Construction And Application Of Digital Elevation Model Of The Lunar Rümker Region Based On Multisource Altimeter Data

Rümker region is located in Oceanus Procellarum on the Moon,which is chosen as a candidate-landing region for Chang'E-5 sample return mission.The digital elevation model,analysis of illumination and communication conditions in this region can support the decision-making and implement of Chang'E-5 lunar sample return mission.Based on the altimetry data acquired by LAM on Chang'e-1,LALT on SELENE and LOLA on LRO,a reasonable data processing method was devised,then merged DEMs of the Mons Rümker region was produced and the accuracy of the merged DEMs was discussed.Last,the ray-tracing method was adopted to analyze the illumination and communication conditions based on the DEM,The main work of this paper can be summarized as follows:1)The method of combined fltering and clustering analysis can be used to precisely eliminate noise points in altimeter data.Effective points at small bumps or depressions in local flat areas were preserved,while problems associated with mean fltering along the track were overcome.Through crossover adjustment,the RMS of the residuals was reduced from 1.98 m to 1.31 m,which improved the radial accuracy of the data.2)The Mons Rümker DEM was constructed by interpolation at a resolution of 1/256°.Various errors in the NASA DEM were exposed by comparison of the NASA DEM to our DEM.3)A special crossover adjustment was used to model the radial errors between the LAM / LALT data and LOLA data.The LAM radial residual RMS was reduced from 154.83 ± 43.60 m to 14.29 ± 27.84 m and the LALT radial residual RMS was reduced from 3.50 ± 5.0 m to 2.75 ± 4.4 m.4)The adjusted LOLA ?LAM and LALT data were used to produce the merged DEMs.The LAM + LOLA merged DEM shows that there are large horizontal geolocation errors in the adjusted LAM data but the LALT + LOLA merged DEM is more credible than the LOLA-only DEM.A comparison between SLDEM2015 and LALT + LOLA merged DEM was carried out to show the advantages and disadvantages of each other.5)The Mons Rümker has suffcient sunlight conditions.From November 2017 to December 2019,the accumulated illumination ranged from 30% to approximately 53%.The terrain had a significant influence at some local areas in craters and at the back of the mountain.Most of the locations within the region have 50% accumulated communication.The accumulated communication was lower than 16% only in some local areas in craters and in the back of the mountain.This is consistent with the illumination conditions.During October 2019,the two example points suggested communication accessibility for approximately 9–15h per day at each Chinese observation station(Jiamusi,Kashi,and Neuquén).Continuous communication for 24 h per day could be maintained when the three ground stations were coordinated.