Scientists confirm existence of first lunar cave that may help protect astronauts from extreme moon temperatures

CNN
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Scientists have long hypothesized the existence of lunar caves – underground passages formed by Volcanic processes which is related to Craters cover the surface of the moonNow, an international team of researchers has found the first direct evidence that the deepest known crater on the Moon is connected to a cave that could provide shelter for astronauts.

Identifying areas on the Moon that can protect humans and robotic explorers from the harsh lunar environment — including strong radiation and extreme temperatures — could be crucial to future space exploration as countries like the United States and China race to create a sophisticated lunar system. long term human presence On Earth's closest natural satellite.

To find the cave, the team studied archival radar measurements of a crater found within a vast plain called calm seaOr the Sea of ​​Tranquility, which was the landing site. Apollo 11 mission In 1969.

NASA's Lunar Reconnaissance Orbiter collected radar data in 2010 using wavelengths to reveal what was beneath the surface. Analyzing the data, the researchers found an empty space 130 to 170 meters (426 to 558 feet) underground, according to their study published Monday in the journal Nature. Journal of Natural Astronomy.

The newly uncovered cave, which is at least 45 meters (about 148 feet) wide and between 30 and 80 meters (98 and 262 feet) long, may be just the beginning of a longer tubular cavity formed by lava — and there are likely more caves yet to be found, the researchers say.

“Lunar caves have long been a mystery. Scientists have hypothesized their existence for more than 50 years. So it was surprising to finally be able to prove the existence of a subsurface channel,” Leonardo Carrer, study co-author and assistant professor in the Department of Information Engineering and Computer Science at the University of Trento in Italy, said in an email.

Future research and exploration of lunar caves may also provide new insights into the evolution of the Moon and lunar volcanismAs the authors of the study noted.

“Caves are a unique environment that preserves the history of the Moon,” Lorenzo Bruzzone, professor of telecommunications and director of the Remote Sensing Laboratory at the University of Trento, said in an email. “Analyzing the rocks inside these caves could enable new discoveries regarding the evolution of the Moon…such as the timeline and duration of lunar volcanic activity as well as the actual composition of the lunar mantle.”

“Lunar caves could be an alternative or complement to a base on the moon,” he added.

Near the Moon's equator, temperatures average a scorching 250 degrees Fahrenheit (121 degrees Celsius) in daylight and drop to minus 208 degrees Fahrenheit (-133 degrees Celsius) at nightfall, According to NASAThe extreme temperatures dropped to minus 410 degrees Fahrenheit (minus 246 degrees Celsius), as recorded by the Lunar Reconnaissance Orbiter.

Researchers from Study July 2022 Who looked at a number of craters on the moon – some of which were supposed to lead to caves NASA on discovery Shaded shelters were found to be more thermally stable and remained constant at about 63°F (17°C).

“Having additional evidence of a cave extending from the bottom of Mare Tranquillitatis is really exciting,” Tyler Horvath, a UCLA planetary science doctoral student who was lead author of the 2022 study, said in an email.

“Lunar caves could provide enormous benefits to astronauts and rovers, who could seek shelter from lunar surface hazards such as radiation, micrometeoroids and extreme temperatures, which could also open the door to a long-term human presence on the Moon,” added Horvath, who was not involved in the new study.

The moon has more than 200 known craters like the one in the Sea of ​​Tranquility, but only a few of them likely extend into caves, Horvath said. Some lava tubes may be inaccessible because of debris blocking the passages, Carrier added.

The interior features of the newly discovered cave will remain unclear until a rover or human exploration can provide more insight. Horvath said the interior could look similar to a freshly formed lava tube on Earth, but much larger. It would likely have smooth walls except where lava may have formed ridges and mounds known as lava troughs, added Paul Hayne, an associate professor in the Department of Astrophysical and Planetary Sciences at the University of Colorado at Boulder. The cave would be very dark, except where sunlight hits and reflects off the crater floor.

The cave’s large size isn’t surprising, said Hein, who co-authored the 2022 study but was not involved in the new research, given the moon’s lower gravity and the effects it can have on the stability of lava tubes, where larger caves can form with less risk of collapse. Most lava tubes on Earth are found in Hawaii, the Canary Islands, Australia and Iceland, and range from Diameter from 33 to 98 feet. a August 2020 Study It has been suggested that lava tubes on the Moon may be up to 1 kilometer (3,280.84 feet) in diameter.

“We shouldn’t be too surprised if future explorations reveal even larger caves,” Hein said in an email. “We’ve gotten a glimpse of the Moon’s interior volcanic drainage system.”

The authors of the new study found that the cave may be flat or tilted at a maximum angle of 45 degrees, suggesting it was likely accessible, Carrier said.

But because of the depth of this cave (and perhaps other lunar caves), it may take some creativity to lower the astronauts to the crater floor — possibly involving rock-climbing equipment such as ropes, anchors, larger cables for equipment and building materials, Hein said. The process could eventually involve building a more permanent structure such as a cargo elevator, he added.

Other ideas for exploring the deep Mare Tranquillitatis crater and the newly discovered cave inside it include an automated crane that could be used to lower an astronaut or spacecraft to Earth, which is currently being explored by European Space Agency.

Noah Petro, head of NASA’s Planetary Geology, Geophysics and Geochemistry Laboratory, noted that skywatchers looking at the moon could identify the Sea of ​​Tranquility, where the cave was discovered, by looking for a large, dark plain. He recommended looking up and taking a look at the site on July 20 to mark the 55th anniversary of the Apollo 11 landing, the first mission to put humans on the moon.

“The discovery of (potential craters and caves) goes back several years, (but) this new information from radar data says, ‘Oh, my God. It’s a little bit bigger than we expected,’” said Pietro, a project scientist for the Lunar Reconnaissance Orbiter and Artemis III, a mission aimed at landing humans on the moon for the first time since Apollo 17 in 1972. Pietro was not involved in the new study.

“LRO has been on the Moon for 15 years, generating some amazing data sets that have changed our view of the Moon, which is used to make these kinds of discoveries,” said Petro. “(The cave) is one of those wonderful surprises that the Moon always has in store for us.”