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Old 01-30-2019, 11:07 PM
luke strawwalker's Avatar
luke strawwalker luke strawwalker is offline
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Join Date: Dec 2007
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Default Study Summary- Single Launch Venus Flyby using Extended Apollo Hardware

This is an interesting study from early 1967. The Advanced Mission Design Branch at the Manned Spacecraft Center (later Johnson Space Center in Houston) did the math and decided that it was POSSIBLE to launch a crewed FLY-BY mission of Venus in the 1972-1975 time period using a SINGLE Saturn V launch. No "wet workshop" conversion of the S-IVB into a hab module, either. It would replace the Lunar Module on the regular Apollo-Saturn V spacecraft "stack" with a dedicated "mission module" within the LM fairing panels beneath the CSM. The mission would launch like a lunar mission, go into a 100 nautical mile parking orbit, then perform a second S-IVB burn to put them into a 70,000 nautical mile apogee elliptical orbit, similar to the regular Trans-Lunar Injection (TLI) manuever. This two-day long orbit would set them up with most of the delta-V (velocity) needed to reach Venus, while allowing time for transposition and docking of the CSM to the Mission Module (MM) in a method identical to that used for docking to and removing the Lunar Module from the spent S-IVB stage on a lunar mission. It would also provide time for checkout and testing during the coast phase of the orbit, plane and phasing change burns at apogee of the orbit, (and including ground-tracking by radar to determine that the guidance system of the Apollo CSM and MM were "up to speed" and working properly by comparing its predicted orbital flight path to that measured by actual ground radars tracking the spacecraft in the elliptical orbit.) The spacecraft would then swing back towards Earth, reaching perigee of the elliptical orbit at 100 nautical miles the next day, and at that time perform a 3,000 fps burn of the SPS engine on the Service Module of the CSM to get the additional velocity needed to reach Venus as it completed the Trans-Venus Injection (TVI) maneuver that would put it on a path to Venus in 109 days. There would be a six-minute abort window for the CSM to jettison the MM, turn around, and perform a two-burn abort from TVI back first into the elliptical orbit, and then burning the SPS again at the apogee of the 70,000 nautical mile elliptical orbit the next day to put it on a path to atmospheric reentry about 24 hours after that second burn. If everything had of course checked out and gone as planned, however, the Apollo CSM/MM combination would be on course for Venus.

The spacecraft would fly by the planet and swing back out to Earth. Three midcourse corrections were required on the path out to Venus, and three more on the return to Earth, all carried out by the CSM SPS. The last midcourse correction would be about 1 hour before reentry. The main modification to the Apollo spacecraft was beefing up the heat shields to allow for a 45,000 fps reentry velocity, considerably higher than the typical 35,000 or so fps reentry velocity on a lunar return. This was seen as a basic, well understood modification that would pose no issues.

The scientific goals of the mission were astronomical and solar observations on the coast phase before and after the Venus flyby, and observations, mapping, and various studies of Venus during the flyby itself. A Venus surface sample return mission rendezvousing with the flyby mission was also briefly mentioned, but it would require a second launch of another vehicle and mission to get the surface lander, sampler, and sample return vehicle down onto Venus and back up into position to rendezvous with the Venus flyby mission.

Probably a bit of a stretch, but it certainly demonstrated the confidence of the men and their machines to even consider such an audacious mission, and the flexibility and capability of both the Apollo and Saturn V launch vehicle that it was even capable of such a mission in the first place, particularly with only "minor modifications" (the Saturn V wasn't modified AT ALL for this mission concept!) This was big thinking from a time when "thinking big" was considered a GOOD thing, not like the NASA we have now, which is incapable of doing even simple things without a decade of planning and another decade or two of development and testing before they even lay the groundwork to do anything...

Enjoy!

Later! OL J R
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