Footage from lost tapes of NASA's Apollo missions has revealed that the mysterious warming of the moon in the 1970s is due to the presence and activity of astronauts on the lunar surface.

NASA Astronauts Disturbed Regolith On The Moon

Seiichi Nagihara from Texas Tech University and colleagues said that when astronauts walked and drove a rover on the surface of the moon, they disturbed the moon's regolith, a layer of loose dust and rocks from space rock bombardments.

The disturbance exposed the darker soil that absorbs more energy from the sun.

"The regolith on the paths of the astronauts turned darker, lowering the albedo," the researchers wrote in their study, which was published in the Journal of Geophysical Research: Planets on April 25.

"We suggest that, as a result of the astronauts' activities, solar heat intake by the regolith increased slightly on average, and that resulted in the observed warming."

Study researcher Walter Kiefer from the Lunar and Planetary Institute said that the findings show how human activity can disrupt a system that has been in isolation for billions of years. Kiefer added that the findings could also provide valuable information for future missions, including those on planet Mars.

Space Missions May Contaminate Mars

It is not yet clear if Martian life still exists, but scientists raised concern that that if life does exist on the Red Planet and manned missions become a reality, humans and the microbes that hitchhiked a ride from planet Earth may contaminate and even wipe out native Martian life that may not have immunity against pathogens from Earth.

A 2014 study conducted aboard the International Space Station has in fact revealed that bacteria from Earth can quickly colonize Mars.

The launch of SpaceX CEO Elon Musk's Tesla roadster into space earlier this year also raised the issue of potential contamination.

Some scientists said that the car carries with it the largest amount of bacteria from Earth to space, which can possibly land on the Red Planet and contaminate it.

Contamination can jeopardize the search for alien life in other worlds. For missions intended to find life, it is crucial that no Earth organism contaminates the surface since they could be mistaken as a Martian organism.

"Such a contamination could harm existing life and muddle scientific efforts to search for said life. This concern might only last until humans arrive," said Jason Davis of The Planetary Society. "There are endless debates on whether current rovers like Curiosity, or future rovers like Mars 2020, should be allowed to investigate spots where briny water may (or may not) ooze onto the surface."

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