InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a NASA Discovery Program mission that will place a single geophysical lander on Mars to study its deep interior. InSight’s primary objective will be to uncover how a rocky body in space forms and evolves to become a planet.
Generally, a rocky body begins its formation through a process called accretion; dust particles and small meteorites gradually stick together to form larger and larger bodies, eventually reaching planetary size. As the body increases in size, its interior heats up and melts forming a molten sphere. As dust subsequently cools and recrystallizes it evolves into what we know today as a terrestrial planet, containing a core, mantle and crust.
While all of the terrestrial planets share similar structures, and their bulk compositions are roughly the same as the meteoritic material from which they were formed, they are by no means uniform. Each of the terrestrial planets reached their current formation and structure through a process known as differentiation, whereby different elements and minerals crystallize and settle out of the molten ‘blob’ at different rates.
InSight’s goal will be to solve the mystery of differentiation in planetary formation — and to bridge the gap of understanding that lies between accretion and the final formation of a terrestrial planet’s core, mantle, and crust; the structure of Mars.
The mission’s secondary objective is to conduct an in-depth study of ‘marsquake’ activity and meteorite impacts on Mars, both of which could provide valuable knowledge about such processes on Earth.
InSight will conduct six investigations at the Martian surface.
The MarsQuake education project will focus on the seismology experiment on InSight and provide resources and tools, including classroom activities, to help users understand and interpret the results of this seismic experiment.
The InSight lander will be a conventional parachute-based static lander based on the tried and tested NASA Phoenix lander technology. The lander will be solar powered with a scientific payload designed by European partners in France (the main long period seismometer), the UK (a simpler and more robust short period seismic sensor), Germany (a temperature heat probe that can burrow up to 5 m underground and measure heat flux from the planet) and Switzerland (providing the on-board electronics and high resolution positional information).
The lander has a robotic arm that will be used to deploy the heat probe sensor (HP3) and to place the seismometer package (SEIS) directly onto the surface. Placing the seismic sensor directly in contact with the ground and adding a windshield cover will greatly reduce the background noise detected and increase the sensitivity of the system to marsquakes.
The SEIS long period sensor (designed at IPGP in Paris) has a sensitivity and frequency response comparable to the best research seismometers on Earth. The instrument houses three separate detectors in a vacuum enclosure to allow ground motion in three directions to be recorded (up–down, north–south and east–west). An early version of this sensor flew (briefly) on the failed Russian Mars (1996) mission.
Scientists are not yet certain if the core of Mars is solid, liquid, or in two distinct sublayers, like Earth’s. Future measurements will tell us more. Mars shows no evidence of tectonic plates.
The SEIS package also includes a MEMS (micro-electro-mechanical system) accelerometer (designed and built at Imperial College, London) that can record high frequency seismic signals using the same principles as the sensor in your smartphone that tells it which way is up. This sensor is not as sensitive at the lowest frequencies, but is a very robust and lightweight design.
Contact Paul Denton, MarsQuake project leader, for further information.