The space station crew welcomes the surrogate Soyuz amid preparations for the Crew Dragon launch in Florida

Russia’s uncrewed Soyuz crew ship performed a flawless robotic rendezvous and docking at the International Space Station on Saturday, replacing a ship. Damaged ferry shipgiving three lab crew members a reliable lifeboat and a safe ride home at the end of an extended mission.

Meanwhile, SpaceX in Florida prepared to launch its Crew Dragon capsule early Monday to ferry another four-man crew to the outpost.

The Soyuz MS-23/69S spacecraft launched from the Baikonur Cosmodrome in Kazakhstan on Thursday, carrying supplies and equipment in lieu of a crew, and oriented itself to photo-perfect robotic docking at Russia’s Poisk space-front module at 7:58 p.m. EST.

The new Soyuz will replace the MS-22 vehicle that carried Sergey Prokopyev, Dmitry Petlin, and NASA astronaut Frank Rubio into orbit last September.

They were originally planning to return to Earth next month, but on December 14, their Soyuz MS-22 vehicle wash it By a micrometeor rupture of a line carrying coolant to the external radiators. As a result, all available coolant was emitted into space.

After conducting an analysis, Russian engineers determined that the spacecraft could not safely transport the three crew members back to Earth due to the potential for critical computers and other sensitive equipment to overheat after being disengaged.

Instead, they moved the MS-23 launch vehicle to serve as an emergency evacuation-class lifeboat, except for the crew’s eventual return to Earth. To get the normal crew rotation schedule back on track, Prokopyev and his colleagues will now spend an entire year in space instead of six months.

But with the arrival of the Soyuz MS-23 ferry, they will once again have a reliable spacecraft to take them home in case of a medical emergency or some other problem that might require immediate evacuation from the space station.

The space station’s four other crew members — Crew 5 Commander Nicole Mann and Josh Kasada, Japanese astronaut Koichi Wakata, and astronaut Anna Kikina — were launched to the laboratory complex last October aboard the SpaceX Crew Dragon spacecraft. They plan to return to Earth around March 6th.

Their replacements — Crew 6 Commander Stephen Bowen, Woody Hoburgh, Cosmonaut Andrey Vidyaev and Emirati astronaut Sultan Al Neyadi — are scheduled to launch from Pad 39A at Kennedy Space Center Monday at 1:45 a.m.

Bowen and his cohorts strapped on the Crew of the Dragon on Thursday night and took part in the countdown rehearsal. A few hours later, after the crew had departed, SpaceX engineers tested the Falcon 9’s first-stage engines to verify that they were ready to fly.

The crew plans to work for real after 11 p.m. on Sunday. Assuming liftoff early Monday, the Crew-6 ferry ship will arrive at the space station at 2:38 a.m. Tuesday, docking in the Harmony module’s forward port facing space.