The in-flight acceptance for the PHEBUS instrument is divided into 3 phases. The first, carried out 3 days after the launch, essentially consisted of unlocking the scanner’s locking mechanism (the instrument’s pointing mechanism).
The second phase, which has just been completed, has made it possible to carry out a functional test of almost all the subsystems:
1. Switching ON the instrument in “standby” mode (DPU on, sub-systems OFF), verification of basic telemetry (statutes, temperatures, voltages…)
2. Checking the operation of the slit flipping mechanism
3. Verification of the decontamination heaters of the diffraction gratings
4. Basic functional check of the pointing mechanism (scanner), in “step” mode (i.e. open loop) and in “absolute” mode (i.e. closed loop) and its associated shutter
5. Performance test of the scanner in both modes (step and absolute)
6. Patch/Dump test in different memory zones of the instrument
7. Functional check of the two main detectors (EUV and FUV) in 5 different calibration modes, with high voltage OFF.
8. Opening the EUV detector window
9. Verification of various automatic procedures (“Emergency Switch OFF”, “reboot”, etc…).
The results indicate that the instrument behaves nominally and that no major defects have been identified. However, the PHEBUS data obtained will need to be analyzed in more detail to confirm the total absence of anomalies.
The activities were carried out with a “live” contact between the Earth and the Bepi probe, while the latter was about 16 million kilometers (propagation time of the order of 50 seconds). The MIXS/SIXS and ISA instrument teams were also present at the ESOC to ensure part of their instruments ‘ flight proceeds.
The last phase of PHEBUS’s acceptance will take place in the summer of 2019, after a long propulsion phase. The activities will consist of progressively activating (over 5 days) The high voltages of the 2 main EUV/FUV detectors (up to near 4000V and 5000V respectively) as well as those of the NUV channels (K and Ca, 1000 V), which will complete the functional verification of PHEBUS. Observations on interplanetary background and star Calibrations will then begin.