Observation and Exploration
The apparent magnitude of Ariel is 14.4; similar to that of Pluto near perihelion. However, while Pluto can be seen through a telescope of 30 cm aperture, Ariel, due to its proximity to Uranus's glare, is often not visible to telescopes of 40 cm aperture.
The only close-up images of Ariel were obtained by the Voyager 2 probe, which photographed the moon during its flyby of Uranus in January 1986. The closest approach of Voyager 2 to Ariel was 127,000 km (79,000 mi)—significantly less than the distances to all other Uranian moons except Miranda. The best images of Ariel have a spatial resolution of about 2 km. They cover about 40% of the surface, but only 35% was photographed with the quality required for geological mapping and crater counting. At the time of the flyby the southern hemisphere of Ariel (like those of the other moons) was pointed towards the Sun, so the northern (dark) hemisphere could not be studied. No other spacecraft has ever visited the Uranian system, and no mission to Uranus and its moons is planned. The possibility of sending the Cassini spacecraft to Uranus was evaluated during its mission extension planning phase. It would take about twenty years to get to the Uranian system after departing Saturn. See Planetary Science Decadal Survey for other Solar System mission concepts.
Read more about this topic: Ariel (moon)
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