Final answer:
The drilling team will look for changes in rock samples that indicate a transition from normal bedrock to impact-related materials, like shocked minerals and breccia, to determine when they have reached the crater from the NEO impact. Knowledge of cratering processes and crater rates can assist in these determinations.
Step-by-step explanation:
The drilling team studying the crater impact from an NEO (Near Earth Object) will have to analyze the rock samples that are being recovered as they drill. Changes in the geologic strata, such as shocked quartz or a layer of ejecta materials, are indicative of an impact event. As the drill approaches the crater depth, between 500 and 1,500 meters, the team will likely encounter rocks that have been subjected to the intense pressures and high temperatures associated with the impact, which can create distinctive features such as breccia, a rock composed of broken fragments of minerals or rock cemented together by a fine-grained matrix. Moreover, the drilled materials might transition from intact bedrock to a mix of impact melt rock and brecciated materials upon reaching the crater. Therefore, sharp changes in rock types and textures will signal the drill's approach to the impact site.
Cratering processes suggest that when a fast projectile strikes a planet, it transfers its energy into a shock wave and heat, vaporizing the projectile and fracturing the surrounding rock. The size of the excavated crater depends on the speed of impact but generally is 10 to 15 times the diameter of the projectile. Taking the example of Meteor Crater in Arizona, which is about 1 mile across and was created by a 40-meter projectile, the team can hypothesize the extent of the crater's diameter and the related disruptions in the geological strata.
Understanding the cratering rate and analyzing the lunar maria can give insight into the age of craters. While Earth's active geology can complicate estimations, these studies and the analysis of rock samples from the drilling process play a critical role in determining when the drill reaches the NEO impact crater.