The last two weeks have been quite busy, with a few very late nights, but here is a quick update regarding our little one-unit CubeSat launched almost exactly two weeks ago.
After separation ZACUBE-1 switched on and waited under a antenna deployment timer for 30 minutes, after which it deployed its UHF and VHF antennas used for telemetry and telecommand and started beaconing on UHF. The deployment only happened after the first pass over South Africa and we had to wait just over an hour for the second pass to confirm the satellite was OK and beaconing. On the second pass we were able to receive two telemetry beacon messages confirming the satellites battery voltage and internal temperature. Over the first few days we were sent quite a few telemetry beacons from amateur radio operators from across the world helping us to confirm the satellite health (Thank you very much!).
Progress has been steady over the last few days. It is hard to explain the excitement of receiving the first responses to telecommands and requests for telemetry information from the satellite. As operations continue much of this initial excitement subsides and you start to take for granted these first little victories. But luckily each new test and task brings its own excitement.
From our ground station on campus we are now able to send requests for information (telemetry) to the spacecraft and receive the responses. The sending of telecommands to the satellite has also been verified. The initial telemetry beacon transmission period was adjusted from a 20 second interval to a slightly longer 30 second interval. The battery voltage and internal temperatures has also been verified to be within expected limits, with the battery charging when the satellite is in sunlight.
On-board log files show that the UHF and VHF antennas used for telemetry and telecommand deployed successfully on the first attempt. The deployment times for antenna elements one to four are as follows: 1.6 seconds, 1.55 seconds, 1.6 seconds, 1.9 seconds.
Settings files were uploaded successfully to the satellite, which enabled the logging of telemetry data to the on-board SD card. Two graphs generated from some of the downloaded data can be seen in Figure 1 and 2. The graphs show data that was collected over one orbit at 10 minute intervals. The long interval was selected to allow easy downloading of the data in one pass. The battery voltage stays more or less constant with a slight decrease noticed during the time the satellite is in the earth’s shadow. The on-board computer (OBC) or internal temperature stays quite hospitable during the orbit, which is expected as it is shielded from the outside. While the antenna board sees lower temperatures as it is closer to the outside of the satellite. Temperature values from the solar panels should show a much wider swing between eclipse and full sunlight.
We are also working on visualising telemetry beacon data received and submitted by amateur radio operators.
The two-line element (TLE) data for the DNEPR launch has also matured a bit. Currently we are still tracking object 2013-066B (13066B) from the DNEPR launch. Elements for two new objects close to Object B are now available. It is likely that Objects B, AE, AF correspond to the satellites from ISISPOD 1 namely HiNCube, FUNcube-1 and ZACUBE-1. Although it is difficult to match an object to a specific satellite currently.
For the curious out there that do not have access to the proper equipment an audio recording of the telemetry beacon message is below.