The Alice instrument – a lightweight (4.4 kg), low-power (4.4 Watt) imaging spectrograph aboard NASA’s New Horizons – has observed Pluto’s nitrogen-rich atmosphere as far as 1,000 miles (1,600 km) above the dwarf planet’s surface. The spacecraft has also discovered a region of ionized nitrogen tens of thousands of miles beyond the planet. This figure shows how New Horizons’ Alice instrument count rate changed over time during the...
