# What physiological effects did the Apollo astronauts experience due to the lower lunar gravity?

When humans are exposed to weightlessness they often experience space adaptation syndrome (similar to motion sickness). Also fluid redistribution to the upper body is nearly immediate causing bulging neck veins, puffy face and sinus and nasal congestion. https://en.wikipedia.org/wiki/Effect_of_spaceflight_on_the_human_body

Since these effects are immediate, did anyone collect data (or was it reported by the astronauts) on whether these symptoms completely disappeared, completely remained or somewhere in between the two while the Apollo astronauts were on the moon?

• I'm guessing most chronic effects couldn't be isolated to their time on the moon by any means. Most effects studied would likely be categorized under "effects of spaceflight on the human body" because the effects observed on all astronauts is from their cumulative time in space. I doubt they have isolated information on the chronic effects of being on the moon. The majority of the time on the missions to the moon was spent traveling there, meaning any observed effects could related to the time spent on the moon OR in transit to it. Might want to reword a little bit. – Magic Octopus Urn Aug 2 '18 at 20:35
• Honestly, a great paralell would be looking into what effects living on the ISS has on humans-- though we have absolutely no data beyond a 438 days: Russian cosmonaut Valery Polyakov spent nearly 438 consecutive days aboard the Mir space station, from January 1994 to March 1995. He therefore holds the record for longest single human spaceflight — and perhaps set another one for wobbliest legs when he finally touched down. -- I cannot attest to what data the Russians kept, but it may be a place to start. (SOURCE). – Magic Octopus Urn Aug 2 '18 at 20:55
• Effects of lunar dust, and effects of Van Allen belts are going to be rather hard to isolate. You do have the astronauts who stayed in the Command Module as a control group to compare lunar landing ones against, for impact of the Moon environment on health. – SF. Aug 2 '18 at 21:55
• But the immediate effects of weightlessness may have stopped as soon as they touched down. The motion sickness and fluid redistribution to the upper body, these would have been felt immediately, or not felt if there wasn't enough of a difference between micro g and lunar gravity. But has anyone studied it or asked the astronauts? – Brooks Nelson Aug 3 '18 at 13:27
• I thought the Apollo crew debriefings might be a good source for the crews' subjective impressions but I didn't see anything specific to the question in a skim of the A12 or A14 debriefs; don't have time to look at the others. – Russell Borogove Aug 22 '18 at 20:44

## Lunar gravity provided relief from problems caused by weightlessness

Nearly every Apollo astronaut suffered from space adaptation syndrome during the weightless trip from the Earth to the moon. The most common symptom was sinus congestion:

With only two exceptions, the crewmen for all eleven flights experienced a fullness-of-the-head feeling upon orbital insertion. The persistence of the feeling was variable, lasting from 4hours to 3days.

Apollo Program Summary Report, section 8.2.3

Another condition resulting from the lack of gravitational pull was puffiness of the face. This symptom was specifically reported by the crews of the Apollo 11, 12, 13 and 15 missions; however, it probably occurred on all the flights.

Apollo Program Summary Report, section 8.2.3

Eight astronauts had nausea, but this was entirely limited to the trans-lunar coast. There was no nausea on the moon.

Four crews reported soreness of the back caused by weightlessness. Stretching and exercising alleviated the problem before they reached the moon.

The medications used in each Apollo flight are covered in another answer. Some of the medications addressed the sinus congestion and sleep issues addressed in this answer.

One they reached the gravity of the moon, these problems disappeared:

The Command Module Pilot apparently experienced no difficulty in adapting to weightlessness; but the Lunar Module Pilot reported that his sensation of head-fullness lasted 3 days. In addition, the Lunar Module Pilot experienced slight giddiness which precluded rapid head or body movements. This sensation disappeared shortly after landing on the lunar surface and did not recur on returning to the zero-gravity environment.

Apollo 15 Mission Report

Food, drinking water, and waste disposal were problematic in zero gravity, but improved considerably with the moon's gravity:

All crews reported that food preparation and waste management functions were easier to perform in the lunar gravity field as compared to the zero-gravity conditions of flight. On the lunar surface, for example, food bags conveniently stayed where they were placed. Also, air bubbles in water, permanent in zero gravity, automatically floated out of the in-suit drink container and the hydrated food bags.

Apollo Program Summary Report, section 6.1.2.7

As far as negative health effects caused by the lunar environment, inhaling moon dust was a danger:

A troublesome and ever-present problem that was corrected only partly during lunar surface missions was that of dust. On all missions, large amounts of floating dust were present in the lunar module cabin after insertion into lunar orbit. The Apollo 12 crew noted that dust made breathing without helmets both difficult and hazardous.

Apollo Program Summary Report, section 6.1.2.7

The worst health effect on the moon was sleep deprivation. The lunar module was an uncomfortable place to sleep:

The Apollo 11 crewmen reported that their sleep on the lunar surface was a complete loss because of light leakage into the cabin, excessive cabin noise, and an uncomfortably cool cabin temperature. The Apollo 12 crewmen, who slept in their pressure suits in sleeping hammocks, noted that the cabin noise was loud, but not loud enough to prevent adequate sleep. The Apollo 14 crew reported that very little sleep was obtained on the surface, primarily because they were uncomfortable in the suits, and recommended that crews remain unsuited during sleep periods. When this recommendation was adopted for Apollo 15 and subsequent missions, crews obtained adequate sleep. Also, a correlation was noted between the ability of the crews to sleep soundly and their increasing confidence in the proper operation of lunar module systems, based on proven performance.

Apollo Program Summary Report, section 6.1.2.7

The Apollo 14 lunar astronauts could not sleep because they were paranoid that the lunar module would tip over!

The [Apollo 14] lunar module crewmen received little, if any, sleep between their two extravehicular activity periods. The lack of an adequate place to rest the head, discomfort of the pressure suit, and a 7-degree starboard list of the lunar module on the lunar terrain were believed responsible for the lack of sleep. The crewmen looked out the window several times during the sleep period for reassurance that the lunar module was not starting to tip over.

Apollo Program Summary Report, section 8.2.4(h)

This last item is technically caused by the moon's gravity. But in general, the moon's gravity had only positive health effects.

• Thank you, great answer. I've been curious for some time about this because of the unknown question of long term effects on humans in low g environments but I knew we did have a dozen or so who had experienced low g for a short time and so the information had to be out there. (Even if it meant actually asking those who are still alive who have been on the moon, which I looked into doing!) – Brooks Nelson Sep 18 at 12:58