Hello Nature readers, would you like to get this Briefing in your inbox free every day? Sign up here
The biggest, most complex rover ever sent to Mars is now on its way, following the successful launch of NASA’s Perseverance mission. The rover will be the first mission ever to attempt to collect rock samples to return to Earth; it will also search for signs of ancient alien life, launch the first helicopter on the red planet and use microphones to capture Mars’s sounds. “Returning samples will be the first time we will have done a round trip to Mars,” says former astronaut John Grunsfeld. “That’s important because it’s a metaphor for human space flight. Most astronauts who go to Mars are going to want to come back.”
Researchers have pinpointed the origin of Stonehenge’s giant sarsen stones after a sample that was taken from the site more than 60 years ago was finally returned. A detailed geochemical analysis of the sample, a tube-shaped core that was drilled from one of the stones in 1958, compared its trace-element levels with those of rock samples from sites across southern England, and researchers concluded that it came from an area near Marlborough, 25 kilometres away from Stonehenge. “What it really brings home for me is the Herculean effort that went into making this structure in a reasonably short time window,” says physical geographer David Nash. Other mysteries remain, including how Neolithic architects were able to transport the 20-tonne stones.
The proportion of children around the world that have dangerous levels of lead in their blood. (The Guardian | 6 min read)
Reference: Unicef report
Features & opinion
Many PhD students are facing tough choices about their future as the pandemic causes laboratory shutdowns and cancelled fieldwork. Walking away without a doctorate will be the right choice for some people, but it’s important to ask the right questions before making a decision. “Students need to separate the fake and real reasons for leaving,” says strategy adviser Shane Huntington.