The astronomer Rafael Bachiller shows us in this series the most spectacular phenomena of the Cosmos. Topics of pulsating research, astronomical adventures and scientific novelties about the Universe analyzed in depth.
The Japanese Akatsuki probe, which suffered a serious failure after its launch and was deemed lost, was saved by the engineers of JAXA, successfully inserted into the orbit of Venus, and put into operation to achieve these extraordinary images of our planet brother.
Success after the initial failure
In a previous Chronicle of the Cosmos, we narrated a couple of years ago the great odyssey of the Japanese ship Akatsuki (‘Amanecer’). The probe was launched in 2010 and, when it arrived on Venus, suffered a serious technical failure that made it pass by leaving the planet far behind.
However, the engineers of the Japanese Space Agency (JAXA) devised an emergency plan that allowed, after five years of difficult calculations and tests, to recover the ship and return it to the orbit of Venus.
The apoapside (point of maximum distance from the planet) has stabilized at about 360,000 kilometers above the surface of Venus, while the periapside (point of maximum approach) is about 10,000 kilometers.
At this altitude, the measuring instruments can not offer all the detail that was expected at first, but even so, the data obtained are of great relevance for the study of clouds and their movements. This is demonstrated by the first images that reach us and that we show here.
Infrared and ultraviolet
The ship is equipped with several cameras that, working in different wavelengths, can penetrate to different depths of the dense atmosphere of Venus. Two of these cameras, which worked in the infrared (at 1.7 and 2.3 micrometers), was out of operation in December 2016. But while they worked, they obtained images of the night area, specifically the region about 50 kilometers away.
On the surface of the planet, the clouds of that region are sensitive to the topography of the surface and, therefore, can give an idea of some characteristics of the terrain.
Two other cameras working in the ultraviolet (at 283 and 365 nanometers) allow to see the highest clouds illuminated by sunlight. These clouds contain sulfuric acid and sulfur dioxide, as well as another component that absorbs light in the 365-nanometer band and has not been identified yet.
In the second semester of 2017, JAXA scientists released the first scientific images obtained by the probe in the Ataksuki Archive. Since then, Dama Bouic, a French specialist in digital image processing, has been processing the ‘raw’ data from the archive to obtain the spectacular images that illustrate this article.
In the images, you can see the dynamics of the atmosphere in all its complexity. The changes of color show, in the ultraviolet, variations in the sulfur dioxide and in that other unknown component that absorbs these wavelengths creating dark zones, as well as the convective movements that mix the gases.
Sulfur dioxide can be photodissociated by the effect of sunlight to form sulfur monoxide, or it can be oxidized to form trioxide which, in combination with water, ends up giving sulfuric acid.
However, there are still many unknowns to solve to explain all the chemical processes of the atmosphere of Venus and, without a doubt, the detailed analysis of all these images will help to elucidate many of these phenomena.
More images processed by Bouic can be seen on his blog, on the website of the Planetary Society and in a recent article by Sky & Telescope.