SpaceX prepares for historic mission to ISS (photos)

This week Space Exploration Technologies, known as SpaceX, will make history with the launch of the Dragon cargo capsule aboard a Falcon 9 rocket. It will be the first attempt by a commercial company to send a spacecraft to the International Space Station, a feat previously performed by only a handful of government agencies.

The launch, scheduled for Saturday, May 19, from Space Launch Complex 40 (SLC-40) at the Cape Canaveral Air Force Station in Florida, is ambitious endeavor, and SpaceX warns that "success is not guaranteed." In a more can-do vein, the company also said that "if any aspect of the mission is not successful, SpaceX will learn from the experience and try again."

The unmanned mission, expected to last about 21 days, will be the first privately built and funded spacecraft rendezvous with the space station. If successful, the mission is expected to pave the way toward regular operational commercial cargo missions to space, opening a new chapter in space exploration.

Editors' note: This slideshow was originally published May 1 at 8:57 a.m. PT. It has been expanded with additional photos and updated information.

At the Cape Canaveral launch complex on April 26, the SpaceX Dragon capsule was being prepped for joining with the second stage of the Falcon 9 rocket.

On April 30, the Falcon 9 rocket fired all 9 engines for 2 seconds as part of a day-long simulation in preparation for the actual launch day.

The International Space Station, seen here, awaits the arrival of the unmanned SpaceX Dragon capsule carrying resupply cargo. If all goes according to plan, the Dragon capsule will make many return trips -- manned and unmanned -- to the ISS over the next decade.

The Dragon will approach the ISS, as depicted here in an illustration, so astronauts can retrieve the capsule with its robotic arm.

An illustration depicts the Dragon spacecraft docked with the International Space Station.

The SpaceX mission patch for what's being referred to as the COTS 2 mission -- COTS standing for Commercial Orbital Transportation Services.

Dragon's protective nose cone awaits installation onto the SpaceX Dragon capsule at SLC-40 on April 26.

Nine Merlin engines for the inaugural Falcon 9 flight, ready for integration onto the thrust structure sit in the SpaceX Headquarters in Hawthorne, Calif.

The Dragon spacecraft being rotated before it was mated to the Falcon 9 rocket in SpaceX’s hangar at Cape Canaveral.

This diagram of the Dragon spacecraft shows the features of the vehicle.

The National Center for Earth and Space Science Education commissioned 22 mission patch designs to fly in the the Student Spaceflight Experiments Program (SSEP) payload to the International Space Station aboard SpaceX's Dragon capsule.

Lily Heese, a 4th grade student at Watkins Elementary in Washington, D.C., designed this patch, which will represent the Capitol Hill Cluster Schools.

Fourth grader Emma Catherine Collo from Valentine Elementary School in San Marino, Calif., designed this patch

SpaceX technicians load cargo into the Dragon capsule at SLC-40 in preparation for its scheduled liftoff aboard a Falcon 9 rocket.

At SLC-40 at Cape Canaveral, technicians load cargo into the SpaceX Dragon capsule for its scheduled liftoff aboard a Falcon 9 rocket. The reusable Dragon capsule will carry nearly 1,200 pounds of cargo in pressurized and unpressurized payloads.

NASA awarded a $1.6 billion commercial resupply services (CRS) contract to SpaceX in December 2008, with options that potentially increase the maximum contract value to $3.1 billion. The contract calls for 12 flights to the ISS, carrying a minimum of 20,000 kilograms (44,000 pounds) of cargo.

On April 30, SpaceX took the final big step toward the historic flight when it "static fired" the Falcon 9 rocket at Cape Canaveral.

The SpaceX Dragon spacecraft sits atop the Falcon 9 rocket at SpaceX’s launch site at Cape Canaveral.

The Dragon spacecraft is seen being mated to the Falcon 9 rocket in SpaceX’s hangar at Cape Canaveral.

SpaceX engineers prepare for the launch test last month at SpaceX’s control center in Cape Canaveral. The mock launch exercise had the rocket's nine engines all firing at full power for two seconds, as various sensors within the complex monitored the activity and ensured everything was up to standard for launch.

In addition to the successful static fire test, SpaceX already has two successful Falcon 9 launches to its credit, along with a history-making demonstration of the Dragon capsule that in December 2010 became the first privately built and operated spacecraft to be launched to and recovered from Earth orbit. That launch is shown here.

At a hands on demo day, SpaceX and NASA conducted a daylong review of the Dragon crew vehicle layout this spring using the Dragon engineering model equipped with seats and representations of crew systems. Industry leaders and former astronauts were invited to peruse the private spacecraft.

In the SpaceX clean room, the crew prepares the Dragon for its visit to the ISS. The view is looking through the forward hatch from the ISS side of the berthing adapter.

The Falcon 9 rocket and its Dragon capsule are lowered onto a transporter at Cape Canaveral Air Force Station's Space Launch Complex 40.

The rocket was being returned to the protection of its hangar following a wet dress rehearsal on the pad on March 1, which included loading the rocket with its propellants and a simulated countdown.