BY SPACEFLIGHT NOW

Follow the second test flight of the second SpaceX Falcon 1 rocket. Reload this page for the latest on the mission.

WEDNESDAY, MARCH 28, 2007

SpaceX has issued an update on last week's launch. You can read it here.

WEDNESDAY, MARCH 21, 2007
0630 GMT (2:30 a.m. EDT)

A collection of images from the launch is posted here.

0545 GMT (1:45 a.m. EDT)

The Falcon 1 rocket, a gleaming symbol of hopes to revolutionize space exploration through private industry, took its second shot at orbit Tuesday night but fell back to Earth after experiencing a problem mid-way through the ascent.

Read our full story.

0410 GMT (12:10 a.m. EDT)

More post-launch news briefing quotes from Elon Musk:

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."

0345 GMT (11:45 p.m. EDT Tues.)

More post-launch news briefing quotes from Elon Musk:

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."

0315 GMT (11:15 p.m. EDT Tues.)

Some quotes from the media briefing with Elon Musk following tonight's launch:

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."

0245 GMT (10:45 p.m. EDT Tues.)

The following is a transcript of SpaceX founder Elon Musk's opening comments to reporters:

"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."

0220 GMT (10:20 p.m. EDT Tues.)

Musk promises to provide additional information later tonight about whether a low orbit was achieved or if the rocket re-entered.

0218 GMT (10:18 p.m. EDT Tues.)

"I think it is fair to characterize this as a success," Musk says.

0214 GMT (10:14 p.m. EDT Tues.)

Musk says 90 percent of the Falcon 1 rocket's technical challenges were proven out with this launch. He doesn't foresee needing another test flight before launching the first operational mission in late summer carrying the U.S. military's TacSat 1 spacecraft.

0204 GMT (10:04 p.m. EDT Tues.)

Musk says "the high likelihood" is the vehicle re-entered the atmosphere prior to making an orbit.

0156 GMT (9:56 p.m. EDT Tues.)

Musk says the rocket didn't reach the intended orbit and actually may have re-entered the atmosphere. The rolling motion caused the second stage engine to shut down early. Despite the problem, Musk considers this to be "a very good day" for SpaceX.

0154 GMT (9:54 p.m. EDT Tues.)

"We did have a roll-control anomoly," Musk says of the second stage. Some oscillations could be seen in the last bit of video from a camera mounted on the second stage before the webcast stopped. Fate of the rocket remains unknown.

0145 GMT (9:45 p.m. EDT Tues.)

SpaceX founder Elon Musk will be addressing the media momentarily.

0140 GMT (9:40 p.m. EDT Tues.)

No further information is available at this time. To recap, the Falcon 1 rocket blasted off at 0110 GMT (9:10 p.m. EDT) tonight on a demonstration test flight from Omelek Island in the central Pacific Ocean. The first stage engine, which had experienced an abort on the pad earlier tonight due to low chamber pressure readings, powered the rocket skyward for nearly three minutes. The spent stage then separated for a planned parachute-aided splashdown in the ocean for recovery.

The second stage ignited and the rocket's nose cone jettisoned as the ascent continued. About two minutes into the second stage firing, a SpaceX spokeswoman said the stream of telemetry data from the rocket had been lost and the company's webcast showing video from cameras mounted on the rocket was turned off.

The fate of the rocket is not known. The second stage was supposed to fire until almost T+plus 10 minutes to reach the planned orbit featuring a high point of 425 miles, a low point of 205 miles and inclination of 9 degrees north and south of the equator.

0124 GMT (9:24 p.m. EDT Tues.)

"I just wanted everybody to know that we in the Washington, D.C., office are celebrating with champagne. We don't have any information yet from the launch control center, but the Falcon clearly got to space with a successful liftoff, stage separation, second stage ignition and fairing separation," says Gwynne Shotwell, SpaceX vice president of business development.

However, what happened during the second stage burn is not clear.

"Regardless, we're thrilled here."

0119 GMT (9:19 p.m. EDT Tues.)

The last bit of video seen from a camera mounted on the second stage showed perhaps some oscillations just before SpaceX said telemetry had been lost and the webcast feed was cut.

0116 GMT (9:16 p.m. EDT Tues.)

We're awaiting further information.

0115 GMT (9:15 p.m. EDT Tues.)

T+plus 5 minutes, 5 seconds. Telemetry has been lost, SpaceX's Gwynne Shotwell tells reporters. The webcast provided by the company has stopped, too.

0114 GMT (9:14 p.m. EDT Tues.)

T+plus 4 minutes, 20 seconds. Altitude 161 km.

0114 GMT (9:14 p.m. EDT Tues.)

T+plus 4 minutes. The Kestrel engine continues to fire, burning a mixture of kerosene fuel and supercold liquid oxygen.

0113 GMT (9:13 p.m. EDT Tues.)

T+plus 3 minutes, 30 seconds. Altitude 117 km.

0113 GMT (9:13 p.m. EDT Tues.)

T+plus 3 minutes, 20 seconds. The two halves of the five-foot diameter nose cone have separated.

0112 GMT (9:12 p.m. EDT Tues.)

T+plus 2 minutes, 55 seconds. The Kestrel second stage engine has ignited!

0112 GMT (9:12 p.m. EDT Tues.)

T+plus 2 minutes, 50 seconds. Main engine cutoff. The Merlin has consumed its supply of fuel and shut down to complete its firing.

And stage separation is confirmed. The separation system with a pneumatic pusher jettisoned the parachute-equipped first stage to fall into the Pacific for retrieval. An awaiting vessel will recover the stage to permit SpaceX the opportunity to thoroughly examine the hardware and potentially reuse it in the future.

0112 GMT (9:12 p.m. EDT Tues.)

T+plus 2 minutes, 30 seconds. Nearing the end of first stage burn. Engine performance remains normal.

0112 GMT (9:12 p.m. EDT Tues.)

T+plus 2 minutes, 10 seconds. Guidance is nominal.

0112 GMT (9:12 p.m. EDT Tues.)

T+plus 2 minutes. Falcon is soaring entirely on the thrust generated by the Merlin powerplant, which was developed in-house by SpaceX.

0111 GMT (9:11 p.m. EDT Tues.)

T+plus 90 seconds. Altitude 13.9 km.

0111 GMT (9:11 p.m. EDT Tues.)

T+plus 82 seconds. Falcon has passed the region of maximum aerodynamic forces, or MaxQ.

0111 GMT (9:11 p.m. EDT Tues.)

T+plus 60 seconds. One minute into flight. The Merlin main engine continues to fire, burning a mixture of kerosene fuel and supercold liquid oxygen. Engine performance is reported normal.

0110 GMT (9:10 p.m. EDT Tues.)

T+plus 45 seconds. Altitude 2.6 km.

0110 GMT (9:10 p.m. EDT Tues.)

T+plus 30 seconds. The 70-foot tall rocket is climbing away from Earth.

0110 GMT (9:10 p.m. EDT Tues.)

T+plus 10 seconds. Tower is clear.

0110 GMT (9:10 p.m. EDT Tues.)

LIFTOFF! Liftoff of the SpaceX Falcon 1 rocket, demonstrating a new low-cost pathway to space.

0109 GMT (9:09 p.m. EDT Tues.)

T-minus 10 seconds. The vehicle tanks have been pressurized.

0109 GMT (9:09 p.m. EDT Tues.)

T-minus 30 seconds. Launch pad water system has activated.

0109 GMT (9:09 p.m. EDT Tues.)

T-minus 60 seconds.

0108 GMT (9:08 p.m. EDT Tues.)

T-minus 75 seconds. The vehicle has switched to internal power.

0108 GMT (9:08 p.m. EDT Tues.)

T-minus 85 seconds. The Range has telemetry lock.

0108 GMT (9:08 p.m. EDT Tues.)

T-minus 1 minute, 45 seconds. SpaceX confirms all systems remain "go" for launch.

0108 GMT (9:08 p.m. EDT Tues.)

T-minus 2 minutes. The liquid oxygen topping has been stopped and the systems are being configured for launch.

0107 GMT (9:07 p.m. EDT Tues.)

T-minus 3 minutes. Ignition is being enabled.

0106 GMT (9:06 p.m. EDT Tues.)

T-minus 3 minutes, 30 seconds. Battery heaters have been turned off.

0106 GMT (9:06 p.m. EDT Tues.)

T-minus 4 minutes and counting. Thrust vector control is being pressurized.

0105 GMT (9:05 p.m. EDT Tues.)

T-minus 5 minutes. Weather conditions, although cloudy, are acceptable for launch.

0104 GMT (9:04 p.m. EDT Tues.)

T-minus 6 minutes. Vehicle pyrotechnics are enabled.

0103 GMT (9:03 p.m. EDT Tues.)

T-minus 7 minutes. The flight termination safety system is ready.

0102 GMT (9:02 p.m. EDT Tues.)

T-minus 7 minutes, 30 seconds. The strong-back is fully retracted for launch.

0101 GMT (9:01 p.m. EDT Tues.)

T-minus 9 minutes. The strong-back structure is being retracted away from the rocket again.

0100 GMT (9:00 p.m. EDT Tues.)

T-minus 10 minutes. The Terminal Countdown sequence has been initiated.

0058 GMT (8:58 p.m. EDT Tues.)

T-minus 12 minutes.

0056 GMT (8:56 p.m. EDT Tues.)

T-minus 13 minutes, 30 seconds. A readiness poll of the launch team indicates all elements are "go" for liftoff.

0054 GMT (8:54 p.m. EDT Tues.)

T-minus 16 minutes and counting. The day's second launch attempt for the Falcon 1 rocket has begun. Liftoff time is 0110 GMT (9:10 p.m. EDT).

0053 GMT (8:53 p.m. EDT Tues.)

First and second stage fuel reloading has concluded.

0046 GMT (8:46 p.m. EDT Tues.)

The abort was triggered because the main engine chamber pressure was about 0.2 percent lower than allowable, says Gwynne Shotwell, SpaceX vice president of business development. The low pressure was caused by the fuel being colder than desired, she said. The refueling of the rocket is supposed to correct this problem for the next launch try tonight.

0043 GMT (8:43 p.m. EDT Tues.)

Topping of the rocket's liquid oxygen supply is being performed.

0040 GMT (8:40 p.m. EDT Tues.)

Time to launch is now 30 minutes.

0039 GMT (8:39 p.m. EDT Tues.)

Propellant loading for the first and second stages is underway.

0037 GMT (8:37 p.m. EDT Tues.)

Refueling of the rocket is about to begin.

0035 GMT (8:35 p.m. EDT Tues.)

Officials are coordinating a fresh countdown starting from the T-minus 16 minute mark at 0054 GMT (8:54 p.m. EDT) for a liftoff of Falcon at 0110 GMT (9:10 p.m. EDT).

0033 GMT (8:33 p.m. EDT Tues.)

Fuel offloading is being completed.

0030 GMT (8:30 p.m. EDT Tues.)

Local radar shows some rain moving toward the island.

0025 GMT (8:25 p.m. EDT Tues.)

Cloud cover beginning to roll across the island. It is past noon Wednesday local time on Omelek.

0022 GMT (8:22 p.m. EDT Tues.)

The low chamber pressure is believed to have been caused by the RP-1 kerosene's temperature, Shotwell says. The launch team is draining some of the fuel and will reload the propellant for the next try.

0021 GMT (8:21 p.m. EDT Tues.)

Now starting the second stage fuel drainback.

0019 GMT (8:19 p.m. EDT Tues.)

The first stage fuel offload is starting.

0018 GMT (8:18 p.m. EDT Tues.)

The ground crew will be partially offloading fuel and reloading the propellant for another launch attempt.

0017 GMT (8:17 p.m. EDT Tues.)

The available launch period ahead is 0028 to 0114 GMT (8:28 to 9:14 p.m. EDT).

0015 GMT (8:15 p.m. EDT Tues.)

The launch team is setting up for a recycle of the countdown to try again tonight.

0012 GMT (8:12 p.m. EDT Tues.)

The abort was tripped when computers detected main engine chamber pressure was less than 0.1 percent lower than the redline limit, Gwynne Shotwell, SpaceX vice president of business development, tells reporters. She added they are looking to recycle the countdown. Launch has not been scrubbed.

0011 GMT (8:11 p.m. EDT Tues.)

The Terminal Countdown abort procedures have been completed.

0010 GMT (8:10 p.m. EDT Tues.)

There is no word yet on what caused the countdown to be aborted in the final moments before liftoff. The Merlin first stage main engine was igniting when the abort was called.

0006 GMT (8:06 p.m. EDT Tues.)

The pad's strong-back structure is being raised back into position next to the rocket.

0005 GMT (8:05 p.m. EDT Tues.)

A problem was detected as the main engine was firing to life, causing computers to halt the countdown. The vehicle was not permitted to lift off. Safing is in progress.

0005 GMT (8:05 p.m. EDT Tues.)

ABORT! A pad abort declared during main engine start.

0004 GMT (8:04 p.m. EDT Tues.)

T-minus 30 seconds. Launch pad water system has activated.

0004 GMT (8:04 p.m. EDT Tues.)

T-minus 60 seconds.

0003 GMT (8:03 p.m. EDT Tues.)

T-minus 70 seconds. The vehicle is switching to internal power.

0003 GMT (8:03 p.m. EDT Tues.)

T-minus 1 minute, 30 seconds. Range telemetry source switching as planned. This is where the problem occurred last night.

0003 GMT (8:03 p.m. EDT Tues.)

T-minus 2 minutes. The liquid oxygen systems are being configured for launch.

0002 GMT (8:02 p.m. EDT Tues.)

T-minus 3 minutes. All systems remain "go" for launch.

0001 GMT (8:01 p.m. EDT Tues.)

T-minus 3 minutes, 30 seconds. Battery heaters are being turned off.

0001 GMT (8:01 p.m. EDT Tues.)

T-minus 4 minutes and counting. Thrust vector control is being pressurized.

0000 GMT (8:00 p.m. EDT Tues.)

T-minus 5 minutes.

TUESDAY, MARCH 20, 2007
2359 GMT (7:59 p.m. EDT)

T-minus 6 minutes. Vehicle pyrotechnics are being enabled.

2358 GMT (7:58 p.m. EDT)

T-minus 6 minutes, 30 seconds. The flight termination safety system has been confirmed ready.

2358 GMT (7:58 p.m. EDT)

T-minus 7 minutes. The strong-back is fully retracted for launch.

2356 GMT (7:56 p.m. EDT)

T-minus 9 minutes. The strong-back structure that has been against the side of the Falcon 1 rocket is now slowly lowering away from the vehicle.

2355 GMT (7:55 p.m. EDT)

T-minus 10 minutes. The Terminal Countdown sequence is being initiated.

2353 GMT (7:53 p.m. EDT)

T-minus 12 minutes and counting.

2350 GMT (7:50 p.m. EDT)

T-minus 15 minutes. The mission director is giving his "clear to launch."

2348 GMT (7:48 p.m. EDT)

A status poll of launch team members indicated no problems are being worked.

2345 GMT (7:45 p.m. EDT)

T-minus 20 minutes. The Range remains go for launch.

2343 GMT (7:43 p.m. EDT)

The downrange recovery ship is reported in position. The vessel will retrieve the first stage, which parachutes into the ocean to allow post-flight examination and possible reuse.

2339 GMT (7:39 p.m. EDT)

Both liquid oxygen tanks on the rocket have been topped off at 100 percent. The helium necessary pressurizing has been placed aboard the rocket as well. The Falcon now stands fully fueled for liftoff 26 minutes from now.

2338 GMT (7:38 p.m. EDT)

A check of the weather indicates some rain approaching but clear conditions are projected for launch time.

2337 GMT (7:37 p.m. EDT)

"We have a good vehicle ready for launch," SpaceX launch control says.

2335 GMT (7:35 p.m. EDT)

T-minus 30 minutes and continuing to count down to the launch of Falcon 1.

2334 GMT (7:34 p.m. EDT)

And now the second stage kerosene fuel tank has been fully filled for launch.

2333 GMT (7:33 p.m. EDT)

Loading of liquid oxygen into the second stage is reported complete. Topping of both the first and second stage will proceed to keep the rocket full of this cryogenic oxidizer.

2330 GMT (7:30 p.m. EDT)

T-minus 35 minutes. First stage RP-1 kerosene loading has just concluded successfully.

2328 GMT (7:28 p.m. EDT)

The first stage liquid oxygen tank has reached the 95 percent level, awaiting topping. The first stage fuel tank is 89 percent full. On the second stage, the LOX tank is 78 percent loaded and the RP-1 kerosene is passing the 74 percent mark.

2325 GMT (7:25 p.m. EDT)

T-minus 40 minutes. Propellant loading continues in progress. No problems have been reported by the launch team.

2320 GMT (7:20 p.m. EDT)

First stage liquid oxygen tank is now 90 percent full.

2315 GMT (7:15 p.m. EDT)

T-minus 50 minutes and counting. Weather looks good and there are no technical issues are standing in the way of liftoff at 0005 GMT today, SpaceX launch control reports.

2309 GMT (7:09 p.m. EDT)

Fueling of the Falcon 1 rocket is underway on Omelek Island. The first and second stages are being filled with a highly refined kerosene propellant and supercold liquid oxygen.

2305 GMT (7:05 p.m. EDT)

T-minus 60 minutes and counting. The Range is about to begin C-band tracking and flight termination safety system checks in preparation for today's launch.

2230 GMT (6:30 p.m. EDT)

The 0005 GMT (8:05 p.m. EDT) target launch time has been confirmed.

2220 GMT (6:20 p.m. EDT)

"We are in a hold right now. We've got a potential RF (radio frequency) compatibility issue with the payload, which we're working through. I anticipate we will come out of the hold in about 10 or 15 minutes and get back on track," says Gwynne Shotwell, SpaceX vice president of business development.

Weather conditions are acceptable at the launch site today, she added.

2218 GMT (6:18 p.m. EDT)

It appears launch time has been delayed further to 0005 GMT (8:05 p.m. EDT).

2215 GMT (6:15 p.m. EDT)

Now SpaceX indicates the launch time has moved to 2330 GMT (7:30 p.m. EDT).

2210 GMT (6:10 p.m. EDT)

SpaceX tells reporters that launch remains on schedule for 2300 GMT.

2205 GMT (6:05 p.m. EDT)

We're still awaiting an update on SpaceX about the progress of the countdown. We'll begin our play-by-play of the launch when information starts becoming available.

1601 GMT (12:01 p.m. EDT)

SpaceX identified and corrected the software glitch that caused Monday's launch delay, the company says, and liftoff has been rescheduled for 2300 GMT (7 p.m. EDT) today.

"The abort that occurred a few minutes before T-0 was triggered by our ground control software. It commanded a switchover of range telemetry from landline to radio, which took place correctly, however, because of the hardware involved, this transition takes a few hundred milliseconds. Before it had time to complete, our system verification software examined state and aborted," SpaceX founder and CEO Elon Musk said today.

"Our simulations done beforehand all passed, because the simulator did not account for a hardware driven delay in the transition. We considered putting the vehicle into a safe state yesterday and updating the ground control software to make the very minor fix needed, but the safer course of action was to stand down.

"Yesterday afternoon and evening (Kwaj time), our launch team updated the software to address the timing issue and verified that there were no similar problems elsewhere. We ran the software through several simulated countdowns and then once again with the rocket and range in the loop."

Musk said all systems are now go for launch later today.

0014 GMT (8:14 p.m. EDT Mon.)

The launch team is preparing to start draining the fuel from the Falcon 1 rocket following today's postponement. We'll update this page when additional information about the problem and details of the next launch attempt are made available.

0011 GMT (8:11 p.m. EDT Mon.)

A new launch date has not been announced. But SpaceX says another try could be made on Tuesday or Wednesday.

0010 GMT (8:10 p.m. EDT Mon.)

SCRUB! Today's launch attempt has been called off.

0003 GMT (8:03 p.m. EDT Mon.)

A possible explanation for the countdown abort being called:

"At about a minute-and-a-half out of launch, we shift from communicating to the vehicle through the land lines to communicating through the Range RF (radio frequency). And it is possible we were just not picking up the Range RF signal. So that's what I know so far," says Gwynne Shotwell, SpaceX vice president of business development.

2355 GMT (7:55 p.m. EDT)

The problem appears to be related to the Range and telemetry. The team needs another 10 minutes to examine the situation.

2350 GMT (7:50 p.m. EDT)

Engineers are working on the problem that stopped the countdown. SpaceX has time available to troubleshoot the issue and try the launch again -- so the flight has not been scrubbed for today.

2346 GMT (7:46 p.m. EDT)

The launch team has completed the post-abort procedures to put the rocket into a safe configuration. There was no immediate word on what caused the countdown abort to be triggered.

2344 GMT (7:44 p.m. EDT)

The pad's strong-back structure has rotated back into position next to the rocket.

2343 GMT (7:43 p.m. EDT)

"We have a Terminal Count abort. Stand by," the launch team was just instructed.

2343 GMT (7:43 p.m. EDT)

ABORT. The countdown has been halted.

2343 GMT (7:43 p.m. EDT)

T-minus 2 minutes. Liquid oxygen system is being configured for launch.

2342 GMT (7:42 p.m. EDT)

T-minus 3 minutes. All systems remain "go" for launch.

2341 GMT (7:41 p.m. EDT)

T-minus 4 minutes and counting.

2340 GMT (7:40 p.m. EDT)

T-minus 5 minutes.

2339 GMT (7:39 p.m. EDT)

T-minus 5 minutes, 55 seconds. Vehicle pyrotechnics are being readied.

2338 GMT (7:38 p.m. EDT)

T-minus 6 minutes, 30 seconds. The flight termination system has been confirmed ready.

2338 GMT (7:38 p.m. EDT)

T-minus 7 minutes. The strong-back is fully retracted.

2337 GMT (7:37 p.m. EDT)

T-minus 8 minutes.

2336 GMT (7:36 p.m. EDT)

The strong-back structure that has been against the side of the Falcon 1 rocket is now slowly lowering away from the vehicle.

2335 GMT (7:35 p.m. EDT)

Countdown has entered the final 10 minutes to launch.

2333 GMT (7:33 p.m. EDT)

T-minus 12 minutes.

2331 GMT (7:31 p.m. EDT)

T-minus 14 minutes. The mission director reports he is "go" for launch. No further holds in the countdown are planned.

2328 GMT (7:28 p.m. EDT)

A status poll of launch team members indicated no problems.

2325 GMT (7:25 p.m. EDT)

T-minus 20 minutes and counting.

2324 GMT (7:24 p.m. EDT)

The loading of kerosene propellant and liquid oxygen into the two-stage Falcon rocket has been completed.

2323 GMT (7:23 p.m. EDT)

Range Safety reports the resticted areas around the launch site are clear for liftoff. Also, winds have been verified acceptable.

2315 GMT (7:15 p.m. EDT)

Now 30 minutes to launch of Falcon 1.

2257 GMT (6:57 p.m. EDT)

NEW LAUNCH TIME. Liftoff is now targeted for 2345 GMT (7:45 p.m. EDT). Fueling of the rocket had been suspended while trying to correct the data transmission problem between Omelek Island and the company's headquarters in El Segundo, California. Only a limited part of the launch team is deployed to the remote location, with a larger group overseeing the mission from California.

With the data stream now working, engineers are processing ahead with the countdown.

2252 GMT (6:52 p.m. EDT)

"The data is back up in El Segundo. I do believe we are a little bit behind in the count. I think we delayed some of the propellant loading activities," says Gwynne Shotwell, SpaceX vice president of business development. "It looks good for today, which is obviously good news."

How far behind the countdown is running or the target launch time isn't clear at the moment.

2229 GMT (6:29 p.m. EDT)

"We're still having data connectivity problems. The rocket is fine. Everything is good there. We're still trying to determine whether we can launch without the data in El Segundo," Shotwell says.

2219 GMT (6:19 p.m. EDT)

Gwynne Shotwell, SpaceX vice president of business development, just told reporters following today's launch that there has been some difficulty getting the telemetry stream from Omelek Island to the company's headquarters in El Segundo, California. Shotwell indicated that the data transmission was a requirement for the launch to proceed today.

2200 GMT (6:00 p.m. EDT)

The final hour of the countdown should be getting underway. It is a sunny and windy day on Omelek Island. We expect a status from SpaceX momentarily.

1800 GMT (2:00 p.m. EDT)

Launch of the Falcon 1 rocket remains targeted for 2300 GMT today. SpaceX plans to begin providing live updates to the news media one hour prior to launch. Watch this page for the latest as information becomes available.

SUNDAY, MARCH 18, 2007

An update from SpaceX came late Sunday night, when the company announced the official launch attempt would be Monday at 2300 GMT (7 p.m. EDT).

SATURDAY, MARCH 17, 2007

A private space company's second shot at flying its low-cost rocket into orbit could come as early as Monday after engineers successfully completed a critical pre-launch test firing of its main engine Thursday.

Developed by Space Exploration Technologies Corp., the two-stage Falcon 1 rocket currently stands ready for launch on a remote seven-acre island in the middle of the Pacific Ocean.

The SpaceX launch team cleared one of the final hurdles before launch Thursday, when controllers loaded the booster's first stage with propellant and ignited the Merlin main engine for a static test firing lasting about four seconds.

"We had a very successful static fire yesterday that proceeded smoothly with no aborts," SpaceX founder and CEO Elon Musk said Friday in an update posted on the company's Web site.

The launch team uncovered a small glitch in the rocket's GPS guidance system shortly after the test, but the anomaly is not considered major since the Falcon 1 primarily relies on inertial navigation during its flight, Musk said.

Another update from SpaceX is expected Sunday, when the company is planning to announce the official planned launch date.

The Falcon 1 rocket will fly due east from its secluded launch pad on Omelek Island, part of the U.S. military's missile test range at Kwajalein Atoll in the Marshall Islands.

This week's launch will be a demonstration mission for the Pentagon's Defense Advanced Research Projects Agency. Two NASA-sponsored experiment packages are bolted atop the booster's second stage.

Less than 10 minutes after launch, the Falcon 1's second stage Kestrel engine should be commanded to cut off. SpaceX is targeting an orbit about 425 miles high with an inclination of about 9 degrees.

SpaceX officials spent the past year wrangling with upgrades to the Falcon 1 launch system after the first attempted flight of the new rocket ended in failure last March due to a rapid fuel leak in its first stage.

A government investigation traced the cause of the leak to a corroded aluminum nut in the first stage's Merlin engine, which burns highly refined kerosene called RP-1 and liquid oxygen.

The leaking fuel trickled down the outside of the Merlin's thrust chamber and caused a fire after the engine ignited. The Merlin prematurely shut down about 30 seconds after liftoff, and the 70-foot-tall rocket fell from the sky and plummeted into the ocean just offshore from the launch site.

Last year's failure caused SpaceX to implement several changes to the rocket and overhaul much of the Falcon 1's countdown operations. Engineers increased the number of system aborts by a factor of 30, according to Musk.

SpaceX also added upgrades to the Merlin main engine to make the powerplant more robust, and new software was developed to conduct health checks of the Merlin after engine ignition before the seven-story tall launcher is released by hold-down clamps, Musk said.

The return-to-flight launch was postponed from January due to an issue with the second stage engine's thrust vector control pitch actuator, which pivots the engine's nozzle to guide the rocket toward space.

The problem, coupled with the unavailability of the Kwajalein Army Range due to another missile test, pushed the launch to this month.