Ground penetrating radar has unearthed (unmarsed?) a great find. A huge bed of frozen CO2.
Thawing out this bed of CO2 would only double the pressure of the Martian atmosphere, so the majority of the planet would still be unable to have liquid water. But in the lowest depths of the Valles Marineris doubling the air pressure would make it thick enough for liquid water. That would be enough to transport life to the planet and jump start the process of terraforming it to be an Earthlike world.
A second habitable world in the solar system will lead to a fantastic future.
By Darrell B. Nelson author of I KILLED THE MAN THAT WASN'T THERE