Gravity gradient noise from asteroids

Seismic gravity-gradient noise in interferometric gravitational-wave detectors

When ambient seismic waves pass near and under an interferometric gravitational-wave detector, they induce density perturbations in the Earth, which in turn produce fluctuating gravitational forces on the interferometer’s test masses. These forces mimic a stochastic background of gravitational waves and thus constitute a noise source. This seismic gravity-gradient noise has been estimated and d...

Human gravity-gradient noise in interferometric gravitational-wave detectors

Among all forms of routine human activity, the one which produces the strongest gravity-gradient noise in interferometric gravitational-wave detectors ~e.g. LIGO! is the beginning and end of weight transfer from one foot to the other during walking. The beginning and end of weight transfer entail sharp changes ~time scale t;20 msec! in the horizontal jerk ~first time derivative of acceleration!...

From Accelerators to Asteroids*

Low-Earth Orbit Determination from Gravity Gradient Measurements

An innovative orbit determination method which makes use of gravity gradients for Low-Earth-Orbiting satellites is proposed. The measurement principle of gravity gradiometry is briefly reviewed and the sources of measurement error are analyzed. An adaptive hybrid least squares batch filter based on linearization of the orbital equation and unscented transformation of the measurement equation is...

Better Gradient Noise

We present three improvements to Perlin’s gradient noise algorithm. First, a small change in the permutation hash function combined with separate pseudorandom tables yields significantly better axial decorrelation. Second, a modification to the reconstruction kernel approximating a global higher-order differencing operator produces better bandlimitation. Third, the quality of 2D surfaces using ...