Asteroid Vesta

thingiverse

This is a printable model of the Asteroid 4 Vesta, one of the largest asteroids in the main belt between Earth and Mars. The Dawn probe is currently in orbit and its images are the source of the model. NASA has not as of yet released a 3d model, so this is a bit of a scoop. Vesta is a partially differentiated body and hence has a rounded shape, although much of its south pole was removed in a collision with another body. Instructions This was an interesting lesson in how to develop small space body shapes when there was no model released. Skip this if you think it's tl;dr, but it does give some ideas about how to print globes of space bodies. My first approach was to take the released orbit view (http://en.wikipedia.org/wiki/File:Vesta_Rotation.gif), break it down into individual frames using ImageJ and then submit the individual sequential shots to an online point cloud generator such as my3dscanner. This created distortion at the poles where there is less data, but with some mesh editing in Meshlab could be printed, although it required a lot of work. This version is based on using the ApplyMeshUVN command in Rhino3d - using the projected map of Vesta (found here) http://dawn.jpl.nasa.gov/multimedia/images/PIA14703_750_equi+CL.jpg), I created a mesh heightfield (2 mm max height), then created an oblate spheroid that matched the approximate ratio of equatorial vs polar diameters of vesta based on the still equatorial images. The spheroid's major diameter should be based on dividing the length of the mesh along its long axis (equatorial circumference) by pi to get the diameter. The mesh is then positioned above the spheroid, aligned in the center and the ApplyUVNMesh command wraps it around the body. I then smoothed it (UVN 0.1 ratio) just to get rid of some of the weirder cliff edges, exported it as an stl and then used meshlab to get rid of a lot of non-manifold thingies. It now prints very cleanly although the north pole (bottom) is flat because of limited data from that region. This technique will ONLY work for relativel;y regular differentiated bodies. Trying it on something oddly shaped like asteroid Kleopatra, Toutatis or a comet and you'll cry. Promise. But you can download flat projected maps of almost all planets and moons from the USGS and start making a collection of small globes using this technique - next I'm trying Europa.