🚨 Decision Point #2

Shut Down the Command Module?

GET 58:00 | The Same Terrible Evening

⚠️ The Situation

You just sent the crew climbing into Aquarius. Before that move is even finished, Mission Control faces the second hard call of this terrible evening: what to do with Odyssey.

Command Module "Odyssey" is dying—the explosion destroyed its oxygen supply and killed the fuel cells that made its electricity
All Odyssey has left are three small re-entry batteries
The CM is the ONLY spacecraft with a heat shield—it MUST be working when they return to Earth
Problem: Odyssey's systems are still running, draining those batteries. At this rate they'll be dead within hours.
Dead batteries at re-entry = no computer, no guidance, no parachutes

🔋 Current Battery Status:

Three re-entry batteries, full capacity: ~120 amp-hours
Already burned in the post-explosion scramble: ~20 amp-hours
Remaining: ~99 amp-hours
A normal re-entry uses: roughly 70–80 amp-hours
Time until re-entry: about 84 hours (3½ days!)

The math is brutal: re-entry needs nearly all of those 99 amp-hours in 3½ days—and out here, there is no way to make more.

⚡ KEEP CM RUNNING

Leave Command Module systems powered up

✓ Advantages

No risk of shutdown or restart procedure failure
Systems stay warm, no condensation damage
Can keep using the CM computer and instruments
Psychologically comforting—always have it ready

✕ Disadvantages

Batteries will be completely dead within hours
Re-entry is about 84 hours away
Re-entry alone uses roughly 70–80 amp-hours—almost everything that's left
Guarantees running out long before reaching Earth—every hour awake burns power that can never be replaced

🔌 SHUT DOWN THE CM

Power down all Command Module systems immediately

✓ Advantages

Preserves battery power for re-entry (the only thing that matters)
Keeps the remaining ~99 amp-hours intact—enough for computer, guidance, and parachutes
Leaves some margin for unexpected power needs
Only option that gives the crew a chance to survive re-entry

✕ Disadvantages

Never been done before—no shutdown procedure exists; engineers must write one from scratch
Restart procedure never tested—might not work
CM will freeze to 38°F—condensation on the electronics could short circuits at power-up
Systems designed to stay warm—cold damage unknown
Guidance platform alignment lost—must be rebuilt before re-entry
Crew must later restart it perfectly, with frozen hands, in the final hours before re-entry—if the restart fails, they die

One thing NOT at risk: the computer's memory. The Apollo Guidance Computer used magnetic-core memory, which keeps its contents even with the power off.

🤔 WHAT SHOULD MISSION CONTROL DECIDE?

👆 Choose one of the options above 👆

NASA's Decision

✓ SHUT DOWN THE COMMAND MODULE

Mission Control made the call: power down Odyssey. All of it.

The Shutdown Process:

Houston read up a shutdown procedure that had never existed before—the CM was designed to stay on from launch to splashdown. Systems had to go down in the right order, and before the guidance system died, Lovell copied its alignment angles onto paper and transferred them to Aquarius's computer by hand.

GET 58:40 - Odyssey Goes Dark:

Step by step, Jack Swigert powered down Odyssey:

Guidance system: IMU (Inertial Measurement Unit) and computer - off
Environmental controls: Heaters, fans, pumps - off
Communications and instruments: Everything - off

Swigert pulled the final circuit breakers. The hum of fans stopped. For the first time in the whole Apollo program, a Command Module hung completely dead in space.

"Odyssey is completely powered down, according to the procedure that you read to Jack."
— Jim Lovell, GET 058:40:12

"Roger; we copy. That's where we want to be, Jim."
— CAPCOM Jack Lousma, Mission Control

Result: Shutdown Successful!

The drain fell to essentially zero, banking ~99 amp-hours for re-entry. Odyssey began its long, cold soak toward 38°F, water droplets forming on every cold surface.

And the crew faced a new fear: Will it restart in 3½ days?

⏳ The New Challenge:

Mission Control now had about 84 hours to write restart procedures from scratch, test them in simulators, fit the power-up into the battery budget, radio it all up to the crew—and hope everything works. Three lives now depended on perfect procedures for something that had never been done before.

Why it was the right decision: Without power, there is no re-entry. The shutdown was mathematically necessary; the restart was uncertain, but it was their only chance. Like every choice on Apollo 13, it was a pick between bad and worse—and Mission Control chose the option that kept hope alive.

"Shutting down Odyssey felt like closing the lid on our own coffin. We'd have to open it again in three days and hope everything inside still worked." 🎬 Dramatization — not a documented quote

📚 Sources for Skeptics

Not convinced shutting down was the right call? Good—engineers earn their pay by doubting. Dig into the real record:

Apollo 13 Flight Journal — every radio call between the crew and Houston, annotated day by day (see Day 3, "Minimising Power")
Apollo 13 Mission Report (PDF) — NASA's official engineering report, including the exact battery numbers
Air-to-Ground Voice Transcript (PDF) — the verbatim record of every transmission, including Odyssey's shutdown