Asteroids are the ancient remnants of our solar system's birth, rocky fragments that never formed into planets. Most of these celestial wanderers inhabit the asteroid belt between Mars and Jupiter, where Jupiter's immense gravitational influence prevents them from assembling into a single world.

Tianwen, which means "questions to heaven," is the name given to China's program of robotic Solar System exploration. Tianwen-3 has a chance to become the first mission to return pristine samples from Mars to Earth. At the same time, NASA's plans for a Mars Sample Return mission are faltering.