Next Generation Mass Memory Unit (MMU-NXT)

The MMU (mass memory unit) is a crucial component in the data handling, processing, and downlink chain. In recent years, NAND flash memories have become the dominant technology for large non-volatile storage, serving as the foundation for modern MMUs. NAND flash memories offer significant storage capacities and fast read/write speeds for mass storage applications.

MMUs require the use of commercial-off-the-shelf (COTS) parts that must undergo screening for suitability in the harsh space environment.

The goal of the MMU-NXT study is to design a new architecture for MMUs that improves data rate and storage capacity while slightly increasing size and weight. The increased capacity is achieved by utilizing state-of-the-art NAND flash technology with synchronous interfaces.

The MMU-NXT architecture consists of two main components: the Command and Control Module for input, output, and monitoring, and the Mass Memory Module (MMM). This separation allows for efficient handling of high data rates, which is achieved by incorporating state-of-the art FPGAs and SpaceFibre interfaces.

In summary, the MMU-NXT will provide the following performance:

• Aggregated data rate of 20 Gbps
• Storage Capacity of 48 Tibit
• 4 instrument SpaceFibre interfaces (all active), operating at 3.125 Gbps
• 2 downlink SpaceFibre interfaces working at 6.25 Gbps each for a combined data rate of 12.5 Gbps
• 4 SpaceWire interfaces (all active), operating at 200 Mbps
  
• 1 WizardLink interface, operating at 2.5 Gbps
  

This sets the basis for the following functionalities:

• reception of data from one or several payload instruments over medium or high speed links
• storage of the buffered data to flash memory, employing appropriate ECC schemes
• preparation of the retrieved data for downlink (CFDP PDU Generator, TM Encoder etc.).
• transfer of the data to the payload data transmitter
• error management of the NAND flash devices
  handling of telecommands, the collection of housekeeping data, and the generation of telemetry