The following is a partial transcript of SpaceX founder Elon Musk's post-launch briefing to reporters. It begins with Musk's opening comments:

"I think I'll characterize this as a very good day for SpaceX. We successfully reached space and really retired almost all the risk associated with the rocket. So I feel very good about where things are.

"I feel extremely good about having successful satellite launches later this year, especially when I know we've got two satellite launches lined up for later this year -- one is a Defense Department satellite and the other a Malaysian space agency satellite. We've been in touch with our customers. They are very excited by the results of this test, and so we feel really good actually.

"The things we were most concerned about were the first stage ignition and liftoff, the trajectory, the first stage because that goes through the most difficult portion of the atmosphere where you can have high winds and potentially go unstable or potentially have a structural problem and that went flawlessly. We had zero anomalies whatsoever on the first stage.

"Stage separation also went very well. Separation events are the No. 2 killer of rockets after engine issues. Both the stage separation and fairing separation went flawlessly. Second stage ignition also was perfect, and we achieved steady state burn on the second stage.

"We did encounter, late in the second stage burn, a roll-control anomaly, which you may have seen on the video webcast. We feel that is something that's pretty straightforward to address. So all in all we feel pretty good about this launch.

"This was a test launch, which I think most people are aware. So, yes, I think it was a pretty good test."

Question: What is the fate of the second stage?

"We didn't achieve the desired orbit. But at this point I don't exactly know the fate of the second stage. We got to 300 km. That's about all I know at this point."

"All that I can say for sure right now is it's not in the intended orbit. The likelihood is that it re-entered after probably half an orbit or so."

"The roll-control anomaly did cause the second stage to shut off prematurely. So that's not achieving the intended orbit. However, I would say we've retired probably in excess of 90 percent of risk associated with the rocket. And it is worth noting, this was a test launch not a satellite launch."

Question: How disappointed are you?

"This was a pretty nerve-wracking day, to say the least...The rocket business is definitely not a low-stress business, that's for sure. I don't think I'm disappointed actually. I'm actually pretty happy, so I'm sorry if I'm not conveying that...It definitely could have gone a little better today, but if we've retired almost all the risk associated with the rocket, I think it is hard to characterize that (as) anything but a success, at least in my book, because this is a test launch of the rocket and not a satellite launch. I think if it had been a satellite launch, you know, one could perhaps argue differently. But in terms of it being a test launch, the question being have we...learned essentially everything we need know to deliver a satellite successfully to orbit, I think the answer is absolutely. We've learned everything we need to know to deliver a satellite successfully to orbit."

Question: Was the loss of telemetry associated with the roll-control problem?

"It is very speculative at this point. It is hard for me to say. I think that is a possible cause."

Question: What was the debris seen floating away from the second stage engine?

"What you might have seen was basically titanium half-hoops that are used to stabilize the nozzle on ascent. However, once you get to a certain temperature the bonding agent for those titanium rings comes off and the titanium rings float away, which occurred as expected."

Question: Do you expect to fly another test flight before starting operational launches?

"We feel that there is really no need for an extra test flight...We really retired all of the major risk events, the ones we were most concerned about. So I really doubt there is any need for a third test flight. The next flight will be the TacSat mission, which is a Naval Research Lab satellite funded by the Office of Secretary of Defense. I don't anticipate another test launch before that mission."

Question: Have you received assurances from both customers for this year -- TacSat and the Malaysian RazakSat spacecraft?

"I believe so. Certainly from RazakSat, and the TacSat folks have been on record before as saying no matter what happened to our second launch they were with us. So I assume that remains the same."

Question: What caused the roll oscillations?

"I can speculate there are a few possible causes. It is could be a helium leak or it could be...we have a cold gas roll-control system, it could be that there was a problem with one of the roll-control jets. But it is difficult to say anything definitive until we have a close look at the telemetry...The only thing we can say definitely at this point is that there was a roll anomaly on the second stage that resulted in us not achieving the intended orbit and, like I said, not likely a full orbit. However, that is fairly easy thing to address. Certainly if it is a leak issue we'll go over and make sure that any potential leaks are addressed in spades. If it's roll-control, one of the cold gas thrusters, I think that would be a very easy thing to address as well. Of the possible causes, I think there's very few that would really take much effort to address."

Question: Will the telemetry tell you enough to give you confidence for next launch with real payload?

"I think so. It is hard to predict right now but I find it difficult to imagine a circumstance where it wouldn't, where we wouldn't know enough. What we will do at this point is if the telemetry is ambiguous as to the source of the issue, we'll identify all of the possible sources and address all possible sources."

Question: Do you know the apogee of the orbit?

"Well the maximum altitude was approximately 300 km."

Question: Was the second stage intact when it re-entered?

"I don't know quite yet. The stage was certainly intact at the loss of telemetry."

Question: Could the stage have fallen in a populated area?

"No. One of the advantages of being at (Kwajalein) is it's ocean for thousands and thousands of miles."

Question: Why would rolling cause premature engine shutdown?

"If you have a significant roll, what could happen is that the propellants can centrifuge out."

Question: What is the significance of today's launch?

"I think it's really a big step forward for SpaceX. It gives me great confidence in our upcoming launches. Another thing to bear in mind, Falcon 1 is intended as a scale model, a test vehicle of our larger rockets. As we iron things out on Falcon 1, we're really going to put that knowledge to work on Falcon 9."

Question: What is realistic aspiration for SpaceX some 10 years from now?

"I feel very confident 10 years from now that we can be putting both satellites and people into orbit, and maybe beyond (Earth) orbit. I feel very confident in the future of commercial spaceflight, private spaceflight and I think this bodes very, very well actually for achieving some of the goals that I mentioned. It is really an excellent indicator that a small company can achieve great things....We had what I would call a relatively minor issue with the roll-control very late in the flight. But all the really big risk items, the ones we were most concerned, have been addressed. If you look at the early history of rocketry, I think they had something like 12 Atlas failures before the 13th one was successful. To get this far on our second launch being an all-new rocket -- new main engine, new first stage, new second stage engine, new second stage, new fairing, new launch pad system, with so many new things -- to have gotten this far is great."