Landsat Looks To The Moon For Calibration  July 14, 2014 Image
Credit: NASA's Goddard Space Flight Center  [ Watch The Video:
Landsat Looks To The Moon]  Kate Ramsayer, NASA  Every full
moon, Landsat 8 turns its back on Earth. As the satellite’s
orbit takes it to the nighttime side of the planet, Landsat 8
pivots to point at the moon. It scans the distant lunar surface
multiple times, then flips back around to continue its task of
collecting land-cover information of the sunny side of Earth
below.  These monthly lunar scans are key to ensuring the land-
imaging instrument aboard Landsat 8 is detecting light
consistently. For this, engineers need a consistent source of
light to measure. And while there are some spots on Earth – like
the Sahara Desert or other arid sites – that reflect a
relatively stable amount of light, nothing on our planet beats
the moon, which lacks an atmosphere and has an unchanging
surface, barring the odd meteorite.  We really wanted something
we could trust for Landsat 8,” said Brian M