Stealth in space is remarkably difficult. Atmosphere and terrain, even just clouds go a long way in the hiding game. In the vacuum of space, heat sources pop, electromagnetic signatures are as subtle as a brass marching band, and given the presence of stars, finding something is just a matter of a computer catching a star vanishing. Then the telemetry is calculated and there is no element of surprise.
Or at least that is how it used to be.
Mirage technology was developed at the Lunar Colonies out of a R&D think tank funded by a joint effort between the South African United Republics, United States of South America, Free India, and the Kingdom of Scandinavia. These four powers had spent the last decade watching their influence in space wane in the face of the Atlantic Federation and to a lesser extent, the Eurasian Alliance. Their ships were fewer in number, smaller, and less capable than their Federation counter parts, and the same held for their habitats, and non-terrestrial colonies.
The BlitzCorp R&D team came up with an active electromagnetic camouflage system that created a 'photon sheath' around the object it was built into. This sheath hid the object from active EM sensors such as radar and passive sensors like optical scanners. The only sign that something was there was a funhouse mirror/mirage optical effect.
There were several major limitations to the improved stealth ability offered by the new Mirage system. The most obvious limitation was the sheer size of the Mirage equipment. Only ships larger than 50 feet in length could mount it effectively, and this prevented it from being used on most mecha. The BlitzCorp group created a ship based Mirage system that allowed for ships to have fully functional optical/EM cloaking systems. A larger generator system was created that allowed for concealing entire space habitats and settlements on airless moons and planets. This larger Grand Mirage System is powerful enough to cover and cloak objects as large as arcologies and space habitats up to two miles in length.
The System is also energy hungry, even in the Cosmic Era. Mirage systems aren't left just running in the background unless they have their own dedicated power generators. These permanent/long term systems are mostly used on hidden habitats and secret space stations, or on the larger more powerful ships fielded by the BlitzCorp backer nations.
Mirage also completely fails inside an atmosphere as the presence of gas particles interrupts and disrupts the operation of the system. Mirage systems only work in space, on on planets and moons like Mercury, the Moon, and the Martian moons, and so forth.
The best defense is for the enemy to never know you were there.
The Mirage System is a very good space stealth system. If it's power demands can be met, there are few that come close. Amerikka Command's shroud technology comes close, but it only works on the ground and not at all in space.
The Mirage System exists to hide big things in space. This is fairly important because it can be really hard to hide out in space. Space stations and habitats have their share of defensive strategies and there is always a need to make somewhere that can't be found.
Stealth Space Ships
Working the same role as steath craft in the Petroleum Era, Mirage ships are lightly armed and lightly armored, but sneaky as hell and packed to the gills with electronic warfare equipment. These stealth patrol ships, and frigates are no match for the ships of the Federation or the Alliance, which is all the more reason for the ships to remain hidden in their photon sheaths.
A bunker's first and most important line of defense is ignorance. There are space habitats (small ones) and demi-arcos on other planets and moons in the Solar system that the legal residents of that world know nothing about. These secret and secure locations are used as military communication relays, secret research and development centers, and military installations.
Author's Note: This is a foundation technology, and will possibly be drawn upon by other submissions. Like classified genetic material this is as much an explanation of a freetext or common point of reference as it is a submission.