Absence of Gravity
A "stationary" micro-g environment would require travelling far enough into deep space so as to reduce the effect of gravity by attenuation to almost zero. This is the simplest in conception, but requires traveling an enormous distance, rendering it most impractical. For example, to reduce the gravity of the Earth by a factor of one million one needs to be at a distance of 6 million km from the Earth, but to reduce the gravity of the Sun to this amount one has to be at a distance of 3700 million km. (The gravity due to the rest of the Milky Way is already smaller than one millionth of the gravity on Earth, so we need not move away further from its center.) Thus it is not impossible, but it has only been achieved by a few spaceships such as Voyager 1, which do not return to Earth. To reduce the gravity to one thousandth of that on Earth one needs to be at a distance of 200,000 km.
| Location | Gravity due to the Earth | Gravity due to the Sun | Gravity due to the rest of Milky Way | Total |
|---|---|---|---|---|
| Earth's surface | 9.81 m/s2 | 6 mm/s2 | 200 pm/s2 = 6 mm/s/yr | 9.81 m/s2 |
| Low Earth orbit | 9 m/s2 | 6 mm/s2 | 200 pm/s2 | 9 m/s2 |
| 200,000 km from Earth | 10 mm/s2 | 6 mm/s2 | 200 pm/s2 | up to 12 mm/s2 |
| 6 million km from Earth | 10 μm/s2 | 6 mm/s2 | 200 pm/s2 | 6 mm/s2 |
| 3700 million km from Earth | 29 pm/s2 | 10 μm/s2 | 200 pm/s2 | 10 μm/s2 |
| Voyager 1 (17,000 million km from Earth) | 1 pm/s2 | 500 nm/s2 | 200 pm/s2 | 500 nm/s2 |
| 0.1 light-year from Earth | 400 am/s2 | 200 pm/s2 | 200 pm/s2 | up to 400 pm/s2 |
From stationarity the gravity from "the rest of the Milky Way" would cause a free fall, covering a distance of 100 pm in one second, 360 nm in one minute, 1.3 mm in one hour, 70 cm in one day, 37 m in one week, 100 km in one year, and 10,000 km in 10 years (at a speed at that last location of 6 cm/s).
Compare the gravitational potential at some of these locations.
Read more about this topic: Micro-g Environment
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