The State Space Agency of Ukraine was forced to bring its latest crewed mission to an early conclusion on Saturday after a malfunction in the reaction control system of its KL-6K spaceplane.

 

The Spaceplane-5 mission was intended to carry four astronauts on an extended orbital flight to deploy the Helios-A space probe and conduct orbital operations, but instead returned to Earth after just one orbit.

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The anomaly occurred while the crew was preparing for a scheduled spacewalk. Approximately eight minutes before hatch opening, Mission Control commanded a minor orbital correction manoeuvre. During the burn, one of the RCS thrusters became clogged, sending the vehicle into an uncontrolled spin.

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For nearly two minutes, the crew worked to stabilise the spacecraft, eventually regaining control. By that point however, Mission Control in Kyiv had already made the decision to terminate the mission, prioritising safety risks in continuing orbital operations.

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“Crew safety is our absolute priority,” a spokesperson said. “Although the astronauts were able to recover the vehicle, the incident showed us a need for caution. The correct course of action was to bring the crew home immediately.”

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The order was given to perform an Abort Once Around procedure, a contingency flight plan in which the spacecraft completes a single orbit before re-entering. The four member crew carried out the sequence without difficulty, executing reentry and landing at Izmail Space Center.

 

All astronauts disembarked safely, with post flight medical checks confirming no injuries.

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Following the safe return, SSAU’s Engineering & Production Department issued a preliminary statement attributing the failure to a blockage in one of the RCS thrusters. Early analysis suggests debris contamination within the feed system, which prevented the thruster from expelling propellant correctly.

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“The issue has been isolated and we are confident that corrective measures will be in place ahead of the next mission.” the department said. “Spaceplane-6 remains on track, and we do not anticipate further related incidents.”

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With the deployment of the Helios-A probe, and the return of the crew despite the issues, SSAU officials said that the mission should be considered a success in terms of crew safety and proof of the capability of the KL-6K system under emergency conditions. The quick reaction of both astronauts and ground controllers ensured a controlled recovery rather than a more serious outcome.

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The KL-6K spaceplane, which has now flown five missions since its debut, remains central to Ukraine’s expanding crewed spaceflight program. While Spaceplane-5 showed vulnerabilities in onboard systems, it provided valuable data for refining procedures and hardware ahead of future flights.

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"Unfortunate setback, some objectives will be achieved today’s launch with the second spaceplane. First one is undergoing repairs and upgrades." Said Amara, SSAU's Administrator.

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The next mission, Spaceplane-6, will launch on the agency's new Mavka (KL-7K) orbiter. This is the second in the line of their orbital spaceplane fleet. While Mavka flies, the Lebid (KL-6K) orbiter will undergo repairs and re-certification prior to its return to flight.

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For now, full mission objectives will await reassignment to a later mission, while SSAU works to ensure the reliability of its spacecraft. The agency confirmed that lessons learned from Spaceplane-5 will be incorporated directly into Spaceplane-6, currently scheduled for launch today.