Have you ever wondered why all the craters on the Moon are round?
After all, Its inevitable that some impactors hit the moon at oblique angles and should then logically create an elongated gouge in the surface (a skid mark) rather than form a round divot. This is why geologist originally argued with scientists that the craters were volcanic in nature not the result of impacts. So why are all the craters round? The reason has to do with velocity. At the extreme velocities of several to tens of kilometers per second there is a tremendous amount of kinetic (speed) energy contained in the asteroid/comet. |
Boris Ivanov, in 2001, estimated the average impact velocities of our moon and Mars to be 16.1 km/s and 9.6 km/s. Our Moon's impact velocities = slowest 2.38, fastest 71.9, average 16.1. Mars impact velocities = slowest 5.027, fastest 58.3, average 9,6.
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In other words, their average impact velocities are 2 to 7 times greater than their slowest impact escape velocity.
Like the moon and most of Mars, Pluto's craters are round When the velocity (kinetic energy) of an object is greater than the binding energy that holds the object's mass together, on impact, the kinetic energy is driven into the object causing it to explode like a bomb. |
There are a number of low angle impact craters on Mars
E. Sefton Nash et al., LPSC 2017 In my view one of the more interesting low impact angled craters are the two shown below. The image has a box outlining one impact but there are clearly two which are directly related to each other. These two impacts demonstrate that one object likely hit then broke into a second object forming two inline skid marks as the impactor skipped like a stone across the surface.
Elliptical craters with "butterfly" ejecta patterns make up roughly 5% of the total crater population of terrestrial planets and moons. Pop quiz; What direction do you think the asteroid was traveling when it made the above skid mark on Mars?
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An example of skipping like a stone. Wait for it. Skip, skip, skip gone. Below is a close up of the elongated impact outlined in the white box to the left. <<<<<<<< |
On Earth our atmosphere has enough mass to act somewhat like a solid when objects collide with it at high enough velocities and this is why objects explode without even hitting the surface. The more shallow the angle the more atmosphere the object impacts and so greater the chance of exploding prior to impact.
The kinetic velocity energy of an object, when slowed quickly enough by our atmosphere, is driven back into the object's bonding energy and when the one is greater than the other, kaboom. Objects with more density require more kinetic energy (speed) to reach their explosive state. |
I'm not aware of any elongated impact craters on Pluto which means all Pluto impacts occurred at velocities greater than the object's density bonding energy required to explode, hence circular craters.
This means all the objects that impact Pluto are traveling fast enough and have low enough internal binding composition energy (density) to explode on impact, the same holds true for Pluto's small satellites. The image resolution quality of Pluto's small satellite's is fairly weak so there may be undetected elongated impact skid marks. |
According to this NASA page, Pluto currently has an escape velocity of 1.21 km/s.
That means the slowest an impacting object can hit Pluto is 1.21 km/s since Pluto's gravity will drive the object toward its center at this minimum velocity regardless of their initial relative velocities. Based on our Moon and Mars' average impact speeds, Pluto's average impact speed would then be somewhere between 2.42 and 8.47 km/s with a lowest potential impact speed of 1.21 km/s. The small satelllite's densities (escape velocities) are not known but they are physically puny compared to Pluto. The smallest Pluto moon is a little larger than comet 67P (a solar short period comet from the Kuiper Belt) whose density is only 0.533 g/cm^3 with an escape velocity of 1 meter per sec. |
One meter per second would translate into a lowest potential impact velocity of about 2.25 mph, the average walking speed of a human is about 3.5 mph. This is the slowest an object can impact comet 67p and is likely closely related to the slowest speed objects could collide with Pluto's smaller moons. Impacts this slow should leave evidence of elongated skid mark impacts. At impact velocities this slow, impactors would gently come to rest on the surface to become a part of the main body similar to what we see on asteroid Ryugu. Ryugu has been hit at both high and low impact velocities. There are large round impact craters and rocky rubble piles resting on the surface but the surface appears too chaotic and loose to identify any well defined skid marks. |
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The focus of the Davies/Stuart paper was to support the idea that large scale impacts could produce elevated Pluto temperatures which could be sustained for billions of years and these large scale impacts could produce the active geology we now see at SP 4 byr after the impact event.
At one point in the paper, they refer to the impactor as having a 300 km radius (not diameter) rock composed of dunite impacting head on at 90 degrees down to as low as 45 degree angles. Dunite is a rock material that has a density of about 3.25 g/cm^3. As a point of comparison, granite (same stuff of kitchen counter tops) has a density around 2.75 g/cm3. Dunite is rock that is more dense than granite (requires more kinetic energy to explode on impact). In this model Pluto has a fully differentiated (gray) core. In Figure 1 Davies/Stuart indicate the impactor is 400 km but don't say if it has a 400 km radius or diameter but they do say it is dunite. Putting this together, I conclude they are saying the impactor in the figure 1 model has a radius of 400 km (diameter = 800 km) constructed of dunite rock. >>>>>>>
Pluto's radius is 1188 km (diameter = 2376). As a point of comparison, Pluto's moon Charon has a radius of 606 km with an escape velocity of 0.59 km/s. Charon is only 206 km larger than their SP basin forming impactor. Another critical point in Figure 1 is the speed of the impactor (3 km/s). Something to keep in mind, this paper is focusing solely on impact temperature as the formative factor in Sputnik Planitia's active geology. |
When Robin Canup produced her Charon/Pluto impact model she used an impact velocity of less than 0.9 km/s which could only occur on a body with less mass (gravity, escape velocity) than Pluto.
Pluto's escape velocity is 1.21 km/s and if our Moon and Mars can be used as average impact rate samples then impacts would typically occur 2 to 7 times faster (on average) than its slowest potential impact velocity but never slower than its escape velocity of 1.21 km/s. At speeds greater than 0.9 km/s, things got too messy for Canup's model. Canup's successful collision model also required that the two bodies be uniform not differentiated as differentiation affects mechanical bonding (compaction). |
Robin's modeled bodies are loosely held together releasing energy more gradually or diffusely upon impact. Even in Robin's greater than 0.9 km/s messy scenario's where impactors had differentiated cores the impacts were not head on, they were glancing blows otherwise both bodies would have likely been pulverized and the system would be non existent. Color indicates material type; blue, water ice; orange, dunite; red, iron |
Lets run Dr. Douglas P. Hamilton's (Solar System Collisions) impact simulator with some of these numbers. |
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Plugging in an impactor diameter of 800 km traveling at 3 kilometers per second constructed of rock produces a 3,830 km diameter impact crater to a depth of 33 km. This is a head on collision not a glancing blow.
I created this drawing to show the scale of the 800 km impactor (red) relative to the size of Pluto (blue) and the impact crater (gray) which it would create. A problem becomes immediately apparent. The crater's radius is 61% larger than Pluto. This would have the likely effect of obliterating Pluto, similar to Robin Canup's models. It seems difficult to imagine they could miss this obvious disastrous conclusion but, after all, their model's focus was only on temperature while completely ignoring crater size. Perhaps the surface temperatures would reach 1,000 degrees Kelvin (as their model suggests) under these conditions which is the whole point of the paper but Pluto wouldn't survive the impact so it becomes a mute point to suggest this is how Pluto got hot enough to generate its geology at SP. My red impactor relative to Pluto is the same proportional size as theirs so I'm confident they meant their impactor's radius not its diameter is 400 km. |
In every Canup model simulation, all impact scenarios completely eject Charon or lose all satellite accretion disk material if the initial impact velocity is greater than or equal to 0.9 km/s. |
Robin Canup produced an impact model supporting the Pluto Charon collision concept. Canup, however, was trying to demonstrate how both Pluto and Charon could survive a mutual impact.
She needed to not only slow down the impact by more than the escape velocity of Pluto but Charon had to graze Pluto at a highly oblique angle and on top of that NOT allow the two bodies to be differentiated into a highly compressed rock to ice ratio, otherwise, kaboom. In Canup's successful model, both Pluto and Charon's pre-impact compositions were uniform homogeneous evenly diffused materials, (denser bodies create more explosive impact energy). In her model Pluto lost 8% of its mass so its initial escape velocity would have been greater (1.31 km/s) prior to impact than its current 1.21 km/s yet Robin uses a successful impact velocity of 0.9 km/s. |
For another perspective on the size of the Davies/Stuart 400 km radius dunite rock impactor relative to Sputnik Planitia, I drew this, to scale, image prior to contact.
Completely ignoring the impact crater's size which is 62% larger than Pluto and only looking at the size of the 3.25 g/cm^3 dense dunite impactor, its safe to say that a hard dense rock object which is larger in some places than SP is not responsible for creating the speculatively conjectured SP "crater" basin. On top of that, we must completely ignore the fact that there are NO 400 km dense dunite rocks observed in the Kuiper Belt - ZERO. Rocky asteroids transition to icy bodied objects at the solar system's frost/snow line which is around 3 AU from the Sun. Pluto and the Kuiper belt reside at 30 to 50 AU from the Sun where all objects are ice balls infused with gravel. ALL objects in the KB are ice/rock objects with densities below 2 g/cm^3. But again, let's ignore reality in favor of myth-ematical models. |
Pluto is 30 to 50 AU from the Sun and yet Davies/Stuart use an 800 km diameter dunite rock asteroid in their simulations. Its common knowledge that water rich icy bodies exist beyond the frost/snow line but this doesn't seem to matter. As long as we can make our model say what we want it to say, reality is irrelevant. Fred Whipple was the first to accurately portray the Kuiper belt as a zone beyond Neptune similar to the asteroid belt but 2o times as wide, 20 to 200 times as massive and filled with dirty ice balls. Quote from the Davies/Stuart paper |
In this quote, it sounds like they are doing their due diligence while testing their model but they are missing a few critical points.
The impact crater is 62% larger than Pluto, the velocity is too fast for Pluto to survive the impact, the angles are too steep (compare to Canup's oblique impact angle) and the material is too dense to match potentially real life observable Pluto scenarios but (and this is the point of producing the model), they were able to get the desired impact temperatures up to 1,000 degrees Kelvin (727 C, 1,340 F). |
Look at their model results in this image, the only thing that matters is "The final thermal profile" temperature.
When all you want is a single result of temperature from a model then other fundamental reality factors seem to become irrelevant. Robin's model shows you can't have a survivable Pluto/Charon system with impact velocities greater than 0.09 km/s while the Davies/Stuart model utilizes a 3 km/s head on impact velocity. |
On my Weebles and Wobble pages, I present two plausible scenarios under which Pluto's thermal geological energy could be induced. Lets not forget, there is absolutely no evidence to suggest Pluto has a subsurface ocean of water (currently there are only myth-ematical models supporting the water ocean concept) but there's plenty of evidence demonstrating how nitrogen can and does reach its mobile fluid/liquid and gaseous state (triple point).
Neither scenario requires impact or radiogenic induced heat energy. In a nut shell, what is needed is called tidal flex or tidal stress but its not current tidal flex from an eccentric orbital dance with Charon, rather a tidal flex induced energy from obliquity tides (axial polar precession induced tidal torque (wobble)). All that's needed is axial wobble which is a known existing process on Pluto. |
November 21, 2018
I just came across this statement by Luu and Jewitt in which they quote a 1995 Stern paper. The quote says that collisional timescales between objects within the KB with a diameter larger than 100 km (50 km radius) are longer than the age of the solar system. |
Next, I'll run Bill McKinnon's SP basin creation impactor sizes (150 km, 250 km diameter) through Hamilton's impact simulator.
Perhaps smaller bodies of this size will be able to produce SP which is considered by Bill to be a 4 byr geologically active impact "crater" basin. Smaller impactors mean less energy so now we have to migrate away from the idea that the active temperature driven geology at SP was created by an impactor and simply move into physical diameter characteristics of the crater and ignore the geological activity at SP. How do McKinnon's impactor sizes compare when run through the impact simulator? Bill's objective is to demonstrate how an impactor can create the physical dimensions or perimeter of SP. As a matter of fact he originally used an impact angle of 5 degrees along with this Mars elongated impact skid mark image to suggest this is how SP got its irregular shape. |
When Bill was asked "if SP was formed from a low angle impact, where's the butterfly ejecta", he simply agreed and said astute observation as if someone has to be astute to see the obvious fallacy in Bill's errant concept.
One problem for the 5 degree impact scenario is that SP traverses Pluto's horizon. SP is longer than the arch of its sphere. In other words, a 5 degree, 3 km/s impact would skim the surface continuing off into space not bend around the arch (horizon) of Pluto. He later changed this 5 degree impact angle to greater than 45 degrees. which would then create a circular exploded hole not an elongated pear shape which is the observed shape of SP. Bill's impactor's are much smaller than Davies/Stuart as he is not trying to use an impact to explain the heat that is driving the geology. Bill uses a differentiated radioactively hot core to explain the geology so impact temperature is not a focus for him only impact crater dimensions. Running the simulator for objects 150 to 250 km diameter at 3 km/s constructed of both rock and ice gives a crater range from 360 km to 885 km at depths of 16.2 to 21.3 km. |
Impact craters have steep walls because of the explosion and SP has some areas where the nitrogen migrates slowly onto the bedrock ice similar to a beach or swamp.
Based on the largest size of the Sputnik Planitia nitrogen "polygonal convection cells" that make up its surface, the deepest SP's basin can be is 9 km (according to Stern, McKinnon and Nimmo).
While that is a maximum depth, Bill's largest scale impactor would produce a crater 18.5 km deep which is more than twice the possible depth based on their own assessment. |
Kelsi Singer used impacts to age date the Pluto system at 4 byr but there were several problems with her method.
Loosely compacted regolith was used to scale the data points in her paper even though it is known spectrographically that Pluto's small moon's surfaces are bright young ice not 4 byr old dark cosmically radiated regolith dust. Singer also removed 10 of the 19 impacts from the data set and she then had the nerve to call this manipulated chart data "proof" of their old age. Here again we have the creation of myth-ematical models/charts used as evidence to ignore actual real observations. Lets ignore the fact these moons are water ice and skew the scaled data with regolith to push the results toward our expected outcome. |
Instead, what we have taking place with this New Horizons team is reality is substituted with models favoring conjecture over observational evidence.
Davies/Stuart utilize 800 km rocks where none exist, Canup uses impact speeds slower than possible, Mckinnon employs self contradicting concepts while Singer alters and falsifies data in order to produce models that support their concepts not observations. When observational evidence is completely ignored in favor of constructing self gratifying egotistically driven models, then understanding reality is no longer the objective. Stroking my ego is the objective. KABOOM!!! |
Rockets, moon shots
Spend it on the have nots Money, we make it Fore we see it you take it Oh, make you wanna holler The way they do my life Make me wanna holler The way they do my life This ain't livin', this ain't livin' No, no baby, this ain't livin' No, no, no Inflation no chance To increase finance Bills pile up sky high Send that boy off to die Make me wanna holler The way they do my life Make me wanna holler The way they do my life Dah, dah, dah Dah, dah, dah |
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