NASA NTRS2019
Due to lighting conditions, the program decided to only fly to the north pole in June 2022 and south pole in December 2022. Starting with the June 2022 landing sites at the north pole, a trajectory scan was run for one landing per day for the latitudes from 85 up to 88 degrees at 0.5 degree increments. Each landing site was at lunar dawn, which determined the landing site’s longitude as described in the previous section. The results of the June 2022 scan showed that LPL had the capability to reach a landing site at least once per day for the region examined as see in in Figure 12. There appears to be a correlation between the landing site’s altitude and the propellant remaining above the lander’s FPR, Figure 13. This is most likely due to the >10 km altitude constraint at SRM burnout. This constraint was applied to keep the lander high above the lunar terrain to avoid mountains, but can be relaxed when the full terrain data is added. Figure 12. June 2022 Nominal Usable Propellant Remaining vs Landing Date/time Similarly, the December 2022 landing sites were run showing that LPL was also capable of reaching a landing site at the Moon at least once per day. Figure 14 shows the results of the December scan, however, there were 3 landing sites that LPL could not reach. Two were very low in altitude (-5 and -4 km in altitude), which looking at the altitude trends in Figure 15, indicates that these sites may not be feasible with the current mission design. It may be possible to achieve the low altitude landing sites by lowering the SRM burnout altitude constraint, but that requires detailed terrain modeling, planned for a future phase of the analysis. The third non-reachable landing site is most likely due to an optimization error, as its altitude was high enough, at -2 km, that it should not have been a problem for the lander to arrive there. More analysis is required to verify this observation.