NASA’s Rover Perseverance is currently investigating rocks next to the rim of Belva Crater on Mars. About 2,300 miles (3,700 kilometers) away, NASA’s Curiosity rover recently drilled a sample at a site dubbed ‘Ubajara’. Although the crater has an official name, the drill site is identified by a nickname, hence the quotation marks.

According to NASA both the nickname and the official name of a site are among thousands applied by NASA missions not only to craters and hills, but to every boulder, pebble and rock face they study.

“The No. 1 reason we’re choosing all these names is to help the team track what they’re finding every day,” said Ashwin Vasavada, project scientist for the Curiosity mission at NASA’s Jet Propulsion Laboratory in Southern California. “Later, we can refer to the many hills and rocks by name as we discuss them and at the end record our discoveries.”

The way scientists come up with identifiers has evolved since the early days 25 years ago when they used cartoon character names.

Official names

The difference between an official name on Mars and an unofficial one is seemingly simple: Official names are approved by a body of scientists known as the International Astronomical Union (IAU). The IAU sets standards for naming planetary features and records the names in the Gazetteer of Planetary Nomenclature.

For example, craters larger than 37 miles (60 kilometers) are named after famous scientists or science fiction writers. Smaller craters are named after cities with a population of less than 100,000. Jezero Crater, which Perseverance is exploring, is named after a town in Bosnia. Belva, an impact crater in Jezero, is named after a town in West Virginia that, in turn, was named after Belva Lockwood, the first woman to run for president in 1884 and 1888.

More than 2,000 locations on Mars have official names, but even more unofficial nicknames can be seen on the Mars map.

Nicknames

Early Mars missions sometimes went a whimsical nickname route, even using cartoon character names. “Yogi Rock,” “Casper” and “Scooby-Doo” were among the unofficial names used by the team behind NASA’s first rover, Sojourner, in the late 1990s.

The philosophy changed with the Spirit and Opportunity rovers, whose teams began using more purposeful names. For example, the Opportunity team named a crater “Endurance” to honor the ship that carried explorer Ernest Shackleton’s ill-fated expedition to Antarctica. The names for the Curiosity and Perseverance landing spots honor science fiction authors Ray Bradbury and Octavia E. Butler, respectively. And the Curiosity team named a Martian hill after their colleague Rafael Navarro-González, who died of complications from COVID-19.

Earth on Mars

Despite occasional exceptions, the Curiosity and Perseverance missions stick to nicknames based on ground locations. Before Curiosity landed in 2012, the rover team created a geological map of the landing area. They began by drawing a grid, making squares, or quadrants, equal to about 0.7 miles (1.2 kilometers) on each side. These quadrants will be themed around a site of geological significance on Earth.

Then, as now, team members suggested topic ideas based on locations where they had worked or had a personal connection, and informally discussed which would be the most interesting to include, keeping in mind various names that would be commemorated in future scientific papers. Once a topic is selected, hundreds of names matching that topic are gathered. It takes a lot because available names can dwindle quickly, given that Curiosity can stay in a quadrant for several months.

For Curiosity’s final quadrant, the rover team chose a subject called Roraima, Brazil’s northernmost state, and Mount Roraima, the highest peak in the Pacaraima Mountains, located near the borders of Venezuela, Brazil and Guyana. This marked the first issue of the South American quadrant. The sulfate-rich region Curiosity is currently exploring, with its flat-topped hills and steep slopes, reminded them of the “table” mountains in the Pacaraima range.

For Perseverance, the scientists chose to deal with national park issues. The rover is now exploring the Rocky Mountain Quadrant and recently drilled into rocks at a site nicknamed “Powell Peak” in Rocky Mountain National Park.