Soyuz 2.1a | Progress MS-31 (92P)

Soyuz 2.1a Launches Progress MS-31: Sustaining the International Space Station

On July 3, 2025, a Soyuz 2.1a rocket lifted off from the Baikonur Cosmodrome in Kazakhstan, carrying the Progress MS-31 spacecraft on a vital resupply mission to the International Space Station (ISS). Designated as mission 92P, this unmanned flight underscores Russia's enduring role in maintaining the orbital outpost, delivering essential supplies amid evolving geopolitical dynamics in space exploration.

The primary objective of Progress MS-31 is to transport cargo to the ISS, ensuring the station's crew can continue scientific research and operations. The spacecraft is designed to carry up to 2,500 kilograms of payload, including dry cargo like food, clothing, and scientific equipment, as well as propellant for the station's thrusters and water for life support. Upon docking, typically automated via the Kurs-NA system, the Progress vehicle not only unloads its cargo but also serves as a temporary waste disposal unit, eventually burning up in Earth's atmosphere during re-entry. This mission's payload capabilities highlight the spacecraft's efficiency: it can deliver pressurized cargo in a sealed module, allowing for the transfer of sensitive items without exposure to space's vacuum. Such versatility is critical for long-duration missions, where resupply flights like this one prevent shortages that could compromise crew health or experimental timelines.

At the heart of the launch is the Soyuz 2.1a rocket, a modernized variant of the venerable Soyuz family. Standing approximately 46 meters tall with a diameter of 2.95 meters at its core, the rocket features a three-stage design powered by liquid-fueled engines. The first stage consists of four strap-on boosters, each equipped with an RD-107A engine burning kerosene and liquid oxygen, generating a combined thrust of over 800 metric tons at liftoff. The second stage uses an RD-108A engine, while the third stage employs an RD-0110 for orbital insertion. Upgrades in the 2.1a model include digital flight control systems and improved telemetry, enhancing reliability and precision compared to earlier analogs. With a payload capacity of about 7,000 kilograms to low Earth orbit, the Soyuz 2.1a balances cost-effectiveness—estimated at $40-50 million per launch—with proven performance.

The Soyuz family's performance history is a testament to its robustness. Since its debut in 1966, over 1,900 Soy