Space dust can transport life between planets – see www.astronomy.com/news/2017/11/life-in-dust#.Whh0luAwbyE.mailto … dust and debris form ancient asteroid collisions, and outflow from comets as well as interstellar dust is pervasive throughout the solar system. Space is not empty. It is full of dust and no doubt, bigger grains, from gravel to rocks. Roughly 220,000lbs (in old money) of space dust falls on to Earth each day, we are told. In deep space streams of cosmic dust can travel at speeds up to 44 miles per second. Such streams regularly graze the upper atmosphere and can sweep up organic particles, it is hypothesized, and transport them far from Earth. Life on Earth could theoretically have been transported elsewhere.