10 days until the launch of ICON

The Ionospheric Connection Explorer! ? ICON will study Earth’s dynamic interface to space. To get ready for the Oct. 26 launch, we’re counting down with 10 key things to know about the mission:
First up: ?-mile-per-hour sensitivity
Though ICON zooms around Earth at upwards of 14,000 miles per hour, its wind-measuring instrument MIGHTI can detect changes in wind speed smaller than 10 miles per hour. MIGHTI makes use of the Doppler effect — the same phenomenon that makes an ambulance siren change pitch as it passes you — and measures the tiny shifts in color caused by the motion of glowing gases in the upper atmosphere, which reveals their speed and direction.