On Friday 1 October, China will launch their second lunar orbiter, Chang’E 2, which will join it’s predecessor Chang’E 1 in collecting scientific data on the Moon.  Chang’E 2 is almost identical to the first probe, but features a few enhancements.  It will orbit at a lower altitude of 100km compared to the original altitude of 200km, allowing the camera a much closer view of the lunar surface.  The camera itself is much more powerful, allowing photographs of features as small as 10 metres across, compared to the 120 metres of the previous mission.  Chang’E 2 is being launched on a more powerful rocket so that it’s journey will only take 5 days (The original took 12 days to arrive).  It will be equipped with a more accurate laser altimeter, which measures the height of the ground below by sending a pulse of laser light and timing how long it takes to reflect back up.  The old altimeter took one measurement every second, while the new one samples five times faster.

 

But the most ambitious feature of Chang’E 2’s mission is what happens after a complete lunar survey:  Mission controllers will fire the orbiter’s engines, changing it’s orbit from a circle to an ellipse, with the lowest point a mere 15km from the surface!  At this height Chang’E 2 will gradually map out the entire surface of the moon with extreme precision.  Fascinating stuff from the Far East!