Leftover hardware from the Mars mission for use on the Moon

On May 5, 2022, the seismometer aboard the InSight lander recorded a magnitude 4.7 earthquake on the Martian surface, even though the epicenter was 2,250 km from the lander. It was one of the largest earthquakes recorded on Mars and the largest recorded by the Insight mission. In September, in the first measurement of its kind, the instrument recorded an earthquake generated by the impact of a meteorite on Mars.

InSight’s seismometer is called the Internal Structure Seismic Experiment (or SEIS), and it has recorded these and 20 odd additional earthquakes. Now, an instrument based on the same design will measure ground vibrations on the far side of the Moon, the first seismographs of our neighbor since the Apollo era.

Up to SIX

Developed by the Institut de Physique du Globe de Paris (IPGP) and the French space agency CNES, the SEIS Very Broad Band (VBB) seismometer now on Mars can detect the smallest movements, with a tuning of 10 picometers , which is much smaller. than an atom Consisting of three pendulums placed 120 degrees apart, SEIS measures the vertical and horizontal vibrations of the Martian surface.

During the development of InSight, a spare model of SIX was built. Now, the VBB from this spare will be part of the Farside Seismic Suite that will be deployed to the Moon in 2025 as part of NASA’s Commercial Lunar Payload Services. program It is one of two seismometers that will operate on the far side of the Moon in an impact crater called the Schrödinger basin. The other seismometer will be a short period sensor.

According to Gabriel Pont, Farside Seismic Suite CNES project director, the instrument on the Moon will only have a broadband pendulum that will measure the vertical vibrations of the ground. The short period sensor will handle measurements in the other directions.

The new environment required minimal changes. “We used a spare model of the SEIS instrument. The Farside Seismic Suite The seismometer will be adjusted for lunar gravity. It will be placed in a vacuum protective case called a sismobox,” Pont said.

Philippe Lognonné of the IPGP and Université Paris Cité, who is the principal investigator of SEIS on Mars and the co-principal investigator of the broadband sensor on the Farside Seismic Suite, said the single vertical axis sensor would be used with little modification. “Depending on the frequency, this seismometer will be comparable or up to 10 times better than the Apollo seismometers,” commented Lognonné.

many firsts

The Farside Seismic Suite will mark the first time a seismometer has been placed on the lunar surface since the Apollo missions. It will also be the first time a seismometer will operate on the far side of the Moon.

“The originality of Farside Seismic Suite is that it will be independent of the landing gear. This is because it has to survive several lunar days and nights, which is not the case with the lander. The Farside Seismic Suite it will have its own solar panels, antennas to talk to the orbiters and its own thermal control devices,” Pont said.

According to Pont, one of the key objectives of Farside Seismic Suite is to determine the seismic activity and impact rate of micrometeorites in the region where they land. “This may also be useful for future exploration missions, either manned or deploying a telescope to the far side of the Moon,” Pont said.

“Over a long period, the VBB will be able to detect the interaction of seismic waves with a possible deep molten zone of the Moon. This is crucial for understanding how the Moon has evolved since its formation,” Lognonné added.

SEIS’ success on Mars and its selection for the next lunar mission comes after years of research and development. Lognonné recalls that the first proposal for the IPGP broadband seismometer was accepted in 1993. “Since the mid-1990s, we started its development and worked continuously to prepare it for flight. We spent 15 years before it was selected in early 2010 for the InSight mission,” said Lognonné, who has been working on the project since its inception.

Dhananjay Khadilkar is a journalist based in Paris.