Interesting question I hadn’t though of: Why is the Curiosity sending back visuals of Mars but no audio? An excerpt from the answer at Curiosity Watch:

“So why’s there no mic on board? That’s mainly because MSL is a scientific mission and has a clearly defined objective:

The overall scientific goal of the mission is to explore and quantitatively assess a local region on Mars’ surface as a potential habitat for life, past or present. 

Hence, every instrument has to work toward the overall scientific goal. Maybe there have been discussions about including a microphone in the early planning stages but the team decided that a mic would not reveal new facts about Mars’s habitability.

Also, spaceflight is extremely expensive and every extra gram costs money, so you only bring the things you really need.”