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Comments and links from David McClintock's presentation
https://www.youtube.com/watch?v=yXq1i3HlumA
Science Today: Simulating Solar System Formation | California Academy of Sciences
At minute 2:00 begins
Planetary Migration Simulation by Konstantin Batygin, Michael E. Brown, Wesley C. Fraser -- California Institute of Technology
So there was this mass of stuff. For a starting assumption, let’s imagine there was no difference between some part and any other part. The gravity of even little bits attracted other bits, so little bits clumped into larger bits, which had more gravity, which pulled in even more bits. Bigger bits tended to suck in and clear out their immediate neighborhood of most little bits.
As bits came in and clumped, they didn’t happen to all arrive from every side evenly. So the earliest clumps developed some spin. That resulted in rotating gravitational fields which meant later arrivals were attracted inwards to a spinning mass in a preferred spiral path. Eventually the whole mass developed a pronounced spin with a particular orientation.
That spin separated stuff into different parts. It takes more energy to move dense objects than thin lighter ones. So towards the center, denser parts concentrated. Outwards were less dense materials. The spinning increased the separation of materials into more distinct differences. Our outer planets are huge gas giants. Inwards we find smaller but vastly denser planets.
That separation of stuff into different types of stuff is leading us to explore different asteroids and planets because, well, they are so very different.
Mercury is a more fascinating place than we used to suppose.
It is a very dense planet.
Its core seems to make up 85% of the entire planet’s diameter
versus our core takes up about about 18% of Earth’s diameter.
Daytime temperatures on Mercury can exceed 450C (over 840F)
But, there may be water ice at Mercury’s poles!
We humans have sent two spacecraft to Mercury:
NASA’s Mariner 10 (which flew by Mercury but did not get to orbit the planet)
and
NASA’s Messenger (which did orbit Mercury but took seven years into orbit)
On the 19th of this month, we sent a third: BepiColombo.
(It too will take about seven years to get itself into orbit)
Since it will be awhile before we receive results from BepiColombo, the best we have about from Mercury is from the Messenger mission.
So here is a short bit about the Messenger mission:
https://www.youtube.com/watch?v=HmAa7khK-Sk
Since most of what we know today is from the Messenger mission, it is worth looking at what was actually found and the curiosities and questions we hope to learn more about from BepiColombo. So I commend to your attention this longer video:
Exploring Mercury by Spacecraft: The MESSENGER Mission
https://www.youtube.com/watch?v=xQ-dm2zHljk
About the BepiColombo spacecraft, no one does a more informative job than the Japanese space agency JAXA:
http://global.jaxa.jp/activity/pr/brochure/files/sat27.pdf
For why it takes seven years, insertion into orbit around Mercury requires a substantial change of velocity of the spacecraft, about a 10 km/s reduction change of velocity - that is to slow down by about 22,370 miles per hour. It takes a lot of energy to slow down the spacecraft, actually it takes a lot of energy to change an orbit. Here is
Brief - Why Energy goes up to change Orbits
attached is the pdf file
For a decent overview of the BepiColombo mission:
For a little bit about ion engines:
https://www.youtube.com/watch?v=N6lPlyMUtf4
Thanks for listening.
And remember, a tea-cozy, an
English Boomerang Always Returns.
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