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Lunar pits harbor comfortable temperatures

NASA-funded scientists have discovered shadowy locations in pits on the Moon that still hover around a comfortable 63 F (about 17 C) using data from NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft and computer modeling.

The pits and caves they could lead to would be thermally stable sites for lunar exploration compared to areas on the Moon’s surface, which heat up to around 127°C during the day and cool down to around minus 173°C. the night. Lunar exploration is part of NASA’s goal to explore and understand the unknown in space, to inspire and benefit humanity.

NASA’s Lunar Reconnaissance Orbiter camera has now photographed the Marius Hills pit three times, each time in very different lighting. The central panel, with the Sun above, gives scientists an unobstructed view of the floor of the Marius Hills pit. The Marius pit is about 34 meters (about 111 feet) deep and 65 by 90 meters (about 213 by 295 feet) wide.
Credits: NASA/GSFC/Arizona State University

Pits were first discovered on the moon in 2009, and since then scientists have wondered if they lead to caves that could be explored or used as shelters. The pits or caves would also offer some protection against cosmic rays, solar radiation and micrometeorites.

“About 16 of the more than 200 pits are likely collapsed lava tubes,” says Tyler Horvath, a doctoral student in planetary sciences at the University of California, Los Angeles, who led the new research, recently published in the journal Geophysical Research Letters. .

“Lunar pits are a fascinating feature of the lunar surface,” says LRO project scientist Noah Petro, of NASA’s Goddard Space Flight Center. “Knowing that they create a stable thermal environment helps us paint a picture of these unique lunar features and the prospect of exploring them one day.”

Lava tubes, also found on Earth, form when molten lava flows under a cooled lava field or a crust forms over a river of lava, leaving a long, hollow tunnel. If the ceiling of a solidified lava tube collapses, it opens a pit that can lead to the rest of the cave-like tube.

Two of the larger pits have visible overhangs that clearly lead to caves or voids, and there is strong evidence that another’s overhang may also lead to a large cave.

“Humans evolved living in caves, and to caves we might return when we live on the Moon,” says David Paige, co-author of the paper who leads the Diviner Lunar Radiometer experiment aboard LRO. who made the temperature measurements used in the study. .

Horvath processed data from Diviner – a thermal camera – to find out if the temperature inside the pits diverged from that on the surface.

This is a spectacular view in full sun of the Mare Tranquillitatis pit crater revealing boulders on otherwise smooth ground. This LRO Narrow Angle Camera image is 400 meters wide, north is up.
Credits: NASA/Goddard/Arizona State University

Focusing on a roughly cylindrical depression 328 feet (100 meters) deep about the length and width of a football field in an area of ​​the Moon known as Mare Tranquillitatis, Horvath and his colleagues have used computer modeling to analyze the thermal properties of rock and lunar dust and to plot pit temperatures over time.

The results revealed that temperatures in the permanently shaded parts of the pit fluctuate only slightly throughout the lunar day, remaining at around 17°C. If a cave extends from the bottom of the pit, as suggested images taken by LRO’s Lunar Reconnaissance Orbiter Camera, it too would have this relatively comfortable temperature.

The team, which included UCLA planetary science professor David Paige and Paul Hayne of the University of Colorado at Boulder, believe the shading overhang is responsible for the constant temperature, limiting daytime heat and preventing heat from radiating out at night.

A day on the Moon lasts about 15 Earth days, during which the surface is constantly bombarded by sunlight and is often hot enough to boil water. The brutally cold nights also last about 15 Earth days.

The research was funded by NASA’s Lunar Reconnaissance Orbiter project, Extended Mission 4. LRO is managed by NASA’s Goddard Space Flight Center, Science Mission Directorate at NASA Headquarters in Washington. Launched on June 18, 18, LRO collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge of the Moon. Diviner was built and developed by the University of California, Los Angeles and NASA’s Jet Propulsion Laboratory.

NASA returns to the Moon with commercial and international partners to expand the human presence in space and bring back new knowledge and opportunities.