Questions tagged [gravity-fields]

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7
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0answers
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For the mathematical relationship between J2 (km^5/s^2) and dimensionless J2 - which one is derived from the other?

The term $J_2$ seen in discussions of nodal precession of orbits (e.g. sun-synchronous) appears to come in two flavors. For example, in the Wikipedia article Geopotential model it has a value of $1....
2
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1answer
215 views

Which perturbs LEO satellites more, the Moon's gravity directly, or the changes in Earth's gravity field due to the Moon?

Reading this tutorial answer on models of Earth's gravity field I was realized that I'd never thought of it as time dependent. According to it, the biggest short term changes in the shape of Earth's ...
2
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3answers
305 views

Do Curiosity's reported measurements of Mars' surface gravity (~3.717 m/s^2) include centrifugal effects?

In this answer I discuss the first results in the 47th Lunar and Planetary Science Conference (2016) conference paper First Gravity Traverse on the Martian Surface from the Curiosity Rover and a more ...
16
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2answers
1k views

What was the mascon “fix” used by Apollo 12?

According to the mascon entry on wikipedia: At that time, one of NASA's highest priority "tiger team" projects was to explain why the Lunar Orbiter spacecraft being used to test the accuracy of ...
18
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1answer
1k views

How does orbital eccentricity affect positions of Lagrange points $L_4$ and $L_5$?

It is often said that the $L_4$ and $L_5$ points are "60 degrees ahead and behind" a planet like Jupiter. Clearly this is true only in the case of circular orbits. In more elliptical orbits, I assume ...
10
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1answer
1k views

Alternatives to centripetal force and constant acceleration to simulate Earth-like gravity

This is follow-up to @Erik's answer to the question Is artificial gravity feasible in manned long-term space exploration? I'm curious, whether there's any alternative methods to simulating effects of ...
2
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2answers
154 views

Have gravitation multipoles of Jupiter and Saturn beyond J2 been measured or at least estimated? At least the zonal harmonics?

This excellent answer has me wondering if there are any measurements or estimates of gravitational multipole moments of Jupiter or Saturn beyond J2. Here is what I found for J2 (in unitless form) in ...