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This work is the third in a series on point mascon lunar gravity models. Point mascon models are computationally-efficient replacements for the standard spherical harmonics gravity models used in astrodynamics applications. Weighted cubed-sphere mascon gravity models are introduced as runtime-efficient alternatives to the spherical harmonics representation that do not impose the extreme memory costs imposed by other interpolated gravity modeling schemes. Localized models for the lunar gravity field are generated using sets of point-mass potentials and referenced to a cubed-sphere grid. Adjacent localized point mascon gravity models are combined using Junkins weighting functions to form a smooth global model. Three demonstration models are generated that reproduce the GRGM1200A lunar gravity model with equivalent fidelity to degree 70, 300, and 550 spherical harmonics truncation levels. The weighted cubed-sphere models are benchmarked for runtime and memory cost against the standard spherical harmonics models and two recently-introduced types of globally-defined mascon models. The benchmarking results show that the weighted cubed-sphere mascon models enable significant runtime improvements with reasonable memory costs, especially when using OpenMP parallelization. Comparing acceleration runtime with spherical harmonics, the degree 300 equivalent weighted cubed-sphere model shows up to a 30-fold speedup with an 89 megabyte memory footprint and the degree 550 equivalent model shows up to a 90-fold speedup with a 170 megabyte memory footprint. Order of magnitude speedups are demonstrated without parallelization. The runtime models and driver code are available online. [ABSTRACT FROM AUTHOR]

The cone penetration test (CPT) has shown great potential in coming lunar in-situ resource utilization and base construction missions. To investigate the effect of lunar low gravity and special regolith characteristics, a series of miniature cone penetration tests were conducted under lunar gravity, after which the penetration responses and mechanism were analyzed. Properties of the lunar regolith were reproduced by the CUMT-1 simulant, which shows good consistency with the lunar regolith in mineralogy, particle morphology, grain gradation, and mechanical behaviour. Lunar gravity was simulated through the recently developed geotechnical magnetic-similitude-gravity model testing (GMMT) method. The results show that the increase in gravity leads to a nonlinear increase of the penetration resistance, which is more significant at low relative density and is weakened by increasing assemble density and particle irregularity. The evolution of cone index gradient and normalized penetration resistance at lunar gravity was further analyzed, which shows a good agreement with the in-situ results performed by Lunokhod and Apollo missions. Finally, a back prediction of internal friction angle suggests that the gravity-induced stress level promotes an increase in internal friction angle, but the gravity-induced stress gradient suppresses this trend. [ABSTRACT FROM AUTHOR]

The paper presents the main results of our study on the influence of the physiological effects of simulated lunar gravity on cardiorespiratory responses to exercise in humans. Twelve healthy male volunteers aged 19–31 years (M ± SD: 22.5 ± 4.0 years) took part in the study. They were under 14-day head-up bed rest (HUBR) at +9.6° angle relative to the horizon as a model of the physiological effects of lunar gravity. Cardiopulmonary exercise testing (CPET) was performed 7 days before the onset of HUBR and on the next day after the end of the experimental exposure. A three-stage cycle ergometer test with 5-min steps at 125, 150, and 175 W was used as a CPET protocol. Exposure of the subjects to simulated lunar gravity reduced their tolerance to physical load. This was indicated by more pronounced changes for such parameters of the cardiorespiratory system as heart rate, minute ventilation of the lungs, ventilatory equivalents for oxygen and carbon dioxide, as well as a less pronounced increase in oxygen consumption and oxygen pulse during CPET after 14 days of exposure to HUBR. [ABSTRACT FROM AUTHOR]

The short- and long-term postural effects on the forced expiratory tracheal noise time were studied in a sample of 12 subjects. In contrast to the spirometric parameters, the tracheal forced expiratory noise time does not respond to a short-term change in the body posture from sitting and standing positions to the lying position, as well as to 14-day-long orthostatic hypokinesia in a lying position with a body angle of +9.6°. However, significant multidirectional individual dynamics of the tracheal forced expiratory noise time was observed in all subjects during long-term orthostatic hypokinesia, whereas the spirometric parameters had a dominant growth response. It is assumed that the estimation of the forced expiratory tracheal noise time during long-term orthostatic hypokinesia in lunar gravity simulation may provide useful data in addition to spirometry when assessing the individual lung function dynamics. The dynamics of acoustic parameters, as well as spirometric parameters, during long-term postural effects can be considered as adaptive changes. [ABSTRACT FROM AUTHOR]

It is known from observations of the gravitational field and figure of the Moon that its center of mass (COM) does not coincide with its geometric center, with the line connecting these two points deviating to the Southeast of the direction toward the center of the Earth. The deviation of the lunar COM to the South was explained earlier. Here, the deviation of the lunar COMto the East of the direction toward the Earth is considered. The theory of the optical libration of a satellite orbiting synchronously about a planet for an observer at the secondary (free) focus of the orbit is first refined. It is shown that the main axis of inertia of the satellite undergoes asymmetric, non-linear oscillations whose amplitude is proportional to the square of the orbital eccentricity. A mechanism for the evolution of the orbit has been developed, taking into account the preferred direction of the axis of inertia of the Moon toward the empty focus. Of two alternative scenarios—evolution of the lunar orbit with decreasing or increasing eccentricity—only the latter scenario is consistent with the observed eastward shift of the lunar COM. This mechanism predicts that the lunar orbit had a lower eccentricity in the past than it does today. This conclusion is consistent with the results of observations and also with the fact that the eccentricity of the Moon’s orbit is indeed currently increasing, indicating that it was lower in the past than its current value, e = 0.0549. It is shown by averaging themotion over a rapid variable that thismechanismfor the orbital evolution can explain about 18% of the currently known eastward shift of the lunar COM. The results obtained refine the theory of the tidal evolution of the Moon. [ABSTRACT FROM AUTHOR]

Low-thrust trajectories about planetary bodies characteristically span a high count of orbital revolutions. Directing the thrust vector over many revolutions presents a challenging optimization problem for any conventional strategy. This paper demonstrates the tractability of low-thrust trajectory optimization about planetary bodies by applying a Sundman transformation to change the independent variable of the spacecraft equations of motion to an orbit angle and performing the optimization with differential dynamic programming. Fuel-optimal geocentric transfers are computed with the transfer duration extended up to 2000 revolutions. The flexibility of the approach to higher fidelity dynamics is shown with Earth’s J2 perturbation and lunar gravity included for a 500 revolution transfer. [ABSTRACT FROM AUTHOR]

Spectrum-Röntgen-Gamma (SRG) is a space observatory designed to observe astrophysical objects in the X-ray range of the electromagnetic spectrum. SRG is planned to be launched in 2019 by a Proton-M launch vehicle with a DM3 upper stage. The spacecraft will be delivered to an orbit around the Sun-Earth collinear libration point L2 located at a distance of ~1.5 million km from the Earth. Although the SRG launch scheme has already been determined at present, in this paper we consider an alternative spacecraft transfer scenario using a lunar gravity-assist maneuver. The proposed scenario allows a oneimpulse transfer from a low Earth orbit to a small-amplitude orbit around the libration point to be performed while fulfilling the technical constraints and the scientific requirements of the mission. [ABSTRACT FROM AUTHOR]

We obtain computational expressions for determining the generalized free fall acceleration at any point on the Earth surface depending on the terrestrial, solar, and lunar gravities, height above sea level, season, and diurnal time. The acceleration components due to the solar gravity and the Earth revolution around the Sun take sign-alternating values in the period of 24 hours. The greatest influence of the Sun on the free fall acceleration is in perihelion with the maximal diurnal amplitude of oscillations up to 55.34mGal, while the influence of the lunar gravity is negligible and takes sign-alternating values (up to 3-4mGal). We determine the maximum and minimum values of the acceleration on the Earth surface (983229.81 and 976073.25mGal) and also note the possibility of influence of accelerations due to centrifugal forces on the human organism. [ABSTRACT FROM AUTHOR]

Escape trajectories from the Earth-Moon system can be obtained through a single gravity assist maneuver of a spacecraft with the Moon. This paper presents a semi-analytical study of variations in the semi-major axis and the eccentricity of a spacecraft for a geocentric frame-before and after a close encounter of the spacecraft with the Moon. Studies on the swing-by dynamics between a spacecraft and the Moon were performed in order to establish a set of initial conditions in terms of eccentricities and semi-major axes of geocentric initial orbits. This way, it was possible identify which orbits, launched from Earth parking orbits, accomplish swing-bys with the Moon and generate escape trajectories. [ABSTRACT FROM AUTHOR]

This study mostly concentrates on the sensitivity analysis regarding the future dedicated Moon-ILRS spacecraft gravity mission. Firstly, the new single and combined analytical error models for the cumulative lunar geoid height impacted by the major error sources comprising the inter-spacecraft range-rate of the interferometric laser ranging system (ILRS), the spacecraft orbital position tracked by the deep space network (DSN) and the non-conservative force of the drag-free control system (DFCS) are developed on the basis of the spacecraft-to-spacecraft tracking in the low-low mode (SST-LL) from the future twin Moon-ILRS spacecraft. Secondly, the correctness of the new single and combined analytical error models is proved according to the compliance of the cumulative lunar geoid height errors among the inter-spacecraft range-rate, orbital position and non-conservative force. Finally, in comparison with the past gravity recovery and interior laboratory (GRAIL) program, the preferred design for the future Moon-ILRS mission is achieved in this paper. We recommend that the future twin Moon-ILRS formation-flying spacecraft had better adopt the new-type space-borne instruments involving the ILRS and DFCS. We demonstrate the compatible accuracy indexes of the key sensors (e.g., 10 m/s in the inter-spacecraft range-rate, 1 m in the orbital position and 3 × 10 m/s in the non-conservative force) and the optimal orbital parameters (e.g., 25-km orbital altitude, 100-km inter-spacecraft range and 1-s sampling interval) in the future Moon-ILRS twin-spacecraft mission. [ABSTRACT FROM AUTHOR]

Purpose: Weightlessness has a well-known effect on the autonomic control of the cardiovascular system. With future missions to Mars in mind, it is important to know what the effect of partial gravity is on the human body. We aim to study the autonomic response of the cardiovascular system to partial gravity levels, as present on the Moon and on Mars, during parabolic flight. Methods: ECG and blood pressure were continuously recorded during parabolic flight. A temporal analysis of blood pressure and heart rate to changing gravity was conducted to study the dynamic response. In addition, cardiovascular autonomic control was quantified by means of heart rate (HR) and blood pressure (BP) variability measures. Results: Zero and lunar gravity presented a biphasic cardiovascular response, while a triphasic response was noted during martian gravity. Heart rate and blood pressure are positively correlated with gravity, while the general variability of HR and BP, as well as vagal indices showed negative correlations with increasing gravity. However, the increase in vagal modulation during weightlessness is not in proportion when compared to the increase during partial gravity. Conclusions: Correlations were found between the gravity level and modulations in the autonomic nervous system during parabolic flight. Nevertheless, with future Mars missions in mind, more studies are needed to use these findings to develop appropriate countermeasures. [ABSTRACT FROM AUTHOR]

Main conclusion: Cyclic leaf ascent and descent occur in synchrony and phase congruence with the lunisolar tidal force under a broad range of conditions. Digitized records of the vertical leaf movements of Arabidopsis thaliana were collected under space flight conditions in the International Space Station (ISS). Oscillations of leaf movements with periods of 45 and 90 min were found under light-adapted conditions, whereas in darkness, the periods were 45, 90, and 135 min. To demonstrate the close relationship between these oscillations and cyclical variations of the lunisolar gravitational force, we estimated the oscillations of the in-orbit lunisolar tide as they apply to the ISS, with the aid of the Etide software application. In general, in-orbit lunisolar gravitational profiles exhibited a periodicity of 45 min. Alignment of these in-orbit oscillations with the oscillations of Arabidopsis leaf movement revealed high degrees of synchrony and a congruence of phase. These data corroborate previous results which suggested a correlative relationship and a possible causal link between leaf movement rhythms obtained on ground and the rhythmic variation of the lunisolar tidal force. [ABSTRACT FROM AUTHOR]

This research principally focuses on the requirements analysis in terms of the next-generation Moon-Gradiometer satellite gravity program. Firstly, the new single and combined analytical error models applied to estimate the accuracy of the lunar gravitational field (e.g., geopotential coefficients, cumulative geoid height and cumulative gravity anomaly) influenced by the main error sources consisting of the satellite gravity gradient and satellite orbital position are created for the next-generation Moon-Gradiometer program. Secondly, the dependability of the new single and combined analytical error models is validated by the conformity of the cumulative lunar geoid height errors between the gravity gradient and orbital position. Finally, taking the current GRAIL (Gravity Recovery and Interior Laboratory) satellite gravity mission for reference, the sensitivity analysis for the next-generation Moon-Gradiometer gravity satellite system is comprehensively carried out. We propose to equip this with the new-type pivotal payloads of the lunar spacecraft comprising the electrostatic suspension gravity gradiometer and the drag-free control system and bring forward the matching measurement precision of the space-borne instruments (involving 3 × 10/s in the gravity gradient and 60 m in the orbital position) and the preferred orbital parameters (including an orbital altitude of 25 km, an observation period of 28 days and a sampling interval of 1 s) in the next-generation Moon-Gradiometer program. [ABSTRACT FROM AUTHOR]

The Procellarum region is a broad area on the nearside of the Moon that is characterized by low elevations, thin crust, and high surface concentrations of the heat-producing elements uranium, thorium, and potassium. The region has been interpreted as an ancient impact basin approximately 3,200 kilometres in diameter, although supporting evidence at the surface would have been largely obscured as a result of the great antiquity and poor preservation of any diagnostic features. Here we use data from the Gravity Recovery and Interior Laboratory (GRAIL) mission to examine the subsurface structure of Procellarum. The Bouguer gravity anomalies and gravity gradients reveal a pattern of narrow linear anomalies that border Procellarum and are interpreted to be the frozen remnants of lava-filled rifts and the underlying feeder dykes that served as the magma plumbing system for much of the nearside mare volcanism. The discontinuous surface structures that were earlier interpreted as remnants of an impact basin rim are shown in GRAIL data to be a part of this continuous set of border structures in a quasi-rectangular pattern with angular intersections, contrary to the expected circular or elliptical shape of an impact basin. The spatial pattern of magmatic-tectonic structures bounding Procellarum is consistent with their formation in response to thermal stresses produced by the differential cooling of the province relative to its surroundings, coupled with magmatic activity driven by the greater-than-average heat flux in the region. [ABSTRACT FROM AUTHOR]

A theoretical model that provides a self-consistent description of the concentrations of photoelectrons and dust particles located over the illuminated part of the lunar surface is presented. The model takes account of the observation point location and the effects of production of photoelectrons at the surfaces of the Moon and dust particles, the dynamics of dust particles in the electric and gravitational fields, and the charging of dust particles through their interaction with the solar radiation photons, the solar wind electrons and ions, photoelectrons, etc. An expression that describes the distribution of photoelectrons over the illuminated part of the lunar surface is obtained. The size and elevation distributions of the charged dust particles located over the illuminated part of the lunar surface are calculated for different angles between the local normal and the direction to the Sun. It is shown that no substantial restrictions are imposed on the choice of the landing site for future lunar spacecraft missions aimed at studying the near-surface dust on the Moon. [ABSTRACT FROM AUTHOR]

The Lunar Gravity Ranging System (LGRS) flying on NASA’s Gravity Recovery and Interior Laboratory (GRAIL) mission measures fluctuations in the separation between the two GRAIL orbiters with sensitivity below 0.6 microns/Hz 1/2. GRAIL adapts the mission design and instrumentation from the Gravity Recovery and Climate Experiment (GRACE) to a make a precise gravitational map of Earth’s Moon. Phase measurements of Ka-band carrier signals transmitted between spacecraft with line-of-sight separations between 50 km to 225 km provide the primary observable. Measurements of time offsets between the orbiters, frequency calibrations, and precise orbit determination provided by the Global Positioning System on GRACE are replaced by an S-band time-transfer cross link and Deep Space Network Doppler tracking of an X-band radioscience beacon and the spacecraft telecommunications link. Lack of an atmosphere at the Moon allows use of a single-frequency link and elimination of the accelerometer compared to the GRACE instrumentation. This paper describes the implementation, testing and performance of the instrument complement flown on the two GRAIL orbiters. [ABSTRACT FROM AUTHOR]

We examine the stability of the orbit of an artificial moon of a small celestial body in the presence of an external massive perturbing body in terms of the restricted three-body problem. The orbit of this moon is shown to be dependent on the shape of the small body and central gravitational field of the external body. We study how these factors interact with each other and how they affect the stability of the orbit. [ABSTRACT FROM AUTHOR]

The minimum-time controls (thrust pitch angle and thrust yaw angle) for the three-dimensional transfer of a constant-thrust rocket from one state to another over a flat moon are used to develop guidance laws for operation over a spherical moon. The objective is to evaluate the effect of making approximations on the size of the thrust pitch angle on the suitability of the resulting control law as a guidance law. After assuming small out-of-plane motion (small yaw angle), three pitch angle control laws (exact, first-order, and zeroth-order) are developed. The three laws are employed in the sample and hold guidance of a lunar ascent vehicle. All three laws satisfy the final conditions and give essentially the same pitch and yaw control histories. Since the zeroth-order law can be obtained completely analytically (no iteration processes), it merits consideration for ascent guidance. [ABSTRACT FROM AUTHOR]

The importance of an accurate model of the Moon gravity field has been assessed for future navigation missions orbiting and/or landing on the Moon, in order to use our natural satellite as an intermediate base for next solar system observations and exploration as well as for lunar resources mapping and exploitation. One of the main scientific goals of MAGIA mission, whose Phase A study has been recently funded by the Italian Space Agency (ASI), is the mapping of lunar gravitational anomalies, and in particular those on the hidden side of the Moon, with an accuracy of 1 mGal RMS at lunar surface in the global solution of the gravitational field up to degree and order 80. MAGIA gravimetric experiment is performed into two phases: the first one, along which the main satellite shall perform remote sensing of the Moon surface, foresees the use of Precise Orbit Determination (POD) data available from ground tracking of the main satellite for the determination of the long wavelength components of gravitational field. Improvement in the accuracy of POD results are expected by the use of ISA, the Italian accelerometer on board the main satellite. Additional gravitational data from recent missions, like Kaguya/Selene, could be used in order to enhance the accuracy of such results. In the second phase the medium/short wavelength components of gravitational field shall be obtained through a low-to-low (GRACE-like) Satellite-to-Satellite Tracking (SST) experiment. POD data shall be acquired during the whole mission duration, while the SST data shall be available after the remote sensing phase, when the sub-satellite shall be released from the main one and both satellites shall be left in a free-fall dynamics in the gravity field of the Moon. SST range-rate data between the two satellites shall be measured through an inter-satellite link with accuracy compliant with current state of art space qualified technology. SST processing and gravitational anomalies retrieval shall benefit from a second ISA accelerometer on the sub-satellite in order to decouple lunar gravitational signal from other accelerations. Experiment performance analysis shows that the stated scientific requirements can be achieved with a low mass and low cost sub-satellite, with a SST gravimetric mission of just few months. [ABSTRACT FROM AUTHOR]

The SELENE mission, consisting of three separate satellites that use different terrestrial-based tracking systems, presents a unique opportunity to evaluate the contribution of these tracking systems to orbit determination precision. The tracking data consist of four-way Doppler between the main orbiter and one of the two sub-satellites while the former is over the far side, and of same-beam differential VLBI tracking between the two sub-satellites. Laser altimeter data are also used for orbit determination. The contribution to orbit precision of these different data types is investigated through orbit overlap analysis. It is shown that using four-way and VLBI data improves orbit consistency for all satellites involved by reducing peak values in orbit overlap differences that exist when only standard two-way Doppler and range data are used. Including laser altimeter data improves the orbit precision of the SELENE main satellite further, resulting in very smooth total orbit errors at an average level of 18 m. The multi-satellite data have also resulted in improved lunar gravity field models, which are assessed through orbit overlap analysis using Lunar Prospector tracking data. Improvements over a pre-SELENE model are shown to be mostly in the along-track and cross-track directions. Orbit overlap differences are at a level between 13 and 21 m with the SELENE models, depending on whether 1-day data overlaps or 1-day predictions are used. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the correlation between the lunar-solar tidal deformation processes and seismoacoustic response of the geo-environment. Modified Coulomb-Mohr equation was used for the approximation of the brittle rocks and harmonic analysis of the seismic acoustic emission (SAE) time variations and tidal increments of the gravity force was conducted to distinguish the dominating periods in the spectra of the processes. Tidal waves were separated and its dynamics were analyzed. The study founds that lunar-solar tidal deformation processes have influenced the appearance of diurnal and semidiurnal periods in the time variations of the SAE at large depths because variations in the external influence on the geo-environment are related to the Earth's tides.

In this paper novel Earth-Mars transfers are presented. These transfers exploit the natural dynamics of n-body models as well as the high specific impulse typical of low-thrust systems. The Moon-perturbed version of the Sun-Earth problem is introduced to design ballistic escape orbits performing lunar gravity assists. The ballistic capture is designed in the Sun-Mars system where special attainable sets are defined and used to handle the low-thrust control. The complete trajectory is optimized in the full n-body problem which takes into account planets' orbital inclinations and eccentricities. Accurate, efficient solutions with reasonable flight times are presented and compared with known results. [ABSTRACT FROM AUTHOR]

lunar gravity field model up to degree and order 100 in spherical harmonics, named SGM100i, has been determined from SELENE and historical tracking data, with an emphasis on using same-beam S-band differential VLBI data obtained in the SELENE mission between January 2008 and February 2009. Orbit consistency throughout the entire mission period of SELENE as determined from orbit overlaps for the two sub-satellites of SELENE involved in the VLBI tracking improved consistently from several hundreds of metres to several tens of metres by including differential VLBI data. Through orbits that are better determined, the gravity field model is also improved by including these data. Orbit determination performance for the new model shows improvements over earlier 100th degree and order models, especially for edge-on orbits over the deep far side. Lunar Prospector orbit determination shows an improvement of orbit consistency from 1-day predictions for 2-day arcs of 6 m in a total sense, with most improvement in the along and cross-track directions. Data fit for the types and satellites involved is also improved. Formal errors for the lower degrees are smaller, and the new model also shows increased correlations with topography over the far side. The estimated value for the lunar GM for this model equals 4902.80080±0.0009 km/s (10 sigma). The lunar degree 2 potential Love number k was also estimated, and has a value of 0.0255 ± 0.0016 (10 sigma as well). [ABSTRACT FROM AUTHOR]

The article presents a study which examines the dynamical model of the Earth's rotational—oscillatory motions. The study uses the Euler—Liouville equations to build the model of the Earth's rotation as well as the lunar—solar gravitational-tidal torque and apply corrections for the variations of zonal tides. The study implies that analysis of oscillatory—rotational motions and geophysical characteristics of the Earth cannot be used as basis for its qualitative study.

Lunar geodetic parameters, which play an important role in lunar exploration, can be calculated from the gravity and topography data. With the CE-1 altimetry data and LP gravity model, we calculate such geodetic parameters as the principle moment of inertia, the principle inertia axes, equatorial radius, polar radius, mean radius, flattening and offset between center of mass and center of figure (DCOM-COF). According to the CE-1 altimetry data and the above geodetic parameters, a tri-axial ellipsoid (CE-1-LAM-GEO) and a tri-axial level ellipsoid (CE-1-LAM-LEVEL) are calculated individually, providing mass center and figure center offset ( DCOM-COF) and parameters more reliable in direction and magnitude. [ABSTRACT FROM AUTHOR]

The Japanese lunar explorer SELENE (Kaguya), which was launched on September 14th, 2007, was the target of VLBI observations over the period November 2007 to June 2009. These observations were made in order to improve the lunar gravity field model, in particular the lower degree coefficients and the model near the limb. Differential VLBI Radio sources, called VRAD instruments, were on-board the subsatellites, Rstar (Okina) and Vstar (Ouna), and the radio signals were observed by the Japanese VERA (VLBI Exploration of Radio Astrometry) network, and an international VLBI network. Multi-frequency and same-beam VLBI techniques were utilized and were essential aspects of the successful observing program. Multi-frequency VLBI was employed in order to improve the accuracy of the orbit determination obtained from the phase delay from the narrow-band satellite signals, while the same-beam VLBI method was used to resolve the cycle ambiguity which is inherent in the multi-frequency VLBI method. The observations were made at three S-band frequencies (2212, 2218 and 2287 MHz), and one X-band frequency (8456 MHz). We have succeeded in correlating the recorded signals from Okina/Ouna, and we obtained phase delays with an accuracy of several pico-seconds at S-band. [ABSTRACT FROM AUTHOR]

Abstract  The dynamics of the circular restricted three-body Earth-Moon-particle problem predicts the existence of the retrograde periodic orbits around the Lagrangian equilibrium point L1. Such orbits belong to the so-called family G (Broucke, Periodic orbits in the restricted three-body problem with Earth-Moon masses, JPL Technical Report 32–1168, 1968) and starting from them it is possible to define a set of trajectories that form round trip links between the Earth and the Moon. These links occur even with more complex dynamical systems as the complete Sun-Earth-Moon-particle problem. One of the most remarkable properties of these trajectories, observed for the four-body problem, is a meaningful inclination gain when they penetrate into the lunar sphere of influence and accomplish a swing-by with the Moon. This way, when one of these trajectories returns to the proximities of the Earth, it will be in a different orbital plane from its initial Earth orbit. In this work, we present studies that show the possibility of using this property mainly to accomplish transfer maneuvers between two Earth orbits with different altitudes and inclinations, with low cost, taking into account the dynamics of the four-body problem and of the swing-by as well. The results show that it is possible to design a set of nominal transfer trajectories that require ΔV Total less than conventional methods like Hohmann, bi-elliptic and bi-parabolic transfer with plane change. [ABSTRACT FROM AUTHOR]

Lunar dust presents a potential toxic challenge to future explorers of the moon. The extent of the inflammatory response to lunar dust will in part depend on where in the lung particles deposit. To determine the effect of lowered gravity, we measured deposition of 0.5 and 1 microm diameter particles in six subjects on the ground (1G) and during short periods of lunar gravity (1/6G) aboard the NASA Microgravity Research Aircraft. Total deposition was measured during continuous aerosol breathing, and regional deposition by aerosol bolus inhalations at penetration volumes (V (p)) of 200, 500 and 1,200 ml. For both particle sizes (d (p)), deposition was gravity-dependent with the lowest deposition occurring at the lower G-level. Total deposition decreased by 25 and 32% from 1G to 1/6G for 0.5 and 1 microm diameter particles, respectively. In the bolus tests, deposition increased with increasing V (p). However, the penetration volume required to achieve a given deposition level was larger in 1/6G than in 1G. For example, for d (p) = 1 microm (0.5 microm), a level of 25% deposition was reached at V (p) = 260 ml (370 ml) in 1G but not until V (p) = 730 ml (835 ml) in 1/6G. Thus in 1G, deposition in more central airways reduces the transport of fine particles to the lung periphery. In the fractional gravity environment of a lunar outpost, while inhaled fine particle deposition may be lower than on earth, those particles that are deposited will do so in more peripheral regions of the lung. [ABSTRACT FROM AUTHOR]

The methods of celestial mechanics can be used to construct a mathematical model for the perturbed rotational motions of the deformable Earth that can adequately describe the astrometric measurements of the International Earth Rotation Service (IERS). This model describes the gravitational and tidal influences of the Sun and Moon. Fine resonant interactions of long-period zonal tides (annual, semiannual, monthly, and biweekly) with the diurnal and semidiurnal tides are revealed. These interactions can be reliably confirmed via a spectral analysis of the IERS data. Numerical modeling of tidal irregularities of the Earth’s axial rotation was carried out, focusing on the analysis and forecasting of variations of the day length occurring within short time intervals of a year or shorter (intrayear variations). [ABSTRACT FROM AUTHOR]

This paper compares five mission design scenarios for the proposed Dust Near Earth (DUNE) spacecraft. DUNE's science requires it to carry a dust telescope outside of the Earth's magnetosphere, yet its communication requirements restrict it to orbits within the orbit of the Moon. The scenarios considered in this paper include trajectories that place DUNE into highly eccentric Earth orbits, lunar orbits, and lunar halo orbits. This paper concludes that the most successful mission design option for DUNE implements a lunar gravity assist to place the spacecraft in a very high Earth orbit with a raised inclination. [ABSTRACT FROM AUTHOR]

In the day time of the Moon surface, the strong illumination from high altitude and high albedo rate radical craters will introduce the illumination effect on observing the nearby low altitude, low albedo rate and shallow small slop rate area seriously, and even can "hide" the later area from the light. Based on the lunar global topography model obtained by Chang'E-1 mission, and by comparing with the lunar gravity model, a volcano named "YUTU Mountain" has been identified. It is a volcano with diameter of ~300 km and height of ~2 km located at (14°N, 308°E) in Oceanus Procellarum. Besides, the DEM of another volcano named "GUISHU Mountain" in the same area has been improved. This new discovery will benefit the study of lunar magmatism and volcanism evolution in the nearside of the Moon. [ABSTRACT FROM AUTHOR]

Lunar frozen orbits, characterized by constant orbital elements on average, have been previously found using various dynamical models, incorporating the gravitational field of the Moon and the third-body perturbation exerted by the Earth. The resulting mean orbital elements must be converted to osculating elements to initialize the orbiter position and velocity in the lunar frame. Thus far, however, there has not been an explicit transformation from mean to osculating elements, which includes the zonal harmonic J2, the sectorial harmonic C22, and the Earth third-body effect. In the current paper, we derive the dynamics of a lunar orbiter under the mentioned perturbations, which are shown to be dominant for the evolution of circumlunar orbits, and use von Zeipel’s method to obtain a transformation between mean and osculating elements. Whereas the dynamics of the mean elements do not include C22, and hence does not affect the equilibria leading to frozen orbits, C22 is present in the mean-to-osculating transformation, hence affecting the initialization of the physical circumlunar orbit. Simulations show that by using the newly-derived transformation, frozen orbits exhibit better behavior in terms of long-term stability about the mean values of eccentricity and argument of periapsis, especially for high orbits. [ABSTRACT FROM AUTHOR]

Understanding the structure of and dynamic processes in the deep interior of planets is crucial for understanding their origin and evolution. An effective way to constrain them is through observation of rotation and subsequent simulation. In this paper, a numerical model of the Moon’s rotation and orbital motion is developed based on previous studies and implemented independently. The Moon is modeled as an anelastic body with a liquid core. The equations of the rotation were nonlinear and the Euler angles are cross coupled. We solve them numerically via the Runge-Kutta-Fehlberg (RKF) and multi-steps Adams-Bashforth-Moulton (ABM) predictor-corrector numerical integration. We have found that adequate accuracy is maintained by taking twelve steps per day using eleventh differences in the integrating polynomial. The lunar orbital and rotational equations are strongly coupled, so we integrated the rotation and motion simultaneously. We refer to other planetary informations from the newest planetary and lunar ephemeris INPOP17a, which is reported had fitted the longest LLR (Lunar Laser Ranging) observation data. Using the model GL660B from GRAIL (Gravity Recovery and Interior Laboratory) mission, we firstly compare our numerical results with the INPOP17a to prove the reasonability of our model. After that we apply the lunar gravity model CEGM02 determined from Chang’E-1 mission and SGM100h from SELENE mission to our model, the difference between results from CEGM02 and GL660B are less than −0.20∼0.15 arc-second, and −0.25∼0.20 arc-second for GL660B and SGM100h. Compared to SGM100h, the results show that the low degree and order coefficients (less than 6 from this paper) of lunar gravity field were improved in CEGM02 as expected. It is the first time to demonstrate that these models can be applied to lunar rotation model. These results manifest that a development of the gravity field measure will help us to know the rotation motion more precisely. [ABSTRACT FROM AUTHOR]

The precision of lunar gravity field estimation has improved by means of three to five orders of magnitude since the successful GRAIL lunar mission. There are still discrepancies however, in the low degree coefficients and long wavelength components of the solutions developed by two space research centers (JPL and GSFC). These discrepancies hint at the possibilities for improving the accuracy in the long wavelength part of the lunar gravity field. In the near future, China will launch the Chang’E-5 lunar mission. In this sample-return mission, there will be a chance to do KBRR measurements between an ascending module and an orbiting module. These two modules will fly around lunar at an inclination of ∼49 degrees, with an orbital height of 100 km and an inter-satellite distance of 200 km. In our research, we simulated the contribution of the KBRR tracking mode for different GRAIL orbital geometries. This analysis indicated possible deficiencies in the low degree coefficient solutions for the polar satellite-to-satellite tracking mode at various orbital heights. We also investigated the potential contributions of the KBRR to the Chang’E-5 mission goal of lunar gravity field recovery, especially in the long wavelength component. Potential improvements were assessed using various power spectrums of the lunar gravity field models. In addition, we also investigated possible improvements in solving lunar tidal Love number K2. These results may assist the implementation of the Chang’E-5 mission. [ABSTRACT FROM AUTHOR]

The article focuses on a study which discusses the formation and orbit of the Moon on the equatorial plane of planet Earth. Topics discussed include how elements such as platinum, iridium, and gold were delivered to the outer layers of the Earth, the impact of the gravitational interactions between the Moon and oceans on Earth's rotation, and the researchers' use of Monte Carlo simulations to examine the effect of Earth's precious metals on the early orbit of the Moon.

For many years we have failed to record instrumentally the background variations in seismoacoustic emission in solid consolidated rocks of the Earth's crust at great depths (3200 m) and to confirm their relation to lunar-solar gravitation. We managed to fulfill the task only with significantly improved parameters of the recording system measurement channel. As follows from analysis of new data, the amplitudes in the diurnal cycle vary from 1930 to 2100 fm (10) for the band of 160 Hz and from 129.5 to 132 fm for the band of 500 Hz, while the energy model correlation coefficients are within 0.737-0.852. Hence, this fact proves once again that background variations related to lunar-solar tides are universal in occurrence, and their frequency and amplitude depend significantly on the host rocks, position, and time of observations, while the energy model fits in these variations. [ABSTRACT FROM AUTHOR]