The Japanese derivative of the space shuttle, called the H-2 Orbiting Plane-Experiment (HOPE-X), has hit a snag in its development. The program was already behind schedule by as many as four years.

Differing ideas on how the shuttle should be launched were brought up inside of the National Space Development Agency of Japan (NASDA). According to NASDA officials, these clashing opinions from an advisory board needed more time to be evaluated, so the program was halted temporarily.

The latest idea raised on the panel was to use a jet engine to get the HOPE-X vehicle off the ground. The older concept used rockets to lift the shuttle using only rocket thrust.

Even earlier plans had the unmanned HOPE-X being lifted to space using the H-2 rocket. However, those plans were made less desirable after several failures of the rocket, the most recent being last November.

HOPE-X is based on the U.S. space shuttle, and is designed to test new re-usable technologies. With only minor changes in the system, HOPE-X could perform supply and logistics flights to and from the International Space Station (ISS). NASDA says that HOPE-X program "has growth potential which enables itself to fulfill practical missions by minor improvements."

HOPE-X is set for an experimental flight in 2004, but this latest development brings that date in doubt until a decision is made on the future of the program.

HOPE-X is a joint project between NASDA and the National Aerospace Laboratory (NAL).