NASA's First Mars Rover Was the Size of a Microwave. Now They're SUVs with Helicopters.

On July 4, 1997, a spacecraft wrapped in airbags bounced across the Martian surface like a giant beach ball. When it stopped rolling, it deflated, opened its petals, and revealed a tiny robot the size of a microwave oven.

Her name was Sojourner.

Named by 12-year-old Valerie Ambrose of Bridgeport, Connecticut, who won a NASA essay contest, Sojourner was named after Sojourner Truth, the African-American abolitionist and women's rights activist. Ambrose wrote that just as Sojourner Truth traveled the country speaking about injustice, the rover would travel Mars seeking scientific truth.

“Sojourner was named by 12-year-old Valerie Ambrose of Bridgeport, Connecticut. She wrote: 'Sojourner Truth traveled the country speaking about injustice, this rover will travel Mars seeking truth.'”

Sojourner weighed just 11.5 kilograms (25 pounds). She had six wheels, a solar panel, and an alpha proton X-ray spectrometer for analyzing rocks. NASA designed her to last 7 sols (Martian days). She lasted 83.

It was the first time a rover had successfully operated on Mars. The Soviet Union's Mars 3 had technically landed a rover in 1971, but it transmitted for only 20 seconds before going silent.

Sojourner proved that robotic exploration of Mars was possible. But she was just the beginning.

“Opportunity was designed for 90 days. It lasted 14 years, 5,352 sols, before a global dust storm killed its solar panels. Its last message: 'My battery is low and it's getting dark.'”

In 2004, NASA landed twin rovers: Spirit and Opportunity. At 174 kg each, they were 15 times heavier than Sojourner. Both were designed for 90-day missions. Spirit lasted 6 years. Opportunity lasted 14.

Opportunity's marathon across the Martian surface became legendary. She drove 45 kilometers, a marathon and a half, discovering evidence of ancient water along the way. In June 2018, a massive global dust storm blanketed Mars, blocking sunlight from Opportunity's solar panels. NASA's last communication from Opportunity has been poetically translated as: "My battery is low and it's getting dark."

The next generation arrived in 2012. Curiosity was a beast, 899 kg, the size of a small car, powered by a nuclear battery that would never run out of charge from dust storms. NASA landed it using an unprecedented "sky crane", a hovering rocket platform that lowered the rover on cables. As of 2026, Curiosity has been exploring Mars for over 13 years and is still going.

Then came Perseverance. Landing in February 2021, the 1,025 kg rover carried the most advanced instruments ever sent to another planet. But its most historic payload was Ingenuity, a small helicopter that achieved the first powered flight on another planet on April 19, 2021. Ingenuity was designed for 5 flights. It completed 72.

Perseverance is doing something no other rover has done: collecting and caching rock samples in sealed titanium tubes, left on the Martian surface for a future mission to pick up and return to Earth. If that mission succeeds, they'll be the first samples ever returned from Mars.

From an 11 kg microwave-sized robot that was supposed to last a week, to a 1,025 kg SUV with a helicopter companion, Mars exploration has come further in 29 years than anyone imagined.

The root of every Mars rover is a 12-year-old girl's essay, a bouncing airbag, and a tiny robot named after a freedom fighter.