Flying to the moon: how to choose a landing spot

© Illustration RIA Novosti . Alina Polarisability module Luna-25 will sit in near the South pole of the moonFlying to the moon: how to choose a landing spot© Illustration RIA Novosti . Alina Polyanina

Scientists chose two promising landing sites for the planned in 2019-2020 mission of the spacecraft «Luna-25». In addition to purely engineering constraints influenced the choice of requirements for the academic program.

The scheme of landing on the moon worked in the Soviet space program of the 1970-ies. Take advantage of it and for the new mission, which will explore the surroundings of the South pole, located on the Earth facing side of our satellite. The spacecraft «Luna-25» will go into low orbit with a height of about a hundred kilometers from the surface, slow down and two days will move to pole until you reach the landing, which is a elongated along the Meridian ellipse with dimensions of 30 by 15 kilometers. The lander will descend vertically with the engine running.

«In selecting the landing site, you must consider the engineering requirements, and the first among them is security is dependent on the terrain. Absolutely unacceptable sits on slopes greater than 15 degrees, experts recommend to avoid inclines of 7 degrees,» — said at a meeting of the space Council of RAS, doctor of physico-mathematical Sciences Igor Mitrofanov, head of the Department of nuclear safety and planetology space research Institute of RAS.

There are other conditions: the reliability of radio communications lander with the Earth, the duration of daylight (this is important for the scientific programme), plenty of signs of water geological diversity.

«Most of the water on the South pole, but distant from it areas interesting. The main thing that the water there was, after all, to know its structure, just a few drops,» — said Mitrofanov.

Scientists made maps of the analyzed criteria and the method of their imposition has identified the most promising areas. The first thing that showed up — crater Boguslavskiy, who had previously considered for planting, did not meet all the requirements. In the rating, which summed scores for each of the factors, he was an outsider.

«This is probably the worst candidate since received the lowest priority from the point of view of choice of landing area,» the scientist said.
© I. G. Mitrofanov / ICA rerating the landing ellipses for a set of requirements for missions Luna-25Flying to the moon: how to choose a landing spot© I. G. Mitrofanov / ICA rerating the landing ellipses for a set of requirements for missions Luna-25

The priority is now considered district-ellipse to the North of the crater Boguslavsky, the optimal set of criteria, including ballistics. In addition, there contains 0.1% of water in the soil layer with a thickness of about meter. If the module for some reason will not be able to prionitis, it will stay in orbit for another two days and will sit on standby «at the airport» — South-West from the crater Mancini.

NASA’s Lunar Reconnaissance Orbiter has imaged both the landing site with a resolution of four meters, and scientists had the opportunity to get to explore all. In particular, to assess the risks of tipping or sliding of the apparatus from the slope. This is exactly what happened with the «Lunokhod-2» in 1973. He slid into the five-meter crater, stalled, gained in the cover soil. When you close the lid primer spilled on the radiator, the instrument is overheated and the machine is out of order.

© I. G. Mitrofanov / ICA Repository ellipses on the map of the area around the South pole, where will you go «Luna-25»Flying to the moon: how to choose a landing spot© I. G. Mitrofanov / ICA Repository ellipses on the map of the area around the South pole, where will you go «Luna-25»
«The probability that we will get to the point with a slope greater than 15 degrees is 4%. It’s a risk we have to go. Other areas are even worse», — concluded Mitrofanov.

The developers of the «Luna-25», NPO Lavochkin agree with the choice of landing sites, and now scientists from IKI RAS will send them the coordinates of Roscosmos.

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