A Falcon 9 rocket that was supposed to launch Monday has been rescheduled for Friday afternoon.

The launch is now set for 3:25 p.m. Friday after a first-stage helium leak scrubbed the first attempt.

There is a 40 percent chance of favorable weather at launch time, with a chance of showers and thunderstorms that could violate launch constraints.

If there is a second scrub, SpaceX will attempt to launch Saturday, April 19 at 3:02 p.m.

NASA said this is an instantaneous launch time. That means it must happen for the rocket to launch and the Dragon capsule to catch up to the International Space Station within two days.

Despite a computer problem at the International Space Station last week, NASA gave the go-ahead over the weekend for SpaceX to launch its rocket later Monday.

The launch will also dictate when a contingency spacewalk will be performed to replace a failed multiplexer-demultiplexer aboard the ISS.

The rocket will deliver the Dragon capsule, with 2.4 tons of cargo for astronauts, to the space station.

Once there, astronauts there will unload the cargo, which includes research experiments, food and four high-definition cameras that will stream live video of Earth for online viewing.

The Falcon 9 rocket being used in this launch has been modified with new, 60-foot-long legs designed to help the rocket land back on Earth after launch, making the spacecraft reusable for future launches, like the space shuttles before it.

The plan is that after the Dragon capsule separates and heads for the ISS, the first stage of the rocket will make a soft splashdown in the Atlantic Ocean.

SpaceX said it wants to test the landing legs in the ocean first to improve precision, but eventually the private company wants to land the rocket near the launch pad. The company could save millions of dollars by reusing the rocket instead of having to build a new one for each launch.

SpaceX issued the following statement Wednesday morning:

NASA and SpaceX have confirmed Friday, April 18 for the next launch attempt for the Falcon 9 rocket to send the Dragon spacecraft on the company's third commercial resupply mission and fourth visit to the space station. Launch is targeted for 3:25 p.m. ET. The launch will be webcast live at www.spacex.com/webcast beginning at 2:45 p.m. ET.
 
A launch on Friday results in a rendezvous with the space station on Sunday, April 20 and a grapple at 7:14 a.m. ET.
 
During Monday’s launch attempt, preflight checks detected that a helium valve in the stage separation pneumatic system was not holding the right pressure. This meant that the stage separation pistons would be reliant on a backup check valve.
 
No issue was detected with the backup valve and a flight would likely have been successful, but SpaceX policy is not to launch with any known anomalies. We have brought the vehicle back to horizontal and are replacing the faulty valve, as well as inspecting the whole system for anything that may have contributed to the valve not working as designed.