Proton (rocket family)
Soviet/Russian hypergolic heavy-lift launch vehicle family.
Proton (Протон, also known as UR-500) is a Soviet and Russian heavy-lift rocket family that uses hypergolic propellant and is not reusable. First launched in 1965, it carried interplanetary probes, space station modules, and commercial payloads. Its name came from early scientific satellites it launched.
Quick Facts
- Function
- Heavy-lift launch vehicle
- Manufacturer
- Khrunichev State Research and Production Space Center; Chemical Automatics Design Bureau
- Height
- 53 m / 174 ft
- Diameter
- 7.4 m / 24 ft 3 in
- Mass
- 693,810 kg / 1,529,589 lb, 3 stage
- Stages
- Proton-K: 3; Proton-M: 4
- Sites
- Baikonur, LC-200 & LC-81
- Launches
- 431; Proton: 4; Proton-K: 311; Proton-M: 116
Facts from the source article.
History
Proton began as a super heavy ICBM designed to deliver a 100-megaton (or larger) thermonuclear weapon over 13,000 km, but was never deployed in that role. It was conceived by Vladimir Chelomei's design bureau as a counterpart to Sergei Korolev's N1 rocket, which was intended for crewed circumlunar flights; Korolev opposed Proton due to its toxic propellants. The first stage's unusual appearance stems from rail transport constraints: the central oxidizer tank is at the maximum rail gauge width, and the six surrounding fuel tanks also serve as engine attachment points, but do not separate. The first and second stages are joined by a lattice structure, enabling hot staging where the second stage ignites before separation, eliminating the need for ullage motors. A rushed development caused dozens of failures between 1965 and 1972, and State Trials were not completed until 1977, after which reliability exceeded 90%. Proton's design remained secret until 1986, when the complete vehicle was first shown publicly during the televised launch of Mir. Mass-production of its guidance system began in 1964 in Kharkov, Ukraine. Proton launched uncrewed Soviet circumlunar flights and was intended for crewed circumlunar missions before Apollo 8. It also launched Salyut space stations, the Mir core and modules, and ISS modules Zarya and Zvezda. Commercial launches are managed by International Launch Services, with the first ILS Proton launch on 9 April 1996 carrying SES Astra 1F. Between 1994 and mid-2010, Proton revenues were $4.3 billion, projected to reach $6 billion by 2011.
Proton K
Proton K uses hypergolic fuels—unsymmetrical dimethyl hydrazine and nitrogen tetroxide—which ignite on contact, require no ignition system, and can be stored at ambient temperatures, allowing indefinite pad stays. The fourth stage had several variants: Blok D for interplanetary missions (no guidance module, relying on the probe), and Blok DM, DM2, and DM-2M for high Earth orbits. The Blok D/DM stages stored fuel in a toroidal tank around the engine behind the oxidizer tank. Initial tests in 1965–66 used only the first two stages; the full four-stage vehicle first flew in 1967. When the Soviet space station program began in 1971, Protons flew without the Blok D for heavy-lift LEO launches. Payloads included all Salyut stations, almost all Mir modules (except the Docking Module launched on the Space Shuttle), and ISS modules Zarya and Zvezda. It was intended for the crewed TKS spacecraft and the LKS spaceplane, neither of which flew as planned. The final Proton-K launch was on 30 March 2012.
Proton-M
The initial Proton-M could place 3–3.2 t into geostationary orbit, 5.5 t into geostationary transfer orbit, and up to 22 t into low Earth orbit at 51.6° inclination. Improvements included lower stage modifications to reduce structural mass, increase thrust, and fully use propellants. It typically uses a Briz-M storable propellant upper stage instead of Blok D/DM, eliminating multiple fuel supplies and oxygen top-off; it also flew with a Blok-DM stage. Efforts reduced dependency on foreign (often Ukrainian) component suppliers. The vehicles are designed and built by Khrunichev in Moscow, which owns a majority of International Launch Services. Khrunichev oversees up to 70% of Proton manufacturing through vertical integration. The Phase III Proton-M/Briz-M, flight-proven in February 2009 on a Russian Federal mission, provides 6150 kg of GTO performance, an increase of 1150 kg over the original. On 6 August 2012, a Proton-M failed to orbit a Russian and an Indonesian communications satellite due to a last-stage technical issue.
Future developments
Significant upgrades were paused after the 1992 announcement of the Angara launch vehicle. The largest planned upgrade was the KVRB cryogenic stage, which would have greatly increased capacity; its engine was developed and hardware built, but the stage's larger size would require reevaluation of aerodynamics, flight control, software, and possibly electronics. Switching to cryogenic fuels would also demand additional support equipment at the launch pad, as existing Protons use common hypergolic fuel supplies. Heavy variants of Angara are expected to be simpler and cheaper than Proton, use kerolox instead of hypergolic fuels, and be designed from the start to accept a KVTK stage with existing liquid oxygen supply.
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