Saturday April 13 was the 54th anniversary of the moment when the following conversation took place between the Apollo 13 crew and Mission Control in Houston -
055:55:19 Lovell: ...Houston...
055:55:20 Swigert: ...we've had a problem here.
055:55:26 Fenner (GUIDO): FLIGHT, GUIDANCE.
055:55:27 Kranz (FLIGHT): Go GUIDANCE.
055:55:28 Lousma: This is Houston. Say again, please.
055:55:28 Fenner (GUIDO): We've had a Hardware Restart. I don't know what it was.
055:55:30 Kranz (FLIGHT): Okay. GNC, you want to take a look at it? See if you see any problems?
055:55:35 Lovell: [Garble.] Ah, Houston, we've had a problem. We've had a Main B Bus Undervolt.
055:55:36 Kranz (FLIGHT): Roger, we're copying it, CapCom. We see a hardware restart.
055:55:41 Kranz (FLIGHT): You see an AC Bus Undervolt there, GUIDANCE - ehhhm EECOM?
The Apollo 13 mishap was caused by an explosion in oxygen tank #2 in the service module.
- The O2 tanks had been redesigned to use 65V instead of 28V, but the heater thermostatic switches got overlooked.
- During ground testing, the switches malfunctioned causing the temperature to rise and damage the teflon insulation on the wires to the fans inside the tank.
- On April 13, the fans were turned on for a "cryo-stir". The fan wires shorted, the teflon insulation caught fire in the O2-rich tank, causing the explosion in the O2 tank.
After 4 days of hardships, heroism, improvisations and ingenuity, the crew landed safely on Earth.
Now let’s successfully land today’s puzzle composed in 1917 by noted Italian chess composer Giorgio Guidelli (1897 - 1924).
P.S.
The chess puzzle is published on Sundays, Tuesdays and Thursdays at 6:00 p.m. ET.
It is customary for advanced players to wait till midnight ET before posting the full solution. Before then, they provide some stats about the solution (e.g., the minimum number of distinct checkmate moves), help guide others, and sometimes post hints. But there are no hard-and-fast rules; feel free to post comments as you please.