First moon landing

No, this isn't about the 1969 Apollo mission being a hoax. It was quite real and an impressive feat of human engineering. Everyone involved in that endeavour deserves the praise they've gotten and possibly more. However, Niel Armstrong was not the first human to set foot on the moon. That honour goes to Aelia Hederosus who was inspired by her friend Copernicus (yes, that Copernicus) to explore space. As such, she furthered the understanding of the Space Branch of Arcana by leaps and bounds.
There were several nearly fatal attempts to reach for the stars, which is also how Aelia leaned how the vacuum of space works. This experience gave her permanent marks from burst blood vessels and eventually led to her corporeal death from radiation exposure. It is said that she used her last breaths to throw her spirit out into space.
While no one knows where, Aelia made several laboratories off-planet, she mentions these to several different sources who write about them separately. Finding even one of these would likely bring power to any arcanist trying to use a Space branch.

Spread

The stories of Aelia are widely spread, in many different versions, amongst scholars of the Space branches. Various orders have heralded her as a hero, others a monster. Conspiracy theories leaning towards the latter have been fueled by misogyny and transphobia as Aelia is rumoured to have been assigned male at birth. Those who want to give her credit aren't always better, sometimes using her alleged trans identity to explain her merits rather than acknowledge her for who she was.
It is only in the past century that the true genius of Aelia has been understood and respected. This has been compounded by her notes being found spread out in locations throughout space. Even when arcanists have believed they found an undiscovered path, they have discovered notes Aelia left behind there.

Variations & Mutation

Exactly how Aelia pulled this off is not known, and similar feats have only been made by the most powerful of arcanists. And even so, they are often waking Thorns on the way. The darkness of space can sometimes have dark tentacles reaching for travellers. Some claim Aelia made a deal with some of those creatures, which is also why they prevent anyone following her. Others believe she became something...different to manage what she did.
There are many stories about what is now on the moon where Aelia landed. There might be a growing, hardened, path through the Thicket. Or her spirit is there, feeding trespassers to the darkness. If anyone knows the exact location, they've never returned to tell the story, anyway.

Date of First Recording

1545

Date of Setting

1533