I don't think panspermia is impossible just improbable. These glass turds couldn't reach Earths escape velocity of 25000 mph much less the 119000 mph needed to escape the solar system source. These rocks got up to Mars's escape velocity of 11250mph maybe because mars had already lost its atmosphere? Endospores are hearty but I don't think they could survive in space for very long, especially when you consider solar radiation.   Abiogenesis is simpler you just need wet organics and a heat gradient. I bet we find life inside the moons of gas giants.