The Potassium Orange Drink a Moonwalker Blamed for His Gas

What happened: The Potassium Orange Drink a Moonwalker Blamed for His Gas

The story starts a mission earlier, with a heartbeat. Apollo 15 launched in July 1971 with Dave Scott as commander, Al Worden as command module pilot, and Jim Irwin as lunar module pilot. Scott and Irwin spent about three days at the Hadley-Apennine landing site.

Flight surgeons on the ground watched each astronaut’s heart through electrodes taped to his chest. After Scott and Irwin lifted off from the Moon and docked with Worden’s command module, Irwin’s heart briefly slipped out of its normal rhythm. According to NASA’s medical report, Biomedical Results of Apollo, at 179 hours and 7 minutes into the flight it switched into a “nodal bigeminal rhythm,” a pattern in which every normal heartbeat is followed by an early, extra one. The episode lasted 14 seconds, with 11 coupled beats. Irwin felt nothing. The report says he was “completely unaware that an arrhythmia had occurred.” Scott had a smaller run of early beats later in the flight. Worden’s heart stayed steady the whole time.

NASA’s chief medical officer, Dr. Charles Berry, was worried but stayed calm. As Christopher Kraft recalled in his memoir Flight, Berry said the rhythm would be serious if Irwin were on Earth. In the spacecraft, though, Irwin was breathing 100 percent oxygen and was being monitored continuously, which, by Berry’s reasoning, was about as safe a place as any for a man with an irregular heartbeat. Accounts differ on how much the crew was told while they were still in flight.

After splashdown, the doctors found a likely culprit. Both moonwalkers had come home with a large deficit of potassium, a mineral the heart needs to keep its electrical rhythm steady. NASA’s physicians concluded that short spells of low blood potassium were “of prime importance” in causing the arrhythmias, along with heat, hard work, stress, and fatigue.

So for Apollo 16, NASA changed the menu. Starting 72 hours before launch and continuing until 72 hours after recovery, Young, Duke, and command module pilot Ken Mattingly ate a high-potassium diet, which included large amounts of potassium-fortified fruit drinks, orange among them.

Apollo 16 launched on April 16, 1972. Young and Duke landed in the Descartes highlands, and after their first moonwalk the ground kept encouraging them. “Your biomed looks great down here,” capsule communicator Tony England radioed. “Just keep up the orange juice.” Young asked whether Tony had ever heard of acid stomach. He guessed his own stomach acid was running at a pH of about 3.

Then came the unguarded part. With the mike unintentionally left open, Young told Duke that he thought it was acid stomach, that he hadn’t eaten this much citrus in 20 years, and that once the mission was over he was never eating any more. He added, a little more gently, that he did like an occasional orange. A few minutes later, England broke in: “Okay, John. We have a hot mike.” It had been on, he said, “through the debriefing.” His earthier lines, including a frank complaint about gas, soon made it into print.

Why it was strange: The Potassium Orange Drink a Moonwalker Blamed for His Gas

Apollo crews flew some of the most carefully engineered machines ever built. Yet one of the most memorable medical lessons of the Moon landings came down to a mineral found in bananas, and the man who flew to the Moon after it came home grumbling about his breakfast drink.

Doctors expected space to be dangerous in dramatic ways: radiation, vacuum, lunar dust. One problem they actually had to solve sounded more like a sports-drink commercial. A body working hard in a hot suit loses minerals, and in space that loss can show up on a heart monitor.

For another Apollo crew undone by an everyday ailment, see The Head Cold That Made Apollo 7 Refuse Its Helmets.

What scientists learned: The Potassium Orange Drink a Moonwalker Blamed for His Gas

Your heartbeat is an electrical event. Each beat begins when charged particles called electrolytes, chiefly sodium, potassium, and calcium, flow in and out of heart cells in a precise order. When potassium in the blood drops too low, a condition called hypokalemia, heart cells can fire early or out of turn. That produces premature beats like Irwin’s.

Spaceflight pushes the body toward losing potassium. In weightlessness, fluid shifts toward the head, and the body responds by shedding water and salts through the kidneys. Hormones that help manage that shift can pull potassium out with it. Add a hard workload and heat, and the deficit grows.

The fix seemed to work, though NASA’s doctors were careful about how much credit to give it. Neither Apollo 16 nor Apollo 17 had any medically significant arrhythmias, and postflight tests showed normal potassium balance. But the report says better fluid balance, more sleep, and less fatigue were of “equal or greater significance” than the potassium-rich food.

There was a sobering footnote. NASA’s physicians later concluded that one of the Apollo 15 crewmen with an arrhythmia had undetected coronary artery disease during the mission, which “almost certainly interacted” with the potassium loss. Less than two years after the flight, Irwin had a heart attack at 43. He died of another heart attack in 1991, at age 61.

How it reaches us today: The Potassium Orange Drink a Moonwalker Blamed for His Gas

Watching astronauts’ minerals, fluids, and heart rhythms is now routine. Space station crews eat menus planned by nutrition scientists, and NASA still studies how long missions affect the heart, a question that matters more as agencies plan longer trips beyond Earth orbit.

For a longer look at what spaceflight does to a body, see The Year in Space That Turned Twin Astronauts Into a Living Experiment.

If you’ve noticed a racing, fluttering, or skipping heartbeat, it’s worth mentioning to a doctor. Most are harmless, but checking is the kind of monitoring the Apollo surgeons would have wanted for anyone.

An orange drink prescribed for the heart, and blamed for the gas, sits with the other uncertain medicine in Medicine, Before It Was Sure.

Fun fact: The Potassium Orange Drink a Moonwalker Blamed for His Gas

Apollo 16 was also the first Apollo mission to carry heart-rhythm medicine in its medical kit — packed right alongside all that orange drink.

Sources: The Potassium Orange Drink a Moonwalker Blamed for His Gas

• W. Royce Hawkins and John F. Zieglschmid, “Clinical Aspects of Crew Health”, in Biomedical Results of Apollo (NASA SP-368), NASA, 1975.
• Eric M. Jones (ed.), “Post-EVA-1 Activities,” Apollo 16 Lunar Surface Journal, NASA History Office.
• “Apollo 16”, NASA.
• Christopher C. Kraft with James L. Schefter, Flight: My Life in Mission Control (Dutton, 2001), pp. 342–343.