Mars is littered with 15,694 pounds of human trash from 50 years of robotic exploration

Humans have been exploring the surface of Mars for over 50 years. Nations have sent 18 man-made objects to Mars on 14 different missions, according to the United Nations Office for Outer Space Affairs. Many of these missions are still ongoing, but over the decades of exploration of Mars, humanity has left much debris on the planet’s surface.

I am a postdoctoral research fellow studying ways to track Mars and Lunar rovers. In mid-August 2022, NASA confirmed that the Mars rover Perseverance had spotted a piece of debris discarded upon landing, this time a tangle of webs. And this isn’t the first time scientists have found junk on Mars. That’s because there’s a lot out there.

Where is the debris coming from?

Debris on Mars comes from three main sources: discarded hardware, inactive spacecraft, and crashed spacecraft.

Each mission to the surface of Mars requires a module that protects the spacecraft. This module contains a heat shield in case the vehicle transits the planet’s atmosphere, as well as a parachute and landing hardware to allow it to land softly.

The vehicle ejects parts of the module as it descends, and these parts can land in different places on the planet’s surface – there may be a lower heat shield in one place and a parachute in another. When this debris hits the ground, it can shatter into smaller pieces, as happened when the Perseverance rover landed in 2021. These small pieces can then be blown around by the Martian winds.

Much smaller windblown debris has been found over the years – like the recently found netting material. Earlier in the year, on June 13, 2022, the Perseverance rover discovered a large, shiny thermal blanket wedged in some rocks 2 km from the rover’s landing site. Both Curiosity in 2012 and Opportunity in 2005 also encountered debris from their landing vehicles.

Dead and crashed spaceships

The nine inactive spacecraft on the surface of Mars make up the next type of debris. These spacecraft are the Mars 3 lander, Mars 6 lander, Viking 1 lander, Viking 2 lander, Sojourner rover, the formerly lost Beagle 2 lander, the Phoenix lander, the Spirit rover, and the recently defunct spacecraft, the Opportunity rover . Mostly intact, these could be considered historical relics rather than rubbish.

Deterioration takes its toll on everything on the surface of Mars. Some pieces of Curiosity’s aluminum wheels have broken off and are believed to be scattered along the rover’s track. Some of the junk is targeted as Perseverance dropped a drill on the surface in July 2021 which made this possible Exchange for a new, flawless piece so that it could continue collecting samples.

Crashed spacecraft and their parts are another significant source of waste. At least two spacecraft have crashed and four others lost contact before or shortly after landing. The safe descent to the planet’s surface is the most difficult part of any Mars landing mission – and it doesn’t always end well.

If you add up the mass of all spacecraft ever sent to Mars, you get about 22,000 pounds (9979 kilograms). Subtract the weight of the currently operating vehicle on the surface – 6,306 pounds (2,860 kilograms) – and you have 15,694 pounds (7,119 kilograms) of human debris on Mars.

Why is trash important?

Today, the main concern of scientists about the debris on Mars is the risk it poses to current and future missions. The Perseverance teams are documenting any debris they find and checking to see if any of it could contaminate the samples the rover is collecting. NASA engineers have also considered whether Perseverance could become entangled in debris from the landing, but have concluded the risk is small.

The real reason debris is important on Mars is because of its place in history. The spacecraft and its parts are the early milestones for human exploration of the planet.