Sunday, July 21, 2019

50 Years Ago This Afternoon, It Was Ending

After all the hype and excitement, Apollo 11 spent less than 24 hours on the moon.  They landed at 4:18 PM yesterday and fired the LM ascent engine to leave the moon 1:54 PM today (all times EDT, as has been the convention for these few posts).  Other missions would stay longer, and bring increasing sophistication, including color video cameras and electric vehicles to get the crews around on the surface.

I posted this picture back in 2018, and it's good but incomplete:

After "living or dead", I would add the modifier "in human history" for emphasis.  At 9:44 AM, when Mission Control sent their wake up call to Collins, someone in Mission Control noted,"Not since Adam has any human known such solitude as Mike Collins is experiencing during this 47 minutes of each lunar revolution when he's behind the Moon with no one to talk to except his tape recorder aboard Columbia."

The return flight depended on the performance of a system never tested in its intended use: the Lunar Module ascent engine.  The prime contractor on the engine was Grumman Aerospace; the contractor for the engine was Bell Aerosystems.  They delivered an engine that relied on hypergolic propellants - a system which doesn't require an igniter because the fuel and oxidizer explode on contact.  It worked flawlessly on every Apollo mission that landed on the moon.  It is said that the ascent stage was the one system that Neil Armstrong expressed concern about failing, because there was no backup.  If it failed, they were going to die on the moon.

It wasn't the only such single point failure.  If the engine fired but a set of explosives called the guillotine failed - a system that blew apart all of the connections between the two halves of the lunar module - there was no way to fix or recover from that, either.  I'd be surprised if there weren't more possible single point failures.

The liftoff was at 1:54 PM EDT and the LM docked with the CM at 5:35 PM.  The lunar module was jettisoned at 7:42 PM.   Apollo 11 didn't have the ability to record its departure from the moon, but later missions did.  This is a 30 second video of the LM launch during Apollo 17 - the last men to ever visit the moon.

The crew will start their engine burn for the three day return flight to Earth in the early hours of tomorrow morning, July 22nd; 12:56 AM.  Reentry, splashdown in the Pacific, and transfer of the crew to an isolation unit as a precaution against possible, unknown, lunar microorganisms will occur on July 24th.  Over the course of the last few days, I've read things I haven't read in years, if ever.  One the things that's noteworthy is this sentence from the NASA Apollo 11 log.
It is recognized as the most trouble-free mission to date, almost completely on schedule and successful in every respect.

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