A few days ago I posted about the fact that AMSAT-DL had not received any signals from Tianwen-1 since 2025-12-23. For months, AMSAT-DL had kept listening to the orbiter’s frequency with the 20 m antenna in Bochum and had not detected any signals. Yesterday, AMSAT-DL announced that they had received again the signal from Tianwen-1.
The signal strength looks completely normal, as evidenced by the spectrum plot shared in the announcement.
Telemetry containing state vectors was decoded between 2026-03-17 11:34 and 14:16 UTC. I have updated my plot of orbital parameters to include this new information. The period between 2025-12-23 and 2026-03-17 corresponds to a propagation with GMAT of the last telemetry received in 2025. The end of the plot corresponds to the telemetry received in 2026-03-17.
We can see that the orbit has remained the same, and there have been no manoeuvres during this period. A zoomed in version to the end of the plot shows that there is basically no jump in the orbital parameters. There is a tiny jump in the inclination as the new telemetry is received, but that is all.
So far the reasons why Tianwen-1 has apparently not transmitted telemetry to Earth for almost 3 months remain unknown.