Orbital Sciences has pushed back next week's launch of a commercial resupply mission to the International Space Station by at least one day to Wednesday to dodge frigid temperatures expected on Virginia's Eastern Shore.

File photo of the Antares rocket rolling to the launch pad in December. Credit: NASA/Bill Ingalls

Liftoff of the privately-developed Antares rocket was set for Tuesday after a three-week delay from mid-December to make room for spacewalks to repair a problematic ammonia coolant loop on the space station, but the long-range forecast for early next week predicts freezing temperatures.

"The new target date was set due to the extreme cold temperatures that are forecasted for early next week, coupled with likely precipitation events predicted for Sunday night and Monday morning," Orbital Sciences said in a statement.

The company said it is preserving the option to launch Wednesday, Jan. 8, but it is more likely the launch will take place on Thursday, Jan. 9, because of a much improved weather forecast later in the week.

The National Weather Service forecast for NASA's Wallops Flight Facility, the Antares launch site, shows partly sunny skies expected for Thursday with a high temperature of 46 degrees Fahrenheit.

Temperatures must be above about 20 degrees Fahrenheit to launch the Antares rocket, according to Barry Beneski, an Orbital spokesperson. The forecast high temperature for Tuesday is in the mid-20s Fahrenheit.

The launch window Wednesday opens at 1:32:33 p.m. EST (1832:33 GMT) and extends for five minutes. The launch window Thursday begins at 1:10 p.m. EST (1810 GMT), according to Orbital Sciences.

Rollout of the Antares rocket is scheduled to begin around 8:30 p.m. EST Saturday. The rocket will make the one-mile trip from its horizontal integration facility to launch pad 0A riding a self-propelled motorized transporter.

Once at the launch pad, the 13-story Antares rocket will be hoisted upright on its launch mount by hydraulic pistons to begin several days of umbilical connections, vehicle closeouts and arming.

The Antares was already on the pad in mid-December awaiting a launch attempt. Technicians rolled the launcher back to the hangar Dec. 18 and removed the rocket's 12.8-foot-diameter nose shroud to access time-sensitive experiments and other cargo from the Cygnus spacecraft for refurbishment.

A launch readiness review is scheduled for Monday to give senior managers an opportunity to discuss any unresolved issues before proceeding with final launch preparations and the countdown.

The Antares rocket will put Orbital's Cygnus cargo freighter on course toward the space station. If the launch goes ahead Jan. 8, the unmanned resupply ship will arrive at the complex Jan. 12 after an automated rendezvous guided by GPS and laser navigation aids.

Once the visiting spacecraft gets to a point about 30 feet below the space station, astronauts will extend the lab's 58-foot robotic arm to grapple the Cygnus and maneuver it to a berthing port on the Harmony connecting node for several weeks of cargo transfers.

The mission is the first of eight Cygnus resupply flights to the space station under a $1.9 billion contract signed by Orbital Sciences and NASA in December 2008.

NASA and Orbital jointly financed development of the Antares and Cygnus vehicles. The space agency paid Orbital $288 million in a public-private partnership agreement that concluded with last fall's successful Antares and Cygnus demonstration mission to the space station.

Follow Stephen Clark on Twitter: @StephenClark1.