Final preparations are under way for NASA's Dec. 4 launch of the Orion spacecraft. Not since the final Space Shuttle mission in 2011 has there been so much excitement around American space flight. Sawyer Rosenstein reports from Cape Canaveral.

Take a state-of-the-art capsule designed to go to Mars, stick it on top of the most powerful rocket in the world currently in use, and what do you get? The ultimate space geek fantasy, and Exploration Flight Test One (EFT-1).

Orion's launch is scheduled for 7:05am ET on Thursday, December 4, 2014, from Space Launch Complex 37 at Cape Canaveral in Florida. There is a 2 hour and 39 minute launch window. NASA TV coverage starts at 4:30am ET.

This test flight represents NASA's first step towards manned spaceflight since the final space shuttle flight in 2011.

A Delta IV Heavy rocket provided by United Launch Alliance will launch the Orion crew capsule on a four and a half hour journey that will put the spacecraft through its paces.

The rocket, by the way, is pretty large. Three large boosters power the first stage, delivering almost 700,000 pounds of thrust. The newest Boeing 747s deliver 63,000 pounds of thrust for comparison. Yeah, Queen of the Skies? Not compared to this bad boy! That rocket will deliver the capsule to orbit and then raise its orbit later in the mission so they can complete all of their test objectives.

Orion Project Manager Mike Geyer said they're not only putting the vehicle through its paces, they're pushing it to its limits to see how it handles.

This will not be a typical test flight, however. This test capsule has the same systems that a manned capsule will have in the future. In fact, this capsule would be able to carry astronauts–if they'd installed seats. Instead, there will be weights and instruments to represent people and an automated computer to act as the pilot.

The rocket at Launch Complex 37B at Cape Canaveral Air Force Station with the Delta IV Heavy and Orion at the top [Photo: Sawyer Rosenstein]

The rocket at Launch Complex 37B at Cape Canaveral Air Force Station with the Delta IV Heavy and Orion at the top [Photo: Sawyer Rosenstein]

One of the main goals of this test is to make sure the biggest systems work, such as the heat shields.

"The things that we are testing on this flight you can actually test in this region," Geyer said. "We get close to lunar entry velocity so we can test out the heat shield."

The temperature those heat shields will reach, by the way, is around 4,000ºF (2,200ºC).

Another important test will involve 11 different parachutes that will help Orion descend when the mission is over. Each of those parachutes will have to deploy at just the right time and not rip or tear.

This test mission is being compared to Project Apollo, both lovingly and not-so-lovingly. It's a capsule design, which we haven't seen for 30 years. Many are calling it old-fashioned. However, we know this design can work.

"It's a tested system," said Astronaut Rex Walheim, who has flown to space three times.

"The only way to come back from a long duration flight is in a capsule, because if we were using the shuttle coming in at those speeds, the wings would rip off."

Rex also mentioned that although the Apollo computers were less powerful than a pocket calculator, in some they worked better than contemporary processing tools.

"Computers are powerful, but they're very finicky," Walheim said.

And they're especially finicky when you subject them to large doses of radiation, which a capsule will have to go through to go anywhere beyond low earth orbit. There's a thing called the Van Allen belt that surrounds the Earth. It's a belt full of radiation. Sure, we've learned more about how to protect our astronauts, but we also need to protect the computers that keep the astronauts alive.

"These processors we have now that are so small, they're great for speed and size but they're more susceptible to radiation," Geyer said.

So, they're sending this test capsule loaded with radiation sensors through the Van Allen belt twice. One time up, once down.

NASA's brand-new countdown clock, which displays live video of the rocket in addition to the countdown. [Photo: Sawyer Rosenstein]

NASA's brand-new countdown clock, which displays live video of the rocket in addition to the countdown. [Photo: Sawyer Rosenstein]

The whole flight will be four and a half hours, which is shorter than the six hour trip the capsule took from the processing facility to the launch pad. It will fly two orbits before splashing down in the Pacific Ocean a few hundred miles from San Diego, California. Then, the capsule will be loaded on to a Navy ship and all that data will be retrieved and processed. What we learn from that data will be used to modify the next Orion which will fly atop NASA's newest rocket, the Space Launch System, in 2017.

Yep, that's right. Another three year wait.

"I was a part of the ending of the shuttle program," Walheim said about finally overcoming the last three year gap. "It was a bittersweet time, but after it retired there was a gap– it's nice to see a vehicle come and take its place like we said it would."

The main reason for that three year gap: budgetary constraints. But America is finally getting back into the manned space game, even if it is with an unmanned test flight.

So, get excited! There's a big rocket sitting on a launch pad in Florida that's just waiting to light up the sky and re-spark the imagination of kids and adults everywhere. Sure, it's no moon landing, but if this goes well, in 20 years we could see a Mars landing, and it will have all started with this one test flight.

"Exploration is starting, and we're flying in space, so it's a big day for us," Geyer said.

The planned flight path.

The planned flight path.

Update: The flight has been delayed until Friday at the earliest. — R.B.

Launched!— R.B.