SpaceX has concluded fatigue on an engine cover caused one of the nine Merlin 1D first stage engines on the company’s most recent launch to shut down early during ascent, leading to the loss of the booster during an offshore landing attempt in the Atlantic Ocean, an official said Monday.

A Russian Soyuz rocket and Progress resupply freighter are set for liftoff Monday on an accelerated, less-than-four-hour rendezvous with the International Space Station after last-minute launch scrubs prevented two similar fast-track approach attempts in recent months.

An Antares rocket is being prepared for launch for the first time in two years after emerging from the Horizontal Integration Facility at Wallops Island, Virginia, on Thursday evening for a one-mile trip to the launch pad.