Out of curiosity, I started looking for photos of Venus surface taken by various Russian probes. There is a nice collection here: http://mentallandscape.com/C_CatalogVenus.htm
Not being a geologist, I see rocks, rocks and rocks. Given the average lifetime of a probe reaching Venus' surface being about an hour, I'm really curious what could scientist infer from these photos? What were the hypotheses or discoveries made because of receiving these photos?
That's what I found so far.
In Abdrahimov, Basilevsky [2002] Venera photos are used for geological context interpretation comparing with orbital radar data.
quotes:
The photogeologic analysis shows that the material of plains with wrinkle ridges (Pwr) dominates the Venera-9 landing-site ellipse (it occupies ~60% of the area of the ellipse). The material of plains with fractures and ridges (Pfr) and the material of tesserae (Tt)occupy, respectively, ~21% and ~14% of the area of the landing-site ellipse. The remaining area of the ellipse(~4%) is occupied by the material of shield plains (Psh).Thus, assuming that the probability of landing the spacecraft on a particular material complex is proportional to the area occupied by this complex on the landing-site ellipse, we can suppose that Venera-9 most likely analyzed the Pwr material. Analysis of the TV panorama of the Venera-9 landing site (Florensky et al., 1977) also provides some data on the place where the spacecraft landed. The steep(about 20°) slope strewn with large boulders probably indicates that the spacecraft landed on the slope of the tectonic trough Aikhylu Chasma, where the Pwr material apparently dominates, but where the Pfr material isdeveloped to a considerably smaller extent.
The photogeologic analysis has shown that the ellipse of the Venera-10 landing-site region is dominated by the material of plains with wrinkle ridges, which occupies ~60% of the ellipse area. The material Pl of lobate plains and the material Tt of tesserae occupy, respectively, ~21% and ~15% of this area. The remaining 4% of the ellipse area is embraced by the unit of densely fractured plains (Pdf), the unit of plains with fractures and ridges (Pfr), and the unit of shieldplains (Psh). Assuming that the probability of landing on a particular material complex is proportional to the area occupied by this complex in the landing-site ellipse, it is most likely that Venera-10 analyzed the Pwr material. On the TV panorama transmitted by Venera-10 from its landing site (Florensky et al., 1977), an apparently undifferentiated flat plain is observed. This finding agrees better with the characteristics of Pwr and Pl plains, but in no way with that of tessera terrains.
The photogeologic analysis of this region has shown that ~90% of the area of the Venera-13 landing-site ellipse is occupied by the material of plains with wrinkle ridges (Pwr). The material of lobate plains (Pl) occupies ~3% of the ellipse area. The remaining ~4%of the area is occupied by the material of densely fractured plains (Pdf), by plains with fractures and ridges (Pfr), and by tessera material (Tt). Assuming that the probability of landing on a particular material complex is proportional to the area occupied by this complex, we can suggest, with great probability, that Venera-13 analyzed the material of plains with wrinkle ridges Pwr. The TV panorama transmitted from the Venera-13 landing site also suggests the plain character of the region where the soil of Venus was examined (Florensky et al., 1983)
The photogeologic analysis of this region has shownthat the material of lobate plains Pl dominates the ellipse of the Venera-14 landing-site (this material is located in the central part of the ellipse and occupies ~53% of its area). The RT zones and the Pwr material occupy, respectively, ~14 and ~27% of the area of the landing-site ellipse. The remaining 5% of this ellipse is occupied by the material that forms fracture belts FB and densely fractured plains Pdf, and by the Cu material formed by the impact crater Ingrid. Assuming that the probability of landing on a particular material complex is proportional to the ellipse area occupied by this complex, we can suppose that Venera-14 most likely analyzed the Pl material. This inference agrees with the fact that a plain terrain is observed on the TV panorama obtained by Venera-14 at its landing site (Florensky et al., 1983).
Bold is mine.
I could not find the cited works by [Florensky at al.] online, unfortunately.
Also I found this (in Russian).
quote about chemical weathering:
При дешифрировании первых панорам Венеры геологи обнаружили, что выходы пород как будто несут на себе следы химического выветривания (Флоренский и др., 1979). Выветривание? В инертной углекислой атмосфере? Но геохимики тут же показали, что оно термодинамически возможно, и очень этому радовались. Иным был подход К.П.Флоренского: чтобы такие химические реакции шли, необходимо все время обновлять поверхность, а иначе первые же новообразования создадут защитную пленку, и процесс замрет. Однако на Венере практически нет ни ветра, ни перепада температур. Решение оказалось неожиданно простым: поверхность Венеры — термостат только по латерали, а по вертикали при размахе рельефа до 11 км существуют изменения и давления, и температуры (Florensky et al., 1977). Кстати, сейчас идея о вертикальном градиенте как факторе венерианского выветривания является общепринятой, в литературе она нередко упоминается просто как самоочевидный факт, не требующий ссылок на кого-либо. Геохимики поставили точку, Флоренский пошел дальше. Он добавил, что при реакциях меняется объем фаз: увеличение его наверху ведет к разрыхлению породы (там же). Вспомним, на Земле это и есть одна из главных причин разрушения древних каменных сооружений.
translation:
When interpreting the first panoramas of Venus, geologists discovered that the rock outcrops seemed to bear traces of chemical weathering (Florensky et al., 1979). Weathering? In an inert carbon dioxide atmosphere? But geochemists immediately showed that it was thermodynamically possible, and they were very happy about it. The approach of K.P. Florensky was different: for such chemical reactions to proceed, it is necessary to renew the surface all the time, otherwise the very first neoplasms will create a protective film and the process will freeze. However, there is practically no wind or temperature difference on Venus. The solution turned out to be unexpectedly simple: the surface of Venus is a thermostat only laterally, and along the vertical, with a relief span of up to 11 km, there are changes in both pressure and temperature (Florensky et al., 1977). By the way, now the idea of a vertical gradient as a factor of Venusian weathering is generally accepted; in the literature, it is often referred to simply as a self-evident fact that does not require reference to anyone. Geochemists put an end to it, Florensky went further. He added that the volume of the phases changes during the reactions: an increase in it at the top leads to loosening of the rock (ibid.). Let's remember that on Earth this is one of the main reasons for the destruction of ancient stone structures.
And from the same document, another example of camera use - to observe the external indicator of atmospheric oxygen.
quote:
самыми непонятными были окислительновосстановительные условия на поверхности (разброс предсказываемых величин содержания кислорода составлял 25 порядков). Но как их определить по фотографиям?
«старый, простой и надежный» способ: мерой порогового содержания кислорода будет читаемый на изображении цвет пластинки, укрепленной на опорном кольце станции.
И индикатор был изготовлен. Размером он примерно в ладонь и весом около 80 г. Он был настолько «бесплатным» и никому не мешающим, что, хотя его не было в согласованном списке научных приборов, устанавливаемых на данных космических аппаратах
Какова же была радость создателей, когда на панорамах «Венеры-13, 14» на опорном кольце станции мы увидели наш индикатор уже на Венере и без защитной крышки. Цвет его был черным, но, увы, черными были и набросанные на станцию при ее посадке комки грунта и пыль.
После снятия расчетным путем эффекта пыли получилось, что индикатор, скорее всего, действительно черный, а значит, условия на поверхности относительно восстановительные.
translation:
the most incomprehensible were the redox conditions on the surface (the rqange of the predicted values of the oxygen content was 25 orders of magnitude). But how to identify them from photographs?
"old, simple and reliable" way: the measure of the threshold oxygen content will be the color of the plate, which is fixed on the support ring of the station, which can be read in the image.
And the indicator was manufactured. It was about the size of a palm and weighed about 80 g. It was so “free” and did not bother anyone that, although it was not on the agreed list of scientific instruments installed on these spacecraft
Imagine the joy of the creators when, in the panoramas of Venera-13, 14, on the station's support ring, we saw our indicator already on Venus and without a protective cover. Its color was black, but, alas, the lumps of soil and dust thrown onto the station during its landing were also black.
After removing the dust effect by calculation, it turned out that the indicator is most likely really black, which means that the conditions on the surface are reducing.
PS Please let me know if my translations are unclear
PPS Thanks @A. Rumlin for links that pushed me in right direction.
