The only terrestrial planet in the Solar System on which no machine has landed, Mercury is today the subject of great interest. On the one hand because ESA’s BepiColombo probe flies to join it and also because the Planetary Science Decadal Survey (ten-year planetary science report) is being prepared for the decade 2023-2032. A team of scientists from JHUAPL are working on a daring lander concept and pushing for a Mercury landing to be a priority.
We forgot it, but the sonde BepiColombo which flies to Mercure was originally supposed to embark a lander which would have landed on Mercury. But for lack of a sufficient budget, the project was abandoned. However, the difficulty of financing does not explain everything. Land on an object devoid ofatmosphere is very difficult because the machine cannot count on an atmospheric layer to slow down its reentry and must embark a large mass d’ergols. To this strong constraint, another is added. Mercure is the closest planet to Soleil, which complicates the production of a probe and the operations on the surface.
Since the abandonment of this idea, ten years have passed and today the technology necessary to land on Mercury and function long enough for a successful scientific return has matured. It makes a landing possible although the task will not be simple, in particular because the selection of a landing site promises to be complicated.
In a year from now, the US National Research Council will unveil its new Planetary Science Decadal Survey, a ten-year report that explores key questions in planetary science to help the Nasa define its exploration priorities for the next decade (2023-2032). It is written by the National Research Council of the United States. This report will direct billions of dollars in funding over the next decade to destinations identified as of major scientific interest.
A landing on Mercury could be one of those priorities. At least this is the opinion of a team from the Laboratory of physique applied by Johns-Hopkins University (JHUAPL) which regularly offers its concept of the Mercury landing mission. Under the leadership of Dr. Carolyn Ernst, this team is convinced that the time has come to land on Mercury.
« Mercury is the only rocky planet on which we have not landed and for which we have never seen the surface up close. We need in situ measurements to better understand it and put our own Earth in context », Explains Carolyn Ernst at the initiative of this proposal. Corn, compare Mercury to Earth is not the only reason to go. Dr. Nancy Chabot, who co-directs the study of the concept of mission, underlines that “ data collected so far on Mercury is both limited and difficult to interpret ”, Which suggests that Mercury may be a much more different planet than we think.
A one-day mission of 88 earth days
Wanting to land on Mercury is one thing. To do so is another. You should know that Mercury is not completely mapped and that the most precise images that we have are those acquired by the Messenger probe of NASA between 2011 and 2015. However, with a resolution three or even two meters per pixel these images are not very precise, so the smallest visible structures and details are still six to nine meters. This explains the difficulty in finding a landing site clear enough to land safely. However, while Carolyn Ernst’s team relies heavily on the European probe BepiColombo who should acquire images of Mercury with better definition, she is aware that her Mercury Lander must be equipped with a precision landing system in autonomy complete. That is to say, he will have to identify his landing site himself. To do this, it will use navigation technologies, as well as the detection and avoidance of dangerous situations to provide the probe, during the last minutes of its descent, with the information necessary for its safe landing.
While the lander won’t land anywhere, it won’t land anytime either. Due to its proximity to the Sun, its surface temperatures range from 400 ° C, during the day when the sun shines, to -150 ° C, at night. Since building a lander capable of operating during the day was a waste of time, Carolyn Ernst’s team opted for a night mission. When we know that on Mercury the days last 88 days, that leaves time for science. Mercury Orbiter will therefore arise at dusk of a day and will operate until thedawn. To operate at night, the lander will be equipped with a generator radioisotope thermoelectric and several headlights to illuminate its surroundings.
Among the main scientific objectives, let us quote the first five identified by the team of Mercury Orbiter :
- land in good condition and collect data, necessarily unpublished, on the surface of Mercury;
- learn more about mineralogy and chemistry at work on Mercury;
- study the magnetic field of the planet and its internal structure;
- understand which processes affect the regrets and the exosphere of Mercury;
- get an idea of the size of the surface devices in order to get accurate measurements from theorbit.
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