A space workhorse
The Soyuz launcher was introduced in 1966, deriving from the Vostok launcher, which in turn was based on the 8K74 or R-7a intercontinental ballistic missile. It was initially a three-stage rocket with a Block I upper stage. Later a Molniya variant was produced by adding a fourth stage, allowing it to reach the highly elliptical molniya orbit. A later variant was the Soyuz-U. While the exact model and variant designations were kept secret from the west, the Soyuz launcher was referred to by either the United States Department of Defense designation of SL-4, or the Sheldon designation of A-2 (developed by Charles S. Sheldon, an analyst with the Library of Congress). Both systems for naming Soviet rockets stopped being used as more accurate information became available.
The production of Soyuz launchers reached a peak of 60 per year in the early 1980s. It has become the world's most used space launcher, flying over 1700 times, far more than any other rocket. Despite its age and perhaps thanks to its simplicity, this rocket family has been notable for its low cost and high reliability.
Soyuz / Fregat
In the early 1990s plans were made for a redesigned Soyuz with a Fregat upper stage. The Fregat engine was developed by NPO Lavochkin from the propulsion module of its Phobos interplanetary probes. Although endorsed by the Russian Space Agency and the Russian Ministry of Defence in 1993 and designated "Rus" as a Russification and modernisation of Soyuz, and later renamed Soyuz-2, a funding shortage prevented implementation of the plan. The creation of Starsem in July 1996 provided new funding for the creation of a less ambitious variant, the Soyuz-Fregat or Soyuz U/Fregat. This consisted of a slightly modified Soyuz U combined with the Fregat upper stage, with a capacity of up to 1,350 kg to geostationary transfer orbit. In April 1997, Starsem obtained a contract from the European Space Agency to launch two pairs of Cluster 2 plasma science satellites using the Soyuz-Fregat. Before the introduction of this new model, Starsem launched 24 satellites of the Globalstar constellation in 6 launches with a restartable Ikar upper stage, between September 22, 1999 and November 22, 1999. After successful test flights of Soyuz-Fregat on February 9, 2000 and March 20, 2000, the Cluster 2 satellites were launched on July 16, 2000 and August 9, 2000. Another Soyuz-Fregat launched the ESA's Mars Express probe from Baikonur in June 2003. Now the Soyuz-Fregat launcher is used by Starsem for commercial payloads.
ISS crew transport
Between February 1, 2003 and July 26, 2005 with the grounding of the U.S. Space Shuttle fleet, Soyuz was the only means of transportation to and from the International Space Station. This included the transfer of supplies, via Progress spacecraft, and crew changeovers. Since the retirement of the Space Shuttle fleet in 2011, the U.S. space program is without any means to take astronauts into orbit, and NASA is dependent on the Soyuz to send crew into space for the immediate future. NASA is scheduled to resume crewed flights from the United States in 2019 through the Commercial Crew Development program.
A long string of successful Soyuz launches was broken on October 15, 2002 when the uncrewed Soyuz U launch of the Photon-M satellite from Plesetsk fell back near the launch pad and exploded 29 seconds after lift-off. One person from the ground crew was killed and eight injured.
Another failure occurred on June 21, 2005, during a Molniya military communications satellite launch from the Plesetsk launch site, which used a four-stage version of the rocket called Molniya-M. The flight ended six minutes after the launch because of a failure of the third stage engine or an unfulfilled order to separate the second and third stages. The rocket's second and third stages, which are identical to the Soyuz, and its payload (a Molniya-3K satellite) crashed in the Uvatski region of Tyumen (Siberia).
On August 24, 2011, an uncrewed Soyuz-U carrying cargo to the International Space Station crashed, failing to reach orbit. On December 23, 2011 a Soyuz-2.1b launching a Meridian-5 military communications satellite failed in the 7th minute of launch because of an anomaly in the third stage.
On October 11, 2018, the Soyuz MS-10 mission to the International Space Station failed to reach orbit after an issue with the main booster. The launch escape system was used to pull the Soyuz spacecraft away from the malfunctioning rocket. The two crew, Aleksey Ovchinin and Nick Hague, followed a ballistic trajectory and landed safely over 400 km downrange from the Baikonur Cosmodrome.
Soyuz-2 and Guiana spaceport
The venerable Soyuz launcher is gradually being replaced by a new version, now named Soyuz/ST (or Soyuz-2), which has a new digital guidance system and a highly modified third stage with a new engine. The first development version of Soyuz 2 called Soyuz-2-1a, which is already equipped with the digital guidance system, but is still propelled by an old third stage engine, started on November 4, 2004 from Plesetsk on a suborbital test flight, followed by an orbital flight on October 23, 2006 from Baikonur. The fully modified launcher (version Soyuz-2-1b) flew first on December 27, 2006 with the CoRoT satellite from the Baikonur Cosmodrome.
On 19 January 2005, the European Space Agency and the Russian Federal Space Agency agreed to launch Soyuz/ST rockets from the Guiana Space Centre. The equatorial launch site allows the Soyuz to deliver 2.7 to 4.9 tonnes into sun-synchronous orbit, depending on the third-stage engine used. Construction of a new pad started in 2005 and was completed in April 2011. The pad used vertical loading common at Guiana, unlike the horizontal loading used at the Baikonur Cosmodrome. A simulated launch was conducted in early May 2011. The first operational launch happened on 21 October 2011, bearing the first two satellites in Galileo global positioning system.
The Soyuz-U and Soyuz-FG rockets are gradually being replaced by Soyuz-2 from 2014 onwards. Soyuz-U was retired in 2017, while Soyuz-FG still carries astronaut crews to the ISS as of 2018 .