Lunar Degree-2 Tidal Love Number Determination Based on Combination of Four-way Radiometric Tracking and LLR Data
Lunar tidal Love numbers ( ${k}_{2}$ , ${h}_{2}$ , and ${l}_{2}$ ), critical for understanding lunar interior structures, are traditionally derived from methods such as lunar spacecraft radiometric tracking, Lunar Laser Ranging (LLR), and laser altimetry. The Chang’e 7 lander is expected to carry a...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
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| Series: | The Astronomical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-3881/adb60b |
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| Summary: | Lunar tidal Love numbers ( ${k}_{2}$ , ${h}_{2}$ , and ${l}_{2}$ ), critical for understanding lunar interior structures, are traditionally derived from methods such as lunar spacecraft radiometric tracking, Lunar Laser Ranging (LLR), and laser altimetry. The Chang’e 7 lander is expected to carry a radio transponder and a retroreflector. In order to assess the ability of the Chang’e 7 data to constrain these Love numbers, we conducted a numerical simulation based on a four-way relay tracking model in terms of different orbital inclinations, varying lander positions (nearside, south pole, and farside of the Moon), combined with LLR. Our simulation results demonstrate the effectiveness of the Chang’e 7 in determining tidal Love numbers, with a particular advantage for ${h}_{2}$ and ${l}_{2}$ . By combining the LLR data from the nearside and the south pole of the Moon as well as the four-way lander tracking data of Chang’e 7, the formal uncertainties of ${h}_{2}$ and ${l}_{2}$ are better than ${10}^{-4}$ , which is nearly 1 order of magnitude higher than the existing accuracy estimated by LLR alone ( ${10}^{-3}$ ). For the lunar south pole region, four-way radiometric ranging can still offer higher sensitivity and a longer observation time compared to LLR. This is evident for measurements of ${h}_{2}$ , despite the fact that radiometric ranging precision is an order of magnitude lower than that of LLR. This type of observation not only complements laser altimetry and LLR but also holds potential for application to other celestial bodies (e.g., Ganymede, Callisto, Mars) capable of supporting a landed mission. |
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| ISSN: | 1538-3881 |