Starship Asterisk*

De58te wrote:I am guessing that the hole is not a crater, but an accumulation of CO2 sublimated gas that became explosive and acted as a geyser. The south pole is a combination of water ice and CO2 ice. During spring heating sunlight penetrates the still relatively clear water ice layer and heats the dry ice. But in the meantime global dust storms occur and the pole gets a layer of dust deposit. The CO2 geyser than picks up the dust and with the prevailing wind at the time produces the dark fan debris. The Swiss Cheese effect could be collapse of the water ice layer as the Co2 sublimates.

warmingwarmingwarming wrote:

De58te wrote:I am guessing that the hole is not a crater, but an accumulation of CO2 sublimated gas that became explosive and acted as a geyser. The south pole is a combination of water ice and CO2 ice. During spring heating sunlight penetrates the still relatively clear water ice layer and heats the dry ice. But in the meantime global dust storms occur and the pole gets a layer of dust deposit. The CO2 geyser than picks up the dust and with the prevailing wind at the time produces the dark fan debris. The Swiss Cheese effect could be collapse of the water ice layer as the Co2 sublimates.

You're probably correct. Similar holes appear in farm fields which are heavily manured by cattle dung .. the dung emits gas, which can be trapped, until it explodes through the surface. But I didn't know there were cattle on Mars. Good news for our Marsnauts when they get there .. take a barbecue.

Chris Peterson wrote: What kind of barbecue is required for cattle whose exploding dung creates 100 meter craters?!

hscribner@spp.org wrote:The hole looks like it could have come from an electric plasma discharge.

Baby's Back wrote:

Chris Peterson wrote: What kind of barbecue is required for cattle whose exploding dung creates 100 meter craters?!

Something like this? - https://imgur.com/I6wAZbh

doribeans wrote:
I'm sorry that this isn't a serious question but...
isn't human exploration of tunnels on other planets the subject of about half of scary sci-fi thrillers?

• "it seems such an obvious thing."

https://en.wikipedia.org/wiki/Phobos_(moon)#Shklovsky.27s_.22Hollow_Phobos.22_hypothesis wrote:
<<Around 1958, Russian astrophysicist Iosif Samuilovich Shklovsky, studying the secular acceleration of Phobos's orbital motion, suggested a "thin sheet metal" structure for Phobos, a suggestion which led to speculations that Phobos was of artificial origin. Shklovsky based his analysis on estimates of the upper Martian atmosphere's density, and deduced that for the weak [aerodynamic] braking effect to be able to account for the secular acceleration, Phobos had to be very light—one calculation yielded a hollow iron sphere 16 kilometers across but less than 6 cm thick. In a February 1960 letter to the journal Astronautics,[climate change denier] Fred Singer, then science advisor to U.S. President Dwight D. Eisenhower, said of Shklovsky's theory: If the satellite is indeed spiraling inward as deduced from astronomical observation, then there is little alternative to the hypothesis that it is hollow and therefore Martian made. The big 'if' lies in the astronomical observations; they may well be in error. Since they are based on several independent sets of measurements taken decades apart by different observers with different instruments, systematic errors may have influenced them.

Subsequently, the systemic data errors that Singer predicted were found to exist, and the claim was called into doubt, and accurate measurements of the orbit available by 1969 showed that the discrepancy did not exist. Singer's critique was justified when earlier studies were discovered to have used an overestimated value of 5 cm/yr for the rate of altitude loss, which was later revised to 1.8 cm/yr. The secular acceleration is now attributed to tidal effects, which had not been considered in the earlier studies.

The density of Phobos has now been directly measured by spacecraft to be 1.887 g/cm3. Current observations are consistent with Phobos being a rubble pile. In addition, images obtained by the Viking probes in the 1970s clearly showed a natural object, not an artificial one. Nevertheless, mapping by the Mars Express probe and subsequent volume calculations do suggest the presence of voids and indicate that it is not a solid chunk of rock but a porous body. The porosity of Phobos was calculated to be 30% ± 5%, or a quarter to a third being empty.>>