Where did Mars’ atmosphere go? Scientists say it may be ‘hiding in plain sight’ Space.comMars Rocks May Contain Ancient Atmospheric Carbon – And We Could Use It For Fuel IFLScienceMars’ early thick atmosphere could be locked up in planet’s clay surface Interesting EngineeringStudy shows Mars’ early thick atmosphere could be locked up in the planet’s clay surface Phys.orgScientists believe they finally know what happened to Mars’ missing atmosphere The Independent