Wednesday, December 18, 2013

Trying To Capture The Jade Rabbit In Miniature

Now that China has become the third nation to successfully land a probe on the surface of the Moon, I felt it necessary to do what I usually do.
I decided to build a model.
This isn't normally such a big deal. Just find a good set of drawings, decide on a scale, and start building. In this case, I decided to build the model in the same scale as the old Mattel/Hot Wheel Mars Pathfinder "Sojourner". Unfortunately, the folks at Mattel didn't post the scale for their little rover. Some measurements put it at around 1/12-1/13, so I decided to split the difference and go for 1/12.5, or thereabouts.
The bigger problem, of course, is the lack of drawings. 
This is really not surprising. The CNSA doesn't seem to normally share this information. Trying to build accurate models of their spacecraft is a little daunting. The only dimension that has really come out is the rover's height, 1.5 meters. Fortunately, the shape of the Yutu rover is pretty simple; a box on a box, with six wheels, a neat little suspension system, a mast with both cameras and a radio dish, some weird little masts on the back.  
Actually, it is a bit more complicated than meets the eye. 
There have been various models displayed, namely this larger one.

This model was the oldest displayed, and in actuality is quite a bit different. The wheels are far different than these, the suspension system as well. The hull has a different shape. In short, not really very accurate, but for a long time, it was all we had.
Then, they began showing this model.

(Those Taikonauts are not to scale, by half!)

This one is much closer to the final design. At an indicated scale of 1/8, it seems to show most of the details that actually made it to the operational rover. In fact, there appears to have been a prototype photographed as well, different in small details but otherwise very close

This is the actual Yutu on the Moon.

Looking at the 1/8th scale models, though, there are questions about some details. These details are on the operational rover as well. For instance, on the PV (solar) panels are pairs of probes that stick up for no apparent reason.

The set on the right panel (left in this image) are actually larger in diameter, more like tubes, whilst those on the left (right here) are nothing more than thin rods. Because the panels fold one on top of the other, my guess is that these serve as supports. The port panel folds over the starboard panel. These supports prevent the fragile PV cells from bouncing off one another; the port pair rests inside the tubular starboard, probably down to a stop, while the starboard supports rest against the "floor" of the case on top of Yutu. A simple yet elegant solution.
While I cannot be certain what the other masts and antenna do, at least I have a better idea of their location on the actual rover. We will wait to see if CNSA releases more information. I expect a model to appear soon, but in the meantime, I will plug away on mine.

That little rover below the shiny, foil covered box?
Yes, that's the Mars Pathfinder Sojourner rover from 1997.

No comments:

Post a Comment