Evolution of the Mars Relay Network End-to-End Information System in the Mars Human Era (2030-2040)

摘要

The current Mars Relay Network (MRN) is an evolving international network of Mars relay orbiters along with their supporting ground systems that provides communication and navigation relay services (command, telemetry, time and navigation) to Mars bound assets e.g., landers, rovers, probes. Currently, MRN consists of 4 relay orbiters serving 2 landed assets, whose governance is shared between NASA and ESA. The associated MRN End-to-End Information System (EEIS) is the set of distributed functions allocated throughout the flight, ground, launch, and mission operation systems, that interoperate to transport and manage mission information (e.g., science, engineering, radiometric, command, time) throughout this network. These functions are performed cooperatively by flight and ground elements to achieve mission user objectives. In order to help the reader understand this evolution from the current to the future MRN state in the Mars human era, we will provide a description of the current communication infrastructure supporting Mars mission users, and how we envision it to change in order to meet the needs and challenges of supporting both human and robotic communication by 2030-2040. This includes the introduction of new data types like audio and video, and new in-situ relay services for communications and navigation services. We firmly believe that cost will prohibit any sole nation from providing all communication services required by humans in this era. Therefore interoperability and cross-support will be necessary to achieve the connectivity goals of the MRN in the human Mars era. The authors contend that the best way to achieve the necessary network interoperability and cross support will be through the use of international standards predominately but not limited to CCSDS. This paper will discuss: 1) The end-to-end MRN data flows from the key EEIS architectural points of view (physical, functional, communication, enterprise); 2) End-to-End Data Products. How data management (DM), data transport (DT), and data integration (DI) issues must be transparent to the user, so that users/Mission Operations System (MOS) do all their planning in terms of data products and never have to concern themselves with the artifacts of the DT, DM, DI functions with the End-to-End data system; 3) The layered ISO CCSDS protocol stack envisioned to support the MRN including the Delay-Tolerant Networking (DTN) architecture: 1) Physical Layer - Optical and RF Communication along with higher order modulation schemes; 2) Data Link Layer - Unified Space Link Protocol (USLP) with very high performance coding on both uplink and downlink to be used on all robotic (near Earth and deep space) and manned links; 3) Network Layer - End-to-end DTN Bundle Protocol (BP), with reliability ensured by underlying Licklider 4) Transmission Protocol (LTP), enabling secure seamless transition between IP (terrestrial) and CCSDS space link based networks. 5) Transport Layer - Delay-Tolerant Payload Conditioning (DTPC) providing end-to-end acknowledgment and retransmission as necessary; 6) Application Layer - Asynchronous Messaging Service (AMS), CCSDS File Delivery Protocol (CFDP), and Bundle Streaming Service (BSS);