02 July 2019: Lightsail 2 Mission Manager's Log

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LightSail 2 was deployed into orbit by the Georgia Tech Prox-1 spacecraft at 07:35 UTC on July 2, and 45 minutes later the LightSail 2 radio signal was received by flight team via the Cal Poly tracking station.

A lot had to go right in order to receive the signal. Ten satellites were launched by the Falcon Heavy into a similar orbit (see figure below), and it was not clear which vehicle in the cluster was Prox-1. Based upon the expected turn-on time for the LightSail 2 radio signal, and the overflight timing of the tracking station, it would only be possible to receive the signal from the satellites that were near the trailing edge of the cluster. So the operations team programmed the Cal Poly station to track spacecraft “B” in the cluster. The radio signal was received from LightSail 2 at exactly the predicted time. The fact that the ground station antenna pointing was accurate enough to receive the signal indicates that we guessed correctly, and Prox-1 is one of the trailing satellites in the cluster. The 18th Space Control Squadron at Vandenberg Air Force Base provides tracking of space objects. They will likely confirm the appearance of a new object, LightSail 2, later today.

The radio signal was confirmed to be LightSail 2 based upon a morse code transmission that is embedded within the signal. The carrier wave for the radio signal (the carrier wave is the tone that is modulated to convey telemetry data) is programmed to transmit in a series of short and long bursts, representing dots and dashes per the international morse code convention. The LightSail 2 call sign assigned by the United States Federal Communications Commission is WM9XPA. The morse code signal transmitted by LightSail 2 corresponds to this call sign. The recorded downlink signal showing the morse code pattern is below.

Updated orbit predictions will allow more accurate antenna pointing, and the acquisition of telemetry data from the radio signal. The next tracking opportunity for flight team tracking of LightSail 2 is over the Georgia Tech tracking station is at about 00:30 UTC (July 2 5:30 PM PDT).