New milestone for NASA-ESA asteroid defense

If an asteroid were to hit Earth, it would cause a global disaster.

So, it may not be a surprise that scientists at the European Space Agency have teamed up with NASA as part of a joint project to explore how the huge, dark balls of rock could be deflected if they were heading for our planet.

And as of Tuesday, ESA has now signed a $153.8 million contract with German space and technology group OHB, to cover the production of a spacecraft set to be called Hera, after the Greek goddess of marriage.

Hera will act alongside NASA's Double Asteroid Redirect Test, or DART - which is due to launch in June 2021.

DART will be set on a collision course with the Dimorphos asteroid satellite that orbits the larger Didymos asteroid, to test whether it would be possible to nudge objects that might be threatening Earth onto a safer path.

ESA will then launch Hera later down the line in October 2024.

Hera will map the resulting impact crater and measure the asteroid's mass - reaching the Didymos system in late 2026 for a six-month survey.

If the NASA mission succeeds, ESA said it would be the first celestial body to be deliberately shifted by a human craft.

Director of Technology for ESA, Franco Ongaro, says although asteroids aren't an immediate threat, preventative measures should be put in place should they suddenly become one.

"Yes, it can be one in a million but if that one is tomorrow then you are in trouble. What we know is that it will happen again and it continuously happens. We get tons of material falling from the sky falling onto earth. Luckily three-quarters of the Earth is covered by water and a large part is also desert or ice, but that is luck. That is not a scientific way to approach the problem."

Dimorphos has a diameter of almost 525 feet - which is about the width of the Great Pyramid of Giza in Egypt.

ESA says that's big enough to destroy an entire city if it were to hit Earth.

Its spacecraft, Hera, will only be the size of a desk, and should navigate autonomously around the asteroid while it collects data.