{"id":1266,"date":"2026-07-27T17:30:28","date_gmt":"2026-07-27T21:30:28","guid":{"rendered":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/?p=1266"},"modified":"2026-07-27T17:31:18","modified_gmt":"2026-07-27T21:31:18","slug":"rehearsing-for-the-moon","status":"publish","type":"post","link":"https:\/\/www.geol.umd.edu\/facilities\/seismology\/rehearsing-for-the-moon\/","title":{"rendered":"Rehearsing for the Moon"},"content":{"rendered":"

Three papers led by Jingchuan Wang (formerly a postdoc at Maryland, currently at Caltech) appeared in 2025 \u2014 one in JGR: Planets<\/em>, one in Geophysical Research Letters<\/em>, one in Earth and Space Science<\/em>. They describe fieldwork at sites hundreds of miles apart and they read, at first glance, like three separate projects. But, all three are attempts to answer one question: what would it actually take to image the shallow subsurface of the Moon, under the mass, power, and crew-time budgets that a real mission would impose? With Nick Schmerr and a large group of collaborators (https:\/\/geodes.umd.edu<\/a>), we came at it from three directions \u2014 establishing what a thorough survey can deliver, working out how much of that survives when the effort is cut drastically, and building a method aimed at one target worth going out of your way for.<\/p>\n

The difficulty here is not in the method itself, as seismic imaging of the top few tens of meters is a mature craft on Earth. The difficulty is that every terrestrial workflow is built on assumptions inappropriate on the Moon, where seemingly trivial logistical choices cost mass, power, and irreplaceable time on the surface. The Apollo 14 crew skipped several of their planned shots because the clock ran out during the EVA. Any serious plan for lunar seismic imaging has to be designed around that fact rather than in spite of it.<\/p>\n

The first paper focuses on Kilbourne Hole, a maar volcano in the Potrillo Volcanic Field of southern New Mexico formed roughly 24,000 years ago when rising magma met water-saturated ground and blew itself apart in a series of phreatomagmatic eruptions. Explosive vents of this kind are reasonable analogs for volcanic craters on the Moon, such as Hyginus, a 9 km crater south of Mare Vaporum thought to be volcanic rather than an impact. We ran active-source lines across both the rim and the crater floor and combined three seismic methods that are usually deployed separately: P-wave refraction, shallow reflection, and Rayleigh-wave dispersion. The rim resolves into five distinct seismic facies that line up with the units already geologically mapped at the surface, confirming that this type of multi-method seismic survey is effective even in the fragmented, poorly sorted volcanic material we expect to be dealing with on the Moon.<\/p>\n

The second paper attempts to offer an alternative to dense, regular sampling by deployed seismometers, which is prohibitively expensive on the Moon: compressive sensing.\u00a0 By deliberately randomizing the positions of seismometers and then reconstructing the densely sampled wavefield from what you collected, one can recover much of the resolution of dense, regular sampling. The reason this works is that a coarse regular grid produces coherent aliasing, which is indistinguishable from signal, whereas randomized sampling scatters that energy into incoherent noise, which can be suppressed. The paper demonstrates the capabilities of compressive sensing on synthetics, Apollo data, and on data from a transect in the San Francisco Volcanic Field in Arizona, which is the first field test of compressively sampled seismic acquisition at a planetary analog site and on planetary data. The reconstructed images hold up against those from full dense acquisition. The practical consequence is that boulders, slopes, and other obstacles that force a survey off its ideal geometry stop being a problem to be worked around.<\/p>\n

The third paper goes after a specific target relevant for future lunar exploration.\u00a0 Lava tubes are among the most appealing destinations on the Moon: an intact tube offers shielding from radiation, micrometeorites, and the brutal thermal swing of the lunar day, and the fresh basalt around it may hold usable volatiles. Finding one seismically is hard, because the ceiling and walls are rough, the cross-section is irregular, and reflected seismic waves are complicated by scattering and reverberation rather than clean reflections. This makes conventional processing, which treats scattered energy as noise to be removed, inadequate. Instead, this paper uses the scattered \/ reverberating energy as the signal, mapping where backscattered intensity is enhanced. At Lava River Cave in Arizona and Skull Cave in Lava Beds National Monument in California, the approach detects air-filled voids roughly 10 to 20 m across at depths of 5 to 15 m, and the spatial and frequency character of the returned energy scales with the size of the tube: about 18 m estimated at Skull Cave, against 18\u201320 m from prior LiDAR mapping. It also picked out a second zone of enhanced energy to the north, where no accessible cave exists but earlier magnetic surveys had suggested something might \u2014 a candidate for an inaccessible tube that continues past the end of the line. Because the method does not require a long line with fine source and receiver spacing, its footprint is much smaller than conventional imaging demands.<\/p>\n

Taken together, the three publications present a concrete answer to “how would you actually do seismic imaging on the Moon?”, based on analog datasets collected by the GEODES SSERVI and cutting edge signal processing techniques. We are rehearsing for the Moon, and learning along the way.<\/p>\n

You can read the papers here:<\/p>\n