Progress spacecraft are automated, unpiloted and single-use vehicles that typically deliver fuel and supplies to the International Space Station three to four times each year. They have been supplying the ISS since 2001. The Progress design was modeled after Russia’s Soyuz space capsule, which carries crewmembers to the ISS, but it is specially modified to carry cargo instead of people. Like the Soyuz, Progress vehicles are built to fly themselves but can also be remote-controlled by cosmonauts on the Space Station if required.
While Progress today is best known for ISS flights, versions of the spacecraft have been used since 1978. They were first flown by the Soviet Union for the space stations Salyut 6, Salyut 7 and Mir. Russia continued flights after the Soviet Union breakup in the early 1990s.
More than 150 flights of Progress have occurred to date, with just a handful of mission-stopping flight problems across nearly four decades of work. Two of the most famous incidents, however, took place during the Mir program; Progress M-24 crashed into Mir while docking in 1994, and Progress-M34 damaged the Spektr module during a 1997 docking test.
More recently, two Progress flights (between dozens of successful launches) failed to reach the ISS. Progress M-12M (also known as Progress 44 or 44P) was lost during launch in August 2011. The failure happened due to a malfunction in the Soyuz rocket. In 2015, Progress M-27M (also known as Progress 59 or 59P) spun out of control in low Earth orbit shortly after demating from its rocket, and could not be recovered. The loss was later attributed to a “design peculiarity” between the Soyuz and Progress.
The robotic craft, which are about 24 feet (7 meters) long and nearly 9 feet (2.7 meters) wide, consist of three modules. The first is a pressurized forward module, which carries supplies to the ISS, such as scientific equipment, clothes, prepackaged and fresh food, and letters from home. The current version of the Progress craft can carry 1,700 kilograms (3,748 pounds) of such supplies.