August 26, 2011
In the Loop: One IEM, Two IEM
This month, the Radiation Belt Storm Probes team at the Johns Hopkins Applied Physics Laboratory reached a major development milestone: Both RBSP spacecraft are now equipped with fully operating Integrated Electronics Modules (IEMs), which contain the spacecraft processors and allow subsystems and instruments on the spacecraft to exchange data.
“I was very happy to sit down with [IEM Lead Engineer Geff Ottman] and team to celebrate the delivery of both flight IEMs,” wrote RBSP Program Manager Rick Fitzgerald in a note to the entire RBSP group on Aug. 18. “It has been a long, hard road for this team and through it all, everyone kept plugging away. I know many late evenings, weekends and even holidays were sacrificed in order to get these units delivered. I never take that kind of effort for granted.”
“We have an experienced team that truly enjoys being in the middle of things,” Ottman said of the IEM delivery.
The IEM serves as the main computer for the RBSP spacecraft, and is built with a radiation-hardened processor for execution of APL flight software and a memory array for storage of scientific data. The IEM interfaces with all instruments and components of the spacecraft bus (the “box” of the spacecraft), providing the direct link for command instructions and data transfers. There are also specific features to support spacecraft navigational maneuvers and to recover from on-orbit failures. The variety of functionality provided by the IEM helps tie the science and engineering aspects of the RBSP mission together; it’s a crucial piece in creating the kind of cohesive spacecraft that APL prides itself on delivering to NASA.
“I look forward to watching these units operate in our final pre-launch tests and ultimately for many years on-orbit,” Fitzgerald added. “I send out a big thank you to everyone associated with the IEM build!”
APL manages the RBSP mission for NASA and will operate the spacecraft; check back for more photos and updates as the mission moves toward launch in 2012.
Click on the thumbnail image for a larger version.
Above: RBSP team members install the IEM on Spacecraft A earlier this year; the IEM contains electronics for spacecraft computing and interfaces with the instruments for transfer of critical science data.
Above: IEM qualification includes vibration testing (top, on grey and black platform) and thermal-vacuum testing (bottom, in cylindrical chamber) to simulate the physical environments of launch and space. As a critical component, the IEM is subjected to these strenuous tests to verify functionality and box integrity.