NASA's InSight mission has successfully detected its first Marsquake.

Since NASA's InSight mission deployed its dome-shaped seismometer on the Martian surface in December, there was much anticipation that it would soon detect the first Martian quake, or 'marsquake.' The wait ended when the Seismic Experiment for Interior Structure (SEIS) picked up the first subtle tremor from within the planet on April 6 (the 128th Martian day of the mission), proving that Mars is seismically active.

"We've been eagerly waiting for months for a signal like this," said Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France, in a NASA statement. "It’s thrilling to finally have confirmation that Mars remains seismically active. We’re excited to analyze the data and share the results soon."

NASA aims to use seismic signals like these to perform a kind of health check on Mars. Just as a doctor listens to a patient's heartbeat with a stethoscope, InSight is attempting to 'hear' the planet's inner workings. On Earth, seismic waves become distorted as they travel through areas with varying densities. By measuring these waves, we've gained insight into the unreachable layers beneath our feet.

Mars' interior remains a mystery; the planet lacks a global magnetic field for reasons still unclear, and its volcanic activity ceased hundreds of millions of years ago. If Mars is geologically 'dead' (or, more accurately, 'areologically' inactive), how can it still generate marsquakes? It’s believed that as Mars cools, it contracts, causing small quakes that reverberate through the planet. Scientists also hope to detect meteorite impacts, which could create their own seismic events, potentially turning InSight into a real-time meteorite detector.

Until recently, marsquakes were just a theoretical concept, but now that we know they exist, InSight can use them to probe the planet’s subsurface.

Mission scientists note that this first marsquake is very minor, far from the powerful tremors we experience in Southern California. On Mars, however, this faint quake stands out amidst the planet's otherwise silent interior. Other weak seismic signals have been recorded (on March 14, April 10, and April 11), though their sources remain unclear.

Though the April 6 event was too faint to provide detailed information about Mars' interior, scientists are still excited because it’s reminiscent of similar events observed on the Moon.

"The Martian Sol 128 event is intriguing because its magnitude and extended duration resemble the characteristics of moonquakes observed on the Moon during the Apollo missions," stated Lori Glaze, Director of the Planetary Science Division at NASA Headquarters.

During the Apollo missions, astronauts deployed five seismometers on the lunar surface, which recorded thousands of "moonquakes" from 1969 to 1977. These seismic waves provided valuable insights into the Moon's internal structure and even contributed to models of its formation. Although InSight has just one seismometer on Mars, scientists are hopeful that it will offer a glimpse into the Martian interior, an area we still know very little about.

"InSight's initial readings continue the research initiated by NASA's Apollo missions," said InSight Principal Investigator Bruce Banerdt of NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, in a press release. "Up until now, we've been gathering background noise, but this first event marks the official beginning of a new field: Martian seismology!"