The new SCOS-based EGSE of the EPIC flight-spare on-ground cameras

Abstract

The XMM-Newton observatory, launched by the European Space Agency in 1999, is still one of the scientific community’s most important high-energy astrophysics missions. After almost 15 years in orbit its instruments continue to operate smoothly with a performance close to the immediate post-launch status. The competition for the observing time remains very high with ESA reporting a very healthy over-subscription factor. Due to the efficient use of spacecraft consumables XMM-Newton could potentially be operated into the next decade. However, since the mission was originally planned for 10 years, progressive ageing and/or failures of the on-board instrumentation can be expected. Dealing with them could require substantial changes of the on-board operating software, and of the command and telemetry database, which could potentially have unforeseen consequences for the on-board equipment. In order to avoid this risk, it is essential to test these changes on ground, before their upload. To this aim, two flight-spare cameras of the EPIC experiment (one MOS and one PN) are available on-ground. Originally they were operated through an Electrical Ground Support Equipment (EGSE) system which was developed over 15 years ago to support the test campaigns up to the launch. The EGSE used a specialized command language running on now obsolete workstations. ESA and the EPIC Consortium, therefore, decided to replace it with new equipment in order to fully reproduce on-ground the on-board configuration and to operate the cameras with SCOS2000, the same Mission Control System used by ESA to control the spacecraft. This was a demanding task, since it required both the recovery of the detailed knowledge of the original EGSE and the adjustment of SCOS for this special use. Recently this work has been completed by replacing the EGSE of one of the two cameras, which is now ready to be used by ESA. Here we describe the scope and purpose of this activity, the problems faced during its execution, the adopted solutions, and the tests performed to demonstrate the effectiveness of the new EGSE.