Thales Electron Devices has been pursuing since 2003 frequency standards activities. In the framework of these activities, Thales established a consortium for the development of a space Cs atomic clock for Galileo. This consortium is composed by two of the best scientific laboratories in the European Time-Frequency community: the Observatoire de Neuchatel (ON) and the SYRTE Observatoire de Paris, and by two space industrials: Oerlikon Space AG (OSAG) and Thales Electron Devices. The name of the project is OSCC for Optically pumped Space Cs Clock. The first phase (phase A) of this development started in June 2006 under an ESA contract.The purpose of this phase A is a feasibility study of Cs clock technology for Galileo with the manufacturing and the test of a new compact optically pumped Cs clock breadboard. This technology is well known in laboratories but it has never been industrialized, even for ground applications. This study starts with a strong background at SYRTE and ON, but also with new industrial developments realized at Thales during the last years. Frequency stability in order of 1 to 3x10(-12).tau(-1/2) has been already demonstrated in lab with different configurations.This document will first synthesize the last results obtained by each Partner, followed by the results of the existing hardware analysis performed in the first step of the project. This analysis allowed Partners to share their know-how and to identify the limits of each existing breadboards with respect to the objectives of the project. As a result of this analysis, it was possible to define the atomic resonator best configuration for each subsystem. At least, this document presents a few design drivers of the new OSCC devices.

Observatoire de Neuchatel has developed a compact optically-pumped cesium beam frequency standard in the frame of an ESA-ARTES 5 project. The simplest optical scheme, which is based on a single optical frequency for both preparation and detection processes of atoms, has been chosen to fulfill reliability constraints of space applications. With the last evolution of our laboratory demonstrator, we have measured a frequency stability of sigmay=1.14 times10-12 tau-1/2, which is compliant with the Galileo requirement and our frequency stability goal of sigmay=1.14 times10-12 tau-1/2. Present performance limitations are discussed and further improvements are proposed to possibly increase the frequency stability.

Observatoire de Neuchâtel (ON) is developing a compact optically-pumped cesium beam frequency standard in the frame of an ESA-ARTES 5 project. The simplest optical scheme, which is based on a single optical frequency for both preparation and detection processes of atoms, has been chosen to fulfill reliability constraints of space applications. With our laboratory demonstrator, we have measured a frequency stability of σy=2.74×10-12τ-1/2, which is compliant with the Galileo requirement. Present performance limitations are discussed and further improvements are proposed in order to reach our ultimate frequency stability goal of σy=1×10-12τ-1/2.