Soyuz 2.1a | Progress MS-35 (96P)

Soyuz 2.1a Launches Progress MS-35: Sustaining the International Space Station

On June 17, 2026, a Soyuz 2.1a rocket thundered into the sky from the Baikonur Cosmodrome in Kazakhstan, carrying the Progress MS-35 spacecraft on its vital resupply mission to the International Space Station (ISS). Designated as 96P in the Progress series, this unmanned cargo vessel represents a continuation of Russia's longstanding commitment to orbital logistics, delivering essential supplies to support the station's crew and operations.

The primary objectives of the Progress MS-35 mission center on replenishing the ISS with critical resources. The spacecraft is designed to transport up to 2,500 kilograms of cargo, including food, water, scientific equipment, and fuel for the station's propulsion systems. Beyond mere delivery, Progress vehicles like MS-35 serve dual purposes: they can perform orbital maneuvers to adjust the ISS's altitude, counteracting atmospheric drag, and upon mission completion, they act as waste disposal units, burning up during atmospheric reentry. This efficiency underscores the payload's capabilities, with the MS series featuring advanced docking systems and telemetry for autonomous rendezvous, reducing reliance on ground control and enhancing mission reliability. For instance, the spacecraft's pressurized compartment can carry up to 1,700 kg of dry cargo, while its refueling module handles propellants like unsymmetrical dimethylhydrazine and nitrogen tetroxide, ensuring the ISS remains operational amid extended human presence in space.

At the heart of this launch is the Soyuz 2.1a rocket, a modern iteration of the venerable Soyuz family. Standing approximately 46 meters tall with a diameter of 2.95 meters at its core, the Soyuz 2.1a is a three-stage vehicle powered by liquid-fueled engines. The first stage employs four RD-107A engines, each generating about 838 kN of thrust, augmented by four strap-on boosters. The second stage uses an RD-108A engine, and the third stage relies on the RD-0110. This configuration allows the rocket to deliver payloads of up to 7,000 kg to low Earth orbit (LEO), making it ideal for ISS missions. Technical upgrades in the 2.1a variant include a digital flight control system, which improves accuracy and enables launches from multiple sites, including Vostochny Cosmodrome. These enhancements address the limitations of earlier analog systems, providing greater flexibility in an