Object 524 is an asteroid which was non-negotiably declared off-limits by aliens.
Not much is known about Object 524 other than the fact that it has low gravity and that its surface is a hard vacuum. It is not supposed to be accessible by the Lotus Nodes system; however, in Reducing the Uppity, a portal malfunction sends Empowered to it. She briefly enjoys the low gravity and then leaves; it is not until Mindfuck checks the portal logs afterwards that she learns it is forbidden territory.
In I Never Looked in Your Eyes; I Never Heard Your Voice, Sistah Spooky has Empowered access Object 524 again as part of her attempt to break Mindfuck out of Hell. She reveals that the asteroid is a superweapon depository used by an alien species of ambiguous intent towards humanity. One of the superweapons stored there, the Vorpal Sword, was loaned to the superheroes for a time, but access was revoked and the asteroid declared off-limits after careless use of it resulted in the creation of the San Antonio supervolcano.
In Distress and the Damsel, it is revealed that following Emp and Spooky's theft of the Vorpal Sword, the aliens removed the arsenal of superweapons and reduced the asteroid to rubble. They left behind a war machine to kill any more intruders trying to access the site.