Look inside the Red Planet

Mission InSight will study the Martian crust, mantle and core

Mars has been studied with automatic probes for over 40 years. During this time, scientists began to better understand the processes occurring in the Martian atmosphere and formed the surface of the planet that we are now observing. However, we know as yet what is going on in its depths. How did Mars generate its magnetic field and when it lost it, what is the thickness of the crust and the extent of the mantle, in what state is the aggregate state and is there an inner core, is the Red Planet volcanically active today? These and other questions should be answered by a new Martian automatic “geologist” – the mission InSight, which is scheduled to start on Saturday. Revision N + 1decided to understand what kind of scientific results the scientists expected from the apparatus and talked about this with Igor Mitrofanov, the head of the nuclear planetary department of the IKI RAS, whose instruments work on the rover “Kyuriositi” and the orbiter Mars Odyssey.

Today, astronautics is experiencing a real “Martian boom”: only in the next three years must start immediately six missions to the Red Planet. In many respects this is due to the fact that the neighbor of the Earth really looks attractive – she is not as close to the Sun as Mercury, and not shrouded in sulfur clouds, unlike Venus. Scientists have repeatedly discussed the possibility of colonization of Mars, but before entering the second era of the Great Discoveries and sending settlers to lifeless lands, it is necessary to collect a large amount of scientific data and work out a variety of technologies.

The “Martian boom” also has a less romantic foundation. Starting dates for missions are not chosen by chance: space agencies are trying to cut costs and therefore designate a launch day at a time when the distance between the planets is minimal. In July 2018, there will be a great confrontation between Mars – the Earth and Mars will line up in line with the Sun, and the distance between their orbits will be the smallest. On average, such an event happens every 15-17 years, and NASA decided to use the moment to launch the InSight mission.

The name of the mission stands for “Interior Exploration using Seismic Investigations, Geodesy and Heat Transport” – “Study of the structure of Mars based on seismography, geodesy and thermo-prospecting data.” Its main task is to study the internal structure of Mars, with its help, researchers want to understand how the rocky planets, including our Earth, were formed and evolved, as well as determine the current tectonic activity of Mars and the frequency of falling meteorites on it. The device will determine the extent, density and overall structure of the core, mantle and cortex of the Red Planet, as well as the rate at which heat is transferred from its interior to the surface.

“It’s up to the questions of the internal structure right now, and the main question that everyone is interested in is how far the inner regions of Mars have remained active. Are there any seismic phenomena there, and if so, what exactly is happening, what effects can be observed there, “says Igor Mitrofanov.

“We assume that, most likely, the core of Mars has not yet frozen, it certainly has a complex structure, but the interesting question is, how does this cooling occur – is there convective processes or not? How is the flow of energy from the inner parts of Mars to its surface organized? In addition to seismic activity, it is very interesting to learn about the existence of processes that are associated with volcanism. On modern Mars there are no known active volcanoes, but we know that in ancient times volcanoes were active, for example Mount Olympus, which is a giant volcano, “continues Mitrofanov. “There are hot spots inside the Earth, and I wonder if there are such active geothermal regions on Mars beneath the surface of Mars. This can be related to the problem of methane. It is known that in the Martian atmosphere there is methane, it is not clear its origin and behavior – sometimes methane is registered, and sometimes it disappears. The question arises as to what this is related to – internal geothermal activity or where there are some seasonal changes or local areas where there are sources of methane. All this is connected with the internal structure of Mars “.

The place where the device will sit on the surface of the planet with a probability of 99 percent is an ellipse measuring 130 by 27 kilometers and is located on  the Elysium plain , which is convenient enough and smooth for safe landing and is close to the equator, so that the solar cells of the apparatus can feed it for two years (or 708 sols ). The device itself consists of a landing platform carrying scientific instruments, and a flight module that is designed to deliver a platform from near-earth orbit to Mars, to overcome its atmosphere and to provide the possibility of a soft landing on the surface of the planet. The design of InSight in general is similar to the design of the mission Phoenix, which explored the northern polar region of the Red Planet in 2007. For example, they have the same design of two solar panels and a landing platform, which reduced the cost of the mission and possible risks.”NASA is very well planning its missions, and this project, in fact, repeats in the technological plan the Phoenix project, a successful Martian mission with completely different tasks. But at the same time a very good device was developed, it showed its reliability, its efficiency. And now on the basis of this device, using already known technological solutions, a completely different machine was made for other scientific problems. This is a very correct approach, when people make maximum use of technological developments from previous missions, “Mitrofanov said.

The scientific mission load consists of several instruments and two cameras – color and black and white, which are similar to cameras installed on rovers currently operating on Mars. One of the cameras is located on the robotic arm of the landing platform, the other is on its lower part. In addition, the device is equipped with a weather sensor TWINS (Temperature and Winds for InSight), which determines the wind speed and ambient temperature, a magnetometer, a barometer, and a LaRRI corner reflector (Laser RetroReflector for InSight), which will act as a laser rangefinder for orbiting devices . In addition, the mission will have three main scientific instruments.The RISE (The Rotation and Interior Structure Experiment) device will study the size and density of the Martian core by estimating the rate of precessionand nutation of its rotation axis, which are related to the Doppler shift in the frequency of radio signals transmitted from ground stations to the landing module and back. They will calculate the total polar moment of inertia  and the pattern of mass distribution inside the planet, in particular, it will be possible to determine how liquid the core is in Mars. In addition, the device will give more accurate estimates of changes in the planet’s rotation speed, which are caused by a seasonal redistribution of carbon dioxide reserves between the atmosphere and the polar caps.

The seismometer SEIS (Seismic Experiment for Interior Structure) is designed to accurately measure the tectonic activity of Mars, as well as the frequency of meteorite incidence on the surface of the planet. Comparison of seismometer data with data on weather, wind and magnetic field perturbations will help to reveal surface oscillations created by dust storms or turbulent processes in the atmosphere. On the surface of Mars, a dome-shaped instrument, whose total mass is almost 30 kilograms, will be lowered by the 2.4-meter robotic arm IDA (Instrument Deployment Arm). It is because of the depressurization of the sensors of the seismometer that the InSight flight, originally planned for 2016, had to be postponed for more than two years.

The HP 3 (Heat Flow and Physical Properties Package) is designed to measure heat fluxes in Martian soil. It is a thermo-tape with temperature sensors made of platinum, heaters and tilt sensors attached to it to determine the position of the instrument. The tape will be introduced into the earth through an electromechanical drill capable of submerging in the soil to a depth of up to five meters, which will be lowered to the surface of Mars with a robotic arm. For comparison – the record depth, to which the rover “Churiosity“, is 7.5 centimeters. However, for a full analysis of the soil, the tool is not intended, although it will be able to obtain some information on the mineral composition based on data on the thermal conductivity of various soil sections.

In addition to the main scientific program, an additional one, called Mars Cube One or MarCO, is planned, within which two identical satellite- coussatformat 6U. They will separate from the main vehicle after its launch into outer space and will travel to the Red Planet along other trajectories, and they will not leave the orbit of Mars, but will fly by. The purpose of this program is to test the survival of devices of this type in deep space and demonstrate the possibility of constructing a communication system based on them. The main task of the two coussats will be the transfer of data from the main vehicle to Earth during the descent and landing phase on the surface of Mars. Also two small but important envoys to the Red Planet will be two 8-millimeter silicon chips, which contain about 2.4 million names of people who have left their applications on the NASA website in 2015 and 2017. Both chips will remain forever on the surface of the planet together with the landing platform on which they are installed.

The beginning of the mission’s journey to the Red Planet is scheduled for Saturday, a two-hour launch window opens at 14:05 Moscow time. The launch will be carried out from the cosmodrome at the air base Vandenberg in the state of California, the mission will be the launch of the Atlas V-401 booster . If the launch is canceled for some reason, the starting period in which you can commit it will last until June 8, 2018.The flight to the Martian orbit will take six months, during which the device will check its systems, calibrate the instruments and prepare for the forthcoming landing. Then the most critical part of the mission will start, which will take only six minutes. The device will enter the Martian atmosphere in a calculated place at a speed of 6.3 kilometers per second and will start the controlled descent. From overheating it will protect thermal shields, which were made thicker than the mission of Phoenix – engineers took into account the effects of dust flows. Then the parachute will be opened, which has also been made more durable, thermal shields have been dropped and three landing supports have been opened. When the platform is sufficiently close to the surface, the parachute will be dropped and the final braking and landing will be done using twelve motor units,

The first scientific data from the mission are not expected immediately – in the case of a successful landing, a two-month stage of the deployment of scientific equipment will begin. It is possible, at first we will see photos from the cameras – it is assumed that this will happen in early December this year. It remains to be hoped that all the forthcoming stages of the mission on the way to Mars will end successfully and we will be able to learn more about the secrets hidden in the thickness of the Red Planet.

“The mission is certainly important, and it will help us to understand the nature of Mars and the nature of its evolution. As for science, it is certainly very interesting to obtain data on the internal structure of Mars. I think that the results of measuring seismic effects will be very important in order to understand what happened to Mars, what processes are still taking place, and where it can be considered that it has already “gone out,” says Igor Mitrofanov.

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