If you’ve seen the global warming episode of Cosmos, you might find it unthinkable to try and set a spacecraft down on this hot, gassy planet, but we did. The Soviet Union’s Venera 4 lander reached Venus’ surface on October 18, 1967, making it the first probe to study another planet on location. It may have been the first probe to reach another planet, period, but scientists aren’t sure what happened to its predecessor Venera 3. Maybe it was yanked out of its timeline to help Venera 4, like the Babylon 4 space station or maybe it just crashed. Whatever happened, before it reached Venus its communication systems went kaput, so we’ll never know for sure.
Venera 4 gave us our first on-site information about the Venusian atmosphere, temperature, magnetic field, and radiation field (or lack thereof). As it entered Venus’ atmosphere, the craft’s heat shield measured temperatures of close to 20,000 degrees Fahrenheit, so it’s impressive it didn’t just melt long before it hit the surface. Even so, it only lasted 93 minutes until it was crushed by Venus’ atmospheric pressure.
NASA’s Viking 1 landed on Mars on July 20, 1976. It was supposed to land on July 4, but the landing was delayed because the initial site was deemed unsafe and scientists had to find another location. This was followed shortly thereafter by Viking 2. The Viking landers are featured in Carl Sagan’s Cosmos episode “Blues for a Red Planet,” and provided us with the first on-site photos of the Red lanet, as well as samples and information about the temperature and winds.
Viking 1 chugged along on Mars’ surface for 2,307 days—a record the Opportunity Rover broke back in 2010. Viking 2 lasted for 1,316 days before its batteries gave out and died. Viking 1 and 2 were the parents of Opportunity and the grandparents of Curiosity—it’s pretty awesome that we now have generations of rovers on the Red Planet, it’s like a family reunion, and there are more to come.