Ground Station

Primary Ground Station

The primary ground station has two large Yagi antennas on top of Rhodes Hall at Cornell University: a 2m band antenna and a 20 ft, 19.5 dB gain 70 cm band antenna. The transceiver, rotator controller, and other radio station hardware are located in the top floor of the building and can be remotely controlled.

Secondary Ground Stations

The Cislunar Explorers team plans to use at least two secondary ground stations (currently, Wallops and Goonhilly Earth Station) for verification of lunar orbit via Doppler tracking. These facilities each have large UHF-capable dishes with sufficient gain and resolution to help confirm the achievement of an orbit within 10,000 km of the Moon.

Operations

The flow diagram of the ground system shown below includes schedueling, tracking, data acquisition, data transfer/archival, and off-nominal scenario handling. The spacecraft downlinks the data artifacts described in the next subsection to the primary Cornell ground station, which exchanges data with the Cornell mission control center. Mission control archives data and backs it up to the cloud, as well as reporting data to NASA along with planned and completed comms efforts. The downlinked data contains both spacecraft telemetry (health and other status) as well as the latest spacecraft ephemeris as computed and reported by the optical navigation system. Mission control will decode this information and use it to update ongoing projections of the mission trajectory using AGI Systems Toolkit (STK). Based on these results, mission control will provide correction commands, such as reorientation and propulsion maneuvers, to the primary ground station and schedule them for uplink to the spacecraft. The Wallops and Goonhilly ground stations receive only downlink from the spacecraft (except in off-nominal), tracking the signal for the purposes of prize confirmation, and reporting the results directly to NASA. This data will be provided in the required Consultative Committee for Space Data Systems (CCSDS) Orbit Ephemeris Message (OEM) format.
In the event of an off-nominal where contact is not made by the primary ground station, the team will first attempt to use the backup ground station while assessing the primary to see if repairs are required. As a contingency, the team may attempt contact using other ground stations if available. Additionally, because the spacecraft communication takes place using an open-source format on an amateur radio band, any amateur radio operator with enough antenna gain would be able to assist, in theory.

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