West Virginia University postdoc Cagri Kilic has calculated how much debris humans have left on Mars over 50 years of exploring the surface of the Red Planet.
According to his findings, humans have left 7,119 kilograms (15,694 pounds) of debris on Mars. Klich added up the mass of all the spacecraft ever sent to the Red Planet (22,000 pounds or 9,979 kilograms) and subtracted the weight of the currently operational craft (6,306 pounds or 2,860 kilograms). He ended up with a result of 15,694 pounds or 7,119 kilograms of human debris on Mars.
There are three primary sources of debris on Mars: discarded hardware, inactive spacecraft, or crashed spacecraft.
There are now nine inactive spacecraft on Mars: Mars 3 lander, Mars 6 lander, Viking 1 lander, Viking 2 lander, Phoenix lander, the Sojourner rover, the Beagle 2 lander, Spirit and Opportunity rovers.
Additionally, lots of small, windblown trash has been found on Mars over the years, such as a recently found netting material or a large and shiny thermal blanket spotted by the Perseverance rover distant from where it had landed.
According to the United Nations Office for Outer Space Affairs, different countries have sent 18 human-made objects to Mars as part of 14 different missions.