Your cited article is not a good model for walking in low gravity
The article you cited describes a study using the Short Arm Human Centrifuge at the ESA training center in Colonge, Germany. Here is a picture of that facility from the web page of the contractor that installed it:
The red object is one of four couches for human subjects. They recline with their heads downward and away from the center, and are then spun on the 6 meter diameter centrifuge at 40 revolutions per minute.
According to your cited article,
While whirling around in the centrifuge, the participants took a perceptual test, in which they had to choose whether the tilted letter they were looking at on a circular computer screen was a "p" or "d." In a near-zero-gravity environment, such as the International Space Station, astronauts need to rely on visual cues alone to orient themselves, Harris said. The results of the experiment found that gravity only starts influencing a person's sense of up and down once it hits about 0.15g.
The problems I have with this study are:
- It measures visual perception. There is no attempt to simulate walking.
- It rotates at 40 RPM. That is completely unlike walking on a moon or asteroid. The vestibule of the inner ear can sense the rotation.
- Experiments are limited in time to just a few hours. Measuring long-term effects are not feasible.
There's no good way to study walking at that much gravity
This PDF from the NASA Partial Gravity Analogs Workshop lists every known method of creating less than 1 g. (There isn't space here to describe each of these methods; read the paper for that.) Each method has flaws for simulating walking in low gravity:
- Not enough space for a human subject (short-arm centrifuges on ISS, rotating-wall vessel)
- Method does not last for long enough time (parabolic flight, free-fall wind turbine chamber)
- Could not create low enough gravity (short-arm centrifuge on STS-90 was 0.5 g and 1.0 g only)
- Can only create gravity greater than 1 g (rotating rooms)
- Method merely unloads weight off the feet, but does nothing to eliminate the pull of Earth's gravity on the otoliths (bed rest, harnesses, overhead suspension, head-out graded water immersion, head-out graded dry immersion, whole-body weighted-garment water immersion, lower body positive pressure, free-fall wind turbine chamber)
- Tilts the subject so that the pull of Earth's gravity on the otoliths are at an unnatural angle (vertical treadmill, head-up tilt, supine/head-down short-radius centrifugation)
- The subject rests against a surface, which interferes with attempting to walk (bed rest, head-out graded dry immersion, head-up tilt, supine/head-down short-radius centrifugation)
- The subject is immersed in water or other viscous medium which can interfere with walking (head-out graded water immersion, whole-body weighted-garment water immersion)
- The low-gravity effect changes with posture (free-fall wind turbine chamber)
- Involves rotation, which can be sensed by the vestibular organ (rotating-wall vessel, short-arm centrifuges, long-arm centrifuges, rotating rooms)
- Cancelled because the vibration loads would exceed ISS limits (Artificial Gravity Research with Ergometric Exercise)
- Theoretical, not experimental (physical modeling, computational modeling)
- Concept only, often used in science fiction (long-arm centrifuge in space)
Finally, there is a misconception in the question that Apollo astronauts fell on the moon because of the effects of the 1/6 gravity on the inner ear. Actually, the astronauts fell because the spacesuits were cumbersome and the lunar soil was sometimes slippery.
Most crewmen preferred the loping movement. When the loping movement was used, the inertia of the crewman wearing the extravehicular mobility unit (representing an earth weight of 360 pounds) and the sometimes slippery effect of the lunar regolith required the crewman to plan for a finite stopping distance in advance of the selected point.
[...] The Apollo 11 crew noted that egress operations around the hatch, porch, and ladder were performed easily without losing body balance.
Apollo Program Summary Report
No medicines for motion sickness were taken while on the moon.
Indeed, inner ear function on the moon was good enough that the Apollo 14 astronauts could not sleep because they could sense that their lunar module was leaning 7 degrees.
The tilt was especially noticeable during the sleep periods and made sleep difficult because the crew was uneasy in this awkward position.
Apollo 14 Mission Report
