Vehicle Configurations

Vehicle Components

Japan's Institute of Space and Astronautical Sciences (ISAS) developed the M-5 (or M-V) launch vehicle during the 1990s.  M-5 was part of the long-running "Mu" series of solid-fueled rockets used to launch space science missions. 

M-5, an all-solid, three-stage launcher with an optional fourth "kick" stage, stood 30.8 meters tall, was 2.5 meters in diameter, and weighed about 140 tonnes at liftoff.  The rocket could loft 1.8 tonnes to low earth orbit.  It could also boost more than 0.5 tonnes into solar orbit.

M-5 was launched from a combination launch tower/vertical assembly building at the Kagoshima (Uchinoura) SpaceCenter on the southwest tip of Japan's southernmost main island.  Like its sounding rocket ancestors, M-5 flew from a launch rail that was pointed to an off-vertical launch angle along the desired azimuth. 

The M-5 first stage used two solid motor segments that were assembled at the launch site.  The second and third stages used single-segment motors.  Typical flights consisted of a 75 second first stage burn followed by a 71 second second stage burn.  The vehicle would coast for one to four minutes or more, depending on the mission, before the second stage would separate and the third stage would ignite.  Third stage separation would occur shortly after third stage motor burnout, after the stage had oriented the spacecraft for separation.  M-5 blistered its way to orbit, reaching orbital velocity in about 5.5 minutes.

The first stage used a movable nozzle to provide pitch and yaw thrust vector control (TVC).  A solid motor roll control system provided roll control during first stage flight.  Second stage pitch and yaw control was provided by a liquid injection TVC at the main nozzle.  Roll control was similar to the first stage system.  A "solid motor side jet" system provided pitch, yaw, and roll control during the second stage coast phase.  The third stage used a movable nozzle and a side jet system.  

The first M-5 launch, by vehicle M-V-1,  successfully orbited the HALCA radio astronomy satellite in 1997.  A second launch by M-V-3 in 1998 boosted the Nozomi Mars explorer out of Earth orbit.  The third launch failed in 2000, causing the loss of the Astro-E X-ray satellite.

M-V-4, the Astro-E launcher, suffered a first stage rocket motor nozzle failure 41 seconds after liftoff.  The launcher spiraled slowly upward for about 30 seconds, but never flew totally out of control or suffered structural failure.  The second and third stages continued their portion of the ascent under full control, but were unable to make up for the velocity lost during the first stage portion of the flight. 

After redesign, M-V-5  successfully launched Hayabusa to the 25143 Itokawa asteroid in 2003.  M-V-6 orbited Astro-E2, a replacement for Astro-E, in 2005.  M-V-8, the sixth M-5, launched the Akara infrared astronomy satellite in February 2006.  M-V-7 was expected to launch Solar-B before the end of 2006.

With launch costs approaching $60 million per flight, and given its low flight rate, M-5 fell under cost scrutiny.  In 2006, a decision was made to suspend use of M-5 after the M-V-7 launch.  At least one mission planned for M-5 was transferred to H-2A.  A new launcher, based on the H-2A SRB-A single-segment solid rocket motor, was planned for development to replace the M-5 system.  Cost goals for the new launcher, which might use the M-5 second stage, were in the $20 million per launch range.