I’m watching the Science Channel special on Cassinni-Huygens and they mentioned that the total amount of data transmitted by Huygen could fit on a floppy disk!!
How on earth can they store hundreds of pictures, readings from the numerous sensors, etc into such a little space? I can’t even fit a single mp3 in a standard floppy.
A second, related question: My guess is that the reason why only such a small amount of data was collected in such a long time (3 hours, right?) is some sort of transmition bottle neck.
Do you we still lack the technology to send bigger amounts of data wirelessly? I could transfer thousands of times that amount of data using my wireless d-link router, of course my laptop is not located miles away… is a large antenna the problem? (although I heard that the weak signal from Huygen (about as powerful as a cell phone) was actually picked up here on earth!).
I just looked up the data transfer rate from Huygens to Cassini: 8 kilobits per second. So it looks like the bottleneck is the bandwidth between the lander and the orbiter, and not the transmission to Earth. It only had a ‘window’ of about 2 hours to send data at 8 kb/s.
This makes sense. Cassini is quite a long distance away, it has a small receiving antenna, and the lander is running on batteries. The price for higher bandwidth is either A) more transmitter power, or B) a higher gain receiving antenna. I guess 8kb/s is the compromise the engineers came up with.
I heard a similar claim on UK TV, but I got the impression that they were refering to the volume of data from the “top hat”. That is the package that includes the impactor, sonar, etc but no cameras.
At 8K BPS, I make that a little less than three floppy disks per hour. Not a lot of data, but clearly more than one.
I will assume that JPL is doing what they usually do: going with technology they know has worked in the past. The lander sends data to the orbiter, which uses its dish to collect it, then the orbiter turns toward Earth for broadcast.
Because you have a window for a clear transmission to Earth, and you don’t want to wait for the next one and risk losing the data from the orbiter’s limited memory with a one-shot deal like the Huygens probe, it creates an automatic limit on data gathering.
Sure you could put two dishes on it, but that just adds weight. And, trust me, I’ve been in the same room with the full-sized Cassini twin. You wouldn’t WANT that craft to be one ounce larger than it already is.