SpaceX Starship could have had a more perfect test on the third flight if the landing attempt of both stages had not encountered incidence so why did they fail many blame the Raptor engine as the main culprit because this most sensitive part of the rocket had new problems but is it true how much did the Raptor's new problem affect the test results find out everything in today's episode of tech map one of the biggest milestones in Flight 3 is the successful Ascent burn of Starships both stages but the descent is a totally different story yes according to SpaceX super heavy successfully lit several engines for its first ever Landing burn before the vehicle experienced arud that SpaceX speak for Rapid unscheduled disassembly the booster's flight concluded at approximately 462 m in altitude in just under 7 minutes into the mission the ship was also lost during its Landing attempt SpaceX lost signal from both starlink and NASA tracking and data relay satellite system at the exact same time although after the test SpaceX quickly updated the initial information on their website that still could not satisfy the Curiosity of SpaceX fans while the SpaceX team is busy collecting post launch data why don't we take a look back at the test flight carefully and have our own speculations on March 14 the Beast known as Starship successfully lifted off at 8:25 a.m. central daylight time from Starbase in Texas just like Flight 2 we heard that avionic power and Telemetry were normal 2 minutes and 42 seconds after liftoff all but three super heavy boosters Raptors shut down later three vacuum engines on ship 28 ignited which was followed by the firing of three c-level Raptors yeah can you guess what once again Starship performed successfully hot stage separation all six engines of the ship operated as expected and the Boost back burn continued as planned this time B10 ignited all 10 Raptors in the second rings and three Central ones excellently to navigate the vehicle back towards its designated Landing site a point in the Gulf of Mexico located about 30 km or 18.6 mi from the shore casting our mines back to flight two booster 9 tried to ignite 13 engines for the Boost back burn but one Raptor failed at t plus 2 minutes and 50 seconds this was the first sign that something was about to go wrong unlike the November orbital test the errors on flight three happened much later indeed during its most weighted re-entry process things went a little Haywire at t+ 6 minutes and 48 seconds or during the re-entry process the booster began to spin quite violently The Landing burn kicked off with just one kilometer to go at MCH one but if we look at closer the engines we will see some problems with the engine's ignition given that just three ones were fir firing later one shut down immediately followed by the other ones during the planned enhanced Landing burn ignition the booster speed remained at nearly 2,000 kmph after three engines were ignited the speed reached about 1200 kmph even before losing connection at an altitude below 1 km the booster speed was still up to 1112 kmph in comparison during The Descent of Falcon 99's booster it reaches speeds of around 3,600 kmph double this after more adventurous geostationary missions but its fins and engines control the speed and direction of the Falcon slowing it down as it approaches the Earth at the last minute four legs then deploy and it makes a soft landing at a speed of less than 21.6 kmph all of this delicate navigation is performed by onboard computers and inertial navigation systems The Landing is so fast that no human could react quickly enough to ensure a smooth touchdown it's safe to say that the b10s landing speed at the last minute is much higher than the Falcon 99's so assuming that no error was presented on B10 at that point could the vehicle do a soft Landing with such extreme speed or SpaceX predicted that and was afraid of a potential catastrophe on the ocean so they activated rud until now we have no idea whether the Raptor engine is the perpetrator of the death of booster 10 another hypothesis is that was raised here is the trouble with the grid fins given that they vibrated quite violently during The Descent so what do you think of course we will not have the accurate answer to this question until spacex's lead mishap investigation closes what we can make sure of right now is that the explosion wasn't related to the flight termination system as we heard that it was secured just before landing okay let's move on to ship 28 when booster 10 was gone its partner was still firing all six engines on its way to orbit after the magic engine cut off particularly in t+ 8 minutes and 21 seconds the onboard views were offline but the engine interface showed that three vacuum engines had cut off 15 seconds later it's the turn of the c-level engines what went wrong fortunately nothing it turns out that a few seconds later the vehicle marked a very big success when for the first time the largest vehicle to ever be placed into orbit or very near orbital velocity and cutting the engines just a few seconds shy of orbit is said is just spacex's intention to safely re-enter the next things are so great the vehicle continues to achieve new successes including propellant transfer and testing payload door ship 28 also showed an impressive re-entry attempt but by then plasma was the main reason for the loss of signal from the ship no signs of survival were detected afterward so SpaceX determined that ship 28 had indeed burned up in the atmosphere what led to that incident currently there is no evidence for the link between Raptor and the failure on ship 28 so let's wait more time to have the final answer for this despite being successful ship 28 still missed a thing it is the performance of an inspace Raptor relight at t+ 40 minutes and 46 seconds this will likely be a simulated deorbit burn-like space performed with ship 28 on December 29 2023 to explain this some give their own view as we know starship's rocket engine is very complicated this usually leads to the difficulty of relighting however this is exceptional for solid rocket engines that can't be shut off in any practical way once they've started going it's essential to note that a rocket engine needs the same pressure going into the combustion chamber as there is leaving the combustion chamber through the nozzle or the combusting gases will just flow back into the tanks which you can probably guess is not optimal this accounts for 95% of the complexity of Rocket engines so it leads to the question how do I get the fuel up to the right pressure in an efficient way there are rocket engines that are extremely simple to start as simple as turning a valve or two these are pressure-fed monopropellant engines typically used on reaction control systems for fine Maneuvers in space space and they're so easy to start because they're nothing more than a pressurized tank or two a valve and a nozzle turn the valve and the pressurized gas flows out generating thrust they're called pressure fed because the fuel is already at the same pressure inside the tank as there will be going into the nozzle so you don't need any pumps pressure-fed engines can get more efficient if you pick fuels that can decompose like hydrogen peroxide and in turn generate heat in terms of complexity it's still practically the same thing just now with a combustion chamber between the valve and the nozzle if you want to get even more efficient you can use bipropellant engines that take advantage of a property of hypergolic fuels essentially a hypergolic mixture is a mix of two gases that instantly combust when they meet meaning you don't need any igniters open the valve and the engine Burns it starts getting difficult when you leave the realm of pressure-fed engines the problem is that pressure fed engines are limited by how much pressure you can have in the tanks which isn't a lot when you consider the tanks need to be as light as possible the alternative is to use a pump to get the fuel up to pressure this has been done in Endless different ways throughout the history of space flight and is overwhelmingly the most expensive part of an engine to develop every single time and that just about wraps it up for today's episode if you want to explore more aspects of the world's most powerful Rockets and the world of rockets in general here is a selection of deeper videos for you thank you and we look forward to seeing you next time