OFJ Field Journal from Terry Martin - 11/2/95
THE COST OF THE TAPE RECORDER'S HICCUPSIt has been a depressing two weeks since the Galileo tape recorder was found to have stumbled trying to rewind to where the first global Jupiter image was stored. Worried that we might not have a tape recorder for the mission, the project managers sent a lot of us off to study how we could get data back without the tape recorder. We met for two weeks, and two full Saturdays, and came up with a way to do it: take all the computer memory that is devoted to tape recorder programs, and make room to store data Earth from the memory directly.
This makes it hard to get many images, since they take up so much room. But a lot of other good science can be done without images.
So why the depression? Because it was decided that until engineers understand the tape recorder performance better, the project will cancel all the remote observations of Jupiter and Io as we approach the planet. That means, no pictures of where the Probe will fall in. No pictures of the bizarre moon Io from just 1000 km away. No temperatures of its volcanic surface. The project managers want to ensure that the Probe data will be successfully recorded on the tape, and most other use of the tape is put aside.
As a scientist, it is depressing to see so many wonderful science opportunities that we had coming in to Jupiter disappear like that. We understand the need for conservative engineering when something as important as the Probe data is on the line. But people have thought about these last few days before Dec. 7 1995 for many years, and planned every second in a long integration process, and then had the sequence of events checked and rechecked. We generated piles of paper, and lots of computer files, and plots, and spent endless hours meeting, compromising, negotiating. And now it is decided not to do any of it, because the tape recorder coughed.
We have a lot of good stuff yet to come, and we need to get back to planning for what happens AFTER getting into orbit on Dec. 7. But the loss of our very special plans will take a while to put behind us.