A challenge coin is a small coin or medallion, bearing an organization's insignia or emblem and carried by the organization's members.

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Supreme Court Appears Split Over Opioid Settlement for Purdue Pharma

Is it too late to keep global warming below 1.5 °C? The challenge in 7 charts - Chances are rapidly disappearing to limit Earth’s temperature rise to the globally agreed mark, but researchers say there are some positive signs of progress.

Going Beyond the Challenge for New and Continued Success

Historic dam removal poses challenge of restoring both river and landscape

"Why we scratch an itch: the molecules, cells and circuits of itch." Challenge: Peruse this paper without having an itch in need of a scratch appear.

Challenge accepted: High-speed AI drone overtakes world-champion drone racers

AI’s Invisible Foe: Confronting the Challenge of Digital “Dark Matter”

2 Eye-Opening Findings That Challenge Our Perception Of Loneliness

Atoms vs apples: How quantum effects challenge gravity’s rules

Craton Deception: Geologists Challenge Conventional View of Earth’s Continental History and Stability

Geologists challenge conventional view of Earth's continental history, stability with new study

During the 90s the government of Mauritius imposed tight restrictions on foreign media, and made it illegal to import a private satellite dish. But they didn’t say anything about building your own. Retired mechanic Jaques Gentil took up the challenge “You think it cannot be done? Well I’ll do it!”

NASA serves up $750,000 to Deep Space Food Challenge winners in cook-off for astronaut eats

NASA Selects Winners, Announces Final Phase of Space Food Challenge

Media, Public Invited to Meet Solvers in NASA Space Food Challenge

Last chance to root for JUICE in Kerbal Space Program 2 moon explorer challenge

This global challenge invites people to document the wild side of their cities

California started this community project to document urban nature | The City Nature Challenge is an annual contest to document as many species of plant, animal and other types of critters in a four-day period. This year’s event begins Friday and closes on Monday. It include 488 cities worldwide.

UAE releases stunning images of Deimos, Mars' smaller moon, that could challenge a long-standing theory

Chemists tackle the tough challenge of recycling mixed plastics