# Sentence-Level Insights from the Martian Literature: A Natural Language Processing Approach
## 3 Results
### Semantic Match
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **(b)** & **Challenges and Limitations in Martian Surface Exploration** \\ \hline
**Reference** & **Theme** & **Limitation/Challenge** \\ \hline
[31] & Martian Rock Properties Analysis & Limited compositional data, restricted sample access, and scarce mechanical measurements constrain knowledge of Martian rock properties. \\ \hline
[32] & Earth–Mars Communication Efficiency & Communication delays and data bottlenecks between Earth and Mars impede timely scientific data acquisition and rover decision-making. \\ \hline
[33] & Photometric Corrections on Mars & The movement of various surface materials over time makes photometric corrections difficult. \\ \hline
[34] & Cave Life Detection on Mars & Cave life detection missions exceed NASA’s New Frontiers budget limits, requiring Flagship-level funding. \\ \hline
[35] & Martian Mineral Diversity Analysis & Limited landing site coverage and instrument detection thresholds constrain mineralogical analysis. \\ \hline
[3] & Pre-Noachian Strata Analysis & Few and small pre-Noachian outcrops, combined with dataset and technique limitations, impede analysis of early alteration states. \\ \hline
[36] & Illumination Variability on Mars & Mars’ -25” obliquity causes annual shadow shifts of up to 50\({}^{\prime}\), resulting in inconsistent image illumination. \\ \hline
[37] & Environmental Contamination by Human Activities & Human activity on Mars will introduce anthropogenic materials and degradation products of diverse types. \\ \hline
[38] & Dust Accumulation on Solar Panels & Dust accumulation on InSight’s solar panels led to power loss and early mission termination. \\ \hline
[39] & Limitations of Orbital Imaging Resolution & Orbital imagery lacks the resolution to detect sub-meter rocks, despite their abundance on Mars. \\ \hline
[40] & Limitations of Orbital Spectroscopy for Rock & Visible and Near-Infrared (VNIR) spectroscopy cannot quantify bulk Fe, while gamma-ray spectroscopy lacks resolution for flexperian sulfate-rich outcrops. \\ \hline
[41] & Limited High-Resolution Imaging Coverage & High-resolution ground images are limited to select landing sites, and the High Resolution Imaging Science Experiment (HiRISE) covers only a small surface fraction. \\ \hline
[42] & Shock Environment Analysis on Mars & Laboratory constraints on shock environments are imprecise, as most Martian meteorites are impact-altered. \\ \hline
[43] & Mars’ Bond Albedo Measurements & Comprehensive spatial, spectral, and angular data for accurate Bond albedo measurements are currently lacking. \\ \hline
[44] & Limitations of VNIR Spectroscopy on Mars & VNIR spectroscopy penetrates only shallow depths, making data susceptible to dust obscuration. \\ \hline
[45] & Propellant Requirements for Mars Ascent Vehicle (MAV) & Delivering MAV propellant from Earth demands 12–13 tons in LEO per ton landed on Mars. \\ \hline
[3] & Clay Mineral Characterization on Mars & Crystal–chemical substitution, mixed layering, variable crystallinity, and hydration states complicate clay mineral characterization. \\ \hline
**(c)** & **Challenges and Limitations in Martian Atmospheric Research** \\ \hline
**Reference** & **Theme** & **Limitation/Challenge** \\ \hline
[46] & Challenges in Mars Entry, Descent, and Landing (EDL) Systems & Uncertainties in atmospheric density and wind profiles hinder development of a standardized EDL system. \\ \hline
[47] & Challenges in Martian Data Assimilation & Martian data assimilation depends on fewer and distinct observations, heavily relying on infrared temperature retrievals. \\ \hline
[48] & Methane Detection on Mars & TGO detection limits and methane’s atmospheric lifetime constrain explanations for Mars Science Laboratory (MSL) methane observations. \\ \hline
[49] & Limitations of the Occultation Method for Atmospheric Profiling & Aerosol opacity prevents occultation techniques from retrieving gas profiles near the Martian surface. \\ \hline
[48] & Unresolved Methane Source and Sink Problem & The mismatch between suspected methane sources and proposed rapid destruction mechanisms remains unresolved. \\ \hline
[48] & Uncertainty in In Situ Methane Measurements & MSL is the sole surface platform for methane detection, but Tunable Laser Spectrometer-Sample Analysis at Mars (TLS-SAM) data may be affected by instrument contamination. \\ \hline
**(d)** & **Challenges and Limitations in Martian Space Environment Studies** \\ \hline
**Reference** & **Theme** & **Limitation/Challenge** \\ \hline
[50] & Lack of High–Quality Energetic Particle Observations & High–quality 1-AU equivalent observations of \(\sim\)1 MeV electrons and \(\sim\)40 MeV protons are lacking at Mars’ orbit. \\ \hline \hline \end{tabular}
\end{table}