This answer quotes Marc Rayman's August 21, 2018 Dawn Journal entry:

Not all solar system bodies need such protection. The Moon, Mercury and Venus, for example, have not been of interest for searches for life or for prebiotic chemistry. For that reason, spacecraft are allowed to land or crash on those worlds because there is no expectation of subsequent biological exploration. Also exempt from such rules are tiny asteroids, including two that are being explored this year, Ryugu and Bennu. They are entirely unlike giant Ceres. They are often mistakenly thought of as being similar because of the oversimplified notion that all are asteroids. We will provide an illustration of the dramatic difference in the next Dawn Journal.

This might suggest that Venus might not require planetary protection because it has not recently drawn astrobiological interest.

On the surface there is no doubt, but the possibility of life in the clouds of Venus has gained some traction (see here, for example). Would considerations of Venus' atmosphere have an impact on future planetary protection needs for Venus? Considering historical missions, is it already too late for that?

And what exploration or theoretical efforts are underway to assess any possibility of cloud-based life at Venus?

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    $\begingroup$ I think this is a great question! I've made some modifications, mostly formatting and bringing the quoted section back into your post, but I've also adjusted the question a bit. Please have a look and double check, and feel free to roll back or make further edits. Thanks! $\endgroup$
    – uhoh
    Commented Mar 2, 2019 at 3:36
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    $\begingroup$ Oh. There is a tag for planetary protection? Missed that, thanks! $\endgroup$ Commented Mar 2, 2019 at 10:49

1 Answer 1


Accorcing to NASA's Office of Planetary Protection (NOPP),

"Some scientists have speculated that microbial life might be able to survive in the atmosphere of Venus. The Space Studies Board (SSB) of the National Research Council has considered the possibility of atmospheric venutian life and concluded that the environment of Venus is too harsh to support life as we know it. Planetary protection is therefore currently not a major concern for missions to this planet. Nonetheless, the SSB recommended that missions to Venus be assigned to Category II."

NOPP defines Category II as:

"Category II includes all types of missions to those target bodies where there is significant interest relative to the process of chemical evolution and the origin of life, but where there is only a remote chance that contamination carried by a spacecraft could jeopardize future exploration. The requirements are only for simple documentation. This documentation includes a short planetary protection plan is required for these missions, primarily to outline intended or potential impact targets; brief pre-launch and post-launch analyses detailing impact strategies; and a post-encounter and end-of-mission report providing the location of inadvertent impact, if such an event occurs."

So Venus is just barely short of "You can do anything you want."

  • $\begingroup$ Or one might say "barely above 'You can do anything you want'". $\endgroup$ Commented Mar 2, 2019 at 23:45

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