Venus 73 - A lost opportunity? Options

[gndonald]

I've been browsing through the NTRS and I've stumbled upon a series of reports dealing with an alternative mission plan for the 72/73 Venus launch window (The one used for Mariner 10).

The plan was this:

A modified version of the Mariner 9 probe carrying a 400lb balloon supported atmospheric probe would be launched atop an Atlas-Centaur or Titan IIIc. Upon arrival at Venus the atmosphere probe would be released and the remainder of the craft would either go into orbit or flyby Venus. The RTG powered balloon probe would operate for several months in the upper levels of the Venusian atmosphere.

While I know that Mariner 10 was a great success (albeit with a lot of luck) and the first pictures of Mercury were well worth the effort, I cannot shake the feeling that this plan was a lost opportunity. While the Venusian atmosphere has been studied from orbit and by short term drop probes, only the Soviet Vega probes attempted to carry out 'long term' studies from within the upper atmosphere, though this was limited by the flyby nature of the mission and the fact that the balloon probes were battery powered.

In fact I feel that a good case could be made for such a mission to be attempted in the future, the science payoff would be well worth it.

See:

http://ntrs.nasa.gov/archive/nasa/casi.ntr..._1969006258.pdf

for the 23mb summary report.

This post has been edited by gndonald: Aug 15 2007, 12:53 AM

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[edstrick]

"I often wistfully wonder if Voyager I would've lasted out to Pluto - that was one option at the time."

The titan occultation was absolutely critical to understanding the moon at a basic physical level. We literally did not know where the surface was below the top of the orange fog, and Voyager's other instruments would not have really solved the problem.. They'd have had a fair idea from the infrared spectroscopy, but not a solid, accurate atmosphere temperature/pressure profile and surface radius.

Huygens would have been nearly impossible without that data.

BUT WAIT, THERE'S MORE!!!!!

I believe Voyager 1 did a perfect radio-occultation profile of the entire extant of the rings, not possible from a grand-tour in-the-ecliptic trajectory like Voyager 2 took. They used doppler-delay analysis of the data much like synthetic aperture imagery analysis and resolved the ring structure at tens of meters resolution in low opacity zones, as well as measured the particle size distribution by scatter and different opacity at the 2 wavelengths. Ring studies are as "pre voyager' and "post voyager" due to the occultation data as much as Titan studues are.

[brellis]

I believe Voyager 1 did a perfect radio-occultation profile of the entire extant of the rings, not possible from a grand-tour in-the-ecliptic trajectory like Voyager 2 took. They used doppler-delay analysis of the data much like synthetic aperture imagery analysis and resolved the ring structure at tens of meters resolution in low opacity zones, as well as measured the particle size distribution by scatter and different opacity at the 2 wavelengths. Ring studies are as "pre voyager' and "post voyager" due to the occultation data as much as Titan studues are.

The Voyager ring data helped the Cassini team pick a route for that initial dash through the ring plane behind Saturn at arrival. Other than the launch itself, that must have been the nail-biting moment of the entire voyage of Cassini.

[tedstryk]

nprev, to put it another way, the spacecraft that should have gone to Pluto is not the one that flew by Titan, it is the one hanging from the ceiling in the Air and Space Museum.