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An illustration of NASA's Perseverance rover, which is due to land on Mars in February 2021.Credit: NASA/JPL-Caltech

The US and European space agencies have unveiled a daring plan to bring the first rocks back from Mars. The samples will be collected by NASA’s Perseverance rover, which is due to launch in the coming months. The ambitious interplanetary pilgrimage to return the rocks will involve two spacecraft that travel to Mars in 2026: a small rocket that will blast off the Martian surface, carrying the rocks into orbit, where a second craft will take them and fly back to Earth by 2031. “This is by no means a simple task,” says Jim Watzin, head of NASA’s Mars exploration programme in Washington DC. “But we have kept it as simple as possible.”

Nature | 4 min read

A volunteer-run organization has rediscovered 10 lost apple varieties in the northwestern United States. The Lost Apple Project seeks to rescue some of the 17,000 apple cultivars thought to have once been grown in North America, of which only about 4,500 are known to exist today. Members use old maps, county-fair records, newspaper clippings and nursery sales ledgers to find abandoned orchards and collect fruits. They then ship them to an Oregon conservancy, where they are studied. The organization also tries to reconstruct the history of the orchards. “When I find an apple that’s lost, I want to know who homesteaded it, when they were there, who their children were, when they took their last drink of water,” says amateur botanist E. J. Brandt.

Associated Press | 7 min read

Video of the week

Physicists have found the strongest evidence yet that neutrinos are fundamentally different from their antimatter counterparts. Researchers at the Super-Kamiokande detector in Japan found that one flavour of neutrino — muons — morphed into different types of particle at a different rate than did their antimatter twins. If confirmed, the results could help to solve the Universe’s greatest mystery: why there is more matter than antimatter. (Nature | 4 min video)

Go deeper with the expert perspective from physicists Silvia Pascoli and Jessica Turner in the Nature News & Views.

Reference: Nature paper

Features & opinion

Donald Knuth’s earliest claim to fame was at age 13, when he won a contest by finding 4,700 anagrams for ‘Ziegler’s Giant Bar’ — and was awarded chocolate for his entire class. It was only the first of many honours that would come to include the A. M. Turing Award, the most prestigious in computer science. Knuth describes his multi-volume opus-in-progress, The Art of Computer Programming, as a manifesto for writing code so beautiful that it can be read by humans like a story. “It describes the way I love to do math and the way I wish I had been taught.”

Quanta | 10 min read

Andrew Robinson’s pick of the top five science books to read this week includes how to stay healthy indoors, the past and future of power, and shoe libraries.

Nature | 3 min read

Following a Nature investigation that revealed thousands of coronavirus tests are going unused in US laboratories, researchers tell the Coronapod what they found when they dug deeper into what’s holding things back. Plus, the team discusses what a freeze on US funding means for the World Health Organization, and investigates the role of the immune system in the death of COVID-19 patients.

Coronapod | 29 min listen

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Where I work

Li Hua is a structural biologist and pharmacologist at Huazhong University of Science and Technology in Wuhan, China.Credit: Peng Nian for Nature

“Since January, I have spent every day alone in my laboratory, urgently trying to find a cure for COVID‑19,” says structural biologist and pharmacologist Li Hua, who lives on campus at Huazhong University of Science and Technology in Wuhan, China, the epicentre of the pandemic. Li’s colleagues, who had left for the Lunar New Year holiday, could not return during the lockdown and he is currently the only one who can access the lab. Now the lockdown there has ended, Li is working with collaborators in Shanghai to test the efficacy of the drug candidates he identified. (Nature | 3 min read)