Initial results from the Optical High-Resolution camera (OHRC) onboard Chandrayaan-2

<p>Chandrayaan-2 Orbiter carries eight experiments for studies, including morphology, surface geology, composition, and exospheric measurements based upon the understanding and information from the previous lunar orbital missions. Orbiter high-resolution camera (OHRC), one of the payloads, has a very high spatial resolution of 0.25 m. It operates in a visible panchromatic (PAN) band with a swath of 3 km from an altitude of 100 km. OHRC will search for hazard-free zones and map the landing site for future human missions. This work presents the initial impressions from the first data release of the OHRC on-board Chandrayaan-2. Here the OHRC image is analyzed for large-scale features like boulders, ridges, and craters on the lunar surface. Classification and visual analysis have been carried out to check the shape (morphology) and location of many impact craters. As seen from OHRC images, the lunar surface near to Hagecius lunar impact crater is dominated by the repetitive and frequent bombardment of small meteorites varying from millimeters to centimeters. The extent of degradation and erosion of a few large craters due to space weathering or the continuous meteorite bombardment is clearly observed. The results provide more clarification towards the ongoing physical processes on the moon. OHRC image provides a much detailed understanding of lunar topography and morphology. </p>

The Influence of Heterogeneity on Lunar Irradiance Based on Multiscale Analysis

The Moon is a stable light source for the radiometric calibration of satellite sensors. It acts as a diffuse panel that reflects sunlight in all directions, however, the lunar surface is heterogeneous due to its topography and different mineral content and chemical composition at different locations, resulting in different optical properties. In order to perform radiometric calibration using the Moon, a lunar irradiance model using different observation geometry is required. Currently, two lunar irradiance models exist, namely, the Robotic Lunar Observatory (ROLO) and the Miller and Turner 2009 (MT2009). The ROLO lunar irradiance model is widely used as the radiometric standard for on-orbit sensors. The MT2009 lunar irradiance model is popular for remote sensing at night, however, the original version of the MT2009 lunar irradiance model takes less consideration of the heterogeneous lunar surface and lunar topography. Since the heterogeneity embedded in the lunar surface is the key to the improvement of the lunar irradiance model, this study analyzes the influence of the heterogeneous surface on the irradiance of moonlight based on model data at different scales. A heterogeneous correction factor is defined to describe the impact of the heterogeneous lunar surface on lunar irradiance. On the basis of the analysis, the following conclusions can be made. First, the influence of heterogeneity in the waning hemisphere is greater than that in waxing hemisphere under all 32 wavelengths of the ROLO filters. Second, the influence of heterogeneity embedded in the lunar surface exerts less impact on lunar irradiance at lower resolution. Third, the heterogeneous correction factor is scale independent. Finally, the lunar irradiance uncertainty introduced by topography is very small and decreases as the resolution of model data decreases due to the loss of topographic information.

Multi-criteria GIS analysis of the topography of the Moon and better solutions for potential landing

During the past twenty years, the need to reach theMoon by the private space missions has been growing. Some of the private missions are supported by Google Lunar X-prize and Space-X. In the period between 2020 and 2050 private companies will be planning landing to the Moon with their own capacity. These missions can send new geodesy and cartography data. Lunar topography modelling with new satellite and remote sensing data gives plenty of possibilities for its exploration. GIS (Geographical Information System) may be successfully to the Moon topography analysis. According to the results after GIS numerical analysis 30% of the territory of the Moon showed excellent characteristics for landing. The most useful parts of the Moon for potential landing belong to the altitude between 2,000 and 3,000 m and on the plateaus with the north-east direction of azimuth. These plateaus have an excellent inclination of 3° and azimuth of 120°. The main aim and goal of this investigation would be in better understanding of Moon topography and relief. With help of GIS numerical methods, the astronomical geodesy may be applied in better way. A potential mission to the Moon can use this topography investigation, presented maps and results.

A New Lunar DEM Based on the Calibrated Chang’E-1 Laser Altimeter Data

To improve the lunar DEM accuracy derived from CE-1 altimeter data, CE-1 laser altimeter data are calibrated in this paper. Orbit accuracy and ranging accuracy are the two most important factors to affect the application of altimeter data in the lunar topography. An empirical method is proposed to calibrate CE-1 altimeter data, using gridded LOLA DEM to correct systematic errors of CE-1 altimeter data, and the systematic bias is about -139.52 m. A new lunar DEM grid model based on calibrated CE-1 altimeter data with the spatial resolution of 0.0625° × 0.0625° is obtained as well as a spherical harmonic model at 1400th order. Furthermore, the DEM accuracy is assessed through the comparison with the nearside landmarks of the Moon, and the results show that the DEM accuracy is improved from 127.3 m to 48.7 m after the calibration of laser altimeter data.

GEOMETRIC CALIBRATION OF THE CLEMENTINE UVVIS CAMERA USING IMAGES ACQUIRED BY THE LUNAR RECONNAISSANCE ORBITER

The Clementine UVVIS camera returned over half a million images while in orbit around the Moon in 1994. Since the Clementine mission, our knowledge of lunar topography, gravity, and the location of features on the surface has vastly improved with the success of the Gravity Recovery and Interior Laboratory (GRAIL) mission and ongoing Lunar Reconnaissance Orbiter (LRO) mission. In particular, the Lunar Reconnaissance Orbiter Camera (LROC) has returned over a million images of the Moon since entering orbit in 2009. With the aid of improved ephemeris and on-orbit calibration, the LROC team created a series of precise and accurate global maps. With the updated reference frame, older lunar maps, such as those generated from Clementine UVVIS images, are misaligned making cross-mission analysis difficult. In this study, we use feature-based matching routines to refine and recalibrate the interior and exterior orientation parameters of the Clementine UVVIS camera. After applying these updates and rigorous orthorectification, we are able generate precise and accurate maps from UVVIS images to help support lunar science and future cross-mission investigations.

GEOMETRIC CALIBRATION OF THE CLEMENTINE UVVIS CAMERA USING IMAGES ACQUIRED BY THE LUNAR RECONNAISSANCE ORBITER

The Clementine UVVIS camera returned over half a million images while in orbit around the Moon in 1994. Since the Clementine mission, our knowledge of lunar topography, gravity, and the location of features on the surface has vastly improved with the success of the Gravity Recovery and Interior Laboratory (GRAIL) mission and ongoing Lunar Reconnaissance Orbiter (LRO) mission. In particular, the Lunar Reconnaissance Orbiter Camera (LROC) has returned over a million images of the Moon since entering orbit in 2009. With the aid of improved ephemeris and on-orbit calibration, the LROC team created a series of precise and accurate global maps. With the updated reference frame, older lunar maps, such as those generated from Clementine UVVIS images, are misaligned making cross-mission analysis difficult. In this study, we use feature-based matching routines to refine and recalibrate the interior and exterior orientation parameters of the Clementine UVVIS camera. After applying these updates and rigorous orthorectification, we are able generate precise and accurate maps from UVVIS images to help support lunar science and future cross-mission investigations.