It was on Independence Day, 25 years ago, that a small rover named after a Civil War abolitionist parachuted and fell to the surface of the Red Planet on airbags.
NASA’s first-ever Mars rover, nicknamed Sojourner, landed at Chryse Planitia on July 4, 1997, atop its landing vehicle, Pathfinder. The pair of spacecraft heralded a revolution in Mars exploration technology that NASA’s Curiosity and Perseverance rovers continue to this day, a quarter of a century later.
The name of the Pathfinder rover has been selected (opens in a new tab) of a national contest won by 12-year-old Valerie Ambroise, whose winning essay discussed the importance of Sojourner Truth, aka Isabella Van Wagener. (Now the essay winner appears to be a Connecticut real estate agent.)
Related: 1 year later, the Ingenuity helicopter still going strong on Mars
The namesake rover Sojourner spent nearly four months — 12 times its design lifespan — working on Mars: huddled against rocks, analyzing their chemistry and beaming its observations back to Earth.
The results, streamed in real time over early Internet networks, showed a red planet potentially habitable for life: “The resulting scientific findings suggest that Mars was at some point in its hot and humid past, with water existing in a liquid state and a thicker atmospheric layer,” said NASA’s Jet Propulsion Laboratory (JPL) in California, which managed the rover. (opens in a new tab) of the mission.
Today, Sojourner serves as an important solar-powered progenitor for today’s much larger NASA nuclear rovers: Curiosity (about to celebrate its 10th anniversary from Earth to Mars) and Perseverance (which landed on February 18, 2021 accompanied by the first-ever Martian helicopter, Ingenuity.)
These rovers are part of a generation-long network of landers, orbiters and other vehicles exploring the Red Planet to make sense of its complex history. Why the Martian atmosphere thinned, how much water leaked to the surface, and whether habitable conditions were present are questions that still preoccupy scientists today.
Twenty-five years ago today, a true pioneer landed. Sojourner proved we could drive on Mars; every rover since has done some real earth exploration. I am the fifth in this line, collecting samples that may one day return to Earth and rewrite history. Ahead. pic.twitter.com/ikLdrPOc7cJuly 4, 2022
The mission has also served as a leader in public engagement. Today’s rover teams use tweets, TikTok and live-streamed events to announce new discoveries on Mars.
The much older internet of 1997 saw frequent image uploads to the Pathfinder website, which still sports its pre-millennial design today. At first, NASA thought it would get 25 million downloads after landing; he quickly updated that estimate by three, the agency recalled (opens in a new tab) in 2017. Traffic load forced other agency servers to intervene to avoid website crashes at NASA’s Jet Propulsion Laboratory, but everything worked.
Pathfinder proved so popular in public memory that it represented a crucial turning point in 2015’s “The Martian,” a Hollywood film (promoted by NASA and based on a novel by Andy Weir) about an astronaut doing his way solo to the Red Planet after being stranded.
The mission made its last transmission on September 27, 1997, leaving Pathfinder and Sojourner silent on the surface, but its data will essentially persist forever. NASA still holds 16,500 Pathfinder images and 550 Sojourner images that modern scientists can analyze for new insights into the Red Planet’s history.