Scientists are to send two spacecraft to knock an asteroid off course, as part of a test to block such rocks in future, which may threaten humanity.

The joint US-European Aida (Asteroid Deflection & Assessment) mission will send a small spacecraft to crash into the egg-shaped rock, known as Didymoon.Though the asteroid is too small to pose any threat, the mission will be an important test if we do eventually come at risk of civilisation being wiped out by a space rock.

The missions are set to be launched in October 2020 and are expected to reach Didymoon by May 2022. Nasa will send one craft in the mission, known as Double Asteroid Redirection Test (Dart), which will fire a probe to smack into the rock and see if it can throw it off course.

Besides the nudging probe, scientists will send another spacecraft -the Europe an Space Agency’s Asteroid Impact Mission (Aim)–that will fly around Didymoon watching the effect of the Dart mission, as well as measuring the asteroid’s mass and density , and putting a small lander on the asteroid itself to look at its insides.

“To protect Earth from potentially hazardous impacts, we need to understand asteroids much better–what they are made of, their structure, origins and how they respond to collisions,” said Dr Patrick Michel, lead investigator for the European Space Agency half of the mission.

“Aida will be the first mission to study an asteroid bi nary system, as well as the first to test whether we can deflect an asteroid through an impact with a spacecraft.The European part of the mission will study the structure of Didymoon and the orbit and rotation of the binary system, providing clues to its origin and evolution,” Michel said. “Asteroids represent different stages in the rocky road to planetary formation, so they offer fascinating snapshots into the solar system’s history ,” he added.