This section describes the SCAN Testbed Mission Operations phase.

The Ground System consists of the CoNNeCT Control Center (CCC), the CoNNeCT Experiment Center (CEC), the Ground Verification Facility (GVF), and the external ground systems and their interfaces located at the Huntsville Operations Support Center (HOSC), White Sands Complex (WSC), and Wallops Ground Station (WGS). The NASA Integrated Services Network (NISN) is the network that connects these entities. Other ground stations beyond WGS may also be used during operations, including White Sands 1, or user supplied ground stations. However, WGS is currently the baseline station and was used for operations planning and link analysis.

The SCAN Testbed and Ground System send and receive commands and data, and manipulate (stores, routes, and processes) data. The Flight System and Ground System interface with external systems to send and receive RF signals to and from space. The RF signals carry commands and data between the two CoNNeCT elements. The Ground System provides terrestrial control of the Flight System through the CoNNeCT Control Center, a top-level schematic of the Ground System is shown in Figure 1.

Figure 1. SCAN Testbed Ground System

SCAN Testbed uses two paths for communicating to the ground (Figure 2) – primary and experimental.

Figure 2. Schematic of the SCAN Testbed RF links

SCaN Testbed has line-of-sight connection to NASA’s Space Network (Tracking Data Relay Satellites) and compatible ground stations or other space nodes (e.g., Cubesat).

There are two communication paths for the CoNNeCT mission. The primary communications path (commanding and telemetry) will exist through the ISS link. This link will be coordinated through the Marshall Space Flight Center (MSFC) Huntsville Operations Science Center (HOSC). The HOSC will receive the data from the SN and forward it to the Glenn Research Center (GRC) CoNNeCT Control Center (CCC) through existing architecture.

The SCAN Testbed uses both the primary and experimental paths for commanding. Nominal commanding will use the primary path. Commands will originate from the GRC TSC except for 13 critical commands. The critical commands will be sent by the Payload Rack Officer (PRO) from the HOSC in coordination with the CCC. The critical commands will reside only in the Payload Operations Integration Center (POIC) database.

The second communication path (commanding and bidirectional data) is the experimental link with the SN and the NEN. In the future the SCAN Testbed will have the capability to use this link to send non-critical commands through the SDRs to the Avionics. This link will be scheduled directly by the CCC with the supporting elements. This link includes S-band and Ka-band services to the Space Network and S-band to the NEN. Users will coordinate their ground station use with the CCC.

• Forward Link: GRC CCC through NISN Near Earth Network to White Sands to TDRSS to SCAN Testbed.
• Return Link: SCAN Testbed to TDRSS to White Sands through NASA Integrated Services Network NISN Near Earth Network to GRC CCC.
• Uplink: GRC CCC through NISN Near Earth Network to Ground Station (e.g. WFF) to SCAN Testbed.

Downlink: SCAN Testbed to Ground Station (e.g. WFF) through NISN Near Earth Network to GRC CCC.

The CCC is the Mission Operations CoNNeCT Control Center. It will reside within the TSC and will make use of the existing TSC interfaces to the HOSC. The CCC will use the TSC data network, which is an isolated network from the GRC campus network. The TSC facility located at GRC allows payload developers and scientists on earth to monitor and control experiments onboard the International Space Station (ISS).

The CoNNeCT Experiment Center is the real time mission data analysis and interface for the Principal Investigator team and any other experimenters involved with the CoNNeCT mission. It is physically adjacent to the CCC and located within the TSC. It is separate from the CCC because it is an experimental data center while the CCC is the overall operations center.