Gravity in Space

Developing artifical gravity for long duration missions such as the space station and inter-planetary flight is a necessity.

The following is from

Man-Systems Integration Standards NASA-STD-3000, Volume I Revision B, July 1995 3.2.3.1 Microgravity Effects Design Considerations

{O}

The effects of weightlessness on human body size are summarized below and are discussed in greater detail in Figures 3.2.3.1-1 and 3.2.3.1-2. The primary anthropometry effects of microgravity are as follows:

Figure 3.2.3.1-1 Anthropometric Changes in Weightlessness

Parameter

Anthropometric change

Short-term mission (1 to 14 days)

Long-term mission (more than 14 days)

Pre vs. during mission

Pre vs. post-mission

Height

Slight increase during first week (~1.3 cm or 0.5 in).

Height returns to normal *R+O

Increases caused by spine lengthening

Increases during first 2 weeks then stabilizes at approximately 3% of pre-mission baseline. Increases caused by spine lengthening

Returns to normal on R+O

Circumferences

Circumference changes in chest, waist, and limbs. See Figure 3.2.3.1-2 for chest and waist changes. Changes due primarily to fluids shifts.

Mass

Post flight weight losses average 3.4%; about 2/3 of the loss is due to water loss, the remainder due to loss of lean body mass and fat. Center of mass shifts headward approximately 3-4 cm (1-2in.) See paragraph 3.3.7.3.2.1 for details.

Inflight weight losses average 3-4% during first 5 days, thereafter, weight gradually declines for the remainder of the mission. Early inflight losses are probably due to loss of fluids; later losses are metabolic. Center of mass shifts headward approximately 3-4 cm (1-2in).

Rapid weight gain during first 5 days postflight, mainly due to replenishment of fluids. Slower weight gain from R+5 to R+2 or 3 weeks.

Limb volume

Inflght leg volume decreases exponentially during first mission day; thereafter, rate of decrease declines until reaching a plateau within 3-5 days. Postflight decrements in leg volume up to 3%; rapid increase immediately postflight, followed by slower return to pre-mission baseline.

Early inflight period same as short missions. Leg volume may continue to decrease slightly throughout mission. Arm volume decreases slightly.

Rapid increase in leg volume immediately postflight, followed by slower return to pre-mission baseline.

Posture

Immediate assumption of neutral body posture(see paragraph 3.3.4)

Immediate assumption of neutral body posture(see paragraph 3.3.4)

Rapid return to pre-mission posture.

Reference: 16, Chapter 1, 208, pages 132-133 NASA-STD-3000 265

*Recovery day plus post mission days

a. Height Increase - Stature increases approximately 3%. This is the result of spinal decompression and lengthening.

b. Neutral Body Posture - The relaxed body immediately assumes a characteristic neutral body posture.

(Refer to Paragraph 3.3.4, Neutral Body Posture, for detailed information).

c. Body Circumference Changes - Body circumference changes occur in microgravity such as shown in Figure 3.2.3.1-2. These changes are due to fluid shifts toward the head.

d. Mass Loss - The total mass of the body decreases by 3% to 4%. This is due primarily to loss of body fluids and, somewhat, to atrophy and loss of the mass of muscles that were used in 1-G (muscle mass loss is dependent on exercise regimes).

Figure 3.2.3.1-2 Micro-gravity Changes in Height, Waist, and Chest Measured on Skylab Crewmen: One-G Measurements as Baseline

Reference: 16, Figure 19 and 20, pg. 1-28 and 29 NASA-STD-3000 266

You should check to see if similar data exists for the International Space Station