Planetary Exploration and Science: Recent Results and Advances

To accurately predict the iron abundance of the Moon has long been the goal for lunar remote sensing studies. In this paper, we present a new iron model based on partial least squares regression (PLS) method and apply this model to map the global lunar iron distribution using Clementine ultraviolet-visible (UVVIS) dataset. Our iron model has taken into account of more calibration sites other than Apollo and Luna sample-return sites and stations (i.e., the six additional highland or immature sites) in combination with more spectral bands (5 bands and 2 band ratios), in order to derive reliable FeO content and improve the robustness of the PLS model. By comparing the PLS-derived iron map with Lucey’s band-ratio FeO map and Lawrence’s Lunar Prospector (LP) FeO map, the differences are mostly within 1 wt% in FeO content. Moreover, PLS-derived FeO is more consistent with LP’s result which was derived by direct measurement of Fe gamma-ray line (7.6 MeV) rather than the Lucey’s experiential algorithm applying only two bands (750, 950 nm) of Clementine UVVIS dataset. With a global mode of 5.1 wt%, PLS-derived iron map is also validated by FeO abundances of lunar feldspathic meteorites and in support of the lunar magma ocean hypothesis.

Efficient lunar resource utilization requires accurate and quantitative evaluation of mineral and glass abundances, distribution, and extraction feasibility, especially for ilmenite (TiO₂). The modal analyses have performed on lunar basaltic terrains using hyperspectral remote sensing data along with ground truth chemistry and mineralogy. The main aim of the present work is to characterize the lunar Mare Orientale basalts based on TiO₂ content and quantify the lunar surface minerals, including clinopyroxene, orthopyroxene, plagioclase, and olivine. The Orientale basin is one of the youngest impact multi-ringed basins on the Moon covering 930 km in diameter centered at 20°S 95°W. The morphological features in the Orientale basin have developed interest among geoscientist to explore further study on this region. Based on the Apollo orbital, geochemical, and Earth-based spectral data, it is concluded that the Orientale ejecta are uniformly feldspathic in composition, almost pure anorthosite with no evidence of ultramafic components (Hawke, Geophys Res Lett 18(11):2141–2144, 1991). Greeley et al. (Geophys Res 98:17183–17205, 1993) have conferred the Orientale basin bearing the low-Ti basalts by using Galileo images. In this study, parts of basaltic regions of Mare Orientale, Lacus Veris, and Lacus Autumni of the Orientale basin are investigated using Moon Mineralogical Mapper (M³) data of onboard Chandrayaan-1 orbiter. Lucey’s (1998) TiO₂ estimation method and spectral profiles and spectral unmixing techniques have been used to detect and map the minerals, including plagioclase, clinopyroxene, orthopyroxenes, olivine, and various basalts such as low-, medium-, and high-Ti basalts. The Orientale data were acquired by M³’s reduced resolution mode with 20–40 nm spectral resolution and 140 m/pixel across the 40 km field of view. The RELAB mineral spectra of plagioclase, clino/orthopyroxenes, olivine and various basaltic spectra, chemistry and mineralogy have been employed to unmixing analysis. Comparing the spectral profiles of the basaltic regions with the RELAB basaltic spectra, the distribution and nature of TiO₂ basalts in the Orientale basaltic regions have been analyzed in quantitative manner in the present research.

Gravity Recovery and Climate Experiment (GRACE) twin satellites have been observing the mass transports of the Earth inferred by the monthly gravity field solutions in terms of spherical harmonic coefficients since 2002. In particular, GRACE temporal gravity field observations revolutionize the study of basin-scale hydrology, because gravity data reflect mass changes related to ground and surface water redistribution, ice melting, and precipitation accumulation over large scales. However, to use the GRACE data products, de-striping/filtering is required. We applied the multichannel singular spectrum analysis (MSSA) technique to filter GRACE data and separate its principal components (PCs) at different periodicities. Data averaging over the 15 largest river basins of Russia was performed. Spring 2013 can be characterized by the extremely large snow accumulation occurred in Russia. Melting of this snow induced large floods and abrupt increase of river levels. The exceptional maxima are evident from GRACE observations, which can be compared to the hydrological models, such as Global Land Data Assimilation System (GLDAS) or WaterGAP Global Hydrology Model (WGHM), and gauge data. Long-periodic climate-related changes were separated into PC 2. Finally, it was observed that there were mass increases in Siberia and decreases around the Caspian Sea. Overall trend over Russia demonstrates mass increase until 2009, when it had a maximum, followed by the decrease.

The numerical models and results of the gravimetric interpretation of the crustal density structures and the Moho geometry are presented. The numerical scheme applied utilizes the gravimetric forward and inverse modeling derived in a frequency domain. Methods for a spectral analysis and synthesis of the gravity and crustal structure models are applied in the gravimetric forward modeling of the gravity field generated by the major known crustal density structures. The gravimetric inversion scheme is formulated by means of a linearized Fredholm integral equation of the first kind. In numerical results we show the gravitational contributions of crustal density structures and the refined gravity field quantities, which have a minimum as well as maximum correlation with the Moho geometry. The resulting gravimetric Moho model is finally presented.

Radar is the acronym for RAdio Detection And Ranging. It is an object-detection system, which principles consist basically in the transmission, propagation, and reflection of radio waves. After the first exploitations in the military field, radar evolved as a useful device also in the civil field, widely extending its applications. After having been tested on Earth, radar capabilities to penetrate a planet surface have been applied on Mars exploration. MARSIS, part of the payload of ESA Mars Express mission, and SHARAD, embarked on board NASA MRO spacecraft, are two nadir-looking radar sounders which use synthetic aperture radar (SAR) techniques. The two instruments are complementary: MARSIS is able to detect subsurface interfaces at great depth, while SHARAD can better discriminate subsurface interfaces close to the surface. The two radars achieved information on Martian craters, both exposed and buried, provided geophysical evidences for the former existence of an ocean in the Martian northern hemisphere, investigated Martian pedestal craters, provided a useful contribution to analyze the nature of the Medusae Fossae Formation, and probed the ice-rich polar layered deposits of Mars, detected a boundary in many areas of plains off the south polar layered deposits. The analysis of MARSIS data enables to study also the Martian ionosphere and to estimate its TEC producing the related maps. Through volumetric (3D) study, the two radars provide an opportunity to extend our knowledge of a planetary body to the third dimension, allowing to detect features that are difficult to investigate in vertical profiles. Since Martian polar terrains are considered a close analogue to the material forming the crusts of Jovian satellites Europa and Ganymede, a radar sounder, RIME, has been selected as part of ESA’s first large-class mission in Cosmic Vision Program, JUICE, the first orbiter on an icy moon which will investigate the emergence of habitable worlds around gas giants, characterizing Ganymede, Europa, and Callisto as planetary objects and potential habitats.

Impact craters are the most outstanding and attractive geomorphological features on the surface of the planets, showing variety and complexity of the surface morphology. The accurate recognition of impact craters on Mars is very useful to analyze and understand the relative dating of Martian surface. In this chapter, four crater-detection methods have been presented and discussed with various extent of discrimination ability on Martian images or topography data. The modified ad boosting approach demonstrates the best performance in classification of craters, while the algorithms based on topography data have low efficiency in automatic detection. Comparing to previous solutions, the modified ad boosting method has greatly improved the detecting performance of the algorithm and reduced detection time.

In this chapter, we have described upper and lower ionospheric measurements, which have been obtained from radio occultation experiment onboard Mariners 6, 7 and 9; Mars 4 and 5; Viking 1 and 2; Mars Global Surveyor; and Mars Express. The ionisation sources like solar EUV, X-ray and particle radiations have been discussed. Observations on the upper ionosphere of Mars during disturbances like aurorae, solar flares, solar energetic particles and coronal mass ejections are also described. The understanding of complex behaviour of Martian ionosphere requires a balanced effort in the area of theoretical modelling. Therefore, we have also reported modelling of the upper ionosphere of Mars during quiet and disturbed conditions. At present measurements on the ionosphere of Mars are limited to middle- and high-latitude region. The low-latitude ionosphere of Mars is not observed. The physics of the low-latitude ionosphere could be very different from middle- and high-latitude ionosphere. Therefore, it is necessary to look for opportunities for obtaining observations at low-latitude region.

In this chapter, we begin making a brief review on the history of the studies of planet Mars. Then, we review the modern research (with recent status, data, results, and progress) on the search for possible extinct or extant life on Mars, with special emphasis on the search for the presence (in the past and/or presently) of liquid water within Mars’ surface and subsurface – a prerequisite for the evolution from geochemical state to biogeochemical state, as we are aware of here on planet Earth. Through the chapter, I present some proposals of mine about the astrobiology of Mars. We also analyze recent astrobiological experiments on board the International Space Station (ISS) for the future exploration of Mars. And we make a brief review on the evolution of equipment for its exploration and of future manned presence on the beautiful planet Mars – the “Red Planet.”

The rotation period of the Earth was calculated from the fundamental quantities, mass, distance, and radius, of the Earth-Moon system by almost an exact number 24^h3^m5^s. The rotation periods of Mars, Jupiter, Saturn, Uranus, Neptune, and the Sun were also calculated by the same equation. The Earth spin axis which is inclined by 23.45° with respect to the Earth orbit was derived from the gravitation of the Sun acting on the Earth and calculated by almost an exact number, 23.487°. An optical experiment to measure the reaction torque on the Earth acted by the Moon is proposed and discussed.

The Rosetta mission will begin its comet rendezvous and lander mission in mid 2014. The plasma instruments onboard Rosetta will provide detailed measurements of the plasma environment of comet 67P/Churyumov–Gerasimenko and its responses to solar wind interaction. In this chapter the basic scale lengths connected to the dimension of the radial-expanding magnetic field-free ionosphere and to the boundary separating photoelectrons cooled by collisional interaction with water molecules, respectively, are explained. Their variations at different heliocentric distances along the orbit of comet 67P are described. It is found that the radii of the diamagnetic ionospheric cavity (∼35 km at perihelion) and that of the cold photoelectron zone (∼350 km at perihelion) are all much smaller than those of comet Halley. These theoretical estimates will be tested by the upcoming in situ plasma measurements and remote-sensing observations onboard the Rosetta spacecraft.

Firstly, we review simply the exoplanet transit events and introduce our ongoing optical wavelength project. Then, we present new photometric observations of the transiting planets (HAT-P-10b/WASP-11b, HAT-P-19b, WASP-43b, …) using an 85-cm telescope of Xinglong Station of the National Astronomical Observatories of China in 2012. New transit curves are modeled using the JKTEBOP code and adopting the quadratic limb-darkening law. The preliminary parameters (the orbital inclination, relative radius ……) of these star-planet systems are re-obtained. We also revise the ephemeris with a transit epoch and discuss a period change by the observed minimum minus calculated transit times. Finally, our future plans in China are given and discussed.

Spurred by the discovery of more than 60 exoplanets in multiple systems, binaries have become in recent years one of the main topics in planet-formation research. Numerous studies have investigated to what extent the presence of a stellar companion can affect the planet-formation process. Such studies have implications that can reach beyond the sole context of binaries, as they allow to test certain aspects of the planet-formation scenario by submitting them to extreme environments. We review here the current understanding on this complex problem. We show in particular how each of the different stages of the planet-formation process is affected differently by binary perturbations. We focus especially on the intermediate stage of kilometre-sized planetesimal accretion, which has proven to be the most sensitive to binarity and for which the presence of some exoplanets observed in tight binaries is difficult to explain by in situ formation following the “standard” planet-formation scenario. Some tentative solutions to this apparent paradox are presented. The last part of our review presents a thorough description of the problem of planet habitability, for which the binary environment creates a complex situation because of the presence of two irradiation sources of varying distance.