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A legendary Space Shuttle engine flew 15 times—then SLS sent it on a one-way trip to the Pacific. Why does the RS-25 cost a fortune, how does it compare with Raptor, and is this a scandal, a consequence of physics, or a product of politics? Join Sirwan for the history, numbers, and what’s next for Artemis.
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👉 This channel was created in collaboration with https://www.youtube.com/@marschroniken
0:00 - The RS-25’s Final Flight
1:40 - How the RS-25 Was Developed
3:55 - How the RS-25 Works
8:51 - How the RS-25 Compares
12:50 - Shuttle Reuse and Engine Costs
19:02 - Why SLS Uses Shuttle Engines
23:38 - Artemis Missions and the SLS Future
27:10 - Final Assessment
#Space #NASA #RocketScience
Subscribe for more deep dives into space and rockets.
Comment and tell us what you liked most from the video.
👉 This channel was created in collaboration with https://www.youtube.com/@marschroniken
0:00 - The RS-25’s Final Flight
1:40 - How the RS-25 Was Developed
3:55 - How the RS-25 Works
8:51 - How the RS-25 Compares
12:50 - Shuttle Reuse and Engine Costs
19:02 - Why SLS Uses Shuttle Engines
23:38 - Artemis Missions and the SLS Future
27:10 - Final Assessment
Category
🤖
TechTranscript
00:00On April 1st, 2026, at 6.35 p.m., local time in Florida.
00:05For us, it was already 12.35 a.m.
00:08On the 2nd of April, an engine with the serial number E-2047 launches into space for the 16th time.
00:16Fifteen times before it carried a space shuttle into orbit.
00:20In 2001, it brought the Destiny Laboratory to the space station.
00:25It was there in July 2011 when Atlantis rifted off for the very fast shuttle flight.
00:32Every time it came back, was removed, taken apart, inspected, put back together and flew again.
00:38That's exactly what it was built for, but not this time.
00:42Eight minutes after launch, the SLS core stage separates and E-2047 crashes together with three siblings on the other
00:51side of the Earth into the Pacific Ocean east of Hawaii.
00:54As planned.
00:56An engine that was certified for dozens of flights ends up as a disposable item.
01:02And its replacement costs the taxpayer, by simple calculation, around $145 million each.
01:12How is it that the most reusable rocket engine in history before Merlin and Raptor now flies exactly once?
01:19Why does it cost 100 times as much as a Raptor 3?
01:24And, and is that a scandal or just inconvenient physics plus inconvenient politics?
01:31We'll take a look at that today with all the numbers.
01:33My name is Sirwan and this is Mars Chroniken.
01:40Where does the RS-25 come from?
01:43The story begins in the early 70s.
01:46NASA is looking for an engine for a spacecraft that doesn't even exist yet.
01:50The space shuttle.
01:51The requirements are crazy for their time.
01:55High combustion chamber pressure, throttleable with staged combustion and above all reusable.
02:01Rocketdyne is awarded the contract on July 13, 1971.
02:05But Pratt and Whitney files a lawsuit against it.
02:09And so the process begins.
02:10The actual development doesn't start until March 31, 1972.
02:15The prototype of the combustion chamber had already reached over 218 bar in February 1971.
02:22With a new copper alloy called Narloi Z, Rocketdyne had developed especially for this engine.
02:30Then comes the Hartz-Lock.
02:32The high-pressure turbopumps, the valves, the nozzle, the preburners.
02:36Weaknesses appear everywhere.
02:38On March 16, 1977, a complete engine runs on the test stand for the first time.
02:44And in the following years, several units go up in flames.
02:48NASA requires at least 65,000 seconds of test operation before the fast flight.
02:55When Columbia lifts off for STS-1 on April 12, 1981, the engine has already completed 110,253 test seconds.
03:05That's more than 30 hours of firing before a single person ever sat on it.
03:10Over more than 30 years of shuttle operations, the engine is further developed in blocks.
03:16Phase 2 from 1988 after the Challenger disaster with safety improvements.
03:22Block 1 from 1995 with new turbopumps with ceramic bearings and half as many rotating parts.
03:29Block 2A from 1998 with a combustion chamber with a larger throat.
03:34And Block 2 from 2001 with a completely, completely new high-pressure hydrogen pump from Pratt and Whitney.
03:42This Block 2 version is called RS-25D today.
03:47And these exact engines are now mounted under the SLS.
03:51I link you a video about all the SLS hardware below in the description.
03:55How this thing works.
03:57The RS-25 burns liquid hydrogen with liquid oxygen at a mixture ratio of about 6 to 1.
04:05Hydrogen is the most energy-rich chemical fuel we have.
04:09But it's also extremely thin.
04:11Minus 253 degrees cold.
04:14And it seeps through every seal.
04:17That's why everything about this engine is big, complex and pushed to the limit.
04:24The cycle is called fuel-rich staged combustion.
04:29That means a large portion of the hydrogen goes through two pre-burners,
04:35where part of the oxygen burns with a lot of hydrogen.
04:39This produces hot hydrogen-rich gas, which drives two turbines.
04:43And this gas is not discarded afterwards, like in the gas generator cycle,
04:48but instead is directed into the main combustion chamber and completely burned there.
04:54Nothing is wasted.
04:55That's the reason for the high efficiency.
04:57And it's also the reason for the complexity.
05:00The turbines drive two high-pressure turbopumps.
05:03The hydrogen pump spins at about 35,360 revolutions per minute
05:09and delivers around 53 megawatts.
05:12Over 70,000 horsepower in a component the size of a car engine.
05:18It compresses the hydrogen to about 450 bar.
05:22The oxygen pump delivers about 17 megawatts at around 28,120 revolutions.
05:29And its second stage compresses the oxygen for the pre-burners even to over 500 bar.
05:35Before that, there are two low-pressure pumps,
05:38so that the high-pressure pumps don't cavitate, meaning they don't form vapor bubbles.
05:42Four pumps, two pre-burners, one main combustion chamber,
05:46and everything ramps up within about four seconds.
05:49In the combustion chamber, at 109% power,
05:53there are about 206 bar and around 3,300 degrees Celsius.
05:59That's hotter than the boiling point of iron.
06:02The fact that the chamber survives this is thanks to regenerative cooling.
06:06The inner wall is made of the previously mentioned copper alloy,
06:09Naloisee, into which about 390 channels are milled.
06:14Cryogenic hydrogen rushes through these channels,
06:17absorbs the heat, and then enters the combustion process.
06:20The nozzle below is 3.1 meters long,
06:24has an exit diameter of 2.3 meters,
06:28and is made of over 1,000 braced stainless steel tubes,
06:33through which hydrogen also flows.
06:35The expansion ratio is about 69 to 1.
06:39Unusually high for a first stage engine,
06:42and Rocketdyne had to specially modify the nozzle angle at the edge,
06:46so that the flow wouldn't separate at ground level.
06:49Now the performance data.
06:50At 109%, an RS-25 delivers 1,860 kN at sea level.
06:58That's about 190 metric tons of thrust.
07:01In vacuum, it's 2,279 kN,
07:05so about 232 metric tons.
07:08The percentage values refer to the original design from 1981.
07:13That's the 100% mark.
07:15On the shuttle, they routinely flew at 104.5%.
07:20109% was certified for emergencies.
07:24111% was tested on the ground.
07:27The SLS flies the old engines at 109%.
07:31The new RS-25ES are rated for 111%,
07:36and they were tested up to 113%.
07:40The engine can throttle down to 67%.
07:44The specific impulse, that is the efficiency,
07:47is 366 seconds at sea level,
07:51and 452 seconds in vacuum.
07:55That's still world class for an engine that launches from the ground.
07:58The dry mass is listed as 3,177 kg on the datasheet.
08:03With attachments, NASA estimates around 3.5 metric tons.
08:08This results in a thrust-to-weight ratio of about 73 to 1.
08:13Before we compare the RS-25 to its competitors,
08:17a quick note.
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08:45And now, let's get to the question
08:47of how an engine from the 70s performs today.
08:51The comparison, four opponents.
08:53First, the direct historical competitor,
08:56the Soviet RD-0120,
08:59from the design bureau KBKHA, KHA.
09:04Four of these engines were mounted
09:06under the core stage of the Energia,
09:08also burned hydrogen and oxygen
09:10in a staged combustion cycle,
09:11delivered 1,961 kilonewton in vacuum,
09:16which is about 200 tons,
09:18with a specific impulse of 455 seconds
09:21and a dry mass of 3,450 kilograms.
09:26For the combustion chamber pressure,
09:27common sources stayed around 218 bar.
09:31I have not found a primary source for this.
09:33In short, the Soviets built an equivalent engine.
09:38And then they flew it exactly twice.
09:40In 1987 with the Polius payload
09:44and in 1988 with the space shuttle Buran.
09:48After that, the Soviet Union collapsed
09:50and with it the program.
09:52Europe.
09:52The Vulcan 2.1 of the Ariane 6 from Ariane Group
09:58is also a hydrogen engine,
10:00but it operates in the simpler gas generator cycle.
10:03It delivers 1,371 kilonewton in vacuum,
10:07about 140 tons,
10:10with a specific impulse of 432 seconds
10:13and a chamber pressure of around 119 bar.
10:17Dry mass is about 2,000 kilograms,
10:20a solid, deliberately conservative engine
10:22that has been flying since the maiden flight
10:24of the Ariane 6 on July 9th, 2024.
10:29B-E-4 from Blue Origin,
10:31which we covered in detail in episode 285.
10:35Of course, I'll link the video below.
10:37Methane instead of hydrogen,
10:39oxygen-rich staged combustion,
10:40originally 2,450 kilonewton at sea level,
10:45which is about 250 tons,
10:47now with a target of 2,847 kilonewton,
10:52or around 290 tons.
10:55Combustion chamber pressure about 140 bar.
10:58Specific impulse,
10:59according to public information,
11:01is around 340 seconds.
11:03Dry mass,
11:04previously stated,
11:05as about 5,400 kilograms.
11:07It flies on the Vulcan
11:09and on the reusable booster of the New Glenn.
11:13Vulcane is the rocket from ULA
11:15and Vulcane is the engine from the Ariane group.
11:19And fourth,
11:20Repta-3 from SpaceX,
11:22known among other things
11:24from episodes 256 and 262,
11:28which are also linked below.
11:29Full-flow staged combustion with methane,
11:32about 280 tons of thrust at sea level,
11:35that's around 2,750 kilonewton
11:39with a chamber pressure of about 350 bar
11:42and a mass of only 1,525 kilograms,
11:47according to SpaceX.
11:48Specific impulse,
11:49about 350 seconds.
11:51Thrust-to-weight ratio around 183 to 1.
11:55What does that tell us?
11:56When it comes to specific impulse,
11:58the RS-25 wins,
11:59with its 452 seconds in vacuum,
12:02beating everything that launches from the ground.
12:04Hydrogen beats methane in terms of efficiency.
12:08That's chemistry.
12:09For combustion chamber pressure,
12:10the RS-25 was at the top for decades,
12:13until the Repta surpassed it with 350 bar.
12:16But when it comes to thrust-to-weight ratio,
12:18the difference is brutal.
12:2073 versus 183.
12:23A-Raptor-3 is smaller, lighter
12:26and delivers almost 50% more thrust at sea level.
12:30To be fair,
12:31you have to say that a hydrogen engine
12:33with such a large nozzle
12:35is more optimized for high altitude.
12:37And hydrogen also requires huge pumps.
12:40The RS-25 was built for a vehicle
12:42that launches with solid rocket boosters
12:45and then continues burning
12:46almost alone in thin air.
12:48It's perfect for that.
12:50The price comparison is coming up in a moment,
12:52and it's not fair,
12:53but it's real.
12:53Reusability in shuttle operations.
12:55In the shuttle program,
12:56a total of 46 engines
12:58flew on 135 missions.
13:01That's 405 individual engine flights.
13:05Pratt and Whitney.
13:07Rocketdyne puts the reliability at 99.95%.
13:11There was exactly one failure during flight.
13:14On July 29, 1985,
13:17during STS-51F,
13:19the center engine of Challenger
13:21shut down after 5 minutes and 43 seconds.
13:24Because two temperature sensors
13:26in the hydrogen pump
13:27failed one after the other.
13:29Tricked the computer into thinking
13:31it was overheating.
13:33The shuttle performed an abort to orbit,
13:35meaning a lower orbit,
13:37and the mission was still carried out.
13:39By the way,
13:41the two shuttle disasters
13:42had nothing to do with the main engines.
13:45After each landing,
13:46the three engines were removed from the orbiter
13:48and brought to the engine workshop
13:50at Kennedy Space Center.
13:51There, they were inspected,
13:53turbo pumps were replaced
13:54or overhauled,
13:56weld seams checked,
13:57valves replaced,
13:58and after major maintenance work,
14:00an engine had to prove
14:01on the test stand at Stennis
14:02before the next flight
14:03that it was still fully operational.
14:05That was expensive
14:07and labor-intensive.
14:09You have to be honest about that.
14:10But it worked.
14:11Engine E-2047
14:13managed to fly 15 times that way.
14:16E-2045
14:18made it
14:19to
14:1912th.
14:21The price.
14:22Now it gets uncomfortable.
14:24In November 2015,
14:25NASA awarded
14:26Aerojet Rocketdyne
14:27a contract worth
14:28$1.16 billion
14:30to restart production
14:32and for six new engines.
14:34In May 2020,
14:35there was an increase of
14:37$1.79 billion
14:39for 18 more.
14:41Altogether,
14:42that's around
14:42$3.5 billion
14:44for 24 engines
14:47and the calculator says
14:48that's about
14:50$145 million
14:52each.
14:53The NASA Inspector General
14:54listed the contract
14:55in May 2023
14:56with a current total value
14:58of
14:59$3.6 billion.
15:01Aerojet
15:02disagrees.
15:04And you have to hear
15:05their argument.
15:06Jim Mazur,
15:08who was vice president
15:09for the space business
15:10at the time,
15:11told Space News
15:12in essence
15:12that people
15:13wanted to do
15:14the simple math
15:15and attribute
15:16everything to the engine.
15:18But there was
15:19much more
15:20to this contract.
15:21Test stand,
15:22equipment,
15:23documentation
15:24for manned spaceflight,
15:26mission assurance
15:26and the rebuilding
15:28of a supply chain
15:29that had been dormant
15:30for a decade.
15:31However,
15:32he did not want
15:32to name the price
15:33of a bare engine.
15:35The Inspector General
15:36tried anyway.
15:37In report,
15:38IG-23015
15:40from May 25,
15:422023,
15:43it says,
15:44NASA and Aerojet
15:46are aiming
15:46from the seventh
15:47of the 24 new engines,
15:50manufacturing costs
15:51of $70.5 million
15:53each.
15:54That is supposed
15:54to be a saving
15:55of 30%
15:57compared to the
15:58$104.5 million
16:00that NASA calculated
16:02for an engine
16:03from the shuttle era.
16:04But,
16:05according to the report,
16:06this calculation
16:07leaves out
16:07$2.3 billion
16:09in overhead costs,
16:11recertification
16:12and production ramp-up.
16:14And NASA
16:14currently can't even
16:16track the cost
16:16per engine.
16:17On top of that,
16:18there is the modification
16:19of the old engines.
16:21NASA spent
16:22$581 million
16:23to adapt
16:24the 16 shuttle engines.
16:27That's
16:27$238 million
16:29more than planned.
16:30And by the end
16:31of the contract
16:32in September 2020,
16:34only 5 out of 16
16:36were finished.
16:37Let me just share
16:38my opinion here
16:39for a moment.
16:40I think that all
16:41these costs
16:41should be added
16:42to the price
16:43of the engine
16:43since they wouldn't
16:44exist otherwise.
16:46Anything else
16:47is just smoke
16:48and mirrors
16:49and massaging
16:49the numbers.
16:50Nevertheless,
16:51Aerojet received
16:52a rating of
16:53very good
16:53and performance bonuses
16:55of which the
16:55Inspector General
16:56is questioning.
16:57$19.8 million.
16:59Across all four
17:00booster and engine
17:01contracts,
17:02the report estimates
17:03$13.1 billion
17:05by 2031
17:07instead of the
17:08originally planned
17:09$7 billion
17:10and at least
17:11$4.2 billion
17:13per SLS launch
17:15up to Artemis 4.
17:17Now,
17:17the comparison metric
17:18that will accompany
17:19us through the video.
17:20Price per ton of thrust
17:21at sea level.
17:22For the RS-25
17:23with 190 tons,
17:26the simple calculation
17:27with $145 million
17:29comes out
17:30to about
17:30$760,000
17:32per ton.
17:33If you only take
17:34the $1.79 billion
17:36for 18 units
17:37which is
17:38just under
17:39$100 million
17:40per engine,
17:41that's about
17:43$525,000
17:44and even
17:45with the target value
17:46from the Inspector General
17:47of $70.5 million
17:49that's still
17:50about
17:50$370,000
17:52per ton of thrust.
17:54With the Raptor,
17:54there are no invoices,
17:55only statements
17:56from the manufacturer.
17:57Elon Musk wrote on X
17:58in October 2019,
17:59Raptor Firmout 1
18:00is on track
18:01to be well below
18:02$1 million.
18:03The target for V2
18:05is under
18:06$250,000
18:08so
18:08under
18:09$1,000
18:10per ton
18:11of thrust.
18:12Whether that was achieved,
18:13we don't know.
18:14If we conservatively
18:15calculate
18:15with $1 million
18:16for
18:17280 tons,
18:18we end up
18:19with about
18:19$3,600
18:21per ton.
18:22There is no
18:23official price
18:23for the BE-4.
18:25Observers
18:25infer
18:26from Blue Origin's
18:27promise
18:27to be cheaper
18:28than an RD-180
18:29that the price
18:30is around
18:31$6 to $7 million.
18:33That would be roughly
18:34$21,000
18:35to $28,000
18:36per ton
18:37with a lot
18:38of uncertainty.
18:39For the OD-0120
18:41and Vulcan 2.1,
18:43there are no
18:43reliable public unit prices
18:45so I'm deliberately
18:46not including them
18:47in my calculations.
18:48Even with all
18:49the uncertainties,
18:50it shows,
18:50the RS-25
18:51costs roughly
18:52100 times more
18:54per ton of thrust
18:55than a Raptor-3
18:56and about
18:5720 times more
18:58than a BE-4
19:00and then
19:00it only flies once.
19:02How the shuttle
19:03engine ended up
19:04on the SLS?
19:05To understand that,
19:07you have to go back
19:07to the year 2010.
19:09President Obama
19:10cancels the
19:11Constellation program
19:12with the RS-1
19:13and RS-5 rockets.
19:15The RS-5
19:16was originally
19:17supposed to fly
19:18with five
19:18RS-25 engines.
19:20But as early
19:21as 2006,
19:22NASA switched
19:23to the cheaper
19:24RS-68
19:25from the Delta-4.
19:27After the cancellation,
19:28thousands of jobs
19:29are at risk
19:29in Florida,
19:30Alabama,
19:31Texas,
19:32Louisiana,
19:33Mississippi
19:33and Utah.
19:35The Senate
19:36then writes
19:37a rocket
19:37into law itself.
19:38The NASA
19:39Authorization Act
19:40of 2010,
19:42passed by the Senate
19:42on the 5th of August
19:44and signed
19:45by the President
19:46in October,
19:47it requires NASA
19:48to develop
19:49a heavy lift vehicle
19:51that uses
19:51existing contracts,
19:53investments,
19:54workforce
19:54and capabilities
19:55from Shadow,
19:57Orion and Ares
19:58as much as practicable.
20:00The leading figures
20:01were Senators
20:02Bill Nelson
20:02from Florida
20:03and Kay Bailey
20:04Hutchison
20:04from Texas.
20:05And Hutchison
20:06pushed in 2011
20:08for NASA
20:09to announce
20:10the design immediately
20:11so that
20:12no layoffs
20:13would happen.
20:13That's why
20:14in spaceflight jargon
20:15the SLS
20:16is still called
20:17the Senate
20:17launch system
20:18to this day.
20:19The program
20:20clearly shows
20:21what happens
20:22when politicians
20:22and not engineers
20:24design a rocket.
20:25And why use
20:26the RS-25
20:27again
20:28instead of
20:29the RS-68?
20:30An internal
20:31study
20:32had already shown
20:33that the exhaust
20:34plumes
20:34from six
20:35RS-68
20:36engines
20:36together
20:37with the
20:37solid rocket
20:38boosters
20:38would generate
20:39massive base
20:40heating.
20:41And since
20:41the ablative
20:42nozzle of the
20:43RS wears away
20:43in a controlled
20:44manner during
20:45firing
20:45it can handle
20:46this much worse
20:47than the
20:47regeneratively
20:48cooled nozzle
20:49of the RS-25.
20:50On top of that
20:51there was the
20:52strongest argument
20:53of all.
20:53There were
20:5416
20:55flight-proven
20:56engines
20:57in storage
20:58paid for
20:59and certified
21:00for the first
21:01four flights.
21:02Nothing new
21:03had to be built.
21:04From an engineer's
21:05perspective
21:05that was reasonable.
21:06From a taxpayer's
21:07perspective
21:08it was the beginning
21:09of a bill
21:09that would only
21:10come due
21:11later.
21:12What was
21:13changed
21:13on the
21:13engines?
21:14Now to the
21:15theory I had
21:16in mind
21:16myself.
21:17That the
21:17engines were
21:18modified
21:18so they could
21:19no longer
21:20be reused.
21:21I checked
21:21this and
21:22that's not
21:22true.
21:23What was
21:24actually changed
21:25is the
21:26following.
21:27First,
21:27each engine
21:28got a new
21:29engine controller.
21:30That is,
21:31the control
21:31computer.
21:32Because the
21:33old Honeywell
21:33computers from
21:34the 80s
21:35were no longer
21:36available.
21:37Second,
21:38each engine
21:39got additional
21:39ablative
21:40insulation.
21:41Because on
21:42the SLS
21:42it is closer
21:43to the two
21:44solid rocket
21:44boosters.
21:45And the
21:46environment
21:46there is
21:47significantly
21:47hotter than
21:48on the
21:49shuttle.
21:49Third,
21:50the engine
21:50had to
21:51cope with
21:51higher inlet
21:52pressure
21:52and colder
21:54oxygen.
21:54Because the
21:55oxygen tank
21:56of the SLS
21:56core stage
21:57sits much
21:58higher above
21:58the engine
21:59and the
21:59rocket
22:00accelerates
22:01more strongly.
22:01In force,
22:02the operating
22:03power level
22:03was increased
22:04from 104.5
22:06to 109%.
22:09For this,
22:10two old
22:10engines were
22:11thoroughly
22:12tested from
22:132015 to
22:142017 at
22:15Stennis.
22:16It started
22:17with a
22:18500-second
22:19run on
22:20January 9,
22:212015.
22:22None of
22:22these changes
22:23make the
22:23engine itself
22:24a disposable
22:25product.
22:26It's the
22:26rocket that
22:27makes the
22:27engine single
22:28use.
22:28The SLS
22:29core stage
22:30is not
22:31recovered.
22:32It crashes
22:33into the
22:33Pacific with
22:34its engines.
22:34It's a
22:35different case
22:36with the
22:37RS-25E,
22:38the new
22:39production
22:39version.
22:40That one
22:40is deliberately
22:41designed as
22:41a disposable
22:42engine.
22:42Fewer parts,
22:43fewer welds,
22:44large assemblies
22:45from the
22:463D printer
22:47using selective
22:48laser sintering,
22:49simplified
22:50manufacturing,
22:50and each
22:51new engine
22:52is fired
22:53exactly once
22:53on the ground
22:54before flight.
22:55The first
22:56E-20001
22:57was completed
22:58in February
22:592025
23:00and ran
23:01for 500
23:03seconds
23:03at Stennis
23:04on June
23:0520th,
23:062025.
23:07The second
23:08followed in
23:09November
23:092025.
23:10The certification
23:11series for
23:12the new
23:12design already
23:13ended on
23:14April 3rd,
23:152024.
23:16So the
23:17real takeaway
23:17is more
23:18specific than
23:19I thought.
23:20NASA did
23:21not render
23:22any engine
23:23unusable.
23:23They built
23:24a rocket
23:25that simply
23:26ignored the
23:27reusability
23:27of its
23:28best component
23:29and for
23:30the future
23:30they are
23:31ordering a
23:32version where
23:32it has been
23:33left out
23:33entirely.
23:34I'd like to
23:35know what
23:35you think
23:36about that.
23:36Please write
23:37it in the
23:37comments.
23:38Artemis 1,
23:39Artemis 2,
23:39and the
23:40future.
23:40On Artemis
23:421,
23:43on November
23:4316th,
23:442022,
23:46E-2045
23:47flew E-2056,
23:50E-2058,
23:52and E-2060.
23:54Together,
23:55they've
23:55completed 25
23:56shuttle flights.
23:57E-2045 alone
23:59had 12,
24:00including John
24:01Glenn's flight
24:02in 1998.
24:04All four are
24:05now in the
24:05Pacific,
24:06east of Hawaii.
24:07NASA reports,
24:08the control
24:09valves for
24:10thrust and
24:10mixture ratio
24:11were within
24:120.5%
24:14of the
24:14prediction,
24:15and the
24:15controllers
24:16executed all
24:1782 commands
24:18without error.
24:20The engine
24:20just worked
24:21after an
24:2111-year
24:22break.
24:23That's
24:24really
24:24impressive.
24:25On
24:25Artemis 2,
24:26E-2047
24:28from the
24:28beginning
24:29of the
24:29video
24:29flew,
24:30E-2059
24:31with five
24:32shuttle flights,
24:33E-2061
24:34with two
24:35flights
24:36on Endeavour,
24:37and E-2062,
24:39an engine
24:40assembled
24:40after a
24:41shuttle
24:41program
24:41from
24:42previously
24:42flown
24:43parts.
24:43It was
24:44making
24:44its
24:45first
24:45flight.
24:46Originally,
24:47E-2063
24:48was installed,
24:49but a
24:49hydraulic leak
24:50at the
24:50main
24:51oxygen
24:51valve
24:51led to
24:52its
24:52replacement
24:53in
24:53April
24:532025.
24:54It was
24:55repaired
24:55and is
24:56scheduled
24:56to fly
24:57on Artemis
24:574.
24:58By the
24:58way,
24:58the mission
24:59itself
24:59was a
25:00success.
25:00Launch
25:01was on
25:01April 1,
25:022026,
25:03local time.
25:03Splashdown
25:04near San Diego
25:05was on
25:05April 10th
25:06or April
25:0611th
25:07at
25:072.07
25:08a.m.
25:08in Germany.
25:09You can find
25:10our analysis
25:10on this
25:10in our
25:11Artemis 2
25:11editions.
25:12They are
25:13also linked
25:13in the
25:14description
25:14below.
25:15And now,
25:15let's
25:15look ahead.
25:16For
25:17Artemis 3,
25:18E-2048,
25:20E-2052,
25:22E-2054,
25:23and E-2057
25:25are planned.
25:26All with
25:27shuttle history.
25:29Assembly in
25:29the weekly
25:30assembly building
25:30began at
25:31the end
25:31of August
25:322026.
25:33Since the
25:34reorganization
25:34on February
25:3527th,
25:362026,
25:37Artemis 3
25:38is no longer
25:39a lunar mission
25:39but a crude
25:40test in
25:41Earth orbit
25:41for 2027.
25:43The landing
25:43is now called
25:44Artemis 4
25:45and is
25:46planned for
25:472028.
25:48We broke
25:49this down
25:49in issues
25:51244
25:51and 275.
25:54Important
25:54for our
25:55topic,
25:55Administrator
25:56Jared Isaacman
25:57has simultaneously
25:57cancelled
25:58the Block
25:591B upgrade
26:00with the
26:00exploration
26:01upper stage
26:01and has
26:02frozen the
26:02SLS at
26:03Block 1
26:04with the
26:04goal of
26:04one launch
26:05every 10
26:06months.
26:06This means
26:07the 16
26:08shuttle engines
26:09will be
26:09used up
26:10with Artemis
26:114.
26:12And
26:12Artemis
26:135
26:14would be
26:14the fast
26:15mission
26:15to fly
26:16with the
26:16new
26:16RS-25E
26:18engines.
26:18Whether
26:19it will
26:19continue
26:19after that
26:20is uncertain.
26:21The White
26:21House's
26:22budget proposal
26:22for 2026
26:23wanted to
26:24end
26:24SLS
26:25and Orion
26:25after
26:26Artemis
26:273.
26:27Congress
26:28rejected
26:29that
26:29and
26:29in the
26:30summer
26:30of
26:302025
26:31set
26:32aside
26:326.7
26:34billion
26:34dollars
26:34for
26:35Orion,
26:36Gateway
26:36and
26:36SLS
26:37through
26:37a
26:37reconciliation
26:38bill
26:39specifically
26:39for
26:40Artemis
26:404
26:40and 5.
26:41The
26:41draft
26:42for
26:422027
26:43from
26:44April
26:452026
26:46now proposes
26:47to replace
26:48the SLS
26:48with commercial
26:49providers
26:50after
26:50Artemis
26:515.
26:52Isaacman
26:53has committed
26:53to the SLS
26:54until
26:54Artemis
26:555
26:56before the
26:57Senate.
26:57As of
26:58mid-September
26:592026,
27:00Congress
27:00has not
27:01made a
27:01final decision
27:02on this.
27:03If this
27:03problem
27:04remains in
27:04place,
27:05NASA will
27:05need
27:06exactly
27:064 of the
27:0724
27:07existing
27:08RS-25E's.
27:09Conclusion
27:10and
27:10assessment
27:111.
27:13The
27:13RS-25
27:14is a
27:15masterpiece.
27:16452
27:17seconds
27:17of
27:18specific
27:18impulse.
27:20405
27:20engine
27:21flights.
27:22Only
27:22a
27:22single
27:23failure
27:23and
27:23that
27:24ended
27:24in
27:24orbit.
27:25Anyone
27:26who
27:26laughs
27:27at
27:27this
27:27engine
27:27hasn't
27:28understood
27:28it.
27:28The
27:29systems
27:29surrounding
27:30this
27:30engine
27:30are
27:31another
27:31matter.
27:322.
27:33The
27:33decision
27:34made
27:34in
27:342011
27:35was
27:35justifiable
27:36in
27:36itself
27:37using
27:3716
27:38paid
27:38certified
27:39engines
27:40in
27:40storage
27:40isn't
27:41a
27:41waste.
27:41It's
27:42putting
27:42existing
27:42stock
27:43to
27:43use.
27:43The
27:44waste
27:44lies
27:44in
27:45the
27:45fact
27:45that
27:45the
27:45rocket
27:46around
27:46it
27:46was
27:46never
27:47intended
27:47for
27:48recovery
27:48even
27:49though
27:49the
27:49component
27:50was
27:50built
27:50for
27:50it.
27:513.
27:52And
27:53that's
27:53the
27:53core.
27:54The
27:54counter
27:54arguments
27:55are
27:55real.
27:56Restarting
27:57a
27:57production
27:57line
27:58after
27:5810
27:58years
27:59costs
28:00money.
28:01Manned
28:01spaceflight
28:01requires
28:02documentation
28:03that a
28:03Starling
28:04state
28:04doesn't
28:05need.
28:05And
28:05the
28:05jobs
28:08air
28:09by
28:09political
28:09design.
28:10That's
28:10stated
28:11quite
28:11openly
28:11in
28:12the
28:122010
28:13law.
28:14But
28:14that's
28:14exactly
28:15why
28:15the
28:15inspector
28:15general's
28:16findings
28:16are
28:17so
28:17serious.
28:18A
28:18cost
28:18plus
28:19contract
28:19where
28:20NASA
28:20bears
28:20the
28:20risk
28:21success
28:21bonuses
28:22for
28:235
28:24out
28:24of
28:2416
28:24completed
28:25engines
28:25and
28:26an
28:26agency
28:27that
28:27can't
28:28even
28:28track
28:28its
28:28own
28:29costs
28:29per
28:29engine.
28:30This
28:30is
28:30not
28:31a
28:31criticism
28:31of
28:31the
28:31engineers
28:32in
28:32Stennis
28:32or
28:33Canoga
28:33Park.
28:34This
28:34is
28:34a
28:34criticism
28:35of
28:35a
28:35contract
28:36structure
28:36that
28:37rewards
28:38costs
28:38instead
28:39of
28:39results.
28:40It's
28:40a
28:40jobs
28:40program
28:41in
28:41the
28:41sense
28:42that
28:42preserving
28:43the
28:43workforce
28:43was
28:44explicitly
28:45prioritized
28:45over
28:46efficiency
28:46in
28:47the
28:47law.
28:47Whether
28:48you
28:48call
28:48it
28:49the
28:49Senate
28:49launch
28:49system
28:50or
28:50industrial
28:51policy
28:51is
28:52a
28:52matter
28:52of
28:52taste.
28:53The
28:53calculation
28:53is
28:54the
28:54same.
28:55And
28:55fourth,
28:56the
28:56price
28:56per
28:56ton
28:56of
28:57thrust
28:57is
28:57the
28:57most
28:58honest
28:58number
28:58in
28:59this
28:59video.
28:59And
29:00it's
29:00devastating.
29:01Even
29:02if
29:02you
29:02resolve
29:02every
29:03uncertainty
29:03in
29:04favor
29:04of
29:04the
29:05RS-25.
29:06If
29:06you
29:06want
29:06to
29:07know
29:07what
29:07an
29:07engine
29:07looks
29:08like
29:08that
29:08was
29:08designed
29:09from
29:09the
29:09start
29:09for
29:10reuse
29:10and
29:10mass
29:11production,
29:11then
29:12check out
29:12our
29:12episodes
29:13on
29:13Raptor
29:143
29:14and
29:15the
29:15BE-4.
29:17They're
29:17also
29:18linked
29:18below.
29:19And
29:19let
29:19me
29:19know
29:19in
29:19the
29:20comments
29:20if
29:20you
29:20would
29:21make
29:21the
29:21same
29:21decision
29:22from
29:222011
29:23again
29:24today.
29:25My
29:25name
29:25is
29:25Sirvan
29:26and
29:26this
29:27was
29:27Mars
29:27Chronicles.
29:28Thanks
29:28for
29:29tuning
29:29in
29:29per
29:29aspera
29:30ad
29:30astra.