Top secret US plane X-37B has returned to Earth

A US plane on a top-secret, two-year mission to space has returned to Earth and landed in California on October 17, 2014.

The aircraft, resembling a miniature space shuttle and known as the Orbital Test Vehicle or X-37B, spent 674 days in orbit around the planet.

The purpose of the plane remains unclear and the United States government still refuses to reveal what he was doing. Air Force officials have only told US media the aircraft performs "risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies".

The question is, the X-37B really has remained in "orbital test" which partly given her away their "secret flights" to be orbital? Or did it make an inspection trip to planets in our solar system?

Analysts suggest that the X-37B could be used to spy from space and even see close satellites of other countries including the search for a possible artifact artificial satellite nonhuman.

Another possibility is the top secret human transport. Is it possible, it could have been used to travel to other planets, like the Moon or even Mars, looking for abandoned extraterrestrial bases as part of a hidden population spatial parallel program?

In orbit: 674 days.
Orbital speed: 28.044 km/h
Payload: 2,10 x 1,20 meters
Average distance Earth to Mars = 225,000,000 km