Preparations are underway for getting ready to fuel up the Herschel spacecraft, everything is in place for fueling to be completed this week. This comes after having completed all functional tests on the Herschel spacecraft that has been moved from the S1B building to the S5B building where the hydrazine fueling activities will be performed.

On March 26, while still in the S1B building, the Herschel spacecraft was weighed in order to record the dry mass. This measure will provide the baseline from which the total Herschel spacecraft mass at launch will be calculated once the hydrazine fueling operation has been completed. Date: 07 Apr 2009 Satellite: Herschel Depicts: Weighing the Herschel spacecraft Location: S1B building, Kourou, French Guiana Copyright: ESA —The Herschel spacecraft is weighed while still in the S1 building at CGS, Kourou. The measurement will provide a baseline from which the total spacecraft mass at launch will be calculated after the hydrazine fueling has been completed.

The spacecraft weighing involves inserting a load cell between the crane and the Herschel Vertical Lifting Device (VLD) and then performing a successive series of mass measurements: with the VLD itself, with the VLD and calibrated masses, with the VLD and the Herschel spacecraft, and finally again with the VLD and calibrated masses to achieve the best possible accuracy.

On the morning of March 27 the Herschel spacecraft was placed on top of the launch adapter (ACU) and the combined unit was loaded onto the payload transport container, the CCU, for transport to the fueling building, S5B.

The CCU is a large transport container used to transfer spacecraft between the different satellite preparation sites (S1, S3, S5 and BAF) at CSG. It protects the spacecraft against shock and vibration, and provides a cleanroom-like environment with standard cleanroom levels of cleanliness, relative humidity and pressure. 10-Apr-2009 00:26:21 UT: Transporting Herschel from S1 to S5 Location: Outside the S1 building at CSG, Kourou, French Guiana Copyright: ESA After detaching from the airlock of S1B the CCU (Conteneur Charge Utile; payload transport container) containing the Herschel spacecraft starts the journey to S5 where the hydrazine fueling will take place.

The Herschel spacecraft was transported the 5 km distance between S1B and S5B in the CCU arriving in the afternoon of March 27. It docked with the S5B airlock and once the cleanroom conditions had been re-established in the airlock the CCU was opened and the CCU pallet with the spacecraft on top pushed into the main fueling hall. The Herschel spacecraft was then released from the flight adapter and lifted onto the stand to be used for the RCS fueling. The CCU arrives at S5 late in the afternoon of 27 March and completes the docking with the S5 airlock. Credit: ESA

Preliminary preparations have been made for the fuelling operations: the fuelling team has completed the mandatory safety training exercises and preparatory activities that are required prior to beginning the hazardous fuelling activities and 5 hydrazine-filled tanks have been moved to the S5 building. Everything is now in place for fuelling operations to be completed this week. The Herschel spacecraft in the S5B building ready for hydrazine fuelling. The platforms will be used at a later stage for Helium filling. Credit: ESA