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MT-135 Sounding Rockets

MT-135 Sounding Rockets

The MT-135 is a small rocket primarily for sounding phenomena in the middle atmosphere such as ozone layer depletion.

MT-135 was developed since 1963 jointly by the University of Tokyo and the Meteorology Agency. It has been devoted to meteorological observations since its maiden flight in July, 1964.

Though the initial trials were not completely successful, the flights of MT-135 became stable after a series of improvements. As a result, in April 1968, a series of flights were carried out from Wallops Station, together with U.S. Archus sounding rockets for comparison.

Soon after, the new type MT-135P was developed; it featured a motor case that was recoverable after separation using a parachute for maritime safety. The MT-135P has been launched from Ryori Meteorological Station at Sanriku, Iwate Pref., on Wednesdays on a regular basis, after a series of demonstration flights from Kagoshima Space Center, Uchinoura. It used to be launched from Tanegashima Space Center to obtain atmospheric data over the launch site.

The propellant, a pre-formed grain, polyurethane composite with a low burning rate, is loaded and bonded in the case. The chamber is built up by welding tubes made of chromium-molybden steel, and the outer edge of the nozzle is welded to it. The throat insert material is graphite, and the exit cone is made of ablative silica-phenolic FRP. Each tail fin is a solid titanium plate, while the magnesium-alloy tail cylinder is shaped into a boat tail to reduce drag during flight. At 95 seconds after lift-off, the rocket separates into a sonde, a nose cone, and a motor case, and, 17 seconds later, the sonde deploys its parachute to begin a slow descent. The sonde observes temperature, wind speed, and wind direction from approx. 60km altitude, over a period of 90 minutes. The observational data is reported to the WMO (World Meteorology Organization), and utilized for long term meteorological forecasts.