The U.S. Air Force's mysterious X-37B robot space plane returned to Earth today (Dec. 3) with a successful landing at Vandenberg Air Force Base in California before sunrise.

Air Force officials hailed the unmanned X-37B space plane's successful landing, though its mission remains shrouded in secrecy because of its classified nature. But Vandenberg's 30th Space Wing did not shy from snapping photos of the X-37B vehicle, known as the Orbital Test Vehicle 1. Take a look at those first photos below:

Nose to Nose: X-37B space plane builder Boeing released this photo of the unmanned spacecraft just after its landing on Dec. 3, 2010.

The spacecraft spent 220 days in space before gliding to a predawn landing at the Vandenberg Air Force Base in California.

See a video of the X-37B landing here.

Home Again: Despite its robotic nature, the X-37B space plane received a warm welcome from Air Force crews at Vandenberg.

Here, the vehicle appears to be undergoing safing procedures after landing on Dec. 3 at 1:16 a.m. PST (0916 GMT).

Significant weathering, or discoloration, can be seen on the spacecraft's upper thermal blanket insulation.

X-37B in Profile: An Air Force photographer snapped this profile view of the X-37B shortly after its Dec. 3 landing.

The X-37B is about 29 feet (9 meters) long and has a wingspan of just over 14 feet (4 meters) across. It stands just over 9 1/2 feet (3 meters) tall and weighs nearly 11,000 pounds (about 5,000 kg). For comparison: Two X-37B vehicles, arranged in a line nose to aft, could fit in the payload bay of a NASA space shuttle. Boeing's Phantom Works division in Seal Beach, Calif., built the spacecraft.

This SPACE.com graphic of the X-37B depicts the characteristics and capabilities of the unmanned space plane.

Up Close and Personal: A crew of vehicle handlers clad in suits to protect against hazardous materials (like any remaining rocket fuel) approach the X-37B robot space plane after its successful Dec. 3 landing at Vandenberg Air Force Base in California.

X-37B Walkaround: This photo released by the Air Force shows the nose of the mysterious X-37B space plane as recovery crews take measurements and other readings after its Dec. 3 landing at Vandenberg. The X-37B's unique V-shaped "ruddervators" ? which serve as its tail stabilizers ? are visible as well as a deployed air brake. [Gallery - The Air Force's X-37B Space Plane]

Payload Bay Doors: Here, the X-37B space plane is seen in profile as post-landing work continues. The logos of Boeing and the Air Force are visible on the reusable spacecraft's hull. They appear between lines that outline the X-37B's payload bay, which is about the size of a pickup truck bed and can hold experiments, small satellites and a solar array panel that it used to generate power.

Welcome Home: This X-37B space plane's payload bay is seen clearly in this side view, as is the scale of the spacecraft compared to a human. [Video of the X-37B in space]

The X-37B began its life in 1999 as a NASA project, then transferred to the Pentagon's DARPA office in 2004. The Air Force took over in 2006. This mission launched on April 22, 2010. The flight's purpose and cost are classified.

Looking Up: This side view of the X-37B was taken by a Boeing photographer, revealing the grooved runway of Vandenberg Air Force Base where the robotic space plane landed today. An army of Vandenberg workers replaced hundreds of small steel plates on the runwary to smooth it out in order to avoid damage to the X-37B's tires during landing, according to the Santa Maria Times newspaper.

Job Well Done: With the first X-37B spacecraft back on Earth, the Air Force is now looking ahead to the next launch. The Air Force has ordered the construction of a second X-37B ? the Orbital Test Vehicle 2 ? for a mission to launch in the spring of 2011.

You can follow SPACE.com Managing Editor Tariq Malik on Twitter @tariqjmalik.