The M-V rocket, also called M-5 or Mu-5, was a Japanese solid-fuel rocket designed to launch scientific satellites. It was a member of the Mu family of rockets. The Institute of Space and Astronautical Science (ISAS) began developing the M-V in 1990 at a cost of 15 billion yen. It has three stages and is 30.7 meters high, 2.5 meters in diameter, and weighs about 140 tonnes (310,000 pounds). It was capable of launching a satellite weighing 1.8 tonnes (2 short tons) into an orbit as high as .
The first M-V rocket launched the HALCA radio astronomy satellite in 1997, and the second the Nozomi Mars explorer in July 1998. The third rocket attempted to launch the Astro-E X-ray satellite on February 10, 2000 but failed.
ISAS recovered from this setback and launched Hayabusa to 25143 Itokawa in 2003.
The following M-V launch was the scientific Astro-E2 satellite, a replacement for Astro-E, which took place on July 10, 2005.
The final launch was that of the Hinode (SOLAR-B) spacecraft, along with the SSSat microsat and a nanosatellite, HIT-SAT, on 22 September 2006.