Utopia Planitia

Utopia Planitia (Greek and Latin: "Utopia Land Plain") is a large plain within Utopia, the largest recognized impact basin on Mars and in the Solar System with an estimated diameter of 3,300 km (2,100 mi). It is the Martian region where the Viking 2 lander touched down and began exploring on September 3, 1976, and the Zhurong rover touched down on May 14, 2021, as a part of the Tianwen-1 mission. It is located at the antipode of Argyre Planitia, centered at 46°42′N 117°30′E / 46.7°N 117.5°E / 46.7; 117.5. It is also in the Casius quadrangle, Amenthes quadrangle, and the Cebrenia quadrangle of Mars. The region is in the broader North Polar/Borealis Basin that covers most of the Northern Hemisphere of Mars.

The Utopia basin is estimated to have formed around 4.3-4.1 billion years ago. The impactor was likely around 400–700 kilometres (250–430 mi) in diameter. The basin was subsequently mostly filled in, resulting in a mascon (a strong positive gravity anomaly) detectable by orbiting satellites.

Many rocks at Utopia Planitia appear perched, as if wind removed much of the soil at their bases. A hard surface crust is formed by solutions of minerals moving up through soil and evaporating at the surface. Some areas of the surface exhibit scalloped topography, a surface that looks like it was carved out by an ice cream scoop. This surface is thought to have formed by the degradation of an ice-rich permafrost. Many features that look like pingos on the Earth are found in Utopia Planitia (~35–50° N; ~80–115° E).

On November 22, 2016, NASA reported finding a large amount of underground ice in the Utopia Planitia region. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior.