Mark your calendars, tomorrow (29 December 2013) ESA’s Mars Express spacecraft will flyby the Martian moon Phobos at just 45 km / 28 miles! That’s close!
So close in fact, the Mars Express will be pulled “a few tens of centimeters” off course. ESA scientists will be ready, they will be measuring the small changes in the frequency of the radio signals and turn them into measurements of gravity, mass, and density at different locations on the moon. Cool stuff!
The closest approach will be at 07:09 UTC, let’s see that’s 02:09 EST. For perspective this animation is at x 1000 speed.