It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, March 16, 2024
SPACE
Hubble tracks Jupiter’s stormy weather
NASA/GODDARD SPACE FLIGHT CENTER
IMAGE:
THESE IMAGES OF THE GAS GIANT JUPITER WERE TAKEN BY NASA'S HUBBLE SPACE TELESCOPE IN JANUARY 2024.
The giant planet Jupiter, in all its banded glory, is revisited by NASA's Hubble Space Telescope in these latest images, taken on January 5-6, 2024, capturing both sides of the planet. Hubble monitors Jupiter and the other outer solar system planets every year under the Outer Planet Atmospheres Legacy program (OPAL). This is because these large worlds are shrouded in clouds and hazes stirred up by violent winds, causing a kaleidoscope of ever-changing weather patterns.
[left image]– Big enough to swallow Earth, the classic Great Red Spot stands out prominently in Jupiter's atmosphere. To its lower right, at a more southerly latitude, is a feature sometimes dubbed Red Spot Jr. This anticyclone was the result of storms merging in 1998 and 2000, and it first appeared red in 2006 before returning to a pale beige in subsequent years. This year it is somewhat redder again. The source of the red coloration is unknown but may involve a range of chemical compounds: sulfur, phosphorus, or organic material. Staying in their lanes, but moving in opposite directions, Red Spot Jr. passes the Great Red Spot about every two years. Another small red anticyclone appears in the far north.
[right image] – Storm activity also appears in the opposite hemisphere. A pair of storms, a deep red cyclone and a reddish anticyclone, appear next to each other at right of center. They look so red that at first glance, it looks like Jupiter skinned a knee. These storms are rotating in opposite directions, indicating an alternating pattern of high- and low-pressure systems. For the cyclone, there's an upwelling on the edges with clouds descending in the middle, causing a clearing in the atmospheric haze.
The Hubble Space Telescope has been operating for over three decades and continues to make ground-breaking discoveries that shape our fundamental understanding of the universe. Hubble is a project of international cooperation between NASA and ESA. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. Goddard also conducts mission operations with Lockheed Martin Space in Denver, Colorado. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble and Webb science operations for NASA.
Surprising insights about debris flows on Mars
Research pushes the presence of water on Mars further into the past
SATELLITE IMAGE OF GULLY LANDSCAPES ON MARS, TAKEN BY HIRISE (HIGH RESOLUTION IMAGING EXPERIMENT), A CAMERA ON BOARD THE MARS RECONNAISSANCE ORBITER (PHOTO NO.: ESP_039114_1115). THE WHITE CO2 ICE IS VISIBLE ON THE SIDES OF THE GULLIES.
CREDIT: HIRISE (HIGH RESOLUTION IMAGING EXPERIMENT), A CAMERA ON BOARD THE MARS RECONNAISSANCE ORBITER (PHOTO NO.: ESP_039114_1115)
The period that liquid water was present on the surface of Mars may have been shorter than previously thought. Channel landforms called gullies, previously thought to be formed exclusively by liquid water, can also be formed by the action of evaporating CO2 ice. That is the conclusion of a new study by Lonneke Roelofs, a planetary researcher at Utrecht University. “This influences our ideas about water on Mars in general, and therefore our search for life on the planet.” The results of the study are published this week in the journal Communications Earth and Environment.
“The Martian atmosphere is 95% CO2”, Lonneke Roelofs explains. “In winter, air temperatures drop below -120 degrees Celsius, which is cold enough for CO2 in the atmosphere to freeze.” In the process of freezing, CO2 gas can change directly to CO2 ice, skipping the liquid phase. The process is similar to frost on Earth, where water vapour forms ice crystals and blankets the landscape in a white film. Warmer spring temperatures, combined with the thin Martian atmosphere, causes CO2 ice to evaporate directly back to gas, again skipping the liquid phase. “We call that ‘sublimation’. The process is extremely explosive due to Mars’ low air pressure. The created gas pressure pushes sediment grains apart causing the material to flow, similar to debris flows in mountainous areas on Earth. These flows can reshape the Martian landscape – even in the absence of water.”
“The results of my research suggest that the chance of life having existed on Mars is smaller than previously thought.”
Scientists have long hypothesised that CO2 ice could be a driving force behind these Martian landscape structures. “But those hypotheses were mainly based on models or satellite studies”, Roelofs explains. “With our experiments in a so-called ‘Mars chamber’, we were able to simulate this process under Martian conditions. Using this specialised lab equipment we could directly study this process with our own eyes. We even observed that debris flows driven by CO2 ice under Martian conditions flow just as efficiently as the debris flows driven by water on Earth.”
Extraterrestrial life
“We know for sure that there was once water on the surface of Mars. This study does not prove the contrary”, Roelofs says. “But the emergence of life likely needs a long period where liquid water was present. Previously, we thought that these landscape structures were formed by debris flows driven by water, because of their similarity to debris flow systems on Earth. My research now shows that, in addition to debris flows powered by water, the sublimation of frozen CO2 can also serve as a driving force behind the formation of these Martian gully landscapes. That pushes the presence of water on Mars further into the past, making the chance of life on Mars smaller.” And that makes us even more unique than we thought.
Why Mars?
But what makes someone interested in landscapes 330 million km away? “Mars is our closest neighbour. It’s the only other rocky planet close to our solar system’s ‘green zone’. The zone is precisely far enough from the sun to allow for liquid water to exist, a prerequisite for life. So Mars is a place where we possibly can find answers to questions about how life developed, including potential extraterrestrial life”, answers Roelofs. “Plus, studying the formation of landscape structures on other planets is a way for us to step outside our Earthly context. You ask different questions, which leads to new insights on processes here on Earth. For example, we can also observe the process of gas-driven debris flows in pyroclastic flows around volcanoes, here on Earth. So this research could contribute to a better understanding of terrestrial volcanic hazards.”'
Lonneke Roelofs next to the Mars chamber at the Open University, Milton Keynes (UK)
CREDIT
Mars chamber at the Open University, Milton Keynes (UK)
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