Currently LRO spacecraft commissioning is going smoothly. If this trend continues LROC should be powered up on July 3rd and we can begin our commissioning tests.
On the first few days after powering up, we will be acquiring images on both the night and day sides to test the NAC settings that control the background digital number (DN). You can think of the background DN as signal level with a lens cap on the camera. We want the background level to be small in order to maximize our signal to noise ratio. Right now, we have a thermal model that predicts what our settings should be given a particular temperature. The temperature is controlled by the local incidence angle (the elevation of the Sun above the lunar horizon), LRO's progress in the orbit, and its altitude above the surface. We want to check this model and improve it so that we get the best quality images when the mapping mission begins.
And lets don't forget the WAC - we will also be checking exposure times, geometric and radiometric calibration, and focus.
Through the happenstance of our launch date, LRO will be in a terminator orbit on July 3rd. The terminator is the boundary between night and day. On the third go outside and look at the crescent Moon - you will be able to locate our orbit by looking at the terminator. Initially we will see only very harsh shadowing (here's an example) that exaggerates even subtle topography, making the lunar surface look very rough and foreboding. As time progresses over the next month we will move out of the shadow into a new lunar dawn. If all goes well we should be posting our first images on the weekend of the Fourth. We will be posting images as our calibration imaging progresses, so please check in frequently.
Published by Mark Robinson on 25 June 2009