Rocks from Mars are a prize for the U.S. and China.
Why it matters: Experts stress parallel missions by the two countries to return rock and dirt samples from the Red Planet aren't being driven solely by competition, but the nation that sends back samples first will get international bragging rights and a scientific edge.
NASA will not launch a spacecraft to explore a metal-rich asteroid this year as planned, and it's not yet clear when — or if — the mission will get off the ground.
Why it matters: The Psyche mission is designed to study the asteroid Psyche — which is thought to potentially be a fragment of a dead planet's core — from close range.
