Samizdata

Spacex has released the full high definition video of the flight from liftoff through the first stage impact on the second stage, complete with audio signal. It is really worth watching!

Here is the official word from SpaceX on the cause of the failure last weekend:

On August 2 nd, Falcon 1 executed a picture perfect first stage flight, ultimately reaching an altitude of 217 km, but encountered a problem just after stage separation that prevented the second stage from reaching orbit. At this point, we are certain as to the origin of the problem. Four methods of analysis – vehicle inertial measurement, chamber pressure, onboard video and a simple physics free body calculation – all give the same answer.

The problem arose due to the longer thrust decay transient of our new Merlin 1C regeneratively cooled engine, as compared to the prior flight that used our old Merlin 1A ablatively cooled engine. Unlike the ablative engine, the regen engine had unburned fuel in the cooling channels and manifold that combined with a small amount of residual oxygen to produce a small thrust that was just enough to overcome the stage separation pusher impulse.

We were aware of and had allowed for a thrust transient, but did not expect it to last that long. As it turned out, a very small increase in the time between commanding main engine shutdown and stage separation would have been enough to save the mission.

The question then is why didn’t we catch this issue? Unfortunately, the engine chamber pressure is so low for this transient thrust — only about 10 psi — that it barely registered on our ground test stand in Texas where ambient pressure is 14.5 psi. However, in vacuum that 10 psi chamber pressure produced enough thrust to cause the first stage to recontact the second stage.

It looks like we may have flight four on the launch pad as soon as next month. The long gap between flight two and three was mainly due to the Merlin 1C regen engine development, but there are no technology upgrades between flight three and four.

Good Things About This Flight

* Merlin 1C and overall first stage performance was excellent
* The stage separation system worked properly, in that all bolts fired and the pneumatic pushers delivered the correct impulse
* Second stage ignited and achieved nominal chamber pressure
* Fairing separated correctly
* We discovered this transient problem on Falcon 1 rather than Falcon 9
* Rocket stages were integrated, rolled out and launched in seven days
* Neither the near miss potential failures of flight two nor any new ones were present
* The only untested portion of flight is whether or not we have solved the main problem of flight two, where the control system coupled with the slosh modes of the liquid oxygen tank. Given the addition of slosh baffles and significant improvements to the control logic, I feel confident that this will not be an issue for the upcoming flight four.”

So it looks like I may have to stay up all night for you again in September!

0023. LOX tanking is in progress; there has been some audio coming across now on the live feed.

0025: Note that they are in an ‘unplanned hold’ at the moment. Second tank LOX fill is happening and I believe I heard them discussing Helium pressurization.

0027: On the video you can see the LOX venting on the second stage.

0031: If you think the video quality s… is less than optimal, you are not alone!

0045: http://www.spacex.com/webcast.php in case you don’t know where to go. There is an Aussie presenter at SpaceX you will notice.

0058: I am having diffs due to the bandwidth the video is sucking up, so my posting may be more erratic than I would have liked. When you see the public affairs team again, the thing behind them marked Dragon is the mockup of the manned capsule they will be flying to ISS in the 2012 time frame.

0129: You may have noticed they lost video for awhile until someone rebooted their Mac streaming application. We are down into the t-30 range and all is looking good so far. Other than my Virgin Media cable connection which keeps seems to go off line entirely every now and again…

0133: This rock is so highly automated that there are a lot fewer people acting as controllers than in old fashioned 20th century artillery rockets. Things will not get really interesting until we get into the last few minutes. Also, remember that they have on board cameras so we will get live feeds from the rocket during ascent. Last time we had a really good view of the 2nd stage engine bell glowing red hot as it fired.

0246: My link was down for about 45 minutes… I am hoping it will stay up long enough for me to watch the launch! Looks like they are still in a hold so I have not missed anything big.

0251: The detanking is something they did last time as well. If things take too long, the fuel starts getting cold and this caused a shutdown on flight 2 because the thrust is below nominal if the temps are wrong.

0310: Since I have to sit and wait like everyone else, perhaps I can give a bit more explanation. They have a Helium tank there for pressurization I presume, at least from the size of it. Helium is a super cryogen. It makes LOX look like burning petrol by comparison. If they sit too long, the Helium starts chilling the fuel, which is Kerosene. You want your fuel and oxidizer to be warm and volatile when you
inject them; otherwise some of the energy is taken from thrust to heat them up. That lowers the efficiency of the engine, something usually measured as ISP. The computer controls know the expected profile from initial injection to when the igniter fires and as the burn starts and stabilizes. If it is outside of the expected band, the engine is shutdown.

0319: The have restarted the count and launch is now scheduled for about 0300 UTC, which would be about 0400 here since we are on BDT. Weather at Kwajalein is crystal clear by the way, at least from the weather map!

0325:They are back on the air doing the recycle. Incidentally, you may have noticed that the webcast appears to be done by a video camera focused on a computer screen at the Hawthorne facility. My guess is they have a single circuit from Kwaj and for security reasons wanted to totally isolate the public net from the operations net. I would do the same, but perhaps a little differently. It may simply come down to them having too little time to do anything more than this work around. This is all pure speculation on my part, but it is based on doing a paper system level design for an LCC for someone else.

0338: It looks like along with the rewind of the count we are also getting a replay of the video clips we saw earlier… I’d rather listen to the control loop myself!

0344: Their Mac video application just fell over again… and a few minutes later the talking heads are repeating the same description of the Falcon 1 that they did a couple hours ago. Meanwhile, while they jabber on, from other sources on Kwaj I read that everything is in the green. We should be about 15 minutes or less from launch now.

0352: While they are showing silly repeats, terminal count is about to start, or probably has. Everything is go for launch at the moment.

0403: A terminal abort, But there could still be a launch tonight. Er this morning. I think this is a good time for me to put the kettle on…

0415: If you have been reading the announcements, they think they may recycle the count to t-10, which means they have had a minor issue. The automatic check out that happens at ignition is extraordinary fascist and they want it that way: you can’t bring it back to the pad once you’ve launched!

0426: Wow. They have recycled to t-10 terminal count start in almost no time!

0440: They called it an anomaly. I wish they had not killed the video so quickly… the plume from the first stage was looking rather strange just before that, with streaks and instabilities that didn’t look right to me, also I was seeing a greyish color that did not seem quite right. But I could be totally wrong. We will just have to wait for more information. Not what I was hoping for tonight, but this is rocket science… The most likely response to an ‘anomaly’ is flight termination.

0530: Well, I am calling it quits as there is unlikely to be any real news for quite some time. The vehicle either blew itself up or was commanded to do so; I have the impression it performed its own self disassembly but have nothing to back that up. My own eyeballs are on the new regen engine bell but I will with hold judgement until I have had a chance to watch the video again and more importantly have some expert feedback. But tonight, with my bed calling, I will place my bets on the new engine, perhaps the regen cooling channels. It is a wild stab in the dark and I will probably disagree with myself by the time I have some sleep. But there you go.

Good night all.

0552: Elon issued a statement, and here is an excerpt on the problem:

It was obviously a big disappointment not to reach orbit on this flight. On the plus side, the flight of our first stage, with the new Merlin 1C engine that will be used in Falcon 9, was picture perfect. Unfortunately, a problem occurred with stage separation, causing the stages to be held together. This is under investigation and I will send out a note as soon as we understand exactly what happened.

SpaceX has just test fired nine engines at full thrust in the full Falcon 9 configuration, a test I was not expecting to see until this fall at the earliest. According to their press release:

Major milestone achieved towards demonstrating U.S. transport to the International Space Station following retirement of the Space Shuttle

McGregor TX – August 1, 2008 – Space Exploration Technologies Corp. (SpaceX) conducted the first nine engine firing of its Falcon 9 launch vehicle at its Texas Test Facility outside McGregor on July 31st. A second firing on August 1st completed a major NASA Commercial Orbital Transportation Services (COTS) milestone almost two months early.

At full power, the nine engines consumed 3,200 lbs of fuel and liquid oxygen per second, and generated almost 850,000 pounds of force – four times the maximum thrust of a 747 aircraft. This marks the first firing of a Falcon 9 first stage with its full complement of nine Merlin 1C engines.Once a near term Merlin 1C fuel pump upgrade is complete, the sea level thrust will increase to 950,000 lbf, making Falcon 9 the most powerful single core vehicle in the United States.

“This was the most difficult milestone in development of the Falcon 9 launch vehicle and it also constitutes a significant achievement in US space vehicle development. Not since the final flight of the Saturn 1B rocket in 1975, has a rocket had the ability to lose any engine or motor and still successfully complete its mission,” said Elon Musk, CEO and CTO of SpaceX. “Much like a commercial airliner, our multi-engine design has the potential to provide significantly higher reliability than single engine

“We made a major advancement from the previous five engine test by adding four new Merlin engines at once,” said Tom Mueller, Vice President of Propulsion for SpaceX. “All phases of integration went smoothly and we were elated to see all nine engines working perfectly in concert.”

I will admit to being caught totally flat footed by this announcement. Given that the Falcon 1 launch at Kwajalein is due any time now I felt certain the company’s full attention would be focused there.

I guess Elon and his crew are better multi-taskers than I gave them credit for.

Falcon 9 first stage on test stand: nine Merlin 1C engines at full thrust.
Photo: courtesy SpaceX

and they is US!

US Marine MV-22 Osprey’s landing in Jordan.
Photo: courtesy of US DOD

The first WhiteKnightTwo carrier aircraft was rolled out of its hanger in the Mojave desert on Monday. The second stage vehicle, SpaceShipTwo, has been held back due to the ongoing investigations into the test stand accident of one year ago. Although that accident was little more than a plumbing and pressure test, there is as yet no full understanding of exactly what happened. Because of this uncertainty, Burt has delayed much development of SpaceShipTwo so as to avoid building things he might later have to rip out. This is the reason why the target date for passenger service has slipped into the 2010 time frame.

Still, the roll out of WK2 is a major milestone. As you can see in the photo, it is not a small aircraft! You gain an even better impression of that size from the raw press release video clip. (if you do not have a quick time plug-in, you may need to download first)

Monday July 28, 2008. Roll out of WhiteKnightTwo carrier aircraft ‘VMS Eve’ at Mojave Spaceport.
Photo: courtesy of Virgin Galactic