Irvin Glassman patented a concept which has relevance to the cryogenic conditions on Titan – whose atmosphere rains down acetylene onto the surface and contains 0.1% free hydrogen. One part acetylene mixed with 8 parts hydrogen can produce a jet of methane and hydrogen that sprays forth at ~2,700 m/s. Not superlative performance, but as it’s produced from free materials on the surface, we can say Titan is coated in potential rocket propellant. Curiously the same reaction could potentially power Life, albeit not as we know it.
Equally curious is the new announcement of phosphine in the atmosphere of Venus – a biosignificant gas, even if it’s not (yet) a 100% certain sign of Life.