DECLIC OPERATIONS AND GROUND SEGMENT AN EFFECTIVE WAY TO OPERATE A PAYLOAD IN THE ISS

摘要

DECLIC is a multi-user facility to investigate critical fluids behaviour and directional solidification of transparentalloys.As part of a joint NASA/CNES research program, the payload has been successfully operated onboard the ISSsince October 2009.The operations and the ground segment have been prepared and developed so that the payload is operated in aneffective way from the CADMOS control center (Toulouse, France), by using most of the functions proposed by theNASA's POIC (Payload Operations and Integration Center).For example, the internet is used as a connexion mean between the POIC and the CADMOS. The commands aresent via a secured connexion (VPN) while the telemetry is received via some non encrypted UDP ports.The operations have then been prepared in order to face the main limitations of the chosen way of connexion :1. Because the internet is not an operational network, and also in order to reduce the operations costs byavoiding having people on console 24/7 at CADMOS, the alarms are processed by operational teams at POIC whoare able to issue emergency commands if needed.2. Because the UDP is a connexion less protocol, some telemetry packets are lost (typically much less than1%). But, mainly because of the bandwidth limitations onboard the ISS, and because the DECLIC payload generatesvery large amounts of data (more than 1 TB since the beginning of operations), Removable Hard Disk Drives(RHDDs) are used to return the whole data to the ground as a reference data : the telemetry data is only used for realtimeoperations and rough analysis by the scientists.This example, and few others (the use of existing softwares, a web server development so that the scientists canhave a real-time view of the payloads from their lab etc…) are detailed in the paper showing how we have made theDECLIC operations effective and successful.The paper also discusses how DECLIC will take advantage of future ISS space-to-ground communications andHOSC ground systems services upgrades to further enhance the science collection opportunities of the experiment.