Acceleration of Gravity: Value in Low Earth Orbit

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Discussion Overview

The discussion revolves around the value of the acceleration of gravity in low Earth orbit, exploring various calculations and assumptions related to this value. Participants examine the effects of altitude and orbital mechanics on gravitational acceleration.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • Some participants suggest that the acceleration of gravity in low Earth orbit is approximately 9 m/s².
  • Others propose that the value of gravitational acceleration can be calculated using the formula g(H)/g = [R/(R+H)]², indicating a decrease in gravity with altitude.
  • One participant provides detailed calculations showing that a shuttle in low Earth orbit experiences about 89.8% of Earth's gravitational acceleration, estimating it to be around 8.82 m/s².
  • There is mention of the differences in gravitational acceleration experienced by geostationary satellites, which is significantly lower at about 2.28% g.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact value of gravitational acceleration in low Earth orbit, with multiple competing views and calculations presented.

Contextual Notes

Some calculations depend on specific assumptions about altitude and orbital mechanics, and the effects of Earth's rotation are noted as being eliminated in certain calculations.

delta_simon
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About what is the value of the acceleration of gravity
in low Earth orbit? <9,8m/s² ?
 
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Somewhere in the order of 9m/s^2
 
delta_simon said:
About what is the value of the acceleration due to (not of) gravity in low Earth orbit? <9,8m/s² ?
g(H)/g=[R/(R+H)]^2.
 
A typical low orbit shuttle travels around 17,235 mph, or 25,280fps, every 91.38 minutes or 5483 seconds. Orbital length is about 26250 miles = 138,600,000 feet, with a radius of 4178 miles = 22,060,000 feet. Earth radius is about 3959 miles, so the orbital radius is about 1.0553R, or about 219 miles altitude. The altitude actually ranges from 185 miles to 250 miles depending on the mision (space station is 250miles up). Centrifugal acceleration is v^2/r = 28.97 ft / s^2. Gravitational acceleration is 32.264ft / s^2 = 9.822m / s^2 (once Earth rotational effects are eliminated), so the shuttle in low orbit experiences about 89.8%g. or 8.82 m / s^2. This corresponds with g at shuttle radius = g/R^2) = g/(1.0553^2) = 89.8% g.

Geostationary sattellites are high orbits, speed around 6880mph=10,091 ft/s, altitude 22,240miles, radius about 26200 miles = 138,330,000 ft, for only 2.28% g. v^2 / r = .736ft/s^2 => 2.28% g which checks.
 
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