Starsem’s Soyuz 2-1A launch vehicle has launched six Globalstar satellites from the Baikonur Cosmodrome in Kazakhstan. Launch was on time, at the opening of the window at 2:27am UTC on Wednesday, following a 24 hour scrub due to a technical issue with the launch pad, which was then followed by an additional one day postponement to reconfigure the vehicle.
Soyuz launchers have played a key role in the creation of Globalstar’s satellite constellations. Eight Soyuz missions conducted by Starsem from 1999 to 2007 orbited a total of 32 first-generation Globalstar spacecraft. On these previous flights, each mission carried four of the 450-kg. first-generation satellites.
Globalstar’s second-generation satellites are 700-kg.-class spacecraft with a trapezoidal-shaped main body, enabling six of them to be integrated on a dispenser system for the Soyuz missions.
The Globalstar flights are being performed on behalf of Arianespace by its Starsem affiliate.
These satellites are designed to support Globalstar’s current lineup of voice, Duplex and Simplex data products and services – including the company’s lineup of SPOT retail consumer products. They will join eight first-generation Globalstar spacecraft launched in 2007 to form a 32-satellite constellation.
Globalstar has contracted with Arianespace to conduct a series of four Soyuz launches, each of which will carry six of the second-generation satellites for a total of 24 spacecraft.
Once this new constellation is fully deployed, it will support Globalstar’s mobile satellite voice and data services for commercial and government customers in more than 120 countries.
The Soyuz-2-1a rocket was manufactured by TsSKB-Progress, and is a descendent of the R-7 Semyorka, the world’s first intercontinental ballistic missile. The R-7 was designed by Sergei Korolev, and first flew in 1957. A modified version was used to launch the first satellite, Sputnik 1, on 4 October of that year.
The R-7 formed the basis for the Luna, Vostok, Voskhod, Molniya and Soyuz families of rockets, and to date all Soviet and Russian manned spaceflights have been launched using rockets derived from the R-7. The Soyuz, which first flew in 1966, was a modification of the Voskhod rocket featuring an upgraded and lighter telemetry system, and more fuel efficient engines. It was initially used to launch only Soyuz spacecraft; however with the introduction of the Soyuz-U in 1973 it began to launch other satellites as well.
The Soyuz-U, which remains in service, is the most-flown orbital launch system ever developed, having made around 750 flights to date, plus around 90 more in the Soyuz-U2 configuration optimised to use synthetic propellant.
The Soyuz-2 was developed from the older Soyuz models, and features digital flight control systems and modernised engines. It first flew in 2004, and this is its twelfth launch. Two variants are currently in service; the Soyuz-2-1a used to launch Meridian-4, and the Soyuz-2-1b which features an RD-0124 third stage engine which provides additional thrust. The RD-0124 was declared operational on 3 May 2011. The Meridian launch is the eighth flight of the Soyuz 2-1a configuration, whilst the Soyuz-2-1b has flown four times.
The Soyuz-2 forms the basis for the Soyuz-ST rocket, which is expected to make its maiden flight from Kourou in French Guiana later this year. The Soyuz-ST is optimised to fly from Kourou, and also incorporates a flight termination system and a modified telemetry system. The first launch of the Soyuz-ST is currently scheduled to occur no earlier than late October.
The core stage of the Soyuz-2, the Blok-A, is powered by a single RD-108A engine. This is augmented for the first two minutes of flight by four boosters, each of which is powered by an RD-107A engine. The numbering of the stages of Russian rockets differs from Western systems, with the boosters being numbered as stage one, the core, the Blok-A stage two, the stage atop that stage three, with the upper stage, in this case a Fregat, being considered the fourth stage.
The third stage of the Soyuz-2 is a Blok-I, which is powered by an RD-0110 engine. The first three stages all burn RP-1 propellant oxidised by liquid oxygen. The fourth stage, the Fregat, is powered by an S5.98M engine, which uses unsymmetrical dimethylhydrazine as propellant and nitrogen tetroxide as an oxidiser. The Fregat first flew in 2000, and has been used on Soyuz-U, Soyuz-FG, Soyuz-2 and Zenit rockets. The launch of Meridian-4 is its twenty third flight.
Seventeen seconds before launch, the first and second stage engines will ignite, and began to build up to full thrust. When the countdown reached zero, four swing arms holding the rocket in place will fall back, and the vehicle will begen to climb away. Around 118 seconds after launch, when the rocket reaches a predetermined velocity, the four boosters will be jettisoned.
About 288 seconds after launch the Blok-I will ignite, and two seconds later it will separate from the Blok-A. The Blok-I will burn for around 240 seconds, propelling the upper stage and spacecraft onto a suborbital trajectory. Then, eight minutes and forty six second after launch, the Fregat will separate from the Blok-I, and ignited a minute later for a 23 second burn to insert the spacecraft into a low circular parking orbit.
After reaching the parking orbit, the Fregat will coast for thirty five minutes and 42 seconds, before igniting for its second burn. This will last ten minutes and eight seconds, taking the spacecraft most of the way to its final orbit. This will be followed by another coast phase, lasting 80 minutes and 44 seconds, after which it will ignite again to perform a third burn. This burn will last 35 seconds, and raise the perigee of the orbit.
Spacecraft separation is scheduled for 30 seconds after the completion of this burn. 30 minutes later the Fregat will make a 36 second disposal burn to separate its orbit from that of its payload.