Mars & Asteroids

Autonomy on Mars

Mars rovers cannot be driven in real time, because a signal can take many minutes to travel each way. Instead, teams on Earth plan each day's activities and send a sequence of commands, and the rover carries them out, increasingly using onboard software to navigate around hazards, choose targets and manage its own resources. Mars rovers have shown how far careful autonomy can extend a mission's reach, and each generation has tended to drive further and decide more for itself.

Flying and climbing

Not every planetary robot drives. A small helicopter has flown on Mars, showing that powered flight is possible in its thin atmosphere and opening the door to aerial scouts. Researchers are also studying robots that climb, walk on legs or rappel down cliffs and into caves, places wheeled rovers cannot reach. Each design trades capability for complexity, and many remain prototypes tested on Earth in deserts, lava fields and caves that stand in for other worlds.

Touching asteroids

Asteroids have very weak gravity, so a robot cannot simply land and drive. Missions have instead used brief touch-and-go contacts, small hopping landers and projectiles to collect material, returning samples to Earth for study. Asteroids interest scientists because they preserve material from the early solar system, and they interest industry as possible future sources of metals and water. Asteroid mining remains speculative, but the robotics it would need, from anchoring to autonomous sampling, is an active research area.

Sources and further reading

• After Three Years on Mars, NASA's Ingenuity Helicopter Mission Ends — NASA.
  Wrap-up of the first powered aircraft on another planet, from technology demonstration to aerial scout.
• NASA's First Asteroid Sample Has Landed, Now Secure in Clean Room — NASA.
  OSIRIS-REx returned material from asteroid Bennu, gathered in a brief touch-and-go contact rather than a landing.
• NASA Tests Drones in Death Valley, Preps for Martian Sands and Skies — NASA.
  Desert field tests on Earth of Mars drone autonomy, a legged scout robot and a winged flyer.

Common questions

How long does a signal take to reach Mars?

It depends on where the two planets are in their orbits. The one-way delay is a few minutes at the closest approach and much longer when the planets are far apart.

Is asteroid mining real?

Not yet at any commercial scale. Missions have collected small samples for science, and companies have proposed mining concepts, but the technology and economics are still unproven.