The high-performance Russian hydrocarbon-based propellant, syntin, will continue to be used on the Block D fourth stage of the ILS International Launch Services Proton booster for all currently contracted launches, despite no longer being used on the Soyuz U2 booster, to save costs.
The Soyuz U2 will continue to fly, but with the basic kerosene propellant on its strap-on, core and second stages, as used on the Soyuz U craft.
The use of syntin on the Proton improves performance in comparison with basic kerosene, which translates into 200kg extra payload capability to geostationary orbit (GEO), says the Molniya Space Consultancy in London.
The Proton's maximum GEO capability is 2,600kg.
Source: Flight International
