fuel the vehicle as it sat on the pad; the same modifications were made to Site 81 when Mir, Zarya, and Zvezda were launched from it. On 7 June, work at Site 200 was completed in preparation for the assembly of the launch vehicle and the rollout of Nauka to Pad 39 at the facility. On 30 June 2021, fueling began, but a problem with the spacecraft's guidance sensors was detected and Nauka was rolled back to the instrumentation and test facility at Site 254. The upper fairing was removed and rolled away while workers using safety harnesses changed and replaced the sensors and reinstalled the MLI. On 1 July, more imperfections were found requiring a full scrub down and systems had to be removed and replaced. On 3 July, the fairing was reattached and Nauka was powered on to test the sensors before it was reloaded onto the transfer car and redelivered to the airlock where it was placed on a flatcar for delivery to Site 31 for fueling. On 9 July 2021, ILS completed stacking of the Proton rocket at Site 200 and all three of the lower stages were fueled and standing by for the arrival of Nauka. Because of delays with rewrapping the sensors, rollout was scheduled for 17 July with launch on the 21st. Also on 9 July, teams from ILS, Khrunichev, Roscosmos, Energia, and Yuzhny Space Center conducted a dry countdown to test the new computers and systems at Site 200 which would control Nauka and feed it and the Proton rocket telemetry through the first 12 minutes of flight up until first stage separation and fairing jettison, where telemetry would be controlled from ground stations and from Mission Control Moscow. On 10 July, Nauka was fueled and the aft compartment was closed out in preparation for the transfer to Site 200 to be attached to the Proton rocket. Launch was scheduled for 21 July at 14:58 UTC. On 13 July 2021, Novitsky and Dubrov carried out work on the Pirs module, splitting up the hydraulic circuit and module control communications via the Progress spacecraft, and checked the docking unit and its systems. In this process they closed the Pirs module hatch that was connected to the Zvezda service module, after which Pirs was ultimately undocked on 23 July. Also on 13 July, Roscosmos revealed the mission patch for Nauka which was in the