September 24th, 2018
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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. |
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The high and low end velocity range of an object is largely dictated by its distance from the Sun (high end gravitational escape velocity) and the gravitational escape velocity of the impacted body (low end velocity). At Earth's orbital distance from the Sun and gravitational mass acceleration, impact velocities vary from 11.2 to 72.8 km/s, while at Pluto's distance and density, impact velocities vary from 1.1 to 11.4 km/s. The slowest an impactor can hit an object like Earth is equal to the Earth's escape velocity. The escape velocity is the speed at which Earth's gravity is pulling objects toward itself. Once an object is close enough to impact it, Earth's gravitational pull will accelerate it inward to at least its escape velocity.
Earth bulges at its equator (sorta like sitting on a beach ball) because of its spin speed and that bulge places Earth's equatorial land mass further away from its center hence the escape velocity at the equator is slightly less than at the axial poles. This is why all space vehicle launch facilities are built near the equator, it takes less energy (fuel) to escape Earth's pull at locations farthest from its core.
Earth bulges at its equator (sorta like sitting on a beach ball) because of its spin speed and that bulge places Earth's equatorial land mass further away from its center hence the escape velocity at the equator is slightly less than at the axial poles. This is why all space vehicle launch facilities are built near the equator, it takes less energy (fuel) to escape Earth's pull at locations farthest from its core.
Credit Boris Ivanov
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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.
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. | ||
The exception to this rule is when the impact angle is so obtuse that its center of mass misses impact and only the edge grazes the surface, sorta like skipping a stone across a smooth lake. This skipping stone angle is considered to be less than 5 degrees. At an impact angle of less than 5 degrees, the kinetic energy of the object's mass misses direct impact. On a planet like Mars where the atmosphere is thin this can and has occurred on Earth it is less likely but still possible.
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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. <<<<<<<< 
An elongated < 5 degree impact angle crater on Mars. At LPSC 2016 Bill McKinnon used this crater as supportive evidence for an impact creating Sputnik Planitia
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Asteroid exploding in atmosphere over Chelyabinsk Russia
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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. |
A rock hard ice ball requires less kinetic energy to reach its exploding point than a rock hard ice ball infused with sand or gravel just like granite requires more speed to make it explode than frozen rock hard water ice. When an object hits a planet and explodes, energy is released rapidly and radially creating circular broad based shallow rim divots or craters regardless of their impact angle.
At the point of explosion, the object's forward momentum (kinetic energy) is lower than its explosive discharge energy and the objects exploding force pushes outward radially with more force than its forward velocity. Impactor's contain irregularities of compounds with variations in binding strength (fractures and porosity) so multiple explosions (while impacting an atmosphere) often occur as the object breaks apart into smaller pieces. When there is no atmosphere to impact, usually all the exploding energy is released in one rapid explosive collision event.
At the point of explosion, the object's forward momentum (kinetic energy) is lower than its explosive discharge energy and the objects exploding force pushes outward radially with more force than its forward velocity. Impactor's contain irregularities of compounds with variations in binding strength (fractures and porosity) so multiple explosions (while impacting an atmosphere) often occur as the object breaks apart into smaller pieces. When there is no atmosphere to impact, usually all the exploding energy is released in one rapid explosive collision event.
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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. |
Nix's erratic orbital axial pole wobble
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There are a few larger detectable impacts on the small satellites all of which are round. The small satellites wobble quite rapidly and have very low escape velocities they should then logically display skid mark impacts, that is, if those impacts were occurring at slower speeds less than 1 km/s.
Comet 67P image credit ESA
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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. |
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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. |
Ryugu asteroid image credit JAXA & Roman Tkachenko
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Relative scale size of Ryugu compared to Manhattan Island NY US
Absolutely amazing image of Ryugu asteroid credit JAXA/University of Tokyo & Roman Tkachenko
Figure 1. Image of Ryugu captured by the ONC-T at an altitude of about 64m. Image was taken on September 21, 2018 at around 13:04 JST.This is the highest resolution photograph obtained of the surface of Ryugu. Bottom left is a large boulder. (Image credit※: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST).
Figure 2. Region of the highest resolution image. Yellow boxes correspond to the region in Figure 1. (Left) The region is shown on the ONC-T global image of Ryugu. (Right) ONC-W1 image, taken at 70 m height. 2018-09-21 13:02(JST). (Image credit※: JAXA, University of Tokyo, Kochi University, Rikkyo University, Nagoya University, Chiba Institute of Technology, Meiji University, Aizu University, AIST).
WOW! WOW, WOW, spectacular.
Stunning images of Ryugu as of Sept 27, 2018
If you've ever wondered why scientists use the term rubble pile when describing solar system bodies, that should no longer exist as a question in your mind.
WOW!
Amazing stuff, congratulations to JAXA.
Back to the main theme.
This web site has an interesting asteroid/comet impact simulator (created by Dr. Douglas P. Hamilton) for solar system bodies like Pluto. It allows you to place the size, velocity and composition (ice, rock, iron (density)) of the impactor into the simulator and out comes the diameter and depth of the crater created by the impact. I've copied Dr. Hamilton's script here so if you use it, you'll have to use your browser's back button to return here.
Stunning images of Ryugu as of Sept 27, 2018
If you've ever wondered why scientists use the term rubble pile when describing solar system bodies, that should no longer exist as a question in your mind.
WOW!
Amazing stuff, congratulations to JAXA.
Back to the main theme.
This web site has an interesting asteroid/comet impact simulator (created by Dr. Douglas P. Hamilton) for solar system bodies like Pluto. It allows you to place the size, velocity and composition (ice, rock, iron (density)) of the impactor into the simulator and out comes the diameter and depth of the crater created by the impact. I've copied Dr. Hamilton's script here so if you use it, you'll have to use your browser's back button to return here.
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Astronomy WorkshopThe lower end speed restriction for Pluto in this simulator is 1.1 km/s (Pluto's gravitational escape velocity (the equivalent of NASA's 1.21 km/s)) and the upper end speed restriction is 11.4 km/s (roughly twice the orbital velocity around the Sun at 30 - 50 AU). Pluto's orbital velocity is about 6 km/s so an object traveling pretty much in the opposite direction could potentially impact with the equivalent kinetic impact energy of 12 km/s. The simulator values are pretty closely related to the NASA values for the fastest and slowest velocities an object can impact Pluto.
To my knowledge, three impactor sizes (400 km, 125 km, 75 km radius) have been proposed as creators of the Sputnik Planitia basin on Pluto. At the 47th LPSC conference in 2016, E. J. Davies & S. T. Stuart produced the below paper to support this concept.
Bill McKinnon as well as Davies/Stuart hypothesized an impactor hit Pluto 4 byr ago creating the Sputnik Planitia basin and produced Pluto's active geology. This concept has also been modified to include radiogenic heat from a differentiated rock/iron core with a radius of 850 km as the formation source of an underground ocean of water by F. Nimmo.
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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. |
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In their model there is no impact crater, no debris, no reflection of a realistic impact all they choose to consider is temperature. Crater size is irrelevant in their model as they only want to support a temperature induced scenario by impactors but as we will soon see crater size matters a lot.
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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). |
Credit Robin Canup
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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 |
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Robin Canup paper quote
A second result is that oblique collisions with vimp > 1.3vesc (impact velocities greater than or equal to 1.3 km/s (0.088 km/s higher than the escape velocity)) or (v > 0.9 km/s for Mt ~ MPC) (impact velocities greater than or equal to 0.9 km/s for a system with a total mass approximately equal to the combined mass of Pluto and Charon) do not produce massive disks or satellites orbiting the primary, and this was true for all of the simulations.
Discussion.
This work identifies a range of impacts capable of producing Pluto-Charon type systems.
The impacts are low-velocity (v < 0.9 km/s) oblique collisions by an impactor containing 30 to 50% of the Pluto-Charon system’s mass
Pluto's escape velocity (gravitational pulling speed) is 1.212 km/s. In other words, the slowest an object can possibly impact the surface of Pluto is 1.212 km/s but all Canup's impact scenarios fail at velocities above 0.9 km/s.
The below chart was created by Sarah Greenstreet. In it you can see that the highest average percent of (3:2 resonant black line) objects colliding with Pluto is 9.3% impacting at 1.7 km/s. Follow that black line to the left down to the 1.2 km/s tick mark and impacts drop to zero because nothing can impact Pluto slower than this as its gravitational pull accelerates objects to at least this velocity.
A second result is that oblique collisions with vimp > 1.3vesc (impact velocities greater than or equal to 1.3 km/s (0.088 km/s higher than the escape velocity)) or (v > 0.9 km/s for Mt ~ MPC) (impact velocities greater than or equal to 0.9 km/s for a system with a total mass approximately equal to the combined mass of Pluto and Charon) do not produce massive disks or satellites orbiting the primary, and this was true for all of the simulations.
Discussion.
This work identifies a range of impacts capable of producing Pluto-Charon type systems.
The impacts are low-velocity (v < 0.9 km/s) oblique collisions by an impactor containing 30 to 50% of the Pluto-Charon system’s mass
Pluto's escape velocity (gravitational pulling speed) is 1.212 km/s. In other words, the slowest an object can possibly impact the surface of Pluto is 1.212 km/s but all Canup's impact scenarios fail at velocities above 0.9 km/s.
The below chart was created by Sarah Greenstreet. In it you can see that the highest average percent of (3:2 resonant black line) objects colliding with Pluto is 9.3% impacting at 1.7 km/s. Follow that black line to the left down to the 1.2 km/s tick mark and impacts drop to zero because nothing can impact Pluto slower than this as its gravitational pull accelerates objects to at least this velocity.
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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. |
Substituting ice for rock in the impact simulator reduces the diameter of the crater down to 2,650 km with a depth of 29.6 km. This is still far too large (larger than Pluto by 12%) to have created SP with its active geology as SP's dimensions are considered 900 km x 1,300 km not to mention an ice ball impactor would not generate the heat they were looking for.
This presents a reasonable question; could a 400 km radius dunite rock create Sputnik Planitia?
Answer; no.
Question; Why run a model to prove an invalid point?
Answer; Ignore the physical characteristics of SP and simply focus on temperature to prove geology. This is the problem with creating models with an expected outcome.
Pluto's geological temperature must be accounted for as its geology is visible from a lack of impact craters at SP (surface viscous relaxation) and this giant impact concept is far too weak to hold up to even the simplest rudimentary degree of scrutiny, consequently, another concept must be produced, hence a differentiated radioactively hot core concept. Most papers I've read infer or plainly state (errantly) that the Robin Canup Pluto/Charon collision model caused Pluto to separate its ice from its rock and its rock from its iron to form a fully differentiated core but Canup's model states and supports exactly the opposite.
This presents a reasonable question; could a 400 km radius dunite rock create Sputnik Planitia?
Answer; no.
Question; Why run a model to prove an invalid point?
Answer; Ignore the physical characteristics of SP and simply focus on temperature to prove geology. This is the problem with creating models with an expected outcome.
Pluto's geological temperature must be accounted for as its geology is visible from a lack of impact craters at SP (surface viscous relaxation) and this giant impact concept is far too weak to hold up to even the simplest rudimentary degree of scrutiny, consequently, another concept must be produced, hence a differentiated radioactively hot core concept. Most papers I've read infer or plainly state (errantly) that the Robin Canup Pluto/Charon collision model caused Pluto to separate its ice from its rock and its rock from its iron to form a fully differentiated core but Canup's model states and supports exactly the opposite.
Robin Canup's Pluto/Charon collision model
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. 
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Canup's successfully modeled impact velocity must then impact slower than is possible based on Pluto's escape velocity of 1.21 km/s. In a successful impact scenario, both bodies impacted slower than possible and less than 5% reached a max impact temp of 250 K at the surface which has the effect of leaving both worlds, after the collision, intact, uniform, geologically cold and inactive (dead). Notice Robin's temperature scale doesn't go above 250 Kelvin.
We are then left with two problems in Robin's simulations.
The Davies/Stuart impactor was only 200 km smaller than Charon, hit Pluto head on, was a solid dunite rock with a density of 3.25 g/cm^3, impacted at 3 km/s and generated temperatures up to 1,000 K but would have destroyed the system. Canup's impossibly slow impacting velocity (0.9 km/s) model keeps the system intact but leaves them uniform cold and dead with nothing to jump start their geological pulse.
Both impact models defy reality yet produce the expected non realistic results.
In the Nice grand tack model, 4 byr ago Neptune migrated outward pushing Kuiper Belt bodies like Pluto further away from the Sun and theoretically created the late heavy bombardment. If Pluto was 10 AU closer to the Sun and was pushed outward by Neptune then its orbital speed would have been faster (around 7 km/s) than it's current orbital velocity (4.7 km/s) which would have caused objects to impact at greater velocities in turn creating larger impact explosions. This is the same basic time frame when Canup and Davies/Stuart's impact concepts were taking place.
We are then left with two problems in Robin's simulations.
- Minimum impact velocity is less than possible considering Pluto's escape velocity, even if we completely ignore this problem;
- After the impact, both bodies remain undifferentiated and too cold to become geologically alive.
The Davies/Stuart impactor was only 200 km smaller than Charon, hit Pluto head on, was a solid dunite rock with a density of 3.25 g/cm^3, impacted at 3 km/s and generated temperatures up to 1,000 K but would have destroyed the system. Canup's impossibly slow impacting velocity (0.9 km/s) model keeps the system intact but leaves them uniform cold and dead with nothing to jump start their geological pulse.
Both impact models defy reality yet produce the expected non realistic results.
In the Nice grand tack model, 4 byr ago Neptune migrated outward pushing Kuiper Belt bodies like Pluto further away from the Sun and theoretically created the late heavy bombardment. If Pluto was 10 AU closer to the Sun and was pushed outward by Neptune then its orbital speed would have been faster (around 7 km/s) than it's current orbital velocity (4.7 km/s) which would have caused objects to impact at greater velocities in turn creating larger impact explosions. This is the same basic time frame when Canup and Davies/Stuart's impact concepts were taking place.
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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. |
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Ignoring the obvious while building models, appears to be a somewhat accepted practice among some of these NASA scientists. As long as complicated concepts are used, their paper's are accepted.
In 2011 Turrini et al produced a paper in which four scenarios for Jupiter's migration is considered and its impact on pushing asteroids and comets around the solar system. Jupiter is tested as it migrates from 6.25 AU inward to 5.25 AU. The below image displays the results of those scenarios.
In 2011 Turrini et al produced a paper in which four scenarios for Jupiter's migration is considered and its impact on pushing asteroids and comets around the solar system. Jupiter is tested as it migrates from 6.25 AU inward to 5.25 AU. The below image displays the results of those scenarios.
Ordinary rocky asteroids also known as chondritic and carbonaceous exist sunward of 3 AU (red & dark blue) while water rich (H2O) comets (light blue) only exist outward of 3 AU.
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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 |
Fred Whipple with his Kuiper belt dirty snowball concept
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Numerical Method: We conducted impact simulations using the 3D Eulerian shock physics code CTH, including self-gravity. Ice and rock were modeled using multi-phase equation of states for water and forsterite. The pressure, temperature, and strain-rate dependent rheological model includes a brittle regime for the crust and uppermost mantle and a creep regime for the deeper mantle. The rheological model weakens ice at the melting curve of water. The peridotite solidus and olivine liquidus are used to calculate melting of rock. Crater collapse involves a two-phase flow of melt and solid clasts. This complex debris flow is modeled using a simplified approach: when the temperature exceeds the solidus, (i) a pressure-dependent friction law (coefficient of 0.1–0.2 based on melt-lubricated faults) is used at high strain rates (>10-4 s-1) and (ii) a Newtonian fluid rheology is used at low strain rates (when the viscosity of the fluid dominates. Model parameters are constrained by laboratory data.
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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). 
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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. |
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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. 
Hector Javier Durand-Manterola illustration
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Another potential source of tidal flex energy could be when Pluto/Charon align in conjunction (mutual eclipse) at perihelion (direct vs perpendicular orbital alignment with the Sun while closest to it) Weeble.
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This occurred in 1988 and occurs twice every Pluto season both at perihelion and aphelion. The potential flexing stress would obviously be stronger at perihelion. We see how tidal flex heats Jupiter's moon Io, Europa and Ganymede. |
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We see tidal flex energy on Saturn's tiny (one third the size of Charon) moon Enceladus creating geological activity on this puny world. We see it on Neptune's moon Triton (Pluto's twin). Pluto's nitrogen does not require much flex energy to become mobile. |
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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. |
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But lets go ahead and assume Bill McKinnon's fantasy 150-250 km impactor hit Pluto.
James Keane notes of Bill McKinnon lecture
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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. |
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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. |
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These dimensions fit within the smallest perimeter of SP which is 900 km but there are no known 250 km rocks in the Kuiper belt all the objects are ice/rock material so I will instead use a middle range between an impact crater of 360 km for ice and 885 km for rock which gives a rough impact crater size of 622 km which turns out to be too small to have formed SP.
If Bill's impactor grazed Pluto at a 5 degree angle it would need to bend over the horizon to create the 1,300 km skid mark and form a nonexistent butterfly ejecta pattern both of which are ridiculous so Bill gave up on this skid mark idea pretty quickly and instead went with a greater than 45 degree impact angle which would make a circular impact crater.
Gravel infused ice balls explode at velocities of 3 km/s. With greater impact angle comes a question of impact depth.
If Bill's impactor grazed Pluto at a 5 degree angle it would need to bend over the horizon to create the 1,300 km skid mark and form a nonexistent butterfly ejecta pattern both of which are ridiculous so Bill gave up on this skid mark idea pretty quickly and instead went with a greater than 45 degree impact angle which would make a circular impact crater.
Gravel infused ice balls explode at velocities of 3 km/s. With greater impact angle comes a question of impact depth.
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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.
Gradually sloped bedrock land migrating into SP
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. |
Gradually sloped bedrock land ice migrating into SP
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At impact angles of 45 degrees and greater along with velocities of 3 km/s, impactors explode forming round craters not pear shaped geologically active features with beaches similar to what is observed at SP. In case that statement slipped by you, I'll say it again. To my knowledge there are NO impact craters in the solar system that are geologically active, SP acts and looks much more like a volcanic caldera than an impact crater. Geology can create craters both active and inactive, impacts on the other hand create only inactive craters. Sputnik Planitia is an active basin.
Both Bill and Davies/Stuart's impact scenario models fail to stand up to reason and reality as does Robin Canup's.
Both Bill and Davies/Stuart's impact scenario models fail to stand up to reason and reality as does Robin Canup's.
Age dating via impacts
P. T. Doran et al., 2004 released a paper about age dating Martian events based on impact craters and had this to say about the process.
Currently, the absolute chronology of Martian rocks, deposits and events is based mainly on crater counting and remains highly imprecise with epoch boundary uncertainties in excess of 2 billion years. Uncertainties more than 2 billion years.
Currently, the absolute chronology of Martian rocks, deposits and events is based mainly on crater counting and remains highly imprecise with epoch boundary uncertainties in excess of 2 billion years. Uncertainties more than 2 billion years.
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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. |
New Horizons team spectrograph of Charon, Hydra, Nix, Ice
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These scientists are perplexed by the brightness of Pluto's small moons as in their minds the moons are 4 byr old and should be dark like all other Plutinos.
When age dating Pluto's surface by counting the quantity of impacts Kelsi Singer et al., failed to recognize the presence of some of the craters as cryovolcanically (geologically) produced. This in turn, errantly increased the number of observed impacts. Observational evidence displayed infrequent impacts in some areas of both Pluto and Charon's surface. Since the observations of young surfaces didn't match their models, Pluto/Charon's ages were determined to be 4 byr based on models not observations (see my dating page).
If they would simply stop substituting their models for reality, the explanation for the small moons bright albedos becomes obvious. They aren't that old and the falsified data used to support their old age theory is nothing more than a self induced coma of illusion. The small moons of Pluto are not 4 byr old they are much younger and their albedos prove it, their erratic tumbling's suggest it, their bright ice signatures scream it but these scientists deny it based on falsified data from 3 and 11 impacts that has an error factor greater than 2 billion years.
My point is this.
Real observations are ignored by this New Horizons team in favor of myth-ematical models.
My problem with these papers is they contain so much reality contradicting information as to render them and their conclusions pointless. Models are essential in understanding cosmic phenomenon but not when observational evidence is ignored and instead substituted with them.
When age dating Pluto's surface by counting the quantity of impacts Kelsi Singer et al., failed to recognize the presence of some of the craters as cryovolcanically (geologically) produced. This in turn, errantly increased the number of observed impacts. Observational evidence displayed infrequent impacts in some areas of both Pluto and Charon's surface. Since the observations of young surfaces didn't match their models, Pluto/Charon's ages were determined to be 4 byr based on models not observations (see my dating page).
If they would simply stop substituting their models for reality, the explanation for the small moons bright albedos becomes obvious. They aren't that old and the falsified data used to support their old age theory is nothing more than a self induced coma of illusion. The small moons of Pluto are not 4 byr old they are much younger and their albedos prove it, their erratic tumbling's suggest it, their bright ice signatures scream it but these scientists deny it based on falsified data from 3 and 11 impacts that has an error factor greater than 2 billion years.
- Davies/Stuart want to explain Sputnik Planitia's geologic temperature via an impact so they employ a non existent 800 km diameter dunite rock with a density of 3.25 g/cm^3 even though none exist in the Kuiper Belt. They run it at 3 km/s head on into Pluto and completely ignore the catastrophic effect of the resultant crater/impact which would be 62 percent larger than Pluto but in this non reality process they get their desired 1,000 degrees Kelvin temperature. Kuiper Belt Objects are ice/rock bodies with densities < 2 g/cm^3. Eight hundred kilometer dunite rocks don't exist in the Kuiper belt.
- Robin Canup want's a Pluto/Charon impact where both survive intact so she slows the impact to 0.9 km/s which is below the lowest possible Pluto escape velocity of 1.21 km/s. Robin also utilizes evenly mixed uniform bodies to achieve her desired result which don't heat enough to form differentiated cores or active geology.
- Bill McKinnon wants an impactor that creates the shape of the SP basin so he employs a less than 5 degree 150-250 km object that would skip off into space without wrapping around the arch of the planet so he alters the impact angle to greater than 45 degrees which would then cut a crater too deep and round to match observations according to their own estimates.
- Kelsi Singer wants to prove the age of the system is 4 byr old so she presents data that is scaled to reflect regolith covered moons when spectroscopic signatures prove the moons are bright colored ice surfaces. She also removes more than half the data points to support her concept and completely falsifies the chart data but gets her desired "proof".
- I could add Francis Nimmo to this group with his reality altering and self contradicting comments but his expertise is in the field of oceans not impacts and this page is about impacts so he gets a pass (for now).
My point is this.
Real observations are ignored by this New Horizons team in favor of myth-ematical models.
My problem with these papers is they contain so much reality contradicting information as to render them and their conclusions pointless. Models are essential in understanding cosmic phenomenon but not when observational evidence is ignored and instead substituted with them.
Observational evidence is supposed to be the rule by which models are constructed.
In real science, when models don't match observational evidence the models are adjusted to match the observations.
In real science, when models don't match observational evidence the models are adjusted to match the observations.
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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!!! |
Observational evidence of gravity demonstrates the effect of escape velocity
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Drops the mic and walks away!
Make me wanna holler
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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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