This geological curiosity located in Antarctica has shown that space rovers, like Perseverance, may have missed crucial information while exploring other planets.
In 1911, during an expedition to a remote area of Antarctica, the English geologist Thomas Griffith Taylor made an astonishing discovery: he and his crew came across a blood-red waterfall that stood out against the pristine ice.
The explorer suggested that red algae could be the cause of this color. Half a century later, further analysis has confirmed that he was wrong. As often in nature, it is oxidation of ferrous materials which is the origin of this color.
The concern is that this discovery did not explain another curious phenomenon. Indeed, the water is perfectly clear when it emerges from the glacier where it has been imprisoned for millennia. It is only once in contact with the oxygen present in the atmosphere that it adopts its crimson color. But if it were loaded with iron in its classic mineral form, this transition should take some time; now, in Blood Falls, she is almost instantaneous. And this observation has long puzzled researchers.
Metallic nanospheres that color water
Or at least that was the case until the publication of a study by Ken Livi, a researcher at Johns Hopkins University. He believes he has found an explanation for this geological curiosity. According to him, if the water of Blood Falls changes color so quickly, it is because the iron is present there under a very special shape.
While examining samples taken on site, his team made a strange observation: the water contains an abundance of metallic nanospheres. According to the researchers, these small objects with rather unique physical and chemical properties could be the key to the mystery.
” As soon as I looked at the images, I noticed these little iron-rich nanospheres. They also contain many other elements — silicon, calcium, aluminum… and they are all different “, explains Livi in a press release.
If these balls have never been identified until now, it is because the researchers had concentrated on the search for iron-based minerals. However, these nanospheres are not not minerals per se.
“ To meet this definition, the atoms must be arranged according to a very specific crystalline structure. “says Livi. ” These nanospheres are not crystalline, which explains why the old methods did not detect them “.
A quasi-extraterrestrial environment
The author therefore believes that he has solved the main enigma of Blood Falls. On the other hand, he offers no explanation on the origin of these mysterious spherules. And for good reason: this is not the main objective of this work. Because Livi is not a traditional geologist or microbiologist. Its core business is the study of materials from other planets. Its conclusions are therefore more related to planetology and astrobiology.
Indeed, the age-old waters that rest under the glacier are such an exotic and mysterious environment that one could almost liken them to an extraterrestrial ecological niche. They harbor many strains of bacteria completely unknown to the battalion whose lifestyle and characteristics have never been properly documented.
During the first studies that explored the secrets of the area, researchers therefore decided to treat them as a real extraterrestrial environment. They focused on the analytical tools and techniques that NASA uses to study other planets.
” What would happen if a Mars rover, like Perseverance, landed in Antarctica? Would he be able to determine what gives Blood Falls its color? It’s a fascinating question that only a handful of researchers have considered. “, he summarizes.
Of the ” inadequate identification methods »
And that’s the rub ; since previous studies have missed these famous spherules, we can consider that the answer to this question is a “ No resounding. If a rover had landed in a similar environment, he would not have been able to determine the origin of this amazing color.
This means that the researchers would have missed a potentially very important element for the dynamics of this isolated ecological niche. And according to Livi, it will take take this shortcoming into account during the next missions which will leave to seek traces of life on other planets, like Mars.
” Our work has revealed that the analyzes conducted by rovers are incomplete, and are not sufficient to determine the true nature of environmental materials on a planetary surface. This is especially true for cold planets, like Mars, where materials could also exist in nanoscale, non-crystallized form. Therefore, our identification methods are inadequate “, he concludes.
To find this kind of particularly discreet clue, for example, it would be necessary to mount a state-of-the-art electron microscope directly on a rover. However, it is currently not not feasible according to Livi. The machines currently in operation, such as Perseverance, are not capable of carrying out these analyzes in situ.
An uncomfortable situation for researchers. Because if it were possible to reach these conclusions directly on the spot, it would be possible to modify the continuation of the exploration programs to concentrate on this precious information. However, to hope to make discoveries of this kind in the samples of Martian rocks collected by Perseverance, it will be necessary to wait until they are repatriated to Earth during the Mars Sample Return mission, scheduled for 2030. A regrettable delay which could delay great discoveries.
Livi’s findings may push space agencies to accelerate the development of new instruments to fill this gap. For example, NASA has already been working on an onboard electron microscope since 2016 (see this agency post). And slowly but surely, these works are beginning to come to fruition. It will therefore be very interesting to follow the progress. They could lead to fascinating new discoveries about the history of the solar system and, by extension, life as we know it.
The text of the study is available here.
