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Targeting Halley's comet which had been predicted to reappear in 1985 after 76 years, ISAS started to develop the fourth generation Mu launch system, M-3SII, in 1981. It used the first stage of M-3S, and the rest of the stages were replaced by new ones to enhance its payload capability. The M-3SII-1 and -2, with an optional fourth kick stage, sent the first and second Japanese interplanetary probes, SAKIGAKE and SUISEI, into orbit in 1985 to encounter Halley's comet. Seven M-3SII launches out of eight were successful. It could send a 770 kg satellite into low earth orbit.
Mission by M-3SII Launch Vehicle
The vehicle M-3SII-1 is described as follows
1st st. | SOB | 2nd st. | 3rd st. | 4th st. | ||
---|---|---|---|---|---|---|
Total length | m | 27.785 | 9.140 | 13.1235 | 4.6661 | 2.0084 |
Maximum diameter | m | 1.650 | 0.735 | 1.650 | 1.495 | 1.400 |
Weight (ig.) | kg | 51952.6*1 | 10248.1 | 17267.2*3 | 4208.8 | 605.65 |
Weight (b.o.) | kg | 24718.9*2 | 2225.1 | 6950.2*3 | 910.9 | 185.05 |
Propellant weight | kg | 27098.0 | 8023.0 | 10317.0 | 3297.9 | 420.60 |
Freon | kg | 271.46 | 87.6 | |||
Hydrazine | kg | 40.0 | ||||
Specific Impulse | sec | 266*4 | 266*4 | 282.0*4 | 293.1*4 | 284.6*4 |
Center of gravity (ig.) | % | 63.3 | 61.7 | 55.1 | 49.5 | |
Center of gravity (b.o.) | % | 44.5 | 47.0 | 36.2 | 29.4 | |
Ix (ig.) | kg.m.sec2 | 3537.7 | 472.5 | 93.98 | 6.286 | |
Ix (b.o.) | kg.m.sec2 | 919.2 | 206.0 | 13.04 | 3.536 | |
Iy (ig.) | kg.m.sec2 | 295110.0 | 11754.0 | 304.4 | 14.27 | |
Iy (b.o.) | kg.m.sec2 | 130310.0 | 5019.0 | 124.4 | 6.22 | |
Net payload | kg | 247.4 | SA 138.1 | |||
Nozzle expansion ratio | 7.80 | 9.13 | 23.24 | 51.84 | 49.00 | |
Nozzle exit diameter | mm | 1270.4 | 725.0 | 1349.8 | 1094.4 | 504.0 |
*1:including Freon(271.46kg)
*2:including Freon(135.73kg)
*3:including Freon(87.6kg) & Hydrazine(40.0kg)
*4:in vacuum