Astrobiologists have discovered that Titan may not have enough amino acids to nurture life. A study led by Western astrobiologist Catherine Neish has shown that the subsurface ocean of Saturn's largest moon, Titan, is likely to be an uninhabitable environment, meaning that any hope of finding life in this icy world has been dashed.
This poster shows a planar (Mercator) projection of Saturn's moon Titan taken by the Huygens probe from an altitude of 10 kilometers. The images that make up this view were taken on January 14, 2005, using a descent imager spectroradiometer on the European Space Agency's Huygens probe. The Huygens probe was sent to Titan by the Cassini spacecraft and is managed by NASA's Jet Propulsion Laboratory in Pasadena, California. **ESA NASA JPL University of Arizona.
This discovery means that space scientists and astronauts in the outer solar system (the Big Four"Jumbo"Home to planets) is much less likely to find life: Jupiter, Saturn, Uranus and Neptune.
Earth sciences professor Niš said:"Unfortunately, we need to be less optimistic now in our search for extraterrestrial life forms within the solar system. The scientific community has always been very excited about the discovery of life in the icy world of the outer solar system, and this discovery suggests that this possibility may be smaller than we previously assumed. "
Identifying life outside the solar system is an area of great interest to planetary scientists, astronomers, and space agencies such as NASA, largely because the ice moons of many giant planets are thought to have huge oceans of liquid water beneath the surface. Titan, for example, is thought to have an ocean beneath its icy surface, which is more than 12 times the volume of the Earth's oceans.
Catherine Nish, Professor of Earth Sciences. Source**: Western Communications.
Nish, a member of the Western Institute for Earth and Space Exploration, said"Life on Earth as we know it needs water as a solvent, so planets and moons with a lot of water are of interest when looking for extraterrestrial life. "
In the study, published in the journal Astrobiology, Neish and her collaborators sought to quantify the number of organic molecules transferred from Titan's organic-rich surface to its subsurface ocean, using data from the impact crater.
Throughout Titan's history, the comet that hit Titan melted the surface of the icy moon, creating pools of liquid water mixed with surface organic matter. The resulting melt is denser than the ice crust, so heavier water sinks through the ice, possibly all the way to Titan's subsurface ocean.
Using the hypothetical impact rate of Titan's surface, Niš and her collaborators determined how many comets of different sizes would hit Titan each year in Titan's history. In this way, the researchers were able to ** the rate at which organic-carrying water flows from Titan's surface to its interior.
Niš and the team found that the organic matter transferred in this way weighs small, no more than 7,500 kilograms per year of glycine – the simplest amino acid that makes up the protein of life. This is about the same mass as a male African elephant. (All biological macromolecules, such as glycine, use the element carbon as the backbone of the molecular structure).
Injecting one elephant's glycine into an ocean 12 times the volume of the Earth's oceans every year is not enough to sustain life"Niš said. "In the past, people often thought that water equaled life, but ignored that life needed other elements, especially carbon. "
Other ice worlds, such as Jupiter's moons Europa and Europa and Saturn's moon Enceladus, have little to no carbon on their surfaces, and it's unclear how much carbon can be taken from their interiors. Titan is the most organic and ice-rich moon in the solar system, so if its subsurface ocean is uninhabitable, it doesn't bode well for the habitability of other known icy worlds.
Niš said. "This work shows that carbon from Titan's surface is very difficult to transfer to its subsurface ocean – basically, it's hard to have both the water and carbon needed for life in the same place. "
Dragonflies"It is a twin quadcopter lander that will take advantage of the environment on Titan, fly to multiple locations (hundreds of miles apart), sample materials, determine surface composition to study Titan's organic chemistry and habitability, monitor atmospheric and surface conditions, take geomorphological images to study geological processes, and conduct ** research. Source**: NASA.
Despite this discovery, there is still a lot to be done to understand Titan, and the big question for Nish is, what is Titan made of?
The project plans to carry out a space mission in 2028 to send a robotic gyroplane (drone) to the surface of Titan to study its pre-biochemistry, that is, how organic compounds form and self-organize, thus forming the origin of life on Earth and beyond.
Using a telescope to look at Titan through its organic-rich atmosphere makes it almost impossible to determine the composition of Titan's organic-rich surface. But eventually we will need to land on Titan and sample its surface to determine its composition.
To date, only the 2005 Cassini-Huygens international space mission has succeeded in landing a robotic probe on Titan to analyze samples. It remains the first spacecraft to land on Titan and the farthest ever to land from Earth.
Niš said. "Even if the ocean beneath the surface is uninhabitable, we can learn about the pre-biochemistry of Titan and Earth by studying the reactions on Titan's surface. We would very much like to know if there was an interesting reaction happening there, especially where the organic molecules mixed with the liquid water produced by the impact. "
She had feared it would happen"Dragonflies"The mission has a negative impact, but in fact, the study raises more questions.
If all the melt from the impact had sunk into the ice shell, we would not have found a mixture of water and organic matter near the surface. Dragonfly can look for products of pre-biological reactions in these areas, giving us an understanding of how life arose on different planets. The results of this study are even more pessimistic than I thought about the habitability of Titan's surface oceans, but it also means that there are more interesting pre-biological environments near Titan's surface that we can sample with instruments on Dragonfly"。
Compilation**: scitechdaily