Asteroid 99942, also called Apophis, is a sizeable 370-meter asteroid that has been classified as a Near-Earth Object or NEO due to its trajectory in relation to the planet. The NEO caused a little bit of a panic in late 2004.
This was the time when early observations indicated that Apophis could have a half-decent chance to hit Earth or the Moon in 2029. More attention was poured into the trajectory of the asteroid and it has been calculated that it will probably miss Earth at a narrow margin of 30.000 kilometers.
However, there is no guarantee that Apophis will stick to its present course. Among other gravitational influences in the solar system, phenomena known as gravitational keyholes have been discovered.
These are very small pockets in space, usually under 1 kilometer wide, that have the strange power to distort gravity within their tiny sphere of influence. If Apophis were to be affected by such a gravity keyhole than there is no telling how its course might be affected.
Especially with its narrow window of passing by Earth. Making the 4.5 million miles mark of QQ23 2006, the skyscraper-sized asteroid, seem like a vast distance by comparison. QQ23 2006 misses Earth by a few million miles this summer.
Elon Musk says we’re sitting ducks
Most scientists say that Earth will be hit by a NEO sooner or later. NASA calculations say that the planet is safe from impact for the next 100 years. But everyone agrees that we currently do not have any means of defense against such an event.
Elon Musk has chimed in via Twitter, with everything space related being of interest to the businessman. He approves of the name of the asteroid that is under discussion, probably due to him being a fan of mythology. But Elon also stresses that there is no defense against impact at the moment. He should know as he builds spacecraft.
NASA is aware of the issue and it has an advanced tracking system. But that’s about it. There is no current protocol that we are aware of in case of an actual NEO coming into a direct collision course with the planet. The space agency has announced a demo for redirecting incoming asteroids but who knows what that will bring.