Some Ukrainians have already returned after fleeing Russia's invasion, and almost half of the more than 5 million still abroad want to, according to a survey this year.

Forty years after the Challenger disaster, NPR explores the engineers' last-minute efforts to stop the launch, their decades of guilt and the vital lessons that remain critical for NASA today.

Federal funding cuts, though temporarily blocked by a judge, have upended vaccination outreach across the country, including in Arizona, Minnesota, Nevada, Texas, and Washington state.