Hero Rupes is an escarpment

Escarpment

An escarpment is a steep slope or long cliff that occurs from erosion or faulting and separates two relatively level areas of differing elevations.-Description and variants:...

 on Mercury

Mercury (planet)

Mercury is the innermost and smallest planet in the Solar System, orbiting the Sun once every 87.969 Earth days. The orbit of Mercury has the highest eccentricity of all the Solar System planets, and it has the smallest axial tilt. It completes three rotations about its axis for every two orbits...

 more than 300 kilometers long located in the southern hemisphere of Mercury. Discovered by the Mariner 10

Mariner 10

Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus. It was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program...

 spacecraft in 1974, it was formed by a thrust fault

Thrust fault

A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger...

, thought to have occurred due to the shrinkage of the planet's core

Planetary core

The planetary core consists of the innermost layer of a planet.The core may be composed of solid and liquid layers, while the cores of Mars and Venus are thought to be completely solid as they lack an internally generated magnetic field. In our solar system, core size can range from about 20% to...

 as it cooled over time.

The scarp is named after sloop

Sloop

A sloop is a sail boat with a fore-and-aft rig and a single mast farther forward than the mast of a cutter....

 Hero, Nathaniel Palmer

Nathaniel Palmer

Nathaniel Brown Palmer was an American seal hunter, explorer, sailing captain, and ship designer. He was born in Stonington, Connecticut.-Sealing career and Antarctic exploration:...

's ship to explore Antarctic

Antarctic

The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...

coast, 1820–21.