Many of us watched in real time as NASA got signals from Perseverance sent during its landing maneuvers. However, what we actually watched was video from earth of NASA’s team responding to this news + supplemental videos that were recorded in advance, including a simulation of the landing procedure.
It takes quite a while to send data from Mars to Earth. We can’t easily send a multi-frequency or high-frequency signal. We use radio frequencies for a good bit of the data transfer, and radio frequencies carry very little information compared to, say, a household internet connection. The ubiquitous household internet connections in 2020, after all, allow real time video. But radio signals do not.
You can easily understand how limited these frequencies are by listening to the difference in audio quality between AM radio signals and FM radio signals. Stepping down from FM to AM reduces things so much that not even high quality audio can be sent, even if there is no accompanying video signal. Video signals of any useful quality use much more bandwidth than audio, so it is only now, days later, that Perseverance has been able to successfully communicate over the Mars/Earth radio connection all the data from those video files it recorded during its landing sequence. It may seem like a long wait, but it’s definitely worth it.
This current video is probably the first of several. It includes video from multiple cameras, including on the rover as well as on the separate rocket-powered vehicle that slowed perseverance to a hover and then lowered it to the surface on winch cables. Given that much of the video is made up of a single camera view with no augmentation from other data (radar data, for instance, is not overlayed, but certainly the lander functions required Perseverances brains to coordinate what is was sensing via video cameras with what it was sensing via radar. While the data overlay wouldn’t completely accurately represent the “thought process” of a machine without direct analogs to “thoughts”, it might give humans a sense of what it might be like to be looking at the surface of Mars through a head-up display painted on a human-lander window. Humans, of course, love that kind of shit. For that reason, I think such a mashup is inevitable.
For now, though, let’s enjoy what we have: video from a downward-pointing camera on Perseverance + supplementary views from other cameras, overlayed with audio of NASA flight control staff which you likely already heard on Saturday.