Hi Folks,

Do I have it right that the Mariner 4 tape recorder could only be recorded to once?

That is, the TV camera snapped images, laid to the tape, and then that was it. They could be played back multiple times (and were played twice), but no ability existed to rewind the tape and re-record.

Just trying to clairfy,
Thanks.

Jay Gallentine

It shot several calibration images during its flight, which would have had to be recorded. However, given that it took about 8 hours to return each frame (due to its 8bps transmissions, not limitations of the tape recorder), it definitely only had one go at recording Mars images. Also, Mariner 6 and 7 carried 2 Mariner-4 style tape recorders, which were wiped clean several times during far encounter (although they were used in analogue mode instead of digital to return more images).

I believe the tape was in an endless loop system, but i'm NOT sure on that.

After the encounter pictures were found to be light fogged, and after multiple playbacks of the data had ensured that they had 100% bit-reliable readouts of the images, they attempted some images of a bright star, MAYBE Arcturus, to try to see if they could identify a cause of the problem. I do not recall if they even saw the star and I don't think I ever saw any of the in-flight calibration or test images, which would have been essentially blank-black.

In fact, additional calibration images were also taken (and recorded) when Mariner 4 was contacted again during the summer of 1967.