you'll like this one. I wonder what would happen to the atmosphere on Mars if we reactivated a Volcano on its surface.Volcanoes on Mars Could be Active, Raising Possibility that the Planet was Recently Habitable

Volcanoes on Mars Could be Active, Raising Possibility that the Planet was Recently Habitable

https://spacenews.com/volcanoes-on-mars-could-be-active-raising-possibility-that-the-planet-was-recently-habitable/

It's not so much that Mars is dead, as that it's not showing signs of present life. It certainly had life-compatible conditions a few billion years ago, at about the time life emerged on Earth. Both surface and atmospheric chemistries, and atmosphere density, would have been suitable for life to begin.