A spacecraft-borne gradiometer mission analysis

Numerical simulations were performed to obtain the orbit- and attitude-determination requirements of a spacecraft-borne gradiometer mission. Results demonstrated that position determination of 300 meters in the along-track and cross-track directions and 50 meters in the radial direction are mission requirements. The optimal orientation of the gradiometer sensing plane is achieved when the spin vector elevation is 0 degrees. The attitude-determination requirements are 5 degrees resolution for spin-vector azimuth and 0.2 degree resolution for spin-vector elevation. When these requirements are met, 3-degree gravity anomalies can be recovered globally with an accuracy of 0.025/mm/sq s (2.5 mgals). The Appendix documents the mathematical procedures for estimating detailed gravity fields from gradiometer data

On extracting brightness temperature maps from scanning radiometer data

The extraction of brightness temperature maps from scanning radiometer data is described as a typical linear inverse problem. Spatial quantization and parameter estimation is described and is suggested as an advantageous approach to a solution. Since this approach takes into explicit account the multivariate nature of the problem, it permits an accurate determination of the most detailed resolution extractable from the data as well as explicitly defining the possible compromises between accuracy and resolution. To illustrate the usefulness of the method described for algorithm design and accuracy prediction, it was applied to the problem of providing brightness temperature maps during the NOSS flight segment. The most detained possible resolution was determined and a curve which displays the possible compromises between accuracy and resolution was provided

On estimating gravity anomalies from gradiometer data

The Gravsat-gradiometer mission involves flying a gradiometer on a gravity satellite (Gravsat) which is in a low, polar, and circular orbit. Results are presented of a numerical simulation of the mission which demonstrates that, if the satellite is in a 250-km orbit, 3- and 5-degree gravity anomalies may be estimated with accuracies of 0.03 and 0.01 mm/square second (3 and 1 mgal), respectively. At an altitude of 350 km, the results are 0.07 and 0.025 mm.square second (7 and 2.5 mgal), respectively. These results assume a rotating type gradiometer with a 0.1 -etvos unit accuracy. The results can readily be scaled to reflect another accuracy level

Simulated low-gravity sloshing in spherical tanks and cylindrical tanks with inverted ellipsoidal bottoms

Simulated low gravity sloshing in spherical and cylindrical tanks with inverted ellipsoidal bottom

Simulation of a lunar gradiometer mission

A lunar gradiometer mission involves the mounting of a gradiometer on a satellite which is in a low, polar, and circular lunar orbit. The results of a numerical simulation of the mission is presented. It is shown that if the satellite is in a 50 km orbit, 1 deg and 2 deg gravity anomalies may be estimated with accuracies of 12 mgal and 1 mgal respectively. At a 100 km altitude, 2 deg gravity anomalies can be estimated with an accuracy of 12 mgal. These results assume a rotating type gradiometer with a .1E accuracy. The results can be readily scaled to reflect another level

Equivalent mechanical model of propellant sloshing in the workshop configuration of the Saturn S-4B Final report

Mechanical model for propellant sloshing in irregular compartmentation of S-4B Workshop configuration during roll and lateral excitation

Low-gravity sloshing in rectangular tanks

Low-gravity sloshing in rectangular tank

MEASUREMENTS OF LIQUID DAMPING PROVIDED BY RING BAFFLES IN CYLINDRICAL TANKS

Damping effect of flat ring baffles on liquid sloshing in partially filled cylindrical tank

Propellant dynamics in an aircraft-type launch vehicle

Liquid propellant sloshing in tilted axisymmetric cylindrical tanks for space shuttle application

Experimental and theoretical studies of liquid sloshing at simulated low gravities

Low gravity liquid sloshing in rigid cylindrical tan