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Seismological constraints obtained from receiver function (RF) analysis provide important information about the crust and mantle structure. Here, we explore the utility of the free‐surface multiple of the P‐wave (PP) and the corresponding conversions in RF analysis. Using earthquake records, we demonstrate the efficacy of PPs‐RFs before illustrating how they become especially useful when limited data is available in typical planetary missions. Using a transdimensional hierarchical Bayesian deconvolution approach, we compute robust P‐to‐S (Ps)‐ and PPs‐RFs with InSight recordings of five marsquakes. Our Ps‐RF results verify the direct Ps converted phases reported by previous RF analyses with increased coherence and reveal other phases including the primary multiple reverberating within the uppermost layer of the Martian crust. Unlike the Ps‐RFs, our PPs‐RFs lack an arrival at 7.2 s lag time. Whereas Ps‐RFs on Mars could be equally well fit by a two‐ or three‐layer crust, synthetic modeling shows that the disappearance of the 7.2 s phase requires a three‐layer crust, and is highly sensitive to velocity and thickness of intra‐crustal layers. We show that a three‐layer crust is also preferred by S‐to‐P (Sp)‐RFs. While the deepest interface of the three‐layer crust represents the crust‐mantle interface beneath the InSight landing site, the other two interfaces at shallower depths could represent a sharp transition between either fractured and unfractured materials or thick basaltic flows and pre‐existing crustal materials. PPs‐RFs can provide complementary constraints and maximize the extraction of information about crustal structure in data‐constrained circumstances such as planetary missions. Plain Language Summary: Most of our geophysical understanding about the interior of other planets and moons comes from indirect, remote measurements. Other than Earth, only the Moon and Mars have been directly investigated with seismometers, by the Apollo and InSight missions, respectively. The ground vibration measurements on Mars have revealed much of the interior structure and dynamics of the red planet. A widely used tool for analyzing ground vibrations is the so‐called receiver function technique, which allows us to extract constraints on subsurface structure directly beneath the seismometer. Already, receiver functions have constrained the overall crustal structure of Mars. Our study explores the utility of one of many underused seismic phases from a seismic source, the P‐wave bouncing off the planet's surface (called PP), when studying planetary crustal structures with receiver functions. We show that using PP waves to compute receiver functions provides complementary information, to more commonly used direct P and S seismic arrivals and maximizes the amount of information extracted from limited data, which is particularly helpful in the context of planetary missions. Using data from the five best‐quality marsquakes, we find Mars' crust beneath the InSight lander in Elysium Planitia likely consists of three distinct layers. Key Points: We compute robust P‐to‐S (Ps)‐, P‐waves (PPs)‐, and S‐to‐P (Sp)‐receiver functions (RFs) to infer properties of the crustal layers beneath the InSight lander in Elysium PlanitiaSp‐RFs as well as observed variability of the 7.2 s phase between Ps‐ and PPs‐RFs require a three‐layer crustPPs‐RFs can provide complementary constraints for crustal imaging on Earth and other planetary bodies [ABSTRACT FROM AUTHOR]

A new 1.5 m diameter impact crater was discovered on Mars only ~40 km from the InSight lander. Context camera images constrained its formation between 21 February and 6 April 2019; follow‐up High Resolution Imaging Science Experiment images resolved the crater. During this time period, three seismic events were identified in InSight data. We derive expected seismic signal characteristics and use them to evaluate each of the seismic events. However, none of them can definitively be associated with this source. Atmospheric perturbations are generally expected to be generated during impacts; however, in this case, no signal could be identified as related to the known impact. Using scaling relationships based on the terrestrial and lunar analogs and numerical modeling, we predict the amplitude, peak frequency, and duration of the seismic signal that would have emanated from this impact. The predicted amplitude falls near the lowest levels of the measured seismometer noise for the predicted frequency. Hence, it is not surprising this impact event was not positively identified in the seismic data. Finding this crater was a lucky event as its formation this close to InSight has a probability of only ~0.2, and the odds of capturing it in before and after images are extremely low. We revisit impact‐seismic discriminators in light of real experience with a seismometer on the Martian surface. Using measured noise of the instrument, we revise our previous prediction of seismic impact detections downward, from ~a few to tens, to just ~2 per Earth year, still with an order of magnitude uncertainty. Plain Language Summary: A small new impact crater was discovered on Mars very close to the InSight lander. Photographs from a camera in orbit show it formed between 21 February and 6 April 2019. Three seismic events were detected by InSight during this time. We estimate what seismic data from the impact would have looked like and whether or not each of the seismic events was caused by the new impact, but none of them can be definitely linked. We predict the size, frequency, and length of time of the signal that would have come from this impact. Even though this impact is very close to InSight, it is small, so it was not a large seismic event. The signal would be near the quietest the instrument ever gets. There is only a 1 in 5 chance each Earth year that a crater would have formed this close to InSight, and a much lower chance that it would be imaged; thus, we were very lucky to find this crater. Using what we know about the instrument on the ground, we update the number of impacts we expect to find with InSight to ~2 each Earth year, with a lot of uncertainty. Key Points: A new 1.5 m diameter impact crater formed on Mars ~40 km from the InSight lander between February and April 2019Three candidate seismic events occurred during this time frame, but none of them can be definitively associated with the new craterWe revise our expectations for InSight impact detections above the background noise to be ~2 per Earth year, with large uncertainties [ABSTRACT FROM AUTHOR]