Volcanoes build caves
The caves in the solar system are as diverse as the celestial bodies on which they are located.
On cold, ice-covered objects such as Pluto, Jupiter’s moon Europa, and Saturn’s moon Enceladus, ice volcanoes and geysers can create caves. Volcanoes spew volatile substances such as water and methane, which quickly evaporate and leave cavities in the volcanic crater or ice cap.
The Moon, Mars, and Saturn’s moon Titan are not covered in ice, so caves here are formed by processes we also know from Earth.
What caves have in common is that they are made of liquid materials. For example, most caves on Earth are formed by water currents penetrating the surface.
But caves can also form from molten surface material from meteorite impacts or lava flows from volcanoes.
If scientists can access the caves of planets and moons, they can find answers to a number of scientific questions.
For example, caves can tell us about the geology of objects over time. Studies of solidified lava can reveal the material from which objects are made.
The Earth, for example, serves as an archive of climate history.
Limestone deposits on stalactites in caves on Majorca have revealed that sea levels were more than 16 meters higher 3.3 million years ago – a harbinger of what lies ahead if global warming continues.
On Earth, biologists and archaeologists also benefit from cave research, as countless discoveries show that our ancestors sought shelter in caves.
Caves on land were also attractive to animals, with many species living their entire lives in a protected but dark environment.
Life thrives in eternal darkness
Biologists have found completely isolated ecosystems in caves. It’s teeming with life here, even if the sun never reaches it.
A prominent example of this is the Movil Cave in Romania, which was discovered in 1986, and where life was cut off from the outside world for 5.5 million years.
The dark cave is teeming with yellow leeches, snails, spiders, goblins and scorpions. In a world without light, where no one has eyes, colors have no meaning.
The lack of light presents challenges, but it also presents advantages. The cave provides protection against weather and wind, and the temperature is constant 24 hours a day, all year round.
The same benefits apply to caves elsewhere in the solar system. On the moon, for example, the temperature ranges from 127 degrees during the day to 173 below zero at night – but in caves it is more stable.
in 2022 discovered Researchers at the University of California, USA, have found that the temperature in a crater on the moon, which is supposed to be the entrance to the cave, is a comfortable 17 degrees.
The researchers concluded that caves on the Moon provide stable temperatures and safe environments suitable for exploration and habitation on the Moon.
The same is likely to apply to caves on Mars. Here, the caves will not only provide a constant temperature but will also provide protection against violent sandstorms. On the Moon and Mars, caves would protect against deadly cosmic radiation from the Sun and the rest of the galaxy.
You will explore new robots
Cave exploration on other planets presents significant technical challenges. Initially, exploration will be carried out with the help of robots.
But since the terrain in caves may be as rugged as we know from caves on Earth, robots other than the rovers that researchers have used to explore the surface will need to be developed.
In 2019, the European Space Agency called for new ideas for robots that could explore caves on the moon. One proposal, put forward by researchers at the University of Manchester in the UK, is to send a swarm of jumping robots to investigate the crater at Marius Hills.
And on Saturn’s moon Titan, a group of smaller robots may also be relevant. Unlike the Moon and Mars, Titan has a dense atmosphere. In fact, the atmosphere is so thick and gravity is so weak that humans could fly if they had a pair of wings attached to their arms.
NASA is working on a concept called Shapeshifter, which is an array of up to a dozen drones. The quintuplet drones can fly individually, but can also be assembled into a ball that can roll across terrain or navigate Titan’s lakes of liquid methane.
Thus, the robots are equipped for any environment they may encounter in the caves of Titan.
However, a general technical problem remains: How will researchers stay in touch with robots? Radio waves cannot penetrate the walls and ceiling of the cave, and without communication researchers cannot send instructions to the robots or receive data from them.
But now, a team of engineers has found a solution to this problem as well. Under the leadership of Wolfgang Fink from the University of Arizona in the USA, the team developed Communication system To be used by a group of small robots in Mars caves.
The system is inspired by the fairy tale about Hansel and Gretel, Wolfgang Fink explained when the researchers presented the idea.
“If you remember the book, you know that Hansel and Gretel dropped breadcrumbs to make sure they would be able to find their way back.”
In the researchers’ version, crumbs are small electronic devices that rovers shed every time they turn a corner or move up and down lanes.
The devices act as communication points that receive and transmit radio signals from the rovers. This keeps them in constant contact with the larger “morpher” located at the cave entrance.
The small rovers will be equipped with a lidar device that can scan caves in three dimensions. One goal is to check whether they are suitable for human habitation.
On Mars, lava tunnels are interesting from the standpoint of a permanent base and eventually an actual colony. Kilometer-long tunnels can be several hundred meters wide, meaning there is a lot of space.
“The lava tunnels and caves will be an ideal habitat for astronauts because they do not need to build anything. They are automatically protected from harmful cosmic radiation, so the only thing they have to do is decorate them and make them comfortable,” says Wolfgang Fink.
When scientists find the right place to move to, it will be interesting to see whether astronauts will become the first cave dwellers on Mars, or whether they will share a home with native life on Mars.
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