Attracts dust to an astronaut's clothing

Moon water, tremors, dust - what Armstrong could not yet know

The first man walked on the moon 50 years ago. Since then, scientists have diligently researched the earth's satellite. An overview.

You can find more information about 50 years of the moon landing here

When Neil Armstrong set foot on the moon in 1969, much was still unknown about the earth's satellite. Over the past 50 years, researchers have made some groundbreaking and curious discoveries about the moon:

Ice stocks

The moon is wetter than expected. At the time of the "Apollo" program of the US space agency Nasa, the moon was considered bone dry. In 1994 the NASA "Clementine" probe provided evidence of water in shady craters. Ten years ago, the NASA lunar mission "LCROSS" detected water ice in an eternally dark crater at the south pole of the earth's satellite.

More finds across the moon followed. "Overall, there is probably a lot of water on the moon between Lake Constance and the Caspian Sea," explains Ralf Jaumann, head of the Berlin Institute for Planetary Research at the German Aerospace Center (DLR). "When you reanalyzed samples of the lunar rock from the" Apollo "program, you actually found water inclusions in them as well." Where the moon water comes from is not clear and one of the questions for future missions.

Water factory

A constant stream of particles moves from the sun into space. This so-called solar wind consists primarily of electrically charged hydrogen atomic nuclei and, due to the lack of a magnetic field, pelts unhindered on the moon.

When impacts from micrometeorites melt the rock there, oxygen is released and combines with the hydrogen from the solar wind to form water - the amounts that arise in this way, however, are tiny.

Earth-like

The "Apollo" missions brought a total of around 380 kilograms of lunar rock with them to earth. "Only about half of it has been analyzed," says Jaumann. "The first analyzes back then were surprising: They showed that the moon material is very similar to the earth's crust and mantle." Obviously, both celestial bodies have a common origin.

According to Jaumann, the moon samples are the most important scientific achievement of the "Apollo" missions. The type of rock also showed that the moon must have melted completely or largely at one point.

Neil Armstrong and Buzz Aldrin left these "souvenirs" when they first landed on the moon on Earth's satellite.

Accident product

The surprising resemblance of lunar and terrestrial rocks raised the question of how the moon was formed. Today most researchers assume that a catastrophic collision of a celestial body roughly the size of Mars knocked the moon out of the young earth.

"This impact theory can explain a lot, but not everything," says planetary researcher Urs Mall from the Max Planck Institute for Solar System Research in Göttingen.

Earth archive

Since there is no plate tectonics and no weathering on the moon as there is on earth, it is an archive of the history of the earth. "If you want to know something about the distant past of our planet, the moon is the place to go," stresses Mall. "There, the history of the earth is literally carved in stone."

For example, the impact craters on the moon show when the cosmic bombardment with meteorites in the inner solar system had decreased to such an extent that it allowed life to emerge.

raw materials

"In 1994 the US lunar probe" Clementine "delivered the first lunar map that gave an idea of ​​the mineralogy of the earth's satellite," reports Mall. The lunar soil contains some raw materials such as metals, but their use on earth is not economically feasible.

"But raw materials could be interesting for use on the moon itself," explains Jaumann. "If you want to get water from melting the lunar rock, you get substances like aluminum right away. And the lunar soil is something like cement. The building material for a lunar base should largely be available."

Only once could the noble gas helium-3 turn out to be an export hit: It is a sought-after fuel for future nuclear fusion power plants and is deposited in the lunar soil from the solar wind.

Further away

The moon drifts 3.8 centimeters away from the earth every year. The cause is the tides. Moving the sea water back and forth for ebb and flow requires energy, and this is fed from the rotational energy of the earth-moon system.

The "Apollo" missions left mirrors on the earth's satellite, which can be used to determine the exact distance to the moon based on the travel time of a laser beam. Precision measurements show that the moon is almost two meters further away today than it was when Armstrong landed.

Moondust

The moondust, called regolith, is unhealthy. The "Apollo" astronauts reported mild respiratory symptoms such as sneezing, sore throat and watery eyes after visiting the satellite. Harrison Schmitt, who was the twelfth person to walk on the moon, spoke of "lunar hay fever". The cause were the tiny particles of moondust that, because of their electrostatic charge, got stuck on the astronauts' suits and equipment and were brought into the space shuttles.

Due to the lack of an atmosphere and thus also of wind and weather on the moon, these regolith particles are not round like on earth, but extremely sharp-edged. In laboratory tests with cell cultures on Earth, simulated regolith particles killed cells and caused genetic damage - similar to asbestos.

Shrinking cure

The Earth's satellite has recently shrunk by around 100 meters in geological terms. This shows the existence of cliffs and breaklines across the earth's satellites, which were photographed by NASA's "Lunar Reconnaissance Orbiter", among others.

The cause is the cooling of our companion, who contracts and wrinkles like a drying grape. Since the lunar crust is not as elastic as the skin of a grape, it occasionally breaks. The moon, which was considered a geologically dead celestial body in "Apollo" times, is probably still active today.

Footprints

Armstrong & Co's footprints can still be found today on Earth's satellite. However, they are not forever. Micrometeorites plow the lunar soil much faster than expected. This is shown by measurements from NASA's "Lunar Reconnaissance Orbiter" ("LNO"), which has registered more than 47,000 new spots on the lunar surface in seven years.

"Before the start of the 'LNO' in 2009, we thought it would take hundreds to thousands of millions of years to significantly change the lunar surface," said investigator Emerson Speyerer of Arizona State University in a statement accompanying the publication of the scientific analysis. "However, we have discovered that the top layer of the surface material is completely turned over once every 80,000 years." © dpa