Scientists on Monday unveiled the first global geological map of Saturn’s moon Titan including vast plains and dunes of frozen organic material and lakes of liquid methane, illuminating an exotic world considered a strong candidate in the search for life beyond Earth.
The map was based on radar, infrared and other data collected by NASA’s Cassini spacecraft, which studied Saturn and its moons from 2004 to 2017. Titan, with a diameter of 5,150km, is the solar system’s second-biggest moon behind Jupiter’s Ganymede. It is larger than the planet Mercury.
Organic materials — carbon-based compounds critical for fostering living organisms — play a leading role on Titan. “Organics are very important for the possibility of life on Titan, which many of us think likely would have evolved in the liquid water ocean under Titan’s icy crust,” said planetary geologist Rosaly Lopes of NASA’s Jet Propulsion Laboratory in California. “Organic materials can, we think, penetrate down to the liquid water ocean and this can provide nutrients necessary for life, if it evolved there,” added Lopes, who led the research published in the journal Nature Astronomy.
On Earth, water rains down from clouds and fills rivers, lakes and oceans. On Titan, clouds spew hydrocarbons like methane and ethane — which are gases on Earth — in liquid form due to the moon’s frigid climate. Rainfall occurs everywhere on Titan, but the equatorial regions are drier than the poles, said study co-author Anezina Solomonidou, a European Space Agency research fellow.
Plains (covering 65 percent of the surface) and dunes (covering 17 percent of the surface) made up of frozen bits of methane and other hydrocarbons dominate Titan’s mid-latitudes and equatorial regions, respectively.
Titan is the only solar system object other than Earth boasting stable liquids on the surface, with lakes and seas full of methane being major features at its polar regions. Hilly and mountainous areas, thought to represent exposed portions of Titan’s crust of water ice, represent 14 percent of the surface.
“What is really fun to think about is if there are any ways that those more complex organics can go down and mix with water in the deep icy crust or deep subsurface ocean,” JPL scientist and study co-author Michael Malaska said. Noting that on Earth there is a bacterium that can survive just on a hydrocarbon called acetylene and water, Malaska asked, “Could it or something like it live in Titan deep in the crust or ocean where temperatures are a little warmer?”
The map was created seven years before the US space agency is set to launch its Dragonfly mission to dispatch a multi-rotor drone to study Titan’s chemistry and suitability for life. Dragonfly is scheduled to reach Titan in 2034. “It is not only scientifically important but also really cool — a drone flying around on Titan,” Lopes said. “It will be really exciting.”
Three adopted Japanese shibas — eight-year-old male Hero, three-year-old female Wish and the latest addition to the family in 2017, a male named Tiger — are the main protagonists of a Facebook page created by their owner, called Hero&Wish, which has over 5,000 followers. Tiger was originally a stray, although it is unclear what caused him to be homeless. Fortunately, he tramped onto a school campus in southern Taiwan. While classes were underway, the forlorn sound of feeble footsteps reverberated in the corridor outside. A teacher went out to investigate and discovered Tiger, with an astonishing trail of bloody paw prints
A: It’s difficult to know what we will need for a two-week quarantine. So far I’ve ordered bread, vegetables, meat — and a large box of Korean-style spicy instant noodles. B: Um, if we have a fever, we will want to eat plain food, like rice porridge or chicken soup. A: That’s true. I’ll add a bag of rice to the order and we can make some chicken soup, divide it into individual portions and freeze it. A: 很難想得到我們隔離兩個星期會需要些什麼。到目前為止，我訂了麵包、蔬菜、肉類──還有一大盒韓式辣泡麵。 B: 呃，如果我們發燒的話，應該會想吃清淡的食物吧，像是稀飯或是雞湯。 A: 這倒是真的。我再加一袋米到訂單裡面好了，然後我們可以做一些雞湯，把它分裝以後拿去冷凍。 English 英文: Chinese 中文:
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