IMPROVED TTC SUB-SYSTEM ARCHITECTURE - EXPRO+

Objectives: To consolidate alternative solutions for on-board loss minimization. To develop the prototypes of the most relevant solutions identified, to confirm the predicted performance. To provide road-map to flight models. The state of art TTC Sub-System architectures for Science and Exploration missions are nowadays quite complex. In order to allow communications during all mission phases, several antennas are needed in combination with redundant High Power Amplifiers (HPA) and transponders (DST). The interconnectionamong these components is accomplished by the RF Distribution Unit (RFDU), which has to guarantee the maximum degree of reconfigurability and reliability to failures. In addition, it has also to implement the necessary filtering action, to allow full duplex communications. Its design is therefore quite complex encompassing the use of several switches, Diplexers, Filters and interconnecting waveguides (WG) runs. The latter can be quite long as they have to reach antennas which are typically far from the location of the rest of the TTC subsystem. All this results in high losses with RF power reduction in transmission and increased noise figure in reception.The design solutions used so far in the frame of ESA projects are quite recurrent with no major improvements in the last decades. As shown in a TTC Sub-System architecture survey carried out in 2017, different approaches exist, as identified for example by other agencies and already flown successfully in the past years. For a complex RFDU as used in Deep Space missions, we can consider RF path losses in the order of 1 to 3 dB in X-band and 3 to 4 dB in Ka-band, withsignificant impacts in terms of data return (up to50% reduction) and in terms of spacecraft recovery possibilities in case of anomalies (increasedoperations complexity and limitation on maximum achievable distance). Therefore, there is a clear need for loss reduction in the RFDU paths, through the implementation of novel solutions. A study is on-going to consolidate the possible alternative subsystem Architectures, and define relevant requirements. This will be completed in early 2024, but its conclusions need to be consolidated by experimental results. The activity shall focus on the specification, detailed design, development and tests of prototypes of the components which will have the most significant impact on the TTC subsystem performance and whose feasibility has to be demonstrated. Three main items have been already identified, which may need to be completed by additional technologies as an outcome of the on-going study:- Receiving only antenna with integrated low-noise-amplifier (LNA) and downconverter (D/C), with a possible alternative for a receiving and transmitting solution;- High-gain-antenna dual-band feed including receiving LNA and D/C, and with direct interface to power amplifier;- Transponder front-end to manage the interfaces with new antennas designs.Tasks:1. Consolidation of requirements and design2. Design and manufacturing of bread-boards3. Testing of bread-boards4. Development plan for flight models.