Scientists are trying to find life on hundreds of moons in the solar system

In an effort to understand how life might develop on other planets, astrobiologists often travel to the most inhospitable and extreme places on Earth. And when it comes to simulating environmental conditions on icy moons like Jupiter’s Europa and Saturn’s Enceladus, Antarctica is the closest analog we can get.

A new article by researcher Alessandro Napoli (University of Rome, Italy) highlights the rich diversity of microorganisms near Concordia Station, a Franco-Italian research center located on the Antarctic plateau, more than 3,000 meters above sea level. altitude. Here, the average annual temperature is minus 50 degrees Celsius and winter temperatures can even drop to minus 80 degrees Celsius.

Despite freezing temperatures, the research team using DNA sequencing discovered many types of bacteria, even in samples of snow and ice. Most are proteobacteria, but there are also many types of archaea and fungi.

Although the bacteria are not numerous, their sparse numbers are close to the detection limit, the study shows that techniques based on DNA sequences can work in remote and hostile environments. At these cold temperatures no bacteria are able to function, they exist in a dormant state until the temperature rises enough for metabolism to become active again.

Life in harsh environments

Although conditions in the coldest places on Earth are still very different from those in the outer solar system, this type of research could be very useful for astrobiology. Europa, Jupiter’s moon There is an ocean beneath a layer of ice several kilometers thick, and this ocean may contain more liquid water than all of Earth’s oceans combined. Europa’s ice mantle is thought to be in direct contact with the water above, and due to tidal mixing caused by Jupiter’s gravity (the ice shell resembles a broken eggshell), The Moon may have hydrothermal vent holes similar to what is found at the bottom. of the Earth’s oceans. On our planet, these vents are refuges for life, and the same may be true for Europa.

Simulation of the surface of Europa with Jupiter on the horizon.

The underground ocean of Enceladus much smaller than Europa and does not cover the entire surface. But fortunately for us, near the south pole of this moon, it releases its contents into space. Therefore, we can analyze or even sample by a passing spacecraft. It’s much easier than drilling under the ice to reach water.

Several chemical components, including hydrogen, methane, ammonia, hydrocyanic acid and simple organic compounds, have been identified in Enceladus’ jets into space, fueling hopes that this icy world may contain microbial life. Exploring Europa’s oceans would require a lander, but in the case of Enceladus, only a meticulously designed ship tasked with flying overhead to collect samples tells us what we need to know.

Eruption phenomenon on the moon Enceladus

Eruption phenomenon on the moon Enceladus.

The other two icy moons of Jupiter, Ganymede and CallistoLess interesting for astrobiology, Ganymede also has an underground ocean, but it is probably sandwiched between layers of ice, so it would not have terrestrial-type hydrothermal vents. Triton is a Kuiper Belt Object captured by Neptune as a satellite and is also an object of great astrobiological interest due to the presence of water. Scientists believe an ocean of ammonia lies beneath its mostly frozen nitrogen surface.

Simulation of Triton’s surface with Neptune on the horizon.

Simulation of Triton’s surface with Neptune on the horizon.

Searching for signs of life on Titan

However, perhaps the most interesting world in the outer solar system is Moon of Titan covered by Saturn’s clouds. Imagine it’s Antarctica, but Titan is actually colder. Remove all free oxygen and carbon dioxide, then add an occasional shower of methane from the ever-present clouds. In fact, Titan is the only moon in the solar system with a significant atmosphere.

On its surface are lakes of liquid methane and ethane, containing many organic compounds. Because Titan’s environment is very different from Earth’s, any life near these lakes is quite strange to humans. This only makes the possibility of life on Titan more exciting: if we find life there, it must have arisen independently. And the fact that there are two distinct origins in the same solar system reinforces the hypothesis that life in the universe is common.

Simulation of Titan’s surface with Saturn on the horizon

Simulation of Titan’s surface with Saturn on the horizon.

However, it won’t be easy to prove the existence of life on Titan. We will almost certainly need a landing and this task is much more difficult and expensive than a probe or orbital flight. Additionally, if life on Titan exists, detecting it will be more difficult because we have never encountered new life forms outside of Earth. However, that doesn’t mean it’s impossible. We will specifically look for large organic molecules (which may be different from those used for biochemical reactions on Earth) and lighter isotopes of certain chemical compounds.

Until the day we send landers to Titan, similar work on Earth could help us understand how life might interact with the hydrocarbon matrix. By studying the natural liquid asphalt lake in Trinidad for many years, scientists have discovered different types of microorganisms in the liquid hydrocarbons, many of which were previously unknown. They found that most bacteria live in small water droplets within a hydrocarbon matrix. In fact, these droplets contain a unique microbial ecosystem, perhaps the smallest recognized to date.

These and similar studies teach us how organisms can interact with a seemingly hostile environment and still survive. Of course, such research also has its limitations because the temperature difference between Earth and Titan makes it difficult to extrapolate information from one world to another. However, in principle, two locations can have the same boundary conditions. The better we understand our planet’s harsh environment, the better equipped we will be to recognize life elsewhere in the solar system.

in the solar system, there are currently 92, after the discovery of 12 other natural satellites. Astronomer Scott Sheppard’s report says his research team observed 12 additional moons orbiting Jupiter, bringing the total number of confirmed moons of that planet to 92. Previously, Saturn held the “champion” position with 83 satellites in orbit.

Specifically, it took about a year to clearly identify Jupiter’s 12 new moons, and the research team used the Magellan Telescope in Chile to observe them. The newly discovered moons are small (1 to 3.2 km), have wide orbits and 9/12 of these satellites take more than 550 days to orbit the gas giant planet.

According to astronomer Scott Sheppard, these moons were once asteroids because they had wide orbits and rotated opposite the direction of Jupiter’s rotation, but they were caught in Jupiter’s gravity. In particular, they have a rotation speed equivalent to that of the host planet.

The International Astronomical Union allows the naming of any moon larger than about 2.4 km. Thus, half of these newly discovered moons will soon be named by the Minor Planet Center, responsible for tracking the locations of small planets, comets and meteorites.

Scientists say the discovery of more moons around Jupiter and their orbits could help identify targets for future human space exploration missions.

We know that the European Space Agency’s Jupiter Icy Moons Explorer probe will be launched next April and that NASA’s Europa Clipper should be launched in 2024 to reach Jupiter. Along the way, new probes could bypass newly discovered moons.

Article source: 1thegioi