Falcon 9 on the pad at Cape Canaveral for a static test firing earlier this year.

If all goes as planned, SpaceX’s Falcon 9 rocket will lift off Friday from Cape Canaveral on a mission to demonstrate the capabilities of the new launch vehicle. However, the problem with new launch vehicles is that things often don’t go as planned, a concern not just for SpaceX but for the broader commercial spaceflight industry at a key time for it.

SpaceX CEO and CTO Elon Musk was well aware of the difficulties of launching new rockets, something he and SpaceX have already gone through with the smaller Falcon 1, which failed to reach orbit on its first three launches. “Historically, I think it might be something like a 50/50 shot of the first flight succeeeding,” he said in a teleconference with reporters Thursday, referring to the historical record of first launches of new rockets.

He does feel a little more optimistic about the chances of success with Falcon 9, citing the company’s experience and heritage of some Falcon 9 components on the Falcon 1. “My personal assessment of the likelihood of success is probably 70-80 percent,” he said. He did have a colorful way of putting that into perspective. “I should point out that this is less than the probability of success in Russian roulette,” he noted. (Assuming success in Russian roulette is defined as not getting a bullet, you have a 5 out of 6, or 83%, chance of getting an empty chamber.) “So if anybody remembers that scene from The Deer Hunter, that’s tomorrow.”

Well, that’s one way to look at it. It’s also worth noting that success is not a binary condition for this test flight: there’s a spectrum of outcomes between complete success and complete failure. “One hundred percent success would be reaching orbit” with the model of the Dragon spacecraft the rocket is carrying, Musk said. “But I think that, given that this is a test flight, whatever percentage of getting to orbit we achieve would still be considered a good day.” He added it would be a “great day” if both stages work correctly.

SpaceX is finally ready to launch the Falcon 9, having overcome the last obstacle to launch, the certification by the Air Force of a flight termination system that would be used if the rocket veers off course and has to be destroyed. Getting that approved took much longer than SpaceX anticipated. “There were I think some elements of it we underestimated, some elements that our suppliers underestimated,” he said.

If this launch was just about SpaceX it would be one thing: the company has been through the process of developing and testing a launch vehicle before, and from their accounts seem prepared for a failure, either partial or total. However, the launch also comes at a time when commercial spaceflight has been thrust into the political spotlight by plans by the Obama Administration to have NASA rely more on commercial launch providers, including a $6-billion initiative to develop commercial crew capabilities. That has put a lot of scrutiny on this launch from those skeptical of, or outright opposed to, the president’s plans.

“I feel like sort of a political punching bag, a whipping boy, I suppose,” Musk said. “The opponents of the commercial approach have taken a very calculated strategy of attacking SpaceX” while ignoring alternative vehicles, like United Launch Alliance’s Atlas 5 and Delta 4 rockets, that have already demonstrated the ability to safely launch spacecraft on more than 30 missions since 2002.

The Falcon 9 launch, he continued, “should not be a verdict on commercial space. Commercial space is the only way forward” because of the unsustainably high costs of government programs. He later said that “if some company like SpaceX doesn’t succeed, then the future of space is not a bright one.”

SpaceX will be webcasting the launch starting at 10:40 am EDT (1440 GMT) Friday, 20 minutes before the four-hour launch window opens. They also have the same time block reserved on Saturday should the get scrubbed Friday by technical issues or the weather. In addition, Spaceflight Now will have its own webcast featuring Miles O’Brien, David Waters, and former astronaut Leroy Chiao starting at 10 am EDT.

The Falcon 9 lifts off at 2:45 pm EDT Friday from Cape Canaveral, as seen in this screen capture from the SpaceX webcast.

If you had polled the attitudes of the people watching the launch of the first Falcon 9 on Friday, the most common feeling leading up to liftoff might be something like “hoping for the best but expecting the worst”. People wanted SpaceX to succeed with the Falcon 9 on Friday, but know that first launches of new rockets had no guarantee of success—something that Elon Musk and SpaceX impressed upon the community leading up to the launch.

So when the Falcon 9 lifted off at 2:45 pm EDT today and soared into the skies, eventually placing a demonstration Dragon capsule into nearly the planned orbit, the reaction was something approaching euphoria, even by Musk himself. “It’s been one of the best days of my life,” he said in a teleconference with reporters a couple of hours after the launch. “It’s certainly been one of the greatest days for the people of SpaceX.”

The launch had some drama, as well. The launch window opened at 11 am, but because of problems with an antenna for the rocket’s newly-approved flight termination system, they weren’t ready to launch until 1:30 pm. In the final seconds of the countdown, though, just as the nine rocket engines were about to ignite, the launch was aborted.

Musk said the abort was caused by a reading from an igniter on engine number three on the first stage. “The pressure rise on engine three was higher than expected,” he said, triggering the abort. “We looked at the data and concluded that… we were being a little too conservative” in the allowable values for the pressure in the engine. “So we widened that band [of allowable values], reconfigured the engine three computer, and it lifted off without a problem.”

About the only discernable problem during the launch was a roll in the second stage that appeared to speed up as the burn continued. “There was a little more roll than expected. It didn’t affect the mission,” Musk said. “That is definitely something that we want to refine,” he said, adding they didn’t immediately know the reasons for the roll.

So how did the launch feel, Elon? “When the rocket achieved orbit, there was tremendous relief and elation at SpaceX,” he said. “Upon liftoff there was sort of relief that it cleared the pad; things were obviously extremely tense here.” And his plans to celebrate? “I think with a lot of margaritas.”

After consuming those drinks, Musk and his team plans to spend about a month reviewing the data from the launch to fully characterize it and look for any issues (in addition to the second stage roll) that need to be corrected. Musk said he still planned to launch the next Falcon 9 mission, the first of three planned NASA COTS missions, later this summer. The Falcon 9 for that mission has already been built and is sitting in Texas ready to ship to the Cape; the Dragon spacecraft that it will launch is undergoing final reviews.