We need to recognize that a very real possibility exists that the first human steps on the Martian surface will lead to a collision between terrestrial life and biota native to Mars. If life does exist on Mars, human explorers could easily lead to the extinction of Martian life.

Starting Sunday evening, all of North and South America will be able to see the only total lunar eclipse of 2019 from start to finish this weekend. The entire eclipse will exceed three hours. Totality — when the moon's completely bathed in Earth's shadow — will last an hour

NASA's Opportunity, the Mars rover that was built to operate for just three months but kept going and going, rolling across the rocky red soil, was pronounced dead Wednesday, 15 years after it landed on the planet. The six-wheeled vehicle that helped gather critical evidence that ancient Mars might have been hospitable to life was remarkably spry up until eight months ago, when it was finally doomed by a ferocious dust storm.

University of Nebraska-Lincoln professor Brett Ratcliffe named a new scarab beetle species drogoni, rhaegali and viserioni. The names are Latinized versions of Drogon, Rhaegal and Viserion, three dragons owned by Daenerys Targaryen's character in "Game of Thrones." He's a fan of the series, but ultimately chose the names to draw attention to biodiversity and the amount of undiscovered species. "When you create names like these, you do it to gain a little bit of notoriety and bring public attention to it," he said.

Fifty years ago on Christmas Eve, a tumultuous year of assassinations, riots and war drew to a close in heroic and hopeful fashion with the three Apollo 8 astronauts reading from the Book of Genesis on live TV as they orbited the moon. To this day, that 1968 mission is considered to be NASA's boldest and perhaps most dangerous undertaking.

A NASA spacecraft 4 billion miles from Earth yielded its first close-up pictures Wednesday of the most distant celestial object ever explored, depicting what looks like a reddish snowman.

Environmental research projects on everything from endangered animals to air and water quality are being delayed and disrupted by the month-long partial federal government shutdown, and not just those conducted by government agencies. Scientists with universities, nonprofit organizations and private companies say their inability to collaborate with federal partners, gain access to federal lands and laboratories, and secure federal funding is jeopardizing their work.

NASA's new Mars lander has placed a quake monitor on the planet's dusty red surface, just a few weeks after its arrival. It's the first time a robotic arm has lowered an experiment onto the Martian surface. The project's manager called the milestone "an awesome Christmas present."

An asteroid-circling spacecraft has captured a cool snapshot of home. The tiny asteroid appears as a big bright blob in the long-exposure photo released last week. Seventy million miles away, Earth appears as a white dot, with the moon an even smaller dot but still clearly visible.

The robotic geologist — designed to explore Mars' mysterious insides — must go from 12,300 mph to zero in six minutes flat as it pierces the Martian atmosphere, pops out a parachute, fires its descent engines and, hopefully, lands on three legs. "Landing on Mars is one of the hardest single jobs that people have to do in planetary exploration," said InSight's lead scientist, Bruce Banerdt. "It's such a difficult thing, it's such a dangerous thing that there's always a fairly uncomfortably large chance that something could go wrong."