HUMAN SPACE pioneers have come a long way since last year. Back then we were gently trying to place a probe on the surface of a comet. Now we are trying to smash and bully asteroids off course with one spacecraft while its friend watches, records and, for the sake of the metaphor, presumably laughs. Solar system exploration has turned into an American high school bully nightmare.
Of course, that’s a slight dramatisation. What NASA and the European Space Agency (ESA) are actually doing is much better than that. The American Double Asteroid Redirection Test (DART) mission will collide with an asteroid, while Europe’s Asteroid Impact Mission (AIM) observes and records data to be beamed back to Earth.
The target is the binary asteroid system 65803 Didymos and its moon, aptly named Didymoon. The latter is the impact target, which is 160m in diameter and has an orbital radius of 1.1km.
The motivation for this mission is to assess human ability to mitigate asteroids that would be a serious hazard to life on Earth. Since the threat of impact always exists in the solar system, it was only a matter of time before the dreams of sci-fi fans were sated by national space exploration agencies. However, asteroid impacts are still a relatively unlikely global hazard. Small asteroids are always colliding with Earth, most of them burning up in the atmosphere. According to the Journal of Evolution and Technology, an object with a diameter of 1km strikes our planet once every 500,000 years on average.
The ESA itself admits that the asteroid impact risk is low, though it stresses the global catastrophe that can follow a large strike. The mission awaits launch in 2020. After reaching the system, taking initial observations, deploying a small lander to investigate internal structure, DART will move to collide with Didymoon in October 2022. AIM will analyse the likely plume of material ejected and assess any changes in Didymoon’s trajectory.