To the surprise of scientists, the Aug. 25 quakes were two different types, as well. The magnitude 4.2 quake was dominated by slow, low-frequency vibrations, while fast, high-frequency vibrations characterized the magnitude 4.1 quake. The magnitude 4.1 quake was also much closer to the lander – only about 575 miles (925 kilometers) away.
That’s good news for seismologists: Recording different quakes from a range of distances and with different kinds of seismic waves provides more information about a planet’s inner structure. This summer, the mission’s scientists used previous marsquake data to detail the depth and thickness of the planet’s crust and mantle, plus the size of its molten core.
Despite their differences, the two August quakes do have something in common other than being big: Both occurred during the day, the windiest – and, to a seismometer, noisiest – time on Mars. InSight’s seismometer usually finds marsquakes at night, when the planet cools off and winds are low. But the signals from these quakes were large enough to rise above any noise caused by wind.
Looking ahead, the mission’s team is considering whether to perform more dust cleanings after Mars solar conjunction, when Earth and Mars are on opposite sides of the Sun. Because the Sun’s radiation can affect radio signals, interfering with communications, the team will stop issuing commands to the lander on Sept. 29, though the seismometer will continue to listen for quakes throughout conjunction.
More About the Mission
JPL manages InSight for NASA’s Science Mission Directorate. InSight is part of NASA’s Discovery Program, managed by the agency’s Marshall Space Flight Center in Huntsville, Alabama. Lockheed Martin Space in Denver built the InSight spacecraft, including its cruise stage and lander, and supports spacecraft operations for the mission.
A number of European partners, including France’s Centre National d‘Études Spatiales (CNES) and the German Aerospace Center (DLR), are supporting the InSight mission. CNES provided the Seismic Experiment for Interior Structure (SEIS) instrument to NASA, with the principal investigator at IPGP (Institut de Physique du Globe de Paris). Significant contributions for SEIS came from IPGP; the Max Planck Institute for Solar System Research (MPS) in Germany; the Swiss Federal Institute of Technology (ETH Zurich) in Switzerland; Imperial College London and Oxford University in the United Kingdom; and JPL. DLR provided the Heat Flow and Physical Properties Package (HP3) instrument, with significant contributions from the Space Research Center (CBK) of the Polish Academy of Sciences and Astronika in Poland. Spain’s Centro de Astrobiología (CAB) supplied the temperature and wind sensors.