During the latest Starship mission, I noticed a curious orange ring around the engine plume: My first thought was: Color of nitrogen oxides but no nitrogen fuels High temperature exhaust plume Extreme plume shock waves Disappeared above 45 km, thiner atmosphere Google reports: Themal : The exhaust plumes of rocket engines (especially those burning kerosene, liquid hydrogen, or solid propellants) reach temperatures exceeding \(2000^{\circ }\text{C}\) to \(3600^{\circ }\text{C}\). At these extreme temperatures, atmospheric nitrogen (\(\text{N}_{2}\)) and oxygen (\(\text{O}_{2}\)) dissociate and recombine to form nitrogen monoxide (\(\text{NO}\)) and nitrogen dioxide (\(\text{NO}_{2}\)). [1, 2, 3] Bob Wilson
It might also be possible to just ask the chatbot for a simpler text version of the answer, using Unicode characters instead of TEX.
Well, the combustion is Methane and Liquid Oxygen and I think liquid carbon dioxide is what they're still currently using to ensure there's no fires from excess gasses in the areas between the rocket engines that have in the past been vulnerable to catastrophic fires (aka: unplanned sudden disassembly). So that leaves the metals in the engines burning (not likely) as well as the burning of the nitrogen in the planet's atmosphere (most likely). As in we're talking about a vehicle that weighs 5000 tons when fully loaded that did 0-60mph in about 2.0 seconds via a combined 8-9K tons of thrust from 33 engines. So I'm placing my bets on the engine burning nitrogen in the atmosphere prior to getting above 45km when there's way less nitrogen to ignite. As for your Google AI nonsense. Google is so incompetent with their AI they almost never give the correct answer when compared to the other major AI services and near every time someone shares the answer they got from their garbage I get increasingly more embarrassed by their incompetence, especially with what you shared.
Looks like V3 eliminated them: CO₂ — Engine Bay Fire Suppression (Booster) After the first Starship flight, SpaceX added a fire suppression system on the Super Heavy booster: two large stainless steel tanks mounted under the chines next to the Booster Quick Disconnect. These fed CO₂ into the engine bay, acting like a large fire extinguisher to prevent fires from burning connections to the flight computer. https://nasaspaceflight.com/2025/09/ten-flights-starship-program-successes-failures/ However, that system has since been removed. In the Starship V3 upgrades, SpaceX deleted the CO₂ fire suppression system entirely in favor of a simpler, lighter aft section, with new physical shielding added between engines instead. SpaceX unveils sweeping Starship V3 upgrades ahead of May 19 launch ------------------- Nitrogen in the Atmosphere: The high-temperature reaction of atmospheric oxygen with atmospheric nitrogen, particularly at adiabatic flame temperatures above about 2800°F, produces NOx through what's called the "thermal" or "Zeldovich mechanism." Additionally, the reaction of atmospheric nitrogen with hydrocarbon fuel fragments under fuel-rich conditions in flame fronts produces what's called "prompt NOx." https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/8215117 -------------------- Nitrogen as inert, non-flammable for various uses within the rocket's systems: The FAA's own exhaust plume analysis for Raptor 2 confirms that approximately 0.5% nitrogen is present in both the LOX and liquid methane propellants. A small amount of nitric oxide (NO) forms in the combustion chamber from this N₂, and some burnout of that NO occurs during plume entrainment. The analysis predicts NO emissions of about 5.62 lbs/second per engine, and roughly 185 lbs/second for the full 33-engine Super Heavy booster. So there is a small onboard nitrogen contribution — but it's from dissolved N₂ in the propellants, not from tanks being vented during flight. https://www.faa.gov/sites/faa.gov/files/2022-06/AppendixG_ExhaustPlumeCalculations.pdf -------------------- For perspective on that 185 pounds per second of nitrogen, this rocket during launch burns 47,400 pounds of fuel per second. As in a Prius gets way better gas mileage but much slower than this rocket which can get up to about 17,000 mph.
PS: This discussion is a good example of the nonsense data produced from Google's AI ( @bwilson4web ) versus data produced from Claude AI ( @PriusCamper ) And granted this isn't an example based on asking the same questions to both. And knowing how to frame the question has a huge amount of influence on the results. I encourage everyone to research how to write the best questions for AI because it makes a huge difference.
Actually, I was just curious about the reddish ring in this image: My high school chemistry, the high temperatures, and shock wave pressures suggested nitrogen oxides were being formed. I was not expecting an AI: Bob Wilson
Or just don't use AI. Save the energy being burned at a data center; add -ai to the search text. Sure looks like a nitrous oxide gas I've seen in the lab.
