Context

European ministers in charge of the ESA space agency have approved Hera, a mission that will test whether deflection could save humanity from a rogue asteroid.

About

• Scientists are studying asteroids and trying to find ways to deflect them from a collision course with Earth.
• One such project is the Asteroid Impact and Deflection Assessment (AIDA), which includes NASA’s Double Asteroid Redirection Test (DART) mission and the European Space Agency’s (ESA) Hera.

Additional information

• ESA and partner NASA will send a pair of spacecraft to a double-asteroid system called Didymos.
• NASA will first crash its DART probe into the smaller asteroid (Didymoon). Hera will arrive later to map the impact crater and measure the asteroid's mass.
• The moon orbiting Didymos, called ‘Didymoon’ — almost the size of the Giza Pyramid in Egypt, measuring just 160 metres in diametre — will be the smallest asteroid ever explored.
• Hera will carry two CubeSats that can fly extremely close to the asteroid's surface before touching down.
• Those briefcase-sized spacecraft will act like drones, capturing vital data about the impact crater and giving scientists data including the mass of the asteroid that will help them deduce its composition.
• While an asteroid collision is a pretty unlikely event, it's actually preventable, unlike an earthquake or volcanic explosion.
• However, Hera mission won’t be the first to reach Didymos. The National Aeronautics and Space Administration (NASA) in USA plan to launch the Double Asteroid Redirection Test (DART) between 2020 and 2021, which will target Didymoon as part of its planetary defence programme.

Why we need a planetary defence mechanism

• There are around 25,000 near-Earth objects (NEOs) that orbit the Sun on a trajectory that brings them close to our planet’s orbit.
• NASA tracks such near-Earth objects to ensure they do not become threats.
• However, certain near-Earth objects have been classified as “potentially hazardous” which are 140 metres or more in size.