Twenty-five years ago I was a junior in High School and I spent a good chunk of that year reading absolutely everything I could about Mars. I was doing research for a NASA High School design competition, something that put me on a path to my current career. Part of the research was reading up on the very successful NASA Viking missions. The 1st Viking mission launched just a few months before I was born, Aug of 1975, and the 2nd lander about a year later in July of 76'. The Viking missions were noteworthy for two main reasons (3 of you count the proximity to my date of birth). One, the first Viking lander was the first time the U.S. had successfully landed a spacecraft on the surface of Mars. The 2nd reason was that the Viking landers were designed to find living microbes on the surface of Mars. Their experiments found that evidence, but it was quickly explained away as being the result of a chemical reaction rather than a biological one. It was almost like we knew the answer to our question (there is NOT currently life on Mars), we designed an experiment to test that hypothesis and then when we got evidence that there was current life on Mars we figured out another way to explain it away. I'm not going to get into the details, but the take away from all of this is this...designing a single remote experiment to prove or disprove the existence of life on another planet is exceedingly difficult. After reading all of the research at the time I was convinced that Viking had found proof of existing life on Mars, but I knew that we wouldn't be able to definitively prove that until we got boots on Martian soil.
Fast forward 25 years and we have a recent article from Phys.org (I highly recommend reading this) that talks about a renewed interest in the results from this 40 year-old mission. There is still, even after 40 years, scientists working on the results from the Viking missions. For most people, NASA missions are over after the excitement of the landing or orbiting event is over and we get the first images back. But these missions are all about the science and science is a marathon, not a sprint. We are still analyzing sample brought back from the Moon during the Apollo missions. We also just launched a mission to asteroid Bennu called OSIRIS-REx that will be be bringing back pristine samples of the asteroid and we are expecting to be doing science and making discoveries about those samples for many decades after we get those samples back here on Earth. Little did I know, 25 years ago doing research for my High School Mars project, that I would eventually be involved with a sample return mission that will result in findings just as exciting as Viking. I also have the privilege of working on the next major Mars rover mission, Mars 2020, which will collect samples from the surface of Mars and cache them on the planet for a follow-on mission to eventually bring them back to Earth. Maybe, just maybe before I retire we will finally be able to settle whether Viking really detected life on the surface of Mars. But I think it will take a human mission to settle that one.