Scene Context: After landing, Les descends into the "Tartarus" lava tube, as such cavities are considered one of the most promising environments for finding traces of ancient life or well-preserved biosignatures. It is there that a meteor strike catches up with him.
Essence of the Phenomenon: The Martian atmosphere is significantly thinner than Earth's, meaning it is far less effective at braking and destroying high-velocity entry bodies. Consequently, the meteor hazard on Mars is considerably more severe. A lava tube serves simultaneously as a scientifically valuable environment and a natural shelter: it shields against radiation, reduces thermal fluctuations, and can preserve traces of ancient processes better than the open surface. However, this shielding does not guarantee safety in the event of a massive kinetic impact nearby.
Scientific Basis: Martian lava tubes are genuinely viewed as highly promising natural shelters for future bases and potential targets for astrobiological exploration. At the same time, a nearby meteor strike generates seismic waves capable of fracturing and collapsing the surrounding rock. Thus, in the scene, the cave saves Les from instant death from above, but not from the ceiling's collapse.
Current Limitations: Predicting the exact blast radius and destruction zone of a large impact is exceedingly difficult. Even excellent natural shielding does not equate to absolute safety if the tunnel's geometry and the nature of the rock prove unfavorable.