The Shuttle main engines used LH2 and LOX, and used sparklers to burn off the hydrogen that would be exhausted, unburned, during engine startup. (They pre-chill the engine components so that they are not shocked by the cold LH2. Avoiding shrinkage is important, even if you are an SSME not a guy).

I asked about the Delta 4 Heavy, why they could not do the same in this question. Why not use Sparklers on Delta-4 Heavy launches to burn off the hydrogen?

Some discussion centered around not invented here syndrome, which raised a question. Who provided the sparklers for the Space Shuttle program?

Rockwell (now Boeing) as part of the Orbiter? Aerojet as part of the SSME? Or KSC as part of the launch pad?


4 Answers 4


In the late 70's and early 80's I worked for a company named Unidynamics Defense Systems. We provided this subassembly. We were not the design originators, this design I am quite sure came from NASA.

My guess as to who the upstream contractor was would land on either Martin Marietta or Thiokol. On this particular design my drawings did not indicate who the actual purchasing authority was. My boss held out but finally relented at roughly STS-9 ("need to know" was his normal comment).

As far as production use my name was on this drawing in the design and draft blocks thru STS-51L, and the title block it stated Unidynamics Defense Systems, who later were purchased by Pacific Scientific. This was for the subassembly unit that was mounted on the service masts.

From STS-9 thru 51L, I was told this design held. Afterwards I cannot attest as to who next revised and produced the unit, and doubt they would change manufacturers.

As nothing is static at NASA from a design and cost standpoint, I would be surprised that it held thru STS-135. I have kept an eye out on its use and it certainly didn't look to me that it changed from a form, fit or function perspective. There were not many pieces to the design, but the chemistry and internal disc shapes could easily be modified for a specific output.


Problems Starting Space Shuttle Engines

Prior to the first flight of the Space Shuttle we were test firing the Main Propulsion System Engines at the test site in Mississippi when we experienced a VERY LARGE explosion at the time we attempted to start the engines. Had this explosion occurred on an actual Space Shuttle during launch, it would have destroyed the Shuttle and probably killed the crew.

NASA grounded the Shuttle fleet! I was assigned the responsibility of working with the engine supplier to assure that the problem was corrected before we could fly the first Space Shuttle flight.
I had several meetings with the supplier and we determined that the problem was caused by the way the engines were started. During start, cold hydrogen fuel at -423 degrees was released thru the engine nozzles before it was ignited with a spark plug type device. The problem was that hydrogen is lighter than air, therefore it floated up and formed a cloud of very explosive hydrogen outside of the engines. When the engines were ignited, the cloud exploded very violently. The engine supplier said to correct the problem would require changes to the start sequence and very extensive testing to certify that it was safe. Total cost to NASA was going to be a little over \$9 million!

Shortly after this I was doing fireworks with my son Jason on a 4th of July when I got this brilliant idea. I needed a device to shoot sparks which would burn the hydrogen at the exit of the engine nozzle during start. This would keep the hydrogen from forming a large cloud and therefore prevent the explosion from occurring.

Next day I went to work and called Disneyland to find out the name of their pyrotechnic supplier for their nightly shows. I called the company and explained to them that I needed a device that would shoot sparks about 30 feet at a temperature of 1200 degrees. They told me...no problem, they made that kind of sparkler for the movie industry all the time. The salesman told me that they sold for \$9.85 each!

I later attended a meeting with NASA in which the engine supplier said they could resolve the explosion problem for \$9 million. Needless to say, NASA was overjoyed when I got up and presented my proposal to fix their problem with a few \$9.85 sparklers. My proposed fix, known as the Main Engine Hydrogen Burn-off System, was implemented and has been utilized on every Space Shuttle launch without a single problem. I should mention however, NASA would not certify my supplier to produce the \$9.85 sparklers and the new supplier selected provides the same basic item for about \$1200 each...... but they can meet all the required NASA specs.

  • $\begingroup$ Prefix the $ with \ to prevent MathJax from screwing up the formatting. $\endgroup$
    – Hobbes
    Feb 24, 2018 at 17:59
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    $\begingroup$ "Citation needed" $\endgroup$ Feb 24, 2018 at 18:10
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    $\begingroup$ I doubt that's the original Harvey because he'd be 80 years old at this point, but here's your citation for the origin of the Sparkler. That's real and one of our NASA legends. hall.spacewalkoffame.org/workers/j-harvey-leblanc $\endgroup$
    – ScotT
    Aug 9, 2019 at 15:36
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    $\begingroup$ Also, bit of trivia, that photo of Harvey in the page is taken of him in front of the Space Shuttle just before the first launch. How do I know? The tanks are painted white. Only on the first launch were the tanks painted. After that, they were left unpainted so that the weight of the paint could be shaved off of the launch fuel usage. $\endgroup$
    – ScotT
    Aug 9, 2019 at 15:44
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    $\begingroup$ @ScotT the first two were white, but who's counting. space.com/2282-columbias-white-external-fuel-tanks.html $\endgroup$ Apr 24, 2020 at 19:36

According to descriptions in the KSC's Mission Preparation and Prelaunch Operations and the Launch Pad/Mobile Launcher Platform Interfaces pages, the hydrogen burn-off system for the Shuttle was located on the tail service masts on the launch pad, suggesting that the system was built by the Kennedy Space Center. While the site doesn't go into further detail about who specifically designed the system, it was probably done by NASA themselves.

  • $\begingroup$ The Shuttle MLPs are the Apollo MLPs, modified in the 1970s. I can't find a cite but most likely the mods were done by Lockheed, the main KSC contractor back then. There was a lot to the MLPs, I am afraid their story won't be told. $\endgroup$ Jan 14, 2016 at 0:30

April 2020—I am 80 years old old now and I did develop the Hydrogen Burn-Off System while working for Rockwell on the Orbiter Program.

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    $\begingroup$ Mr. LeBlanc, it looks like you posted on this page a couple of years ago. Please hang around, I am sure you have a lot of great info about the early shuttle days. For example, do you know where to get a shuttle LCC document? I've been looking for years. $\endgroup$ Apr 24, 2020 at 19:38

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