SpaceX Falcon 9 historic landing thread (1st landing attempt & most recent missions)

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Gwynne Shotwell, president and Chief Operating Officer of SpaceX, was recently asked this:

On Sept. 1 it wasn’t clear whether the cause lay in the ground support equipment, or inside the rocket. You have made the determination that it was inside the rocket and not some procedure during preparation for the static test?
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Her reply:

We believe that the composite over wrapped pressure vessel [the helium bottle], known as a COPv, let go in the tank. What caused it, the exact reason it let go, we’re still investigating. I don’t believe it was a ground system cause, but we’re still looking at the data.
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So, they think it was one of the Helium tanks inside of the 2nd stage that “let go” inside of the tank. In the video cam image below of a Falcon 2nd stage in mid-burn (some of the Lox consumed), there are three COPV helium tanks (black) visible along the sides.

SpaceX_Upper_Stage_Oxygen_Tank_Fluid_Dynamics.jpg


What they still do not know is WHY it let go, the root cause. Whether some manufacturing defect, assembly problem, or something else such as filling process that might have gone badly for some reason (such as overpressurizing or something out of sequence). There was some unusual “harmonic” detected during the filling process which may or may not be a clue.
 
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An excerpt from some recent comments by Gwynn Shotwell, SpaceX COO and president:

From SpaceNews: https://spacenews.com/shotwell-says-spacex-homing-in-on-cause-of-falcon-9-pad-explosion/

WASHINGTON — SpaceX is getting closer to finding the cause of a September pad explosion that destroyed a Falcon 9, and the company’s president remains confident the vehicle will return to flight later this year.

In an Oct. 9 speech at the annual meeting of the National Academy of Engineering here, SpaceX President Gwynne Shotwell suggested that the Sept. 1 accident prior to a planned static-fire test on the company’s Cape Canaveral, Florida, launch pad was not a flaw in the vehicle’s design.

“We’re homing in on what happened,” she said. “I think it’s going to point not to a vehicle issue or an engineering design issue but more of a business process issue.”

She didn’t elaborate on what the potential issue or issues the company is examining as a potential cause for the failure, which the company has previously stated is linked to a “large breach” in the helium system in the rocket’s second stage liquid oxygen tank. Speaking Oct. 5 at the Asia-Pacific Satellite Communications Council 2016 conference in Malaysia, Shotwell said it was unlikely there was a design flaw in the bottles used to store helium in the tank, but rather an “operations” issue.

Because it is not a design issue, Shotwell remained confident that the Falcon 9 can resume launches later this year. “Hopefully we’ll recover from this and be back flying a couple times this year,” she said.
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The “business process” issue she refers to would seem to be launch pad procedures for loading the Falcon.

On NASAspaceflight forum, a tiny seed of a possible cause has grown and seems more and more like what may have been the root cause.

A good message to start with for that thread is here:

https://forum.nasaspaceflight.com/index.php?topic=41252.msg1595782#msg1595782

The one right after introduces the theory of a “thermoacoustic heat engine”, from the warm helium (gets heated doing pressurization) and heat sink effect of the lower end of the Helium tank as Liquid Oxygen rises upwards doing filling:

The mention of weird harmonics has made me wonder if they have managed to unwittingly make a thermoacoustic heat engine. This could generate sound waves in the helium, powered by the temperature difference between the LOX and the ambient air. These sound waves can have very large amplitudes and could potentially damage the COPV.*

The COPV would be acting as a resonator with the valves, connectors and piping between the the stage and the GSE acting as a regenerator. The heat input would come from the warm helium being loaded, with the heat sink* being the LOX.
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A few messages after that one, a notable message beginning with this reply:

What you just described is known as "Helium Hammer" and was observed, with near catastrophic effects in early spaceflight projects dealing with cooling systems using liquid helium.
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After that, a lot of people agreeing this sounds very plausible.

The thing is that SpaceX *DID* change the loading procedure in some manner for that test. So, they did something they had not done before. And they picked up some odd sounds (harmonics?) they had not heard before. So indeed it may have been this “Helium Hammer” effect.

Now with Shotwell indicating it was not a vehicle problem, but a “process” problem, this does seem to indicate it was what they did differently that led to the explosion, and the thing they did differently may have inadvertently caused a Helium Hammer effect that had never happened before.

But for example if they had in the past loaded the helium to full pressure AFTER the Lox had covered the COPV tanks, then they may have avoided the lurking problem (since as I understand it the hammer effect only happens when there is an extreme temperature differential form top to bottom).

Whether it ends up as “Helium Hammer” effect, or some other problem caused by loading procedure/process, that’s the kind of thing they can resume flying soon after the investigation is completed. Since it’s easy to change the procedure (go back to what worked before), as opposed to making hardware changes that could take a pretty long time.

-----------------


UPDATE : This story delves further, and does state what the change in procedure was.

"SpaceX resorts to ‘Creative’ Testing in Falcon 9 Explosion Investigation"

Below is only part of the story. Use the link below or the full story.
https://spaceflight101.com/falcon-9...-testing-in-falcon-9-explosion-investigation/

Per Shotwell’s comments, SpaceX currently explores different operational deficiencies that could cause a COPV to fail in a dramatic way. This implies SpaceX is closely looking at the interaction between the helium COPV, its contents, the LOX in the surrounding tank and pressures within the vessel – creating a complex system with many variables (in addition to the fact that practical experience with densified LOX in rocketry is sparse).

The incident occurred at a time in the countdown when the second stage was being loaded with sub-cooled LOX and high-pressure helium. Interaction between the pressurized bottle filled with warm helium and the surrounding oxidizer is most critical when the COPVs are slowly submerged in the rising LOX level which is suspected to occur around this time in the count.

Potential causes of the COPV failure could include weakening of the structural integrity of the COPV due to the thermal difference between the metal liner on the inside subjected to the warm helium and the carbon fiber overwrap material on the outside in contact with the cold oxidizer. Acoustic phenomena resulting from the high-pressure helium being forced into the tank at a critical time during the LOX loading sequence are also on the table as possible scenarios that may have transpired.

The previous iteration of the Falcon 9 used Liquid Oxygen at boiling point temperature and began loading its tanks over three hours ahead of launch – permitting the COPVs to be fully chilled prior to applying high pressures. Falcon 9 FT enters LOX load on the second stage with just 19.5 minutes on the countdown clock followed by Helium load just over 13 minutes prior to launch – an aggressive tanking sequence unprecedented in the space launch business.


It is also understood that SpaceX was testing modifications to the countdown sequence on the Static Fire Test for the previous Falcon 9 mission with JCSat-16 to introduce window management capabilities for the FT version of Falcon 9 that initially had to launch very shortly after propellant loading finished in order to avoid the chilled propellants warming up inside the tanks. These modified countdown steps include adjustments to engine chilldown as well as the propellant and pressurant loading sequence.

It is possible that, with these seemingly minor adjustments to the sequencing of events, SpaceX has inadvertently designed a chain of events that overstressed the Helium bottles.

To gather data on the potential scenarios that can lead to a COPV failure, SpaceX has taken to its McGregor test site where, according to Shotwell, a lot of tests were being run on the COPVs. These tests, in all likelihood, are running different propellant and helium loading modes on highly instrumented tanks to learn about the critical chain of events in both loading sequences that overstress the COPVs.
Observant SpaceX fans passing by McGregor noted experimentation involving LOX tankers and helium supplies was underway in an open area of the facility.
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That's really good news. A process fix is easier than a re-engineer. It's good that they're learning these lessons now rather than once they get people on board.
 
Inmarsat announced that SpaceX has definitively determined the root cause of the explosion and return to flight will happen in December. If SpaceX delays further, they have a slot reserved for their next satellite on a Proton rocket.

Inmarsat article here
 
Elon Musk says SpaceX could resume launches in December

SpaceX CEO Elon Musk, said that an explosion in September that has grounded SpaceX has “never been encountered before in the history of rocketry.”

https://www.latimes.com/business/la-fi-musk-cnbc-20161104-story.html

SpaceX Chief Executive Elon Musk said Friday morning that the company could return to launch next month.

Musk said the company thinks it has “gotten to the bottom of the problem” that led to a September launch pad explosion and the destruction of a Falcon 9 rocket and communications satellite in Florida.

Musk said in an interview on CNBC that it “looks like” SpaceX will start launching again in mid-December. He described the cause of the explosion as something that has “never been encountered before in the history of rocketry.”

Musk provided few specific details but said it “basically involves a combination of liquid helium, advanced carbon fiber composites and solid oxygen, oxygen so cold that it actually enters solid phase.”

“This was the toughest puzzle to solve that we’ve ever had to solve,” he said.

Hawthorne-based SpaceX said last week it had narrowed its investigation of the explosion to one of the composite-overwrapped pressure vessels that store helium to pressurize the rocket’s second-stage liquid oxygen tank.

The company said Friday that it is continuing to make progress on the investigation.
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No official final report on the cause of the AMOS-6 pad explosion yet, but it seems like they know what to do for now to get back to flying again.

It is looking like the next Falcon-9 launch will be at Vandenberg, with a number of Iridium NEXT satellites onboard. It is listed semi-officially as "No Earlier Than" (NET) Late December. But all that really means is it won't be launching before then, it could slip (of course a few weeks ago there was still talk about launching in November, but no aerospace experts took that seriously).

The booster and 2nd stage are at Vandenberg..... again. They were there already when the AMOS-6 pad explosion happened, and were removed for whatever reasons.

If I see anything with what seems to be a solid NET date, I'll post it. Same for whenever an official report might be put out, if one is put out.

This thread is about the Falcon-9 launches, anyway, and hopefully more successful launches and safe booster landings soon.
 
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Posted on NasaSpaceflght forum by site owner & chief reporter Chris Bergin:

*Preliminary* planning schedule shows SpaceX Falcon 9 (Iridium NEXT) - NET December 16 (T-0 around midday, local).

Subject to Change. Not official. Don't go booking flights, etc. Would be that disclaimer at the best of times, but more so with the current concentration on finalizing the Amos-6 investigation, etc.
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CyHsXC2WIAAki9A.jpg:small


So, launch may be as soon as December 16th, from Vandenberg AFB in California. It would be somewhat odd to launch before the final report on the AMOS-6 pad explosion, so that might need to come out first (and they've been doing COPV loading tests at McGregor as recently as a little over a week ago, when something went "boom" during tests (not a whole stage!). Apparently something expected to go boom).

2016-11-22-015434-350x259.jpg


. Mid-day launch would mean daytime landing for the booster on the ASDS barge named "Just Read The Instructions". JRTI was the name of first ASDS SpaceX used, in the Atlantic, which never had a safe landing on it. The barge used (Marmac 300) was retired, "wings" for it removed, then wings added to a newer version of the same barge class (Marmac 303), now used for West Coast landings. So far the "new" JRTI on the West Coast has only tried one landing, IIRC, which was a safe touchdown, but a leg lock failed, allowing it to fall over and blow up. SpaceX has had a lot of safe landings since then, including several ASDS barge landings on "OCISLY".

November 22nd article link: "SpaceX prime Falcon 9 rockets for December return"

https://www.nasaspaceflight.com/2016/11/spacex-rockets-december-return
 
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georgegassaway said:
... Apparently something expected to go boom...
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Were they perhaps trying to replicate the problem that caused the explosion in order to verify the cause and solution? If they were successful at replicating the BOOM, then that's good news.
 
Thanks for the thanks, Woody.

Cabernut said:
Were they perhaps trying to replicate the problem that caused the explosion in order to verify the cause and solution? If they were successful at replicating the BOOM, then that's good news.
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They do not say much, especially about what happens at McGregor (quite literally, a lot of the "news reports" about static firings there often come from a specific nearby neighbor who is a fan and reports notable things he hears/sees on Facebook).

It may have been an attempt to replicate the problem and it went boom, which would be good. If they were testing for a "safe" loading method and it went boom, that would be VERY bad!

However, given the unofficial reports from reliable sources, of a launch as early as Dec 16th, it would seem that was a "good boom". :)
 
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OK, launch date more official now. Set for Friday Dec 16th, little over 2 weeks from now. 12:16 PM PST, from Vandenberg, with Falcon booster trying to land on the ASDS barge JRTI.

https://globenewswire.com/news-rele...unces-Date-for-First-Iridium-NEXT-Launch.html

Iridium Announces Date for First Iridium NEXT Launch

SpaceX Set for First Launch of Iridium’s Next-Generation Global Satellite Constellation

MCLEAN, Va., Dec. 01, 2016 (GLOBE NEWSWIRE) -- Iridium Communications Inc. (NASDAQ:IRDM) announced today the date for the first launch of its next-generation global satellite constellation, Iridium NEXT.* Iridium will be launching on SpaceX’s Falcon 9 rocket on December 16, 2016 at 12:36 p.m. PST. Launching from Vandenberg Air Force Base in California, the Falcon 9 rocket will deliver 10 Iridium NEXT satellites into low-earth orbit.*


This launch is contingent upon the FAA’s approval of SpaceX’s return to flight following the anomaly that occurred on September 1, 2016 at Cape Canaveral Air Force Station, Florida. The investigation has been conducted with FAA oversight. Iridium expects to be SpaceX’s first return to flight launch customer.

“We’re excited to launch the first batch of our new satellite constellation.* We have remained confident in SpaceX’s ability as a launch partner throughout the Falcon 9 investigation,” said Matt Desch, chief executive officer at Iridium. “We are grateful for their transparency and hard work to plan for their return to flight.* We are looking forward to the inaugural launch of Iridium NEXT, and what will begin a new chapter in our history.”

Iridium NEXT will replace the world’s largest commercial satellite network of low-earth orbit satellites in what will be one of the largest “tech upgrades” in history. Iridium has partnered with Thales Alenia Space for the manufacturing, assembly and testing of 81 Iridium NEXT satellites, at least 70 of which will be launched by SpaceX. *The process of replacing the satellites one-by-one in a constellation of this size and scale has never been completed before.

“We are looking forward to return to flight with the first Iridium NEXT launch,” said Gwynne Shotwell, president and chief operating officer of SpaceX. “Iridium has been a great partner for nearly a decade, and we appreciate their working with us to put their first 10 Iridium NEXT satellites into orbit.”

Iridium NEXT will enable the development of new and innovative products and solutions across Iridium’s vast partner ecosystem. Additionally, Iridium CertusSM, Iridium’s next-generation multi-service communications platform enabled by Iridium NEXT, will deliver faster speeds and higher throughputs across multiple industry verticals. A service of this quality and value is unprecedented in the industry, and is poised to disrupt the current market status quo.* Currently, the service is set to be commercially available in 2017 and is undergoing testing on Iridium’s existing network.

Iridium’s primary launch campaign consists of seven SpaceX Falcon 9 launches, deploying ten Iridium NEXT satellites at a time. These 70 Iridium NEXT satellites are scheduled to be deployed by early 2018. For more information about Iridium NEXT, please visit www.iridium.com.
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I would like to echo Woody's comment and thank you George for the updates.
 
A good article about the upcoming launch of Iridium Next Satellites, hopefully in 2 weeks.

BTW - FAA has to sign off on the SpaceX report about the September pad explosion investigation, including plans for corrective action, before this is cleared to fly. So that report ought to come out really soon or the Dec 16th date may get bumped

https://spaceflightnow.com/2016/12/...-for-first-flight-since-launch-pad-explosion/

This photo is of the booster during arrival at Vandenberg.

CxuwqLYWEAAKy8B.jpg
 
Looks like the return to flight may have been pushed off until January. From https://www.spacex.com/news/2016/09/01/anomaly-updates


December 7, 10:30am EDT

We are finalizing the investigation into our September 1 anomaly and are working to complete the final steps necessary to safely and reliably return to flight, now in early January with the launch of Iridium-1. This allows for additional time to close-out vehicle preparations and complete extended testing to help ensure the highest possible level of mission assurance prior to launch.
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Thanks for sharing, Perfect view from Tampa tonight- could see well past the SRM' S burnout . :cool:
 
BTW - the Return To Flight launch of Iridium NEXT satellites from Vandenberg, has been delayed from the 16th to January (no date, simply not happening this month).

No info as to why. But some observers have noted the September Pad Explosion report still has not come out yet, and the FAA has to approve of the proposed solutions to the problem.

Update from SpaceX:

Below are updates regarding the anomaly that occurred in preparation for the AMOS-6 mission:

December 7, 10:30am EDT

We are finalizing the investigation into our September 1 anomaly and are working to complete the final steps necessary to safely and reliably return to flight, now in early January with the launch of Iridium-1. This allows for additional time to close-out vehicle preparations and complete extended testing to help ensure the highest possible level of mission assurance prior to launch.
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Here's a Satellite view of the new Landing Pad at Vandenberg. The RTF flight's booster won't be landing there (It will land on the ASDS barge JRTI), but eventually some will.

6uuv58akp72y.jpg
 
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No solid info on a launch date for the RTF flight that was supposed to happen tomorrow (the 16th). SpaceX may not even have finished their testing yet. Whenever their accident report is submitted (if it indeed is not completed already), the public won't see it for many reasons (ITAR, confidential business, etc.). So the first public indication that the report has been received by the FAA, may not be until the FAA grants a license for the RTF flight (FAA won't get the report one day and automatically grant a license the next day. They have to study the report and give feedback to SpaceX on any aspect of SpaceX's solutions for future launches that FAA may not be satisfied with, or constraints).

So, in the meantime....

National Geographic clip showing Musk during the first RTLS landing, a year ago (Dec 22nd), of the F9 booster #20 that launched ORBCOMM-2.

[video=youtube;5WMV-jE2ySk]https://www.youtube.com/watch?v=5WMV-jE2ySk[/video]


And a fan-made 2 minute video:

[video=youtube;SBXgPJr9Fw4]https://www.youtube.com/watch?v=SBXgPJr9Fw4[/video]


And then this - A SpaceX booster landing game for IOS (iPhone, iPod, iPad)

https://itunes.apple.com/us/app/space-rocket-first-stage-landing/id1151383055?mt=8

screen-1=x355.jpg
 
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