Imagine the testing and planning involved in preparation for the upcoming launch on May 12 of the Hubble Space Telescope Servicing Mission 4 (SM4). The flight spare Science Instrument/Command & Data Handling (SI/C&DH) unit is currently completing ground tests at NASA’s Goddard Space Flight Center. A thorough environmental testing program, comprised of electromagnetic interference/electromagnetic compatibility (EMI/EMC), vibration, and thermal vacuum testing was initiated in mid-December for the SI/C&DH. The unit has successfully completed EMI/EMC and vibration testing late last week. And so now the flight spare is ready for a month-long thermal vacuum test.

A final set of tests on the SI/C&DH will be conducted using an electrical replica of Hubble called the Vehicle Electrical System Test (VEST) facility to ensure total compatibility with Hubble’s space and ground systems prior to shipment to KSC in early April. According to HST program manager Preston Burch, the current SI/C&DH test schedule contains more than one month of schedule reserve, which gives high confidence that the SM4 flight hardware will be ready for the planned May 12 launch.

The six replacement batteries to be installed during SM4 remain in cold storage at Goddard and will be shipped to KSC in late March, where they will undergo final testing and charging before installation into the payload bay of the space shuttle Atlantis.

All other SM4 flight hardware remains in a cleanroom at the Kennedy Space Center, awaiting the arrival of the SI/C&DH unit and batteries.