# General QuestionPerseid Meteor Shower Orbiter Simulation

#### boogabooga

##### Bug Crusher
I had a wonderful view of the Perseid meteor shower last Thursday. I went to a really dark state park, had really clear skies, and saw about 60 over the course of about 90 minutes. :thumbup:

Naturally, I'm now working an Orbiter simulation of the Perseid meteor shower.
I plan to release it as an add-on, and I can write a tutorial that can be applied to other meteor showers if there is interest.

I have a few questions for the community:

1) I want to scale an asteroid mesh down to about one cubic centimeter in size. I've looked into Shipedit.exe to carry out the scaling, but I don't know how much to scale by since I'm not sure exactly how large the asteroid mesh is to begin with. What is "MC integration"? There is a reference to "Volume" but the reported values don't make sense to me. They seem to be the same order of magnitude for Carina as they are for a large asteroid. Are there units to the volume or is it something else?

2) How fast does comet ejecta leave a parent comet? Or more to the point, how different would one expect the orbit of a meteoroid be compared to the parent body? I ask because I wonder how well my technique produces a representative Perseid meteor's orbit.

#### BrianJ

1) I want to scale an asteroid mesh down to about one cubic centimeter in size. I've looked into Shipedit.exe to carry out the scaling, but I don't know how much to scale by since I'm not sure exactly how large the asteroid mesh is to begin with. What is "MC integration"? There is a reference to "Volume" but the reported values don't make sense to me. They seem to be the same order of magnitude for Carina as they are for a large asteroid. Are there units to the volume or is it something else?
Hi,
if you load the mesh into Shipedit.exe, the "Bounding Box" values show the minimum and maximum values of the points defining a box that exactly encloses the mesh. So it's easy to find the mesh dimensions by subtracting the minimums from the maximums.

MC integration calculates the volume of the mesh, the centre of mass, moments of inertia - (assuming constant density within the mesh).

NOTE: Planetary (or Asteroid) surface meshes are automatically scaled by the radius of the planet in it's .cfg file, so the mesh should always be ~1m radius.

2) How fast does comet ejecta leave a parent comet? Or more to the point, how different would one expect the orbit of a meteoroid be compared to the parent body? I ask because I wonder how well my technique produces a representative Perseid meteor's orbit.
Not sure about this, but I would think if the meteoroids orbit ref.Sun is at the right inclination, eccentricity and semi-major axis, and intersects Earth's orbit at the right place, then the Earth relative velocities should in the right ballpark.

I think I tried simulating a meteor shower in Orbiter a while back, but ran into the problem that if your meteors are vessels, Orbiter assumes they are too small to be seen from more than a few km away. Unless you make the "size" parameter really big, which causes other effects. Don't know if there is a way around that (hope there is!). Good luck.

#### boogabooga

##### Bug Crusher
Thanks BrianJ. The scaling works like a charm.

Actually, I seem to be getting good results. Making the meteoroid object artificially very large in the config is a good idea. It produces a big visible fireball for the ground observer and so far the only concession is that you have to turn off the solar radiation pressure.

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