[X] My Assistant

[PhilHorzempa]

I thought that it was time to start a new thread devoted to the JUNO Jupiter
Orbiter mission. This New Frontiers Mission #2 seems to be a "stealth" project
with little information available on the Web. In fact, the official NASA JUNO
web site is quite pitiful. It contains the minimal amount of information on what
seems to be an intriguing mission, in terms of both science and engineering.

Does the UMSF community have information on this mission that has not
been widely seen before?

Another Phil

[edstrick]

"...Venus was nearly frame filling, it is questionable whether the data would have been able to tell us anything that we couldn't tell from earth ..."

Wrong. Earthbased data by the early 70's was poor due to seeing limitations and the need to image the atmospheric features at near UV wavelengths where seeing is worse than terrible even if it's pretty decent at near-IR/Red wavelengths. While the Mariner 4 camera was pretty limited, a well targeted series of UV images with the disk exactly filling the field of view would have provided a first real look at the cloud patterns.

But you're right after all...
My limited understanding was that any camera that might have flown on Mariner 5 would have been a minimally modified version of the Mariner 4 cam, including a 1 axis scan platform that could position the camera left-right (sort of) in azimuth as the spacecraft's trajectory took it's fixed-elevation narrow angle view across the planet. A dozen-ish frames of vague, low contrast streaky and mottled uv absorber features would have been a pretty minimal result for a major experiment. Whatever they are, the UV markings on Venus rapidly lose contrast as you zoom in on them for finer and finer details. 30% contrast at 100 km scale drops to say 3% contrast at 10 km and perhaps 0.3% contrast at 1 km scale. (I'm making up the numbers but they are the right sort of idea and probably in the ballpark estimates.)

They could see a persistent "Y" and "PSI" shaped cloud pattern aligned with the apparent equator and that it often repeated with about a 4 day period. Real cloud patterns and dynamics and meteorology was entirely beyond earthbased observation.

Mariner 10

[tedstryk]

Based on what I have read, the Mariner-R (the design that became Mariners 3-5), with the R standing for "runt," carried a camera that was designed primarily to test conditions for future cameras. One has to remember that the Mariner-R design being used in the 1964 launch was simply due to limited rocket capability. The originally planned probes would have had much better cameras. It was more of a backup that could be flown should they have to depend on the Atlas/Agena. And it served its purpose quite well - even beyond the light leak problem, the Martian surface proved to exhibit much less contrast than expected. This discovery aided Mariners 6 and 7. And of course it made interesting scientific discoveries, such as the lack of albedo/topographic correspondence on Mars, as well as the better known spotting of craters and pretty much killing the canals. But such images of cloudtops, while they would have been more detailed than those of earth, would, as edstrick indicated, not taught us all that much for a major experiment.