For the very first time, NASA has managed to obtain images of Venus in the visible range from space… and we owe them to a solar probe.
Astronomy is one of those disciplines where the most interesting discoveries can occur relatively unexpectedly. It’s a bit like what happened recently with the Parker Solar Probe; Against all odds, this probe, whose existence is nevertheless devoted to the study of the Sun, managed to capture a rare image of… the surface of Venus.
This is already a small feat in itself. Because observing the surface of Venus has to be earned. It is a particularly delicate exercise, mainly because of the very particular atmosphere of this planet. Indeed, it is exceptionally dense, regarding 90 times more than that of our Earth! Obviously, this considerably complicates all observation work.
A fierce and unphotogenic diva
For example, it is notoriously difficult to deposit a probe there, because during a high-speed atmospheric re-entry into such a compact mass of gas, the craft is subjected to absolutely daunting forces. And it’s not just regarding physical exploration; even remote observations, essential for drawing conclusions on a planetary scale, are more complicated than usual. This atmosphere is even so dense that it is relatively impermeable to many instruments. Some instruments like the Magellan or Akatsuki telescopes did manage to provide us with some images, but they were always signals that were outside the visible light range.
This is where the Parker Solar Probe comes in. As its name suggests, this machine was designed to study the Sun. To accomplish its task, it has many instruments including one called WISPR, for Wide-Field Imager for Solar Probe. In English, this acronym means “murmur”; a reference to the fact that it seeks to spot tiny disturbances in the solar atmosphere that might tell us regarding the overall dynamics of the star.
Venus finally laid bare
Fortunately, it happens that Venus sometimes passes in the field of vision of the Parker probe, the official paparazzi of our favorite star. Some astronomers have therefore formulated a rather daring idea: divert this instrument from its main mission for a few moments, the time of an indiscretion on the side of the evening star.
It’s a party that must have raised some eyebrows, knowing that viewing time for these unique craft is extremely valuable. But the team was rewarded for their initiative as WISPR succeeded in capturing the first images of the surface of Venus ever recorded in the visible range.
Inevitably, this is a very emotional moment for astronomers. “The images and the video left me speechless”admits Brian Wood, lead author of the study. “Venus is the third brightest star in our Earth’s sky, yet we had very little information regarding its surface”he summarizes. “Until now, our view of the surface has been blocked by the thickness of the atmosphere. Now we can finally observe the surface in the visible range for the very first time.”
A crucial observation
We thus discover an image that is not necessarily spectacular visually speaking, but quite remarkable on a scientific level. From a technical point of view, it is an excellent complement to the observations already made in the past; we now have a very comprehensive panel of images of the surface, from infrared to ultraviolet, including the visible.
These data will allow astronomers to study even more precisely the geology of this chemical and thermal hell. Indeed, when heated, different materials respond by emitting radiation at a specific wavelength; by measuring this wavelength in a particular area, we can therefore estimate the mineralogical composition of the ground. It is a technique that is already commonly used on other planets, but to which Venus still remained relatively hermetic until today.
This information will then allow researchers to go back in time in the hope of refining their knowledge of Venus. For example, they will seek to identify the mechanism that might have produced such a dense atmosphere. Today, the main track suggests it might be a result of massive volcanic activity. But this still remains to be demonstrated, and this work has laid some of the foundations that will make it possible to approach it.
