This story was updated at 5 p.m. ET.

An unmanned private spacecraft all set to launch the first commercial delivery to the International Space Station tonight (Oct. 7), marking a major shift in how NASA sends supplies and gear to the orbiting lab.

The gumdrop-shaped Dragon space capsule built by the private spaceflight company SpaceX is poised to blast off from a pad at Cape Canaveral Air Force Station in Florida to begin a three-day voyage to the space station. SpaceX raised the Falcon 9 rocket that will boost the Dragon capsule spaceward into launch position this afternoon. Liftoff is set for 8:35 p.m. EDT (0035 Monday GMT) and the weather forecast looks favorable for launch, NASA officials said.

"Tomorrow's SpaceX launch begins a new era for spaceflight and the International Space Station," Sam Scimemi, NASA's space station director, said in a briefing Saturday (Oct. 6). "These flights are critical to the space station's sustainment and to help begin its full utilization."

SpaceX's Dragon spacecraft will launch nearly 1,000 pounds (453 kilograms) of cargo for astronauts living on the space station. The crew plans to welcome the spacecraft on Wednesday (Oct. 10) by grappling it with a robotic arm and attaching it to the station.

The mission is the first of at least 12 cargo runs for NASA that SpaceX will perform under a $1.6 billion deal to deliver 20 metric tons of supplies to the station for the U.S. space agency. [SpaceX's Dragon Poised to Sunday Launch (Photos)]

SpaceX is also working to upgrade the Dragon spacecraft and Falcon 9 rockets to launch seven-astronaut crews into orbit. The spacecraft was designed from the start to enable future crewed flights, according to SpaceX's CEO Elon Musk, the billionaire entrepreneur who founded the company in 2002.

With NASA's space shuttle fleet retired, the space agency is depending on commercial spacecraft like SpaceX's Dragon capsules to ferry cargo and eventually astronauts into and from low-Earth orbit. The agency is outsourcing those services to commercial companies while developing its own new rocket and spacecraft for deep-space exploration.

What goes up can come down

SpaceX is one of two companies with contracts to provide cargo shipments to the space station for NASA. The other firm, the Virginia-based Orbital Sciences Corp., has a $1.9 billion deal for station resupply flights using its new Antares rocket and unmanned Cygnus spacecraft. Of the two companies, only SpaceX's Dragon is capable of returning cargo to Earth for retrieval.

See more here:

Private SpaceX Cargo Ship Launching 'New Era' for Space Station Today