Space is not an uneventful void. On a cosmic time and space scale, over millions of years and millions of miles, there are soundless, smell-less, visually-undetected threats to humankind, threats that might develop over several lifetimes but suddenly cross into our currency, thus changing our lives.
Using visible or invisible waves of energy, generally heat from the asteroid or the Sun’s reflection, only a small percentage of such objects in space – mainly asteroids – are detected. Consequently, by the time undetected physical threats approach our atmosphere, it is too late.