An Ultra Stable Oscillator for the 3GM experiment of the JUICE mission

An Ultra Stable Oscillator is being developed by AccuBeat (named USO) for the Gravity and Geophysics of Jupiter and the Galilean Moons (3GM) radio occultation experiment of the ESA JUICE mission. This paper reviews the oscillator design and the critical issues to be tackled. The USO is a compact 15×13×10cm
³
oscillator, based on a quartz crystal resonator and highly stable double oven. A Partial Engineering Model of (PEM) was built and tested in thermal vacuum. The PEM with 5MHz output has demonstrated a frequency stability below 2E-13 for a at averaging times of 1s to 1000s, thus meeting the requirements for technology readiness level 5 (TRL 5), according to the ECSS.