Maybe one could build some expandable transparent dome and put a selection of species like algae, tardigrades and some extremophiles in there to kick start a biosphere?
Discussion
I think that's exactly how we should start :)
I have made some lists of candidate organisms.
There are several species of cyanobacteria that are extremophiles and can utilise perchlorate as an electron-acceptor, solving two problems at once (hypoxia and perchlorate stress).
Unfortunately they are also able to destroy nitrate in the same way, which would be a nuisance.
A geneticist friend was going to get back to me on whether the nitrate-reduction could be "knocked out" while leaving perchlorate reduction intact. I should annoy him about that again :)