Past Forward: This Little Mars Rover Stayed Home: Marie Curie, Less-Famous Twin to Sojourner, Helped NASA Plan the Mission

As a mere earthling, I remember watching in fascination as Sojourner sent back photos of the Martian surface during the summer of 1997. I was not alone. The servers at NASA's Jet Propulsion Lab slowed to a crawl when they got more than 47 million hits (a record number!) from people attempting to download those early images of the Red Planet. To be fair, it was the late 1990s, the Internet was still young, and most people were using dial-up modems. By the end of the 83-day mission, Sojourner had sent back 550 photos and performed more than 15 chemical analyses of Martian rocks and soil.