The planned launch of an unmanned European supply ship to the international space station has been delayed due to minor cargo packing issues discovered during a preflight inspection, the European Space Agency (ESA) said March 2.

ESA’s third Automated Transfer Vehicle (ATV-3) was on track to launch March 9 aboard an Ariane 5 rocket from Kourou, French Guiana, until engineers noticed that some of its cargo was improperly stowed, ESA officials said.

“Two cargo bags appeared to not be properly strapped in the casing,” an official said. “During photographic inspection, we saw that these two bags were not correctly in their strapped positions, so the fear was that during liftoff, these bags could move or fall. To avoid this, we decided to move the ATV back to the integration room, so this will take a few days of work.”

The ATV-3 is packed with roughly 20 tons of supplies and propellant for the space station. The cylindrical spacecraft is 10.7 meters long and 4.5 meters wide. The ATV-3 is named Edoardo Amaldi after the Italian physicist and spaceflight pioneer.

ESA officials said the cargo stowage work on ATV-3 is expected to take about five or six days.