Geoff Brumfiel

On Dec. 14, 1972, a capsule carrying Apollo 17 astronauts Eugene Cernan and Harrison Schmitt lifted off from the lunar surface.

It was the day that humans left the moon.

For a long while, they didn't come back, but that's changing. China, India and even smaller nations like Israel and South Korea are all pursuing robotic moon missions. Their lunar ambitions are being driven both by a desire to flex their technological muscles and by the rise of global nationalism.

Norwegian researchers have completed a survey of a sunken Soviet-era nuclear submarine that went down 30 years ago. The research team found that the sub is leaking a small amount of radiation from its reactors, but that it poses no threat to the surrounding environment.

Updated on Monday at 12:40 p.m. ET

Iran has crossed another line set in the 2015 nuclear deal between it and major world powers.

According to state media, Iran has begun enriching uranium above levels enshrined in the agreement. The move sends a signal that Iran is losing patience with a deal that has not provided the economic relief promised, more than a year after the United States withdrew from the agreement.

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Iran is on the verge of crossing a key line included in the nuclear deal it reached with the U.S. and other powers in 2015. As soon as Thursday, it's expected to announce that its uranium stockpiles have exceeded limits set by the deal.

Victoria Girgis was leading a public outreach session at the Lowell Observatory in Flagstaff, Ariz., when one of her guests noticed a string of lights moving high overhead.

"Occasionally, you'll see satellites, and they look kind of like shooting stars moving through the sky," Girgis says. "But this was a whole line of them all moving together."

In January, a group of high-level military commanders gathered at an air base in Yemen. It was far from the frontlines of the country's ongoing civil war.

Then, without warning, a small drone appeared out of the sky and exploded, spraying the group with shrapnel. According to news reports, the blast killed several, including the Yemeni government's head of military intelligence.

North Korea's newest missile has a striking resemblance to an advanced Russian design, according to experts analyzing images from a test of the weapon on Saturday morning.

The missile, which North Korea describes as a "tactical guided weapon," appears superficially to be nearly identical to Russia's Iskander missile — a highly accurate short-range weapon capable of striking targets more than 150 miles away.

On the outskirts of Riyadh, Saudi Arabia is building what it sees as the future of its energy production.

Updated at 5:30 p.m. ET

A secretive group of scientists who advise the U.S. government on everything from spy satellites to nuclear weapons is scrambling to find a sponsor after the Defense Department abruptly ended its contract late last month.

The group, known as the Jasons, will run out of money at the end of April. The Pentagon says that the group's advice is no longer needed, but independent experts say it has never been more relevant and worry the department is throwing away a valuable resource.

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