Here, here! I was thinking the same. Ever since they first detected persistent earth-borne little buggers living on the exterior of the spacecraft. [1] I do th

Here, here! I was thinking the same. Ever since they first detected persistent earth-borne little buggers living on the exterior of the spacecraft. [1] I do think the detection of a methane spike by and orbiter and terrestrial rover within a day of each other, is an anomaly on a scale that doesn't seem to make a plausible for the case for earth-based bio-contamination. Perhaps they should have at least addressed that aspect. That said, I do cringe everytime I see an animation of a screw (rotating) propeller-based submarine exploring the oceans of Europa. Screw propellers will always contaminate some material (not necessarily biological) and there is a risk of a lot of contamination should a seal fail. Propellers are a poor propulsion choice for exploration of pristine liquid environments, including Earth's subglacial lakes [2]. Instead they should either use seaglider [3], or some oscillating foil propulsion like Thunniform locomotion [4] (both do not require any parts to penetrate the hull nd risk contaminating the environment). I will say though, that per the article, the findings of methane spike by an orbital craft and a terrestrial craft within 1. https://www.google.com/amp/s/relay.nationalgeographic.com/proxy/distribution/public/amp/2017/11/bacteria-international-space-station-germy-humans-spd https://www.google.com/amp/s/relay.nationalgeographic.com/pr... 2. https://salsa-antarctica.org https://salsa-antarctica.org 3. https://en.m.wikipedia.org/wiki/Underwater_glider https://en.m.wikipedia.org/wiki/Underwater_glider 3. https://en.m.wikipedia.org/wiki/RoboTuna https://en.m.wikipedia.org/wiki/RoboTuna