Spirit and Opportunity

Two rovers, two sides of Mars

In 2003 NASA launched two identical rovers to Mars, each about the size of a golf cart. They were part of the Mars Exploration Rover mission, and their main job was to look for signs that water had once shaped the planet.

To protect them on landing, each rover was wrapped in giant airbags and bounced across the surface before rolling to a stop. Spirit landed in Gusev Crater on 4 January 2004. Opportunity landed three weeks later on the other side of the planet, at Meridiani Planum, rolling into a small crater that scientists called a hole in one.

Each rover had six wheels, solar panels and a mast with cameras at roughly the eye level of an adult, so scientists could see Mars as a person standing there would.

Signs of ancient water

Opportunity quickly found layered rocks and tiny round grains of a mineral called hematite, nicknamed blueberries, which form in water. Spirit, after a slow start, found rocks and soils rich in minerals that pointed to hot springs or steam vents in the distant past.

Together the twins showed that Mars was once much wetter, and that some places might have been friendly to life long ago.

Far beyond the warranty

Each rover was designed to work for about 90 Martian days. Wind kept surprising engineers by blowing dust off the solar panels, giving the rovers power boosts. Spirit worked for more than six years before getting stuck in soft sand in 2009. It sent its last signal in March 2010.

Opportunity kept rolling. It explored crater after crater and in 2015 passed the distance of a marathon, about 42 kilometres, the first such feat on another world. In June 2018 a planet-wide dust storm blocked the sunlight it needed, and it fell silent. NASA declared the mission complete in February 2019, after more than 14 years.

Engineers even drove Spirit backwards for years after one of its front wheels stopped turning, dragging the stuck wheel behind it.

A lasting legacy

Opportunity drove about 45 kilometres in total, a record for driving on another world at the time. The twins inspired the bigger rovers that followed, Curiosity and Perseverance.

They also showed the value of building two of everything. Each twin was a backup for the other, and in the end both far outlived their planned lives, sending home hundreds of thousands of pictures of the red planet.

← Voyager 1 and 2Sister Cities and Twin Towns →