Detection and Classification of Potential Caves on the Flank of Elysium Mons,Mars

Martian caves have revived interest in the field of subsurface exploration because they are the potential destinations for future human habitats and astrobiological research.There are many pits on Mars,but some of them look like collapsed cave roofs.These special pits are formed by the collapse of surface materials into the subsurface void spaces.The signature of life is probable in a subsurface cave on Mars as the subsurface environment can protect life from the harsh and dangerous radiation environment of the surface.In a cave,there may be an abundance of minerals,fluids,and other key resources.Therefore,locating the access point of the subsurface cave is essential and crucial for formulating plans for robotic/human explorations of the Red Planet,Mars.We have used remote sensing data from Mars Reconnaissance Orbiter(MRO;NASA),Mars Global Surveyor(MGS;NASA),and Mars Odyssey(NASA)for identifying,mapping,and classifying selected special pit candidates on the flank of Elysium Mons,Mars.A total of 32 special pit candidates has been identified and classified based upon morphology and geological context.Out of these,26 are newly discovered ones.The thermal behavior of 23 special pit candidates confirms that the special pits are radiating heat energy at nighttime,similar to potential caves.Also,cave entrances have been detected in nine candidates using data from the Hi RISE camera onboard MRO.These sites could be important destinations for future robotic/human exploration and the search for life on Mars.

Periodic orbits around areostationary points in the Martian gravity field

This study investigates the problem of areostationary orbits around Mars in three-dimensional space. Areostationary orbits are expected to be used to establish a future telecommunication network for the exploration of Mars. However, no artificial satellites have been placed in these orbits thus far. The characteristics of the Martian gravity field are presented, and areostationary points and their linear stability are cal- culated. By taking linearized solutions in the planar case as the initial guesses and utilizing the Levenberg-Marquardt method, families of periodic orbits around areo- stationary points are shown to exist. Short-period orbits and long-period orbits are found around linearly stable areostationary points, but only short-period orbits are found around unstable areostationary points. Vertical periodic orbits around both lin- early stable and unstable areostationary points are also examined. Satellites in these periodic orbits could depart from areostationary points by a few degrees in longitude, which would facilitate observation of the Martian topography. Based on the eigenval- ues of the monodromy matrix, the evolution of the stability index of periodic orbits is determined. Finally, heteroclinic orbits connecting the two unstable areostationary points are found, providing the possibility for orbital transfer with minimal energy consumption.

The O^+ Ion Flux in the Martian Magnetosphere and Martian Intrinsic Moment

A model is developed to study the ionospheric ion flux distribution along magnetic force lines in Martian magnetosphere and the influence of Martian intrinsic moment on the distribution. It is discovered that the intrinsic moment has significant influence on the O+ ion flux distribution that a lower flux in the magnetotail will be associated with a stronger intrinsic moment. According to the theoretical result and the observed data on the ion flux which is about 7.6 × 106 cm-2 s-1 in the Martian magnetotail, the deduced Martian moment is about 2×1021 G cm3. This agrees well with the most recent data obtained by MAG/ER on the Mars Global Surveyor spacecraft.