posted 04-27-2009 12:07 PM            

I do a lot of photography and if film is the wrong temperature it can crack, discolour (reciprocity failure springs to mind), etc. How is that on the moon we had temperatures of plus 250 and minus 250 from sun to shade and yet the photos look fine. Is it that no moisture is present?

When you spacewalk at 17,000 mph, on an umbilical cord or not, I presume you are also travelling at 17,000 mph or would get left behind?

Also, when a command module slows down to take in a lunar orbit I presume it had the engine facing the direction of travel or did thrusters do this somehow?

When the Lunar Module was extracted from the third stage, they were parted so the third stage could be shoved off in another non collision direction. If you are travelling at 25,000 miles per hour how is this achieved? How does third stage go sideways to move it away, then accelerated to hit the moon or go where ever?

posted 04-27-2009 12:22 PM               

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Originally posted by flight_plan:
How is that on the moon we had temperatures of plus 250 and minus 250 from sun to shade and yet the photos look fine.

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...the temperature of the lunar surface (i.e., rocks and dust) as quoted by NASA has nothing to do with the equilibrium temperature reached by other objects exposed to sunlight in the lunar environment. Since the film magazine was covered with polished aluminum it would have absorbed very little radiant energy from the sun. Further, Hasselblad confirms that additional shield plates were added to the Apollo magazines to enhance their thermal insulative properties.

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When you spacewalk at 17,000 mph, on an umbilical cord or not, I presume you are also travelling at 17,000 mph or would get left behind?

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An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

posted 04-27-2009 12:37 PM               

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Originally posted by flight_plan:
Also, when a command module slows down to take in a lunar orbit I presume it had the engine facing the direction of travel or did thrusters do this somehow?

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In order to overcome the free-return slingshot, the spacecraft would have to rotate 180 degrees and then, facing rump-forward, fire the service propulsion engine, with its 22,500 pounds of trust, until the craft slowed just enough to allow the moon's gravitational field to take hold.

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How does third stage go sideways to move it away, then accelerated to hit the moon or go where ever?

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The SIV-B meanwhile, continued traveling along the path it was already on (Newton's First Law again). If that path intersected the Moon, it would eventually impact the lunar surface as a result of gravity pulling it in.

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How can it turn around without an engine or again is this the thrusters doing the twisting?

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The CMP maneuvered the spacecraft to an attitude that put the heatshield forward with the crew heads-down and looking back. It wasn't their final entry attitude; a further pitch-up would be required for that -- a maneuver they would execute a few minutes before reaching entry interface. But in this attitude, they could make checks of their attitude control and trajectory, and it was a starting point for the jettisoning of the service module.

posted 04-27-2009 01:15 PM            

As a point to clarify. If the SIV-B carried on in the same direction it started and I presume slower now that it was detached from the service module, I presume the service module sped away, and also move sideways with the thrusters? How far would it need to move away? Or would it be like us in a car changing lanes on a motorway/freeway but leaving the cars behind, behind?

posted 04-27-2009 01:44 PM               

Once the Apollo spacecraft left them, they became spacecraft in their own right, controlled from Earth and by their own internal systems in the Saturn's instrument until either their batteries ran out or the ground stations ceased to track the receding hulks. The people who controlled the SIV-B from Earth had to use what little residual propulsion the stage had left to achieve these final ends.

After translunar injection, both the SIV-B and the spacecraft were on very similar trajectories which were basically long, elliptical orbits. However the intervening gravitational influence of the Moon determined the final fate of both craft. While the Apollo spacecraft continued on a path to lunar orbit, the SIV-B was given one of two fates.

posted 04-28-2009 05:35 AM            

If you ever find a need within NASA for a window cleaner or messenger boy on any space craft from now on please let me know and I will send a CV.