Portuguese scientists point to the secret of Venus hidden in the heat of the night

Despite being close to Earth and being about the same size, Venus really is another world. Beneath the thick mantle of sulfuric acid clouds, the surface predominates at 460°C, a temperature maintained by the greenhouse effect of an atmosphere made almost entirely of carbon dioxide. Seventy kilometers away, there is a perpetual gust of wind, as a result of the so-called super-rotation of Venus. A team of researchers led by the Instituto de Astrofísica e Ciências do Espaço (IAstro) is getting closer to explaining how these hellish traits are interconnected.

One study Published in the magazine Atmosphereled by Pedro Machado, of IAstro and from the University of Lisbon’s Faculty of Science, presents the most detailed and complete set of measurements ever made of Venus’ wind speeds parallel to the equator and cloud base height.

One of the unprecedented results was the simultaneous measurement of wind speeds at an altitude of 20 kilometers apart. The team found a difference in wind speeds of about 150 kilometers per hour faster in the upper part of the clouds, strengthening the hypothesis that the transfer of energy from the heat of the lower layers to the general movement of the atmosphere occurs on Venus. .

“The winds are accelerating as we get higher, but it is not yet known why,” says Pedro Machado, quoted in the note from IAastro.

“This study sheds a lot of light on this, because for the first time we have been able to study the vertical component of the wind, that is, how energy is transferred from the lower layers, which are warmer, to the top of the clouds, and this will cause the wind to accelerate“.

The temperature near Earth reaches 460 degrees Celsius and produces infrared radiation (called thermal emission), which heats the air and makes it rise. This radiation passes through the most transparent areas from the base of the cloud, at an altitude of about 48 kilometers. When Venus is viewed in the infrared, you see this heat radiating from the surface and the silhouette of clouds, opaque and dark.

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By observing and tracking the clouds hourly, and using tracking technology perfected by Javier Peralta, co-author of this study, the researchers indirectly calculated the wind speed driving these clouds, IAastro explains. The speed is about 216 kilometers per hour at the bases of the cloud and in the middle latitudes, approaching by half from the poles.

This work was carried out virtually from pole to pole on the night side, and recovered images taken by the team in infrared using Telescopio Nazionale Galileo (TNG), at La Palma, in the Canary Islands, between July 11 and 13, 2012. Day on those same days In a coordinated fashion, the European Space Agency (ESA) Venus Express spacecraft, which was orbiting the planet, was observed in visible light and provided images of cloud tops, about 20 kilometers high, at an altitude of 70 kilometers.

Also after these clouds, the researchers obtained speeds of up to 360 kilometers per hour. Other studies and computer simulations indicate that the wind speed at the base of the clouds is approximately constant, with no significant differences between day and night. Thus the team can assume that the speed recorded for the night also applies to the lower layers of the atmosphere on the day side.

Thus, for the first time, measurements of the difference between wind speeds at two altitudes were obtained from simultaneous observations, concluding that on the day side and only 20 kilometers perpendicular, there is an increase of about 150 kilometers per hour when the wind speed is parallel to the equator. Surface heat could be the engine keeping cyclonic wind speeds above the clouds.

The accuracy of the data obtained with telescopes on Earth is comparable to that of infrared cameras on space probes, thanks to a method introduced to this study by Javier Peralta. “We used the same georeferencing method for images obtained by space probes, which were developed by NASA and supplemented by the European Space Agency,” Pedro Machado explains.

“It’s like the telescope here on Earth is a spacecraftPedro Machado explains.

With this approach successful, the team now plans to expand research into the vertical component of winds with new observations on Earth in coordination with the spacecraft currently orbiting Venus, AkatsukiFrom the Japanese space agency JAXA. This study demonstrates that observations made from Earth complement data collected at the same time through missions into space. Despite the low spatial resolution, given the distance at which our planet is, it is generally possible to obtain a global view of Venus, which is not immediately achievable due to its orbits.

Meanwhile, ESA’s next mission to Venus is being planned, which is Imaginethat will study the surface of the planet and try to find out its past. Portugal is involved in the mission, and Pedro Machado leads the Portuguese Federation, as well as being the co-investigator in charge of one of the instruments, the infrared spectrophotometer.

This work demonstrates the kind of science that can be done with EnVision tools. We are already demonstrating the great importance of the science that can be achieved in this future mission,” highlights Pedro Machado.

The expertise of Portuguese and IAstro researchers in understanding the dynamics of Venus’s atmosphere will help choose the wavelengths of light that the EnVision mission will monitor, as well as the layers of the atmosphere that are most relevant from a scientific point of view, thus contributing to mission design and planning and its instruments.

It is also expected that the national participation will be able to involve the Portuguese industry in another international project of the European Space Agency, with the possibility of obtaining support from the Portuguese Space Agency, Portugal space.