SpaceX is targeting Saturday for launch of its next space station resupply mission from Cape Canaveral after a problem with an upper stage steering system actuator flared up during a countdown Tuesday, NASA officials said Wednesday.

Saturday's instantaneous launch window is set for 4:47 a.m. EST (0947 GMT), a day later than officials previously hoped to send up the rocket.

The weather forecast calls for an 80 percent of favorable conditions for Saturday’s launch attempt. The prime concerns are violations of the thick cloud and flight through precipitation rules. Read our full story.

Launch of a SpaceX Falcon 9 rocket carrying a Dragon cargo ship loaded with more than 5,100 pounds of equipment and supplies bound for the International Space Station was called off Tuesday less than two minutes before liftoff because of apparent problems with the second stage engine steering system. Read our full story.

While SpaceX engineers analyze the problem with the second stage thrust vector control system, the launch team will drain the Falcon 9's propellant and configure it for another possible launch attempt Friday.

Assuming SpaceX can resolve the problem that triggered today's abort, the next chance to launch the Falcon 9 rocket on a resupply flight to the International Space Station will be Friday at 5:09 a.m. EST (1009 GMT).

The Falcon 9's strongback support structure has been returned to position against the 208-foot-tall rocket as SpaceX safes the launcher.

The NASA TV commentator says the launch team believes "actuator drift" in the Falcon 9 rocket's thrust vector control steering system triggered this morning's countdown abort.

SCRUB. Because this mission has an instantaneous launch window to reach the International Space Station, this countdown hold means liftoff will not occur today.

The next possible launch opportunity is Friday.

HOLD.

T-minus 90 seconds and counting. The SpaceX launch director and the Air Force Eastern Range have given their final approvals for liftoff of the Falcon 9 rocket at 6:20 a.m. EST (1120 GMT).

T-minus 2 minutes and counting. The rocket's Merlin 1D engines have been chilled down for ignition.

T-minus 2 minutes, 30 seconds. The strongback has been locked in to launch position.

T-minus 3 minutes and counting. The rocket's destruct system is on internal power and being armed, and liquid oxygen topping is being terminated.

The strongback has retracted into the launch position more than 20 degrees from the rocket.

The second stage thrust vector steering system has checked out and is ready for flight.

T-minus 5 minutes and counting. The cradles connecting the strongback to the Falcon 9 rocket have opened.

T-minus 6 minutes and counting. The Falcon 9 rocket is now operating on internal power.

The strongback umbilical tower will soon be lowered a few degrees to clear the rocket for launch. The procedure begins with opening of cradles gripping the rocket at attach points, then hydraulics lower the tower into launch position.

T-minus 6 minutes, 30 seconds. The Falcon 9's heaters are being deactivated, and the rocket will be transitioned to internal power in a few seconds.

T-minus 7 minutes and counting. Within the next minute, the Falcon 9's flight computer will be commanded to its alignment state. The Merlin engine pumps are continuing to chill down.

T-minus 8 minutes and counting. Good chilldown continues on the first stage engines, and closeouts of the upper stage's gaseous nitrogen attitude control system are underway.

T-minus 9 minutes, 30 seconds. Prevalves leading to the Falcon 9's Merlin 1D first stage engines are opening, permitting super-cold liquid oxygen to flow into the engines to condition the turbopumps for ignition.

T-minus 10 minutes and counting. The terminal countdown autosequence has started. Any hold after this point will result in an automatic abort and recycle to T-minus 13 minutes.

T-minus 12 minutes. The launch team has verified all consoles are go for liftoff at 6:20:29 a.m. EST (1120:29 GMT).

The terminal countdown autosequence is about to begin at the T-minus 10 minute mark.

T-minus 15 minutes and counting. Here are some statistics on today's launch:

• 14th launch of a Falcon 9 rocket since 2010
• 19th launch of Falcon rocket family since 2006
• 13th Falcon 9 launch from Cape Canaveral
• 9th launch of a Falcon 9 v1.1 rocket
• 8th Falcon 9 v1.1 launch from Cape Canaveral
• 3rd launch of a Dragon on a Falcon 9 v1.1 rocket
• 6th SpaceX mission to the space station
• 7th Falcon 9 night launch
• 1st Falcon 9 launch of 2015
• 7th flight of a Dragon spacecraft
• 1st launch from Cape Canaveral in 2015

T-minus 17 minutes and counting. The Falcon 9 rocket stands 208 feet tall and measures 12 feet in diameter. At liftoff, its nine Merlin 1D first stage engines will generate about 1.3 million pounds of thrust.

Fully fueled for launch, the Falcon 9 contains about 1.05 million pounds of kerosene and liquid oxygen propellants.

T-minus 20 minutes and counting. The final poll of SpaceX's 14-person launch team will begin at T-minus 13 minutes before the countdown enters the final phase.

See our Facebook page for images of today's countdown and launch!