Welcome to International Business Times' coverage of the space shuttle Endeavour's final launch. It is the 25th and final mission for NASA's baby shuttle and the penultimate mission for the space shuttle program.

It also features commander Mark Kelly, husband of congresswoman Gabrielle Giffords, who was nearly shot to death earlier this year. Both Giffords and the President Barack Obama will be in attendance as Endeavour makes its final journey into space. It will be Giffords first appearance since being shot.

The 14-day mission will see the crew of the Endeavour deliver the Alpha Magnetic Spectrometer (AMS) and spare parts including two S-band communications antennas, a high-pressure gas tank, additional spare parts for Dextre to the International Space Station. After it finishes up, NASA will conclude the space shuttle program with the Atlantis. Following that, the three remaining space shuttles and a fourth prototype will head to museums.

05:30 At Least Monday

In a press conference, NASA officials said the final launch of the space shuttle Endeavour will be delayed until at least Monday. Over the weekend, technicians will enter the area where the Auxiliary Power Unit 1 heaters are located and begin troubleshooting. On Sunday morning, they will evaluate whether or not a Monday launch is a go.

President Obama, who was supposed to witness the launch live, got a tour of the Kennedy Space Center facilities. He also met with congresswoman Giffords, in a brief chat.

The NASA officials said this type of delay has happened before; but could not specifically remember when.

We plan on covering the launch live whenever it happens.

01:45: Heating Failure

Check out extensive comments from Shuttle Launch Director Mike Leinbach as to why the launch was called.

12:40: Launch Called Off

In a surprise turn of events, the launch of the space shuttle Endeavour has been called off due to an issue with the Auxiliary Power Unit 1 heaters. The astronauts are still inside the Astrovan and are going back to the Operations and Checkout Building, the facility that houses the Crew Quarters. The external fuel tank will be drained of its oxygen and hydrogen propellants.

The engineering team did not understand how this problem occured and did not feel comfortable proceeding with a launch attempt, NASA Commentator George Diller said in explaining the decision to scrub today's launch attempt of Endeavour.

12:35: 48 Hour Scrub

Shuttle Launch Director Mike Leinbach scrubbed the launch attempt because of an issue associated with Auxiliary Power Unit 1 heaters. There will be at least a 48-hour scrub turnaround while engineers assess the issue. The earliest attempt to launch will likely be tomorrow.

12:05: On Their Way

The crew is in the silver astrovan and is on their way to the launch pad.

12:00 pm: Astronauts Suit Up

Everything is on track and on schedule for the 3:47 p.m. launch NASA says. The six STS-134 astronauts are in the midst of suiting up for launch in their crew quarters at Kennedy's Operations and Checkout Building. Once they are done, the six astronauts will head to Launch Pad 39A and climb into NASA's waiting silver Astrovan.

Weather is still looking favorable, and the 70 percent chance of good conditions at launch time still hasn't gone down.

11:30 am: Tank Is Full

Good news. Endeavour's external tank is fully loaded with more than 500,000 gallons of liquid hydrogen and liquid oxygen in preparation for today's 3:47 p.m. EDT launch. NASA said tanking operations began at 6:22 a.m. and concluded at 9:24 a.m.

10:30 am: OMS Issue Resolved

There was an issue with the Orbital Maneuvering System (OMS) fuel tank pressure, but it has since been resolved. The pressure was at 290 pounds per square inch (psi) and the Launch Commit Criteria limit is 288. However, NASA technicians worked to balance the left and right tanks and are below pressure limits and there are no technical concerns for today's launch.

For more on the scrubbed launch click here.

Follow Gabriel Perna on Twitter at @GabrielSPerna