Is it safe to say that officially, Asuka is the first and currently the only Guilty Gear character who be able to survive and breathe in outer space? The fact that he is on the moon away from Earth is impressive without a space suit, not surprising but still impressive.
To clarify, the Project Tír na nÓg is a Space Colony built ON the Moon that was built back during the Crusades as a sort of base to house the White House in case of emergency.
Tír na nÓg means "Land of the Young" in Irish, and is the Celtic equivalent of a Netherworld or Otherworld (for Deities and the Dead).
While it's true that Asuka can transport himself to and from Outer Space (and even to the Backyard's Dense Space), he still needs "artificial space" to breathe oxygen, though it is the Magic equivalent of a Space Suit, made primarily of dense mana.
The Cube he created back in 2186 (GG2 Overture's events) was just one of many experiments involving testing the viability of the Backyard's space, not just for storing information or Magic, but also a personal living space for Asuka in times where he needed to be somewhere that wasn't Earth.
In fact that's where he invited Axl Low at one point.
Unlike the Cube or other Artificial spaces, though, Tír na nÓg itself was built using more conventional Scientific ideas: a garden to house space-grown crops, a library and database for storing information, and even an observatory with a telescope.
Originally the Space Colony was built to house at least 500 people, though because of the Crusades, many people forgot it even existed (even Erica Bartholomew thought it was a myth), despite the fact it has such advanced facilities. So in a sense it is still classified as "Blacktech" a forgotten War Relic from times when Mankind still used advanced technology despite the threat of the Universal Will.
According to Zato and Millia's P.W.A.B. Intel, the Conclave were partly responsible for its construction, though the construction itself was registered under the United Kingdoms of Illyria, despite being a centuries-old American Military Secret (strangely enough, Illyria is credited for the Colony's construction, even though Illyria as a Nation itself did not become officially established until 2183, nearly 100 years after the base and White House were built).
Despite still being considered a Blacktech War Relic, Asuka uses it as a Bastion of Defense to protect himself and the Tome of Origin from falling in to the hands of others for their own personal gain.
Though it is still somewhat unclear how the United States Government is interpreting and allowing his use of the space colony, at the very least they've established that he has no intentions of using it for any bad purposes (given the intentions he laid out in his presentation at the G4 Summit).
As a side note, this isn't the first time Space Technology was built during the Crusades, as the Mothership (a Gear Terraforming Project) was built and destroyed some time ago as well (GGXtra's events).
