The Proton rocket (formal designation: UR-500) is a Russian unmanned space vehicle design first launched in 1965 and still in use as of 2003.

Proton initially started life as a "super ICBM." It was designed to throw a 10-MT (or larger) nuclear warhead over a distance of 12,000 km. It was, of course, hugely oversized for an ICBM and was never used in such a capacity. Its real purpose was as a launch vehicle.

Proton is fuelled by unsymmetrical dimethyl hydrazine and nitrogen tetroxide. These are hypergolic fuels which burn on contact, voiding the need for an ignition system. They are stored at ambient temperatures avoiding the need for low-temperature-tolerant components and also allowing the rocket to sit on the pad indefinitely without need for continuous topping up of boiling off cryogenic fuels. They are, however, very toxic fuels that require special handling care.

Between the first flight in 1965 and 1970, the Proton was a very unreliable launcher causing the loss of many space vehicles. By the early 1970s the flaws were worked out and it became a very reliable rocket which it remains to this day.

Proton launched the unmanned Soviet circumlunar flights and would very likely have launched the first humans to circle the Moon had the flight of Apollo 8 been conducted as originally planned (i.e. without going to Moon orbit). Proton launched the Salyut space stations, Mir core segment, and both Zarya and Zvezda of the ISS. It also launched many probes to the Moon, Mars, and Venus.

Proton also launched commercial satellites, most of them being managed by the International Launch Services.

Launch capacity to low Earth orbit is about 20 metric tons. Interplanetary transfer capacity is about 5–6 metric tons.

Proton 8K82K Specifications

• Stage Number: 1. Proton K-1
  • Gross Mass: 450,510 kg
  • Empty Mass: 31,100 kg
  • Thrust (vac): 10,470 kN
  • Isp: 316 kgf·s/kg (3.10 kN·s/kg)
  • Burn time: 124 s
  • Isp(sl): 267 kgf·s/kg (2.62 kN·s/kg)
  • Diameter: 4.15 m
  • Span: 7.40 m
  • Length: 21.20 m
  • Propellants: N2O4/UDMH
  • Engines: 6 x RD-253-11D48
  • Other designations: 8S810K

• Stage Number: 2. Proton K-2
  • Gross Mass: 167,828 kg
  • Empty Mass: 11,715 kg
  • Thrust (vac): 2,399 kN
  • Isp: 327 kgf·s/kg (3.21 kN·s/kg)
  • Burn time: 206 s
  • Isp(sl): 230 kgf·s/kg (2.26 kN·s/kg)
  • Diameter: 4.15 m
  • Length: 14.00 m
  • Propellants: N2O4/UDMH
  • Engines: 4 RD-0210
  • Other designations: 8S811K.

• Stage Number: 3. Proton K-3
  • Gross Mass: 50,747 kg
  • Empty Mass: 4,185 kg
  • Thrust (vac): 630 kN
  • Isp: 325 kgf·s/kg (3.19 kN·s/kg)
  • Burn time: 238 s
  • Diameter: 4.15 m
  • Length: 6.50 m
  • Propellants: N2O4/UDMH
  • Engines: 1. RD-0212

• Stage Number: 4
  • Proton 11S824
  • Gross Mass: 13,360 kg
  • Empty Mass: 1,800 kg
  • Thrust (vac): 83 kN
  • Isp: 346 kgf·s/kg (3.39 kN·s/kg)
  • Burn time: 470 s
  • Diameter: 3.70 m
  • Length: 5.50 m
  • Propellants: Lox/Kerosene
  • Engines: 1. RD-58
  • Other designations: 11S824; Block D; D-1-e.

External link

• Proton rocket specifications sheet