The Thermal Control Coatings Protecting InSight’s Marsquake Detector
Robotic Geologist Headed to Mars
NASA successfully launched the InSight lander this month, sending InSight on a half-year journey to reach Mars. It is the first mission to the surface of Mars since Curiosity arrived in 2012 and the first interplanetary launch from the California coast.
Short for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, InSight launched at 4:05 a.m. PDT on Saturday, May 5th from Vandenberg Air Force Base. InSight’s mission is to probe the surface of Mars to study its early geological evolution.
InSight is expected to reach Mars on Nov. 26 and will land in a flat area called Elysium Planitia, just north of the equator. The lander will deploy a set of instrumentation to collect data on ‘marsquakes,’ heat flow from the planet’s interior, and the overall structure of Mars’ core, mantle, and crust.
Thermal Control for the SEIS Seismometer
InSight’s primary instrument, a seismometer called Seismic Experiment for Interior Structure (SEIS), will be responsible for studying the marsquakes. The seismometer sits on the Martian surface and waits to sense seismic waves caused by marsquakes and meteorite impacts. Its measurements provide a glimpse into the planet’s internal activity and will tell scientists about the nature of the material that first formed the rocky planets of the Solar System.
“InSight will not only teach us about Mars, it will enhance our understanding of formation of other rocky worlds like Earth and the Moon, and thousands of planets around other stars,” said Thomas Zurbuchen, Associate Administrator for NASA’s Science Mission Directorate at the agency headquarters in Washington. “InSight connects science and technology with a diverse team of JPL-led international and commercial partners.”
Seismometers are very sensitive to variations in temperature so on Earth they are typically placed in environments where the temperature is stable, such as caves or mine shafts. On Mars the SEIS seismometer will be subjected to wide daily and seasonal temperature variations. At the Elysium Planitia landing site, the fluctuation in temperature from day to night will be 70°C on average.
JPL, a division of Caltech in Pasadena, CA, manages the InSight project and sub-contracted Surface Optics Corporation (SOC) to apply a thermal control coating to SEIS to help protect the instrument from temperature changes on Mars. The SOC Coatings Lab deposited a pure gold thermal control coating to the seismometer hardware.
“We used a physical vapor deposition process to coat gold onto the surface of the SEIS components in our 3 meter chamber,” said Maria Zimmerman, Project Manager at SOC. “The SOC 3m chamber allows us to use a line of sight evaporation deposition process to create a multilayer uniform coating across the three dimensional structure.”
The 3 meter vacuum chamber at Surface Optics Corporation can coat metals and dielectrics up to 2.5 meters in diameter using a single axis of rotation, or up to 24″ using a two axes of rotation with +/- 10% thickness variation or better.
Surface Optics Corporation has a long history of contributing to NASA missions, most notably having supplied coatings to space flight hardware aboard Kepler, NuStar, and Chandra.