I haven't done the maths on how much explosive you'd need to noticeably alter the trajectory, but it's not 4 kg. I'm not sure if 15 million kg (one Hiroshima)

I haven't done the maths on how much explosive you'd need to noticeably alter the trajectory, but it's not 4 kg. I'm not sure if 15 million kg (one Hiroshima) would even do it. Edit: according to Wikipedia [0], a 1967 study suggested that we could alter the course of a 1.4km asteroid enough to avoid an Earth collision by using a handful of Tsar-Bomba-sized nuclear weapons, each equivalent to around 6000 Hiroshimas or 25 billion of the charges proposed for the Hayabusa-2 mission. [0] https://en.m.wikipedia.org/wiki/Asteroid_impact_avoidance https://en.m.wikipedia.org/wiki/Asteroid_impact_avoidance