The European Space Agency (ESA) will accompany the NASA DART spacecraft that will collide with the sun bleached rocky surface in a heroic effort to discover if the asteroid can be deflected from its precarious waltz around the earth. Speaking of Europe’s contribution to an international planetary defence test, Astrophysicist Brian May said: “If we’re going to find out if it’s possible to deflect Didymos, it is going to be really, really hard. Aiming at a 160-metre-wide target across millions of kilometres of void.
“Could we stop an asteroid hitting planet Earth?
“The dinosaurs couldn’t.
“But we humans have the benefit of knowledge and science on our side!”
To give us some appreciation for the size of the near earth hazard Mr May said: “Imagine a rock the size of a mountain with another rock the size of the great pyramid at Giza swinging around it.”
“The Hera spacecraft is going to show us things we have never seen before.
“It will be humanity’s first-ever spacecraft to visit a double asteroid.”
Didymos could be on a collision course with earth
Hera is the first step in helping the ESA to find out if it would be possible to deflect such an asteroid on a collision course with Earth
The mission will revolutionise our understanding of asteroids and how to protect ourselves from them, and therefore could be crucial for saving our planet.
First, NASA will crash its DART spacecraft into the smaller asteroid, known as Didymoon, before ESA's Hera comes in to map the resulting impact crater and measure the asteroid's mass.
Hera will carry two CubeSats on board, which will be able to fly much closer to the asteroid's surface, carrying out crucial scientific studies, before touching down.
Hera's up-close observations will turn asteroid deflection into a well-understood planetary defence technique.
The Hera mission will be presented to ESA’s Space19+ meeting this November, where Europe’s space ministers will take a final decision on flying the mission, as part of the Agency's broader planetary defence initiatives that aim to protect European and world citizens.
DART will then hit the smaller asteroid, which is about 160 metres in length, “nine times faster than a bullet, approximately 3.7 miles per second” according to a statement.
Lindley Johnson, planetary defence officer at Nasa Headquarters in Washington, said: “DART would be NASA’s first mission to demonstrate what’s known as the kinetic impactor technique striking the asteroid to shift its orbit to defend against a potential future asteroid impact.
“This approval step advances the project toward an historic test with a non-threatening small asteroid.”
The full mission is called AIDA and will be run by the ESA and NASA.
AIDA will target 65803 Didymos, a binary asteroid system in which one asteroid is orbited by a smaller one.
The primary asteroid is about 800m (2,600 ft) in diameter.
It’s small satellite is about 150m (490 ft) in diameter in an orbit about one mile from the primary.
Luckily, Didymos is not an Earth-crossing asteroid, and there is no possibility that the deflection experiment could create an impact hazard.
The proposed European Space Agency mission will map data from the diverted asteroid after the impact from the DART probe.
The Hera spacecraft will perform high-resolution mapping of the resulting impact crater.
Patrick Michel, director of research at France's Côte d'Azur Observatory said: ”The actual relation between projectile size, speed and crater size in low gravity environments is still poorly understood.
"Having both Small Carry-on Impactor (SCI) and Hera data on crater sizes in two different impact speed regimes will offer crucial insights.
"These scaling laws are also crucial on a practical basis, because they underpin how our calculations estimating the efficiency of asteroid deflection are made, taking account the properties of the asteroid material as well as the impact velocity involved.
"This is why Hera is so important; not only will we have DART's full-scale test of asteroid deflection in space, but also Hera's detailed follow-up survey to discover Didymoon's composition and structure.
“Hera will also record the precise shape of the DART crater, right down to centimetre scale.
"So, building on this Hayabusa2 impact experiment, DART and Hera between them will go on to close the gap in asteroid deflection techniques, bringing us to a point where such a method might be used for real."
Didymoon will easily be the smallest asteroid ever explored, meaning the space rock will provide insights into the cohesion of material in an environment of negligible gravity – more than a million times weaker than Earth’s.