Nasa rover sighting reignites fears about human space debris

Nasa’s Perseverance rover typically beams back evocative images of bleak dusty landscapes, red-hued sandstorms and Martian rock samples. So its operators were surprised to receive an image on Monday of a shiny silver object resembling a discarded crisp packet wedged between two rocks.

The object, the Nasa team concluded, is a piece of debris discarded by the robotic craft during its touchdown in February 2021.

“My team has spotted something unexpected: It’s a piece of a thermal blanket that they think may have come from my descent stage, the rocket-powered jet pack that set me down on landing day back in 2021,” the Perseverance Twitter account reported.

“That shiny bit of foil is part of a thermal blanket – a material used to control temperatures. It’s a surprise finding this here: My descent stage crashed about 2 km away. Did this piece land here after that, or was it blown here by the wind?”

The image has reignited concerns that space exploration risks contaminating the pristine Martian and lunar environments. The Outer Space Treaty of 1967 created an obligation under international law to avoid the harmful contamination of outer space, the moon and other celestial bodies, but some argue that the law is not detailed enough to ensure protection.

However, in the case of the Perseverance litter, Prof Andrew Coates, a space scientist at UCL’s Mullard Space Science Laboratory, said: “The good news is that everything is sterilised before it goes to Mars, and the space radiation environment helps during the nine-month trip to Mars as does the harsh surface environment.”

“As it is so difficult to land on Mars because of the thin atmosphere, landers always have associated landing system hardware which also lands on the surface – parachutes, back shells, and landing systems – like the sky crane for Perseverance and Curiosity, airbags and retro rocket systems for earlier missions,” he added. “These ‘fly off into the sunset’ from the landing site and ultimately crash, but the contamination risk is very low.”

Avoiding contamination is crucial for missions like Perseverance, which is hunting for signs of ancient life in Mars’ Jezero crater. Scientists believe that more than 3.5bn years ago, the area was flooded with water and was home to an ancient river delta. Conceivably, microbial life could have survived in Jezero during this wetter period and so the car-sized rover is collecting soil samples to return to Earth that scientists can assess for signs of ancient life.

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