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Lunar gravitational field obtained from Lunar Orbiter tracking data, with gravity potential as spherical harmonics series and lunar gravitational constant determined
Lunar gravitational field interpretation based on Apollo data, considering mascons creation, isostasy, thermal history and maria orientation hypotheses
Lunar gravitational field obtained from Lunar Orbiter tracking data, with gravity potential as spherical harmonics series and lunar gravitational constant determined
Lunar gravitational field determination from analysis of Lunar Orbiter spacecraft tracking data
Lunar gravitational field determination from analysis of Lunar Orbiter spacecraft tracking data
Satellite orbit perturbation analysis for lunar gravitational field determination using von Zeipel transformation
Tracking geometry and dynamics of lunar satellite, estimating orbital elements and lunar gravitational field parameters through earth based range and range rate observations
Lunar gravitational field from analysis of long term and secular variations of Keplerian orbital elements from Doppler tracking data for Lunar Orbiter 1 satellite
Sensitivity of short period tracking data from lunar satellite to zonal and sectorial harmonics of lunar gravitational potential
Error analysis of weighted least squares method to determine lunar gravitational field
Dynamic derivation of surface layer representation of lunar gravitational field from Doppler observations on polar and equatorial lunar orbiters
Tracking geometry and dynamics of lunar satellite, estimating orbital elements and lunar gravitational field parameters through Earth- based range and range rate observations
Correlation of lunar radii estimates obtained from earth based photographic study and lunar orbiter gravitational field coefficient measures
Lunar Orbiter tracking data analyzed to yield thirteenth degree and order spherical harmonic approximation to lunar gravitational potential function
Lunar spherical harmonic gravity coefficients are estimated from simulated observations of a near-circular low altitude polar orbiter disturbed by lunar mascons. Lunar gravity sensing missions using earth-based nearside observations with and without satellite-based far-side observations are simulated and least squares maximum likelihood estimates are developed for spherical harmonic expansion fit models. Simulations and parameter estimations are performed by a modified version of the Smithsonian Astrophysical Observatory's Planetary Ephemeris Program. Two different lunar spacecraft mission phases are simulated to evaluate the estimated fit models. Results for predicting state covariances one orbit ahead are presented along with the state errors resulting from the mismodeled gravity field. The position errors from planning a lunar landing maneuver with a mismodeled gravity field are also presented. These simulations clearly demonstrate the need to include observations of satellite motion over the far side in estimating the lunar gravity field. The simulations also illustrate that the eighth degree and order expansions used in the simulated fits were unable to adequately model lunar mascons.
Spherical harmonics for evaluating perturbing forces on lunar satellite due to nonsymmetric mass distribution of moon
Lunar gravitational-wave (GW) detection has been under consideration since Apollo 17 when the Lunar Surface Gravimeter developed under the coordination of Joseph Weber was deployed on the Moon with the goal to observe lunar surface vibrations generated by passing GWs [1]. The experiment did not run with its targeted performance, but even if it had, we know today that it would not have been sensitive enough to detect GW signals. Vibrations caused by GWs are expected to be several orders of magnitude weaker than what the instrument was designed to observe. The main motivation to bring such an experiment to the Moon was that with the extremely low level of seismicity observed with previously deployed Apollo seismometers [2] (see figure 1), Weber suspected that GW signals could be detected.
The Lunar Gravitational-wave Antenna (LGWA) is a mission conceived as a network of stations to measure the vibrations of the Moon caused by gravitational waves (GWs). The long-term vision is to accomplish ground-breaking, paradigm shifting science in the coming decades on the Moon. LGWA will lead to the first observation of GW signals in the decihertz band greatly expanding our understanding of the universe and laying out a path to eventually probe the moment of its creation. LGWA stations will also be unique contributions to a lunar geophysical network shedding light on the Moon’s formation history. LGWA is a project of inclusion and international collaboration, where space-faring and space-aspiring nations can contribute to the LGWA network with their own stations whose cost depends on the targeted station lifetime and deployment location. With respect to the baseline concept proposed here, different sensor technologies can be implemented over time with the goal to continually increase the performance of the LGWA network. The broader context of lunar GW detection and its long-term vision are outlined in an accompanying topical white paper.