Amino acids are common enough -- glycine has been found in comets and, controversially, even in the interstellar medium. Other amino acids have also been found in comets.<p>Comet organics, under pressure, can turn into amino acids <i>in situ</i>: <a href="https://www.llnl.gov/article/36016/amino-acids-could-be-produced-within-impacting-comets-bringing-life-earth" rel="nofollow">https://www.llnl.gov/article/36016/amino-acids-could-be-prod...</a><p>It's also presumed that cometary ice bombardment is the source of Earth's surface water, as ice or water present any earlier would have boiled off when the planet was young and hot.<p>It's not much of a stretch to imagine that comets brought amino acids, organic compounds, and minerals to Earth as they were bringing water ice. A lot of those aminos and organics would turn into tar, but some would be protected from UV radiation by that same tar. With a heat source, maybe some lightning strikes, a good location, and a lot of luck, you get RNA...<p>What we can't yet do is assign a probability or likelihood to this process. But the ingredients should be common enough.