Geoff Brumfiel

Stay inside, don't meet with friends, don't go to work — these are the messages coming from public health officials at every level of government. But increasingly, experts say they believe those stark warnings must be augmented with another message:

If you think you might be sick, even a little sick, get tested for coronavirus.

People infected with the coronavirus can spread it easily, even if they're not yet experiencing severe symptoms of the disease, according to virologists watching the pandemic unfold in Europe.

The fragile peace deal taking shape in Afghanistan could spell the end of an era of for the U.S. military, one marked by efforts at nation-building and winning hearts and minds.

It appears that the Pentagon is also intent on ending a research program from that era — to fund social science for the military.

Acclaimed physicist Freeman Dyson, who pondered the origins of life, interstellar travel and many other topics, died Friday at the age of 96.

His daughter Mia Dyson told NPR that her father died after a short illness.

Freeman Dyson was known for groundbreaking work in physics and mathematics but his curiosity ranged far beyond those fields.

The U.S. has begun deploying a new type of low-yield nuclear warhead aboard some ballistic missile submarines, according to a report by an independent monitor.

When the USS Tennessee, an Ohio-class submarine, went on patrol in the final weeks of 2019, it carried "one or two" of the new weapons, according to a post by the Federation of American Scientists.

A rocket from the commercial company SpaceX lifted off on Wednesday morning with some 60 satellites aboard. Once they reached low Earth orbit, the satellites were released and began to fan out like a deck of cards.

They follow predictable paths around the Earth, but along the way those paths can cross with other things in orbit — satellites from other companies, old rocket stages, loose bits of metal — and cause a catastrophic collision.

New imagery from commercial satellites that was shared with NPR suggests Iran is making repairs and preparing for a space launch, following a recent string of failed attempts.

The imagery, taken Sunday by the commercial firm Planet and shared via the Middlebury Institute of International Studies at Monterey, shows vehicles parked at a building used to assemble Iran's space rockets at the Imam Khomeini Space Center in northern Iran. A second group of vehicles is visible at a circular launch pad that was heavily damaged during failed launch preparations last year.

On the same night that Iran launched a ballistic missile strike against bases used by U.S. troops in Iraq, a Ukrainian jetliner crashed near Tehran, killing all 176 people onboard. Iranian authorities have said the plane suffered a mechanical failure, but the U.S. and other Western governments believe it was shot down, possibly by mistake.

"The evidence indicates the plane was shot down by an Iranian surface-to-air missile," Canadian Prime Minister Justin Trudeau said during a news conference Thursday. "This may well have been unintentional."

Updated at 2:45 p.m. ET

Satellite photos taken Wednesday show that an Iranian missile strike has caused extensive damage at the Ain al-Assad air base in Iraq, which hosts U.S. and coalition troops.

The photos, taken by the commercial company Planet and shared with NPR via the Middlebury Institute of International Studies at Monterey, show hangars and buildings hit hard by a barrage of Iranian missiles that were fired early Wednesday morning local time.

North Korea doesn't really do Christmas cards, but if it did, its card would probably have a picture of the nation's leader, Kim Jong Un, riding a white horse through a snowy wilderness. In fact, North Korean state media released those exact images this month, and the message was clear: Kim, frustrated with how things were going, was pondering a new direction.

A comet from another star will swing by our sun Dec. 8.

Known as 2I/Borisov, it is the first comet to ever be seen coming from interstellar space. But despite its alien origins, astronomers say it actually looks pretty familiar.

"Borisov is a comet very like what we have in our own solar system," says Michele Bannister, a planetary astronomer at Queen's University Belfast told NPR's Short Wave. Whatever planetary system it formed in, "it's a lot like our own."

Fifty years ago, astronaut Pete Conrad stepped out of the lunar module onto the surface of the moon.

His first words were: "Whoopie! Man, that may have been a small one for Neil, but that's a long one for me."

Conrad, who stood at just 5 feet 6 inches tall, was only the third human to set foot on the lunar surface. He did it on November 19, 1969, just four months after Neil Armstrong and Buzz Aldrin made the first lunar landing. However, unlike Armstrong and Aldrin, Conrad and fellow astronaut Alan Bean are not household names.

SpaceX successfully launched 60 communications satellites on Monday using a single rocket.

It's the second time in less than a year that Elon Musk's company has made such a launch, marking a dramatic increase in the number of satellites in orbit.

On Sept. 14, a major Saudi oil processing plant was rocked by a series of explosions. The facility, and another oil field to the south, had been attacked from the air. Here's what we know — at this time — about the attacks based on physical evidence.

The strike was large and sophisticated

On the face of it, NASA's newest probe sounds incredible. Known as Dragonfly, it is a dual-rotor quadcopter (technically an octocopter, even more technically an X8 octocopter); it's roughly the size of a compact car; it's completely autonomous; it's nuclear powered; and it will hover above the surface of Saturn's moon Titan.

Iran almost certainly had some role in a major attack on an oil production facility in Saudi Arabia, according to independent analysts reviewing the available evidence.

The question is how big.

The attack came on Sept. 14. Multiple drones or missiles struck Saudi Aramco's Abqaiq facility, causing massive damage and crippling the nation's oil production. The production of 5.7 million barrels of crude oil per day had to be suspended, according to the company.

A major oil storage terminal on Grand Bahama Island was damaged by Hurricane Dorian and has leaked oil into the surrounding environment, raising concern that the oil could damage local reefs and wildlife.

The South Riding Point facility sits on the shore of the island's eastern side and is home to 10 giant storage tanks capable of holding up to 6.75 million barrels of crude, according to Equinor, the company that runs the facility.

The first thing Melissa Hanham did when she saw President Trump's tweet last week was take a screen grab.

"My reaction was to immediately save the image to my phone just in case it got taken down," she says.

The wording on the tweet was cryptic: "The United States of America was not involved in the catastrophic accident during final launch preparations for the Safir [space launch vehicle] Launch at Semnan Launch Site One in Iran," the president said. "I wish Iran best wishes and good luck in determining what happened at Site One."

Amateur satellite trackers say they believe an image tweeted by President Trump on Friday came from one of America's most advanced spy satellites.

The image almost certainly came from a satellite known as USA 224, according to Marco Langbroek, a satellite-tracker based in the Netherlands. The satellite was launched by the National Reconnaissance Office in 2011. Almost everything about it remains highly classified, but Langbroek says that based on its size and orbit, most observers believe USA 224 is one of America's multibillion-dollar KH-11 reconnaissance satellites.

Timothy Koeth's office is crammed with radioactive relics — old watches with glowing radium dials, pieces of melted glass from beneath the test of the world's first nuclear weapon.

But there is one artifact that stands apart from the rest: a dense, charcoal-black cube, 2 inches on a side. The cube is made of pure uranium metal. It was forged more than 70 years ago by the Nazis, and it tells the little-known story of Germany's nuclear efforts during World War II.

Updated at 1:30 p.m. ET

Satellite imagery shared exclusively with NPR shows that an Iranian rocket appears to have exploded on the launch pad Thursday.