Marcus MacGregor

true it varies as the sixth root of gearth/gmars so about 10% size difference. Still close enough to give a good feel for it. ie: D=0.07Cf(ge/g)1/6(W pa/pt)1/3.4Where: D = Crater Diameter Cf = Crater Collapse Factor ( this is equal to 1.3 for craters >4km on Earth) ge = Gravitational Acceleration at the surface of Earth g = Acceleration at the surface of the body on which the crater is formed W = Kinetic Energy of the impacting body (in kilotons TNT equivalent) pa = Density of the impactor (ranging from 1.8g/cm3 for a comet to 7.3g/cm3 for an iron meteorite). pt = Density of the target rock

True, this can be seen by throwing a rock at sand for example, but the larger the crater the more melt will be in the crater. This melt will tend to flatten out the bottom. Now a nice site for calculating impact effects is this one: http://impact.ese.ic.ac.uk/ImpactEffects/ Using a 400km iron meteor @51km/s and 45 degrees with sedimentary rock, produces a crater close to Hellas size that is completely engulfed by its melt. Feel free to change the parameters. (I find it fun and interesting to see the different effects.) The bottom gets flattened by impacts orders of magnitude smaller than this. This is the crater being engulfed.

Excellent comments, very insightful and helpful. I do imagine there is a range where the influence of gravity deforms another surface to just leaving a mound, all the way to where it deforms the entire side or even entire surface. This is simply an intermediate value. The videos do make many artistic liberties, including the tilt of Mars and the z direction of the impact. The north side facing Jupiter depends what 'season' Jupiter is in. Thank you, that helps limit the possible trajectories. I'm working on several different scenarios regarding the trajectory. The main one is that Mars was caught at L5 for a short time and looped around Jupiter causing a gravity "assist" which actually decelerates it. A quick calculation shows that the new total energy is about the same as the new orbit. However, the e is higher than what we see today (Mars does still possess a fairly high e) so this requires perturbations from other planets to slowly correct itself over a long long time. Alternately, a second close encounter can correct it quickly. Alternately, I read about a N-Body simulation that posited Jupiter being within Mars's current orbit during the formation (end oligarchic; 4.1-3.8Gy) stage then migrates outward due to type II planetary migration. Then Mars can just start with approximately it's current orbit after the encounter When Mars loops around Jupiter it triggers the explosive volcanism. The gravity on the close side drop to net zero, but all the individual particles are still all in "free fall" together. The mass that is thrust up moves via internal pressure (like Enceladus, or any geyser). Thus there is a maximum size. The east-west difference is caused largely by rotation and pressure reduction. Thank you, this is something I will have to explain in depth. The difference in basin depth is curious. If the basin was created by an impact; wouldn't the basin be a uniform depth? The impact melt should settle uniformly (more or less). Seems like that is supporting evidence, (thanks!) but I will need to think about how this scenario explains it more clearly. My math is in several notebooks. I'll compile them for viewing. Thanks again, I don't necessarily expect to convince you but articulate reason for being dubious are refreshing. PS-Erosion has been shown to remove the signs of melting; do you know the paper/text? I'd love to read it. Where did it erode to? up and out of the basin?

Hello, A few years back I had the idea that the topography of Mars could have been largely created by a close encounter with Jupiter. I posted it on several forums and got some great responses. (And some angry trolls, but hey it is the internet so what can you do) The introduction video to this idea is here: http://youtu.be/mGOsw8CLxmE This is a flyby that tears out the Hellas basin. I found that a great many people thought that it went by the Roche limit. I'd just like to point out ahead of time that Mars has a fairly high density so the Roche limit does not come into play. I made a video showing the location of some things around Jupiter because of this common confusion. http://youtu.be/PJumdRcZcUA I just made a video showing what I consider to be the most easily grasped evidence of this: http://youtu.be/zHGX_ZQwGdA I have a video planned for the trajectory of the event. I found that many people are convinced that falling into Jupiter or being flung out of the solar system are the only options. I found many planetary scientists I contacted recommended the L4 or L5 lagrangian point as the start of the trajectory. I have decided to adopt this rather than my initial idea of a highly elliptical Mars triggered by a orbital resonance. L4 would accelerate while L5 would decelerate leading to the correct Hamiltonian. I also have a video planned for the timing of the event. One commenter noted that we would of totally noticed this happening. I guess he was thinking that it was breaking news. We have been watching Mars for quite some time and although it saddens me that I have to make it explicit- This event occurred before the invention of astronomy. So I'm posting on this forum to see if there is other flaws of this idea that I have not addressed. I want to run it by as many people as possible before I start the laborious task of submission to journals. So, if you think you have a debunking concept or just a facet of the idea that needs more depth please tell me. It may be something I have worked out already but have not mentioned, but hopefully it might be something that I have missed. I have had this idea for awhile so it appears obvious to me, I understand if it does not appear so to you; I'd like to know why you have a dubious perspective. If you don't accept the idea but don't have a reason why, perhaps you can share it with someone who can come up with a reason. If you like the idea and have a piece of supporting evidence I have not mentioned, that would be great too. If you simply like the idea, I always appreciate a like, share or nice comment. The internet can be a very negative place. Thank you.

This is an odd news report from today... New solar system formation models indicate that Jupiter's foray robbed Mars of mass June 5, 2011 article Planetary scientists have long wondered why Mars is only about half the size and one-tenth the mass of Earth. As next-door neighbors in the inner solar system, probably formed about the same time, why isn't Mars more like Earth and Venus in size and mass? A paper published in the journal Nature this week provides the first cohesive explanation and, by doing so, reveals an unexpected twist in the early lives of Jupiter and Saturn as well. Dr. Kevin Walsh, a research scientist at Southwest Research Institute® (SwRI®), led an international team performing simulations of the early solar system, demonstrating how an infant Jupiter may have migrated to within 1.5 astronomical units (AU, the distance from the Sun to the Earth) of the Sun, stripping a lot of material from the region and essentially starving Mars of formation materials. "If Jupiter had moved inwards from its birthplace down to 1.5 AU from the Sun, and then turned around when Saturn formed as other models suggest, eventually migrating outwards towards its current location, it would have truncated the distribution of solids in the inner solar system at about 1 AU and explained the small mass of Mars," says Walsh. "The problem was whether the inward and outward migration of Jupiter through the 2 to 4 AU region could be compatible with the existence of the asteroid belt today, in this same region. So, we started to do a huge number of simulations. "The result was fantastic," says Walsh. "Our simulations not only showed that the migration of Jupiter was consistent with the existence of the asteroid belt, but also explained properties of the belt never understood before." The asteroid belt is populated with two very different types of rubble, very dry bodies as well as water-rich orbs similar to comets. Walsh and collaborators showed that the passage of Jupiter depleted and then re-populated the asteroid belt region with inner-belt bodies originating between 1 and 3 AU as well as outer-belt bodies originating between and beyond the giant planets, producing the significant compositional differences existing today across the belt. The collaborators call their simulation the "Grand Tack Scenario," from the abrupt change in the motion of Jupiter at 1.5 AU, like that of a sailboat tacking around a buoy. The migration of the gas giants is also supported by observations of many extra-solar planets found in widely varying ranges from their parent stars, implying migrations of planets elsewhere in universe. More information: "A Low Mass for Mars from Jupiter's Early Gas-Driven Migration," Nature, June 5, 2011.

Those ten points were addressed in the other forum. Since we have an active discussion there I will focus on the other people here. Mars was able to get away from Jupiter gravitational field since it has the momentum gained by falling into Jupiter's field. This is much like comets are able to escape the Sun's even larger gravity well, there is no (very,very little) drag to slow them down.

Excellent point. The simple answer is that this happened a long time ago. The timeframe I am focusing on right now is the Late Heavy Bombardment period, 3.8 Billion years ago. This gives an annual decay rate of Mars's orbit of 145 meters, which I can walk in a few minutes (some people can do it in seconds but I'm not that fit) This seems like a reasonable number, since it is well below the amount of chaos expected in an orbit.

I have looked at the topography of Mars and have come to the conclusion that it was formed primarily by a cataclysmic event with Jupiter. I made a video to show basically what I am suggesting. Any thoughts?