It is notoriously difficult to land on Mars, but NASA has managed just that with its recent InSight landing gear. Since childhood, I loved watching landing and other spacecraft maneuvers on TV – always feeling a bit of the edge of the excitement of the seat. But he did not make me feel like watching the mission I was working on. Each period of silence during the seven-minute InSight descent felt like eternity, with time re-emerging only at calls from system engineer Christine Szalai. I will never forget the joy of the moment she finally announced she had "confirmed the touchdown".
InSight has been planning for more than a decade. Among planetary missions, this is a bit strange. While most missions are designed to look at the surface or atmosphere of planetary bodies, InSight's goal is to look deep under the surface – which helps us dispel the secrets of how it and the other rock formations formed.
Lander has a range of instruments, including seismometers, heat flow probes, magnetometers, and radio transmitters. The Heat Flow and Physical Properties (HP3) probe will knock five meters below Mars' surface, almost twice as long as the manual exercise of the monthly missions. His measurements will tell us how fast heat is lost from the inside of the planet – which helps us understand how Mars is cooling over time.
The Rotation and Internal Structure (RISE) experiment essentially repels the radio signal sent from Earth back to us. The difference in frequency between the original and the returned signal can then be used to quantify the speed of the InSight landing system with respect to the Earth, somewhat like the pitch of the siren, which tells us whether it is moving towards us or from us. We are particularly interested in the speed that tells us how the axis of rotation of Mars is stretching over time. The size of these waves is dependent on the structure of the interior and especially on its dense metal core. Just as raw eggs are pulled more than hard-boiled when rotating on a flat surface, Mars will pull more if its core is liquid.
I am working on a Seismic Experimental Internal Structure (SEIS), which consists of two seismometers located on a leveling system that will sit about 15 cm above the surface of Mars. This experiment is designed to tell us the amount of seismic activity on Mars. We will also use the time needed for the sesame waves to reach seismometers to tell us about the temperature and composition of the interior, rather like a physician using the CT scanner.
In the coming months
Now we have about three months during which the tools will be deployed and activated. In the coming days, the health of the systems and the landing space will be checked and the surrounding areas will be thoroughly displayed so the operating team can decide where to place the InSight probe and seismometers. The first shot taken from the surface indicates that we landed on a shallow, sand-filled crater with almost no rocks, so it seems there will be more options.
Around mid-December, the robotic arm will lift the seismometers mounted on the tripod from the deck of the landing gear and lower them to the surface. After a thorough inspection, a balancing system is used to ensure that seismometers are perfectly horizontal. By mid January, the shield should be placed above the top edge of the seismometers to protect them from the elements. They can then be turned on and the heat flow probe will be deployed.
The heat probe will begin to return the data as soon as it starts to knock under the surface, so we expect the results in the first half of 2019. The radio experiment will take a little longer. It just happens that next year we will not be in the best position to see the ripples of Mars. This will change in the mid-2020 when we should be ideally placed to uncover the secrets of our core.
As for the SEIS experiment, when we see something exciting, it will depend on how often seismic energy is generated. We do not know it at the moment. What we know is that there are two potential sources of seismic activity: the impacts of meteorites and "marsquakes" created by motion along errors directly at the surface.
While we know that meteors often hit Mars, the rate of error is a mystery. Unlike the Earth, Mars has no moving tectonic plate, so it is estimated that the disorder will happen as the inner planet cools. However, some of the youngest mistakes on Mars appeared to have been formed not by cooling but by moving the molten rock under the surface. Discovering the frequency and nature of clouds will help us to solve the exact causes.
Through its three major experiments, InSight will provide a "snapshot" of today's status and composition of Mars. But this is not the place where scientific discoveries will end. Eventually the mission will help understand the processes that occurred over 4.5 billion years ago when the solar system was very young.
Here's the reason. The composition of the planet is set when it was created, which in the case of Mars was only a few million years after the sun was lit. We think that due to its greater distance from the Sun, Mars was formed from another, much more volatile material than the Earth. However, until Mars is known, this idea is very difficult to test and develop. Data returned by InSight will provide the key to understanding how rock formations have formed in our solar system – and perhaps even those around other stars.
The composition, temperature and magnetic field of our planet are also important for sustaining life on our planet. So even though InSight is not looking for life, it will give us new footprints about how the Earth was clearly ready for life more than 4 billion years ago.
InSight has already achieved enormous engineering success, and the science team is now gaining an incredible opportunity to use it to uncover the secrets of Mars. We hope you are as excited as we are.