ESA will try to fetch data from China's Mars rover with a new method: listening

Next month on Mars, the ESA and China's National Space Administration (CNSA) will try something that's never been attempted before in space: Sending data from a planet-based rover to an orbiter that it can't receive any messages from. Specifically, China's selfie-taking Zhurong rover, which has been on the Red Planet since May, will try to shoot data over to the ESA's Mars Express Orbiter. 

As the ESA explains, Zhurong can't actually receive any communications from the Express Orbiter, due to a radio incompatibility. That means it can't hear the hail signal sent from the orbiter, which is typically what a rover waits for before it starts sending out data. Instead, next month Mars and the ESA will attempt a new method that's previously only been tested on Earth. During five tests, Zhurong will send a signal blindly into space, and the Mars Express will listen for that signal and any potential data.

"If [Mars Express] detects the magic signal, the radio will lock on to it and begin recording any data," ESA's Josh Tapley writes. "At the end of the communication window, the spacecraft will turn to face Earth and relay these data across space the same way it does for other scientific Mars missions. When the data arrive at ESOC, they will be forwarded on to the Zhurong team for processing and analysis."    

It's not unusual for rovers to send data to foreign orbiter — that's commonly been seen as a smart backup method — but this test opens the door for communication between incompatible systems. That'll be useful if China has any issues with its Tianwen-1 orbiter down the line, or if the US and other countries need help in turn.