Spacecraft for a mission aimed at saving Earth from an asteroid strike will be built by the European Space Agency (ESA).
The ESA will make spacecraft for Nasa that can inspect the aftermath of an asteroid impact in space, after signing a $154 million (dh565 million) deal.
"We want to try for the first time to steer an asteroid on its potential collision course with Earth," ESA director Rolf Densing said.
Nasa is scheduled to launch a craft in June 2021 to collide with the Dimorphos asteroid to test whether it could nudge objects that might be threatening Earth on to a safer path.
After the Dimorphos collision, the ESA will launch in October 2024 its Hera craft, named after the Greek goddess of marriage, to map the impact crater and measure the asteroid's mass.
It should catch up with Dimorphos in late 2026 for a six-month survey.
Dimorphos has a diameter of 160 metres, which ESA said was big enough to destroy an entire city if it were to hit Earth.
Hera, set to be about the size of a desk, should navigate autonomously around the asteroid while it collects data.
It will also launch mini 10cm satellites, which will be able to fly much closer to the asteroid's surface.
Marco Fuchs, chief executive of German space and technology group OHB that will develop the Hera craft, said trying to divert an asteroid was like "playing billiards" and noted the challenge of steering towards such a small celestial body.
"You have to steer very precisely, you have to find it first and then approach it in such a way that you can really observe what has happened as a result of the impact of the American probe," he said.