SpaceX Super Heavy/Starship
May 6, 2021
Heavy/Starship Flight Log
Heavy/Starship Stage Serial Number Log
2017 Version of Big Falcon
Super Heavy/Starship is Elon Musk's planned future
standard SpaceX launch vehicle, meant to replace Falcon 9 and
Falcon Heavy. It is meant to be a fully-recoverable two-stage
liquid-fueled vehicle powered by new generation staged
combustion SpaceX Raptor engines burning liquid methane and
liquid oxygen (CH4/LOX). The first stage would perform vertical
launch and landing profiles similar to Falcon 9/Falcon Heavy
first stages. The second stage would use a side-ways aerodynamic
reentry method followed by a vertical landing.
earliest days of SpaceX, Elon Musk talked about a giant "BFR" (Big
"Falcon" Rocket) that could lift 100 tonnes or more to low Earth
orbit. Such a rocket would be needed to support his Mars
colonization dreams. During 2005, before SpaceX even attempted
its first Falcon 1 launch, Mr. Musk described plans for such a
rocket, powered by a cluster of "Merlin 2" engines. Merlin 2
would have been gas generator LOX/kerosene producing up to 770
tonnes of liftoff thrust.
During this period SpaceX proposed a "Falcon XX" concept that would
have used six such engines making 4,630 tonnes of liftoff thrust to
power a 10 meter diameter, 104 meter tall two stage rocket capable of
lifting 140 tonnes to LEO. The second stage would likely have been
powered by 68 tonne thrust LOX/LH2 staged combustion Raptor engines
then under study by the company. A modified version of this concept,
using a LOX/LH2 J-2X powered second stage, was included in NASA's
2009-2010 “Heavy Lift Launch Vehicle Study” (HLLV).
During 2012, SpaceX took a new direction,
announcing plans to switch Raptor to full flow staged combustion
LOX/Methane. Plans called for the engine to produce 360 tonnes
of sea level thrust. By 2014, concepts called for a Falcon XX
size rocket to be powered by nine such Raptors at liftoff, with
one or two vacuum optimized Raptors powering the second stage,
to lift 100 tonnes or more to LEO.
As Falcon 9 began to
attempt first stage recoveries during 2015, the "BFR" concepts
began to shift toward reuse, not only of the first stage but of
both stages. As a result, the rocket grew much larger.
On September 27, 2016, at the International Astronautical
Congress, Musk presented a design for a truly enormous 12 meter
diameter, 122 meter tall, 10,478 tonne two-stage rocket named
"Interplanetary Transport System" (ITS). Its first stage would
have used 42 Raptor engines producing 13,154 tonnes of liftoff
thrust. Nine Raptors would have powered its second "spaceship"
stage. ITS would have lifted 300 tonnes to LEO. With multiple
launches to refuel the second stage it would have been possible
to boost nearly 500 tonnes toward Mars. Development costs for
ITS were optimistically projected to be $10 billion.
year later, at the same meeting, Musk presented a scaled down
design named "BFR", capable of lifting 100 tonnes to LEO with
full reuse. It would be 9 meters diameter and 118 meters tall,
weigh 4,400 tonnes at liftoff, and would use carbon composite
propellant tanks and structures. The 3,065 tonne first stage
would use 31 Raptors making 6,305 tonnes of thrust while the
1,335 tonne second stage would have 9 Raptors, three in "vacuum"
configuration, producing 1,406 tonnes of thrust. The concept
retained multiple-launch orbital refueling plans designed to
send 220 tonnes toward Mars.
This 2017 BFR almost seemed
average-size compared to the 2016 plans, but it still would have
outweighed Saturn 5, the heaviest rocket ever launched, by
nearly 1,400 tonnes. It would also have produced 1.8 times more
thrust than Saturn 5, a rocket that created its own 4.6 Richter
scale earthquakes when launched.
During March, 2018,
SpaceX announced plans to build a BFR factory at the Port of Los
Angeles. Clearing of an 18 acre site began, while giant tooling
for BFR composite tank fabrication was being set up in a
temporary structure nearby.
By September 2018, plans
called for seven identical sea-level Raptor engines on the BFR
second stage. SpaceX announced at the same time plans for a
privately funded 2023 lunar circumnavigation mission using BFR.
Hopper Mockup Phase Assembly, January 2019
Then, on October 10, 2018, the U.S. Air Force rejected
SpaceX's proposal to fund some BFR development as part of a
precursor National Security Space Launch (NSSL) Launch Services
Agreement bid. Whether the loss contributed to a 10% SpaceX
employment cutback at the end of 2018 and to cancellation of
plans to build a factory at the Port of Los Angeles is unknown.
Also unknown is whether the NSSL LSA bid was related to
significant BFR design changes revealed in December, 2018. By
then, plans for composite tanks and structures had been replaced
by plans to use stainless steel.
During November, 2018,
Elon Musk announced that the BFR launch vehicle first stage
would be named "Super Heavy" while the second stage would be
"Starship". Musk hinted that more design changes were planned,
including a reduction in the number of Raptor engines.
During the final weeks of December, 2018, SpaceX began building
a stainless steel "Starship Hopper" test article at Boca Chica,
Texas. This was initally a cosmetic build, performed outdoors,
shorter than the planned Starship, with no internal tank
bulkheads and with three dummy Raptor engines, that was set up
for a "photo op". After the flimsier "top hat" portion of the
Hopper was destroyed during a late January 2019 windstorm, crews
completed the installation of bulkheads and other hardware on
the undamaged lower portion of the Hopper. This section,
standing on three heavy landing legs, was built out of thicker
steel plates, sheethed in a stainless steel layer, in the
classic "battleship" style long-used for early propulsion tests
of in-development rocket stages.
Raptor Test Firing, February 3, 2019
On February 3, 2019,
SpaceX briefly test fired its first full-scale Starship Raptor
flight engine in a McGregor, Texas test stand. The engine
reached 172 tonnes of thrust during a subsequent firing, before
it was damaged in an even higher-thrust run a few days later.
Elon Musk reiterated that 200 tonnes thrust was the ultimate goal for
initial Starship use, a number achievable using colder
propellant temperatures then those used during the initial
McGregor test firings.
The second Raptor (SN2) was then
installed on Starship Hopper at Boca Chica, which had by this
time been moved to a new testing pad being built near the beach.
On April 3rd, 2019 the engine was test fired briefly during a
"tethered hop". On April 5, during the evening local time, the
engine fired again to lift the Hopper to its full tether limit.
The engine was then removed as SpaceX began to prepare for
another round of testing.
On April 27, 2019, Raptor SN3
was test fired for 40 seconds at McGregor, the longest duration
to date. By mid-May, Raptor SN4 had been delivered while SN5 was
being assembled at Hawthorne, California. During the first week
of June, SN4 was installed on the Hopper for fit checks, but
plans called for SN5 to be used for the first untether hop
Meanwhile, SpaceX began to build new,
all-stainless tank structures at both Boca Chica and near Cocoa,
Floria. These "Mk1 and Mk 2" ships would be used for
longer-range suborbital test flights using at least 3, and maybe
up to 6, Raptor engines. During this period - the Spring
of 2019 - Elon Musk said that construction of the
first Super Heavy prototype might begin during the summer of
Starhopper ended up fitted with Raptor S/N 6 for its untethered
hops at Boca Chica. A five second static test on July 16,
2019 preceeded an 18 meter altitude untethered hop on July
25, which lasted 22 seconds. A final, 150 meter altitude
flight took place on August 17, 2019. During the 57 second
long flight, Starhopper rose, translated sideways, and landed on a
separate landing pad. The stumpy test vehicle was then
retired from flight service, though plans called for it to serve
as an engine test stand in the future.
September 2019 Starship Update
On September 27, 2019, SpaceX crews completed basic structural assembly of the Starship Mk 1 test article in Boca Chica. One day later,
Elon Musk arrived to provide a program update while standing in front of the 50 meter tall,
200 metric tonne vehicle. Three non-flight Raptor engines
had been fit-tested to the prototype by that time, testing the
propulsion set up planned for Mk 1 suborbital test flights.
Elon announced that Mk 1 would fly to 20 km within two months to
test reentry and landing flight control and propulsion.
Starship Mk 2 would perform similar tests from LC 39A in Florida.
Suborbital testing would culminate in flights up to 100 km
Musk provided new details about the Starships. Mk 1 sported a pair of movable aft delta-fins and a pair of movable forward canards.
These were designed to control the vehicle during reentry, when the vehicle would maintain a 60 degree angle from horizontal. After
scrubbing velocity, the vehicle would flip to a nose-up attitude and start its engines for landing. While Mk 1 used 3/16 inch thick
stainless steel, later vehicles would use steel as thin as 1/16 inch, attempting to reduce dry mass to 120 tonnes or less.
Orbital Starships would carry hexagonal ceramic heat shield tiles
on their leeward side. Musk said that Mk 3 and 4 Starships would also be built, at Boca and Cocoa, respectively. These would use
six Raptor engines and hot gas thruster systems. Ultimately, Starship would have three central, movable "sea level" Raptors
surrounded by three fixed "vacuum" Raptors.
Raptors on Starship Mk1, September, 2019
After completing four prototype Starships, SpaceX would begin work on its first "Super Heavy" booster at Boca
- clearly many months after Musk's earlier "summer 2019"
statements. The booster would
carry 24 to 31 Raptor engines, with a variable number possible.
New launch mounts would be built at both Boca Chica and LC 39A to
handle the massive rocket. The stage would fly much like current Falcon 9 stages, using grid fins
for reentry flight control and engine restarts for vertical landings. Super Heavy
now would stand about 68 meters tall. The 118 meter tall two-stage
vehicle could ultimately weigh about 5,000 tonnes at liftoff and rise on about 7,500 tonnes of thrust,
growing heavier from 2017 plans. It would be able to boost
100 tonnes to LEO initially, with 150 tonnes as a future goal.
After the September 28 presentation, Starship Mk1 was disassembled, its non-flight engines and nose section
disconnected and removed. The disassembly was done to allow further detailed manufacturing to continue.
Multiple Starships Destroyed
The Mark 1 prototype SpaceX Starship was destroyed during a cryogenic loading test at Boca Chica on
November 20, 2019, dealing a setback to the SpaceX Super Heavy/Starship development effort. The top
bulkhead of the propellant section was blown off after an apparent weld failure near or at the bulkhead/tank
interface. The bulkhead flew hundreds of feet into the air and laterally, landing in a field. The tank
section was visibly damaged. Cryogenic vapors were seen leaking both from the top tank and from the bottom,
propulsion section area indicating that substantial internal damage was also likely. The top, nose section
of Starship was not attached during the loading test, and Raptor engines were not believed to have been installed.
After the failure, SpaceX announced that neither the Mark 1 or Mark 2 prototypes would fly. The Mark 3
vehicle would now be the first to be flight-capable. Production near Cocoa, Florida of Mark 2 and Mark 4 was to be
halted, with resources to be consolidated at Boca Chica. Thus ended the first year of work on the stainless steel
Starship, which produced the successful Starhopper flights and substantial Raptor development results, but
a full-scale Starship setback and with no visible work on the even bigger Super Heavy stage.
After moving production to Boca Chica, SpaceX built a new series
of Starships, identifying them starting with Serial Number 1
(SN1). These were sequentially lost in a series of increasingly
violent testing failures during the first half of 2020. The first,
SN1, was destroyed during a cryogenic proof test on February 28,
2020 due to a likely weld failure on a lower bulkhead of the
bottom LOX tank. SN2 was then stripped and scrapped after being
used for some structural tests of the problem area.
Starship SN3 was destroyed during its April 3, 2020 cryogenic
proof test. Elon Musk said that this failure was caused by a
ground setup problem. The vehicle's tanks had been filled with
liquid nitrogen for the test. The vehicle crumpled beginning about
halfway up and the top tank crumpled.
Vehicle SN4 was the
first full-scale Starship prototype to pass its cryo proof test,
accomplished on April 26, 2020 when pressurized to 4.9 bar. A
single Raptor engine was then mounted and on May 5 SN4 completed a
3-second static fire test. The Raptor was removed after the test.
On May 9, the stage was successfully pressurized to 7.5 bar under
mechanical loading at the engine mount area.
A new Raptor,
SN20, was installed and on May 19 another static test was
performed that lasted several seconds. After cutoff, however, a
fire began burning at the base of the vehicle when a ground line
failed. Crews were unable to approach the still-pressurized
vehicle for a day.
After repairs, SN4 performed another
static test on May 28, 2020 that lasted about 6 seconds. A dummy
load had been attached to the top of the vehicle for this testing,
an effort leading toward a planned 150 meter "hop" test flight.
One more static test was performed on May 29. About a
minute or so after Raptor SN20 shut down, a large white gaseous
leak began at the base of the vehicle. This was methane, leaking
in large volume and dangerously pooling in a gas cloud around the
Starship at ground level. After another minute or so, a massive
detonation occurred after the methane ignited at the base of the
vehicle. SN4 and its Raptor were destroyed, along with the launch
mount and some ground support equipment. At the time, SpaceX had
been planning for hop attempts on June 1 or 2.
Starship prototypes lost in six months of testing raised serious
questions about the safety and viability of the program, but
construction of subsequent Starships continued.
Proceed to Hop
The SN4 explosion appeared
to have been caused by a failed propellant quick disconnect that
was tested after the static fire was complete. The disconnect
failed open, flooding the pad with methane.
SpaceX proceeded to build a
small test tank, named SN7, to test new 304L stainless steel and
welds. The tank was pressure-tested on June 14, 2020 and went
through a full cryo pressure test the next day, when it sprung a
leak at 7.6 bar. Elon Musk reported that the test was a success
because it found an expected weak point. The tank was repaired and
purposely tested to failure on June 23.
company completed the SN5 Starship prototype, which moved to the
rebuilt pad on June 24, 2020. SN5 completed a full cryo proof test
on the night of June 30-July 1. Raptor SN27 was mounted to the
vehicle and, on July 30, was static test fired for several
seconds. On August 4, after previous aborted attempts, SN5
performed the long-planned 150 meter "hop", rising from the pad,
translating sideways, and landing on the nearby landing pad,
basically repeating the Starship Hopper flight of one year earlier. Raptor appeared to catch fire during the brief flight, and ground
equipment beneath the launch pad suffered a small explosion after
liftoff, but the test flight itself accomplished its objectives
The "hop" was only a precursor to high-altitude test flights
that would use more Raptors and propellant to explore reentry
profile techniques. The ultimate flight Starship would have to be
coated with protective insulation tiles for reentry, another step
in the long development process. Super Heavy, a much larger stage,
would still have to be developed to boost Starship to orbit.
At the time of the SN5 hop, SpaceX had Starship prototypes SN6
and SN8, at least, under construction. SN8 would be the first
full-scale prototype built with 304L stainless steel. SN6 was
stored in the recently completed Mid-Bay building. The company was
building a new High Bay structure that would be used for
long-promised Super Heavy.
On September 3, 2020, prototype Starship SN6 performed a repeat 150 meter
hop test flight, using single Raptor serial number 29. The stage
had performed a cryo load test on August 16 and a brief static test
firing on August 23.
Super Heavy/Starship Update
On September 1, 2020, Elon Musk provided an update on Super Heavy/Starship
design progress. He said that Super Heavy would now have 28 Raptor engines,
a reduction from the prevously-announced 31. The design now used an outer
ring of 20 fixed Raptors, each producing 250 tonnes thrust. An inner set of
eight lower-thrust, throttleable Raptors would be used control acceleration
during ascent and to descend and land the stage at the end of its missions.
Together, the 28 Raptors would produce about 6,680 tonnes of liftoff thrust.
Musk stated that plans called for the outer Raptors to see thrust increased
up to 300 tonnes eventually, allowing total liftoff thrust to increase to about
7,500 tonnes for a 1.5 thrust to weight ratio. The overall picture presented by Musk was that the company
intended to substantially increase the thrust of its still-in-development
CH4/LOX Raptor engine as a means of reducing engine count on the giant
Super Heavy booster. SpaceX had found that fixed throttle Raptors can
operate at higher thrust than variable-throttle engines. This had forced
it toward development of two sea-level Raptor variants.
Musk also stated that prototype Super Heavy vehicles would use fewer
Raptors - only two at first - during early tests from Boca Chica.
Eventually, the fully-engined Super Heavy would produce so much thrust,
noise, and ground vibration that it would have to launch from, and land on,
floating platforms off shore.
Finally, Musk said that prototype Starship flights would progress to
use of three Raptors for higher altitude flights. These 9 x 50 meter versions
would include nose cones and airfoils for the first time. Orbital versions
to be launched atop Super Heavy would ultimately use six Raptors and
would be equipped with a reentry heat shield. Super Heavy and Starship
together would stand about 120 meters tall.
Testing continued. Small test tank SN 7.1 was cryogenically load tested
on September 21, 2020 and pressurized to failure on September 23.
Starship prototype SN8, the first with movable wings/flaps, was moved to the pad where
it was given cryogenic load tests on October 7 through 9. Three Raptor engines,
SN39, 32, and 30, were installed and on October 20 were static test fired, the first
triple Raptor ignition.
The big nose cone with its built in header tank and twin
canards was installed next. On November 10 a single Raptor was fired using the nosecone
LOX header tank. A spray of bright objects was noted during the test. One day later an
attempt to ignite two Raptors failed, ending in another spray of bright debris. The
engine failure caused loss of pneumatics, which led to a burst disk being required to
relieve pressure in the header tank.
The cause, according to Elon Musk, was debris kicked up by the Raptor thrust ripping
away a ceramic coating on the launch pad during the static test. The debris severed
an avionics cable, causing an improper Raptor shutdown. Raptor SN32 was as a result
removed and replaced by SN42.
SN8's Remarkable Belly Flop Descent
On November 24, Starship prototype SN8 completed a static firing test. An attempt to
perform the long-planned 12.5 km hop was aborted at T-1 second on December 8. The
subsonic hop test flight finally took place on December 9, ending in SN8's destruction
during a hard landing.
During the test flight, SN8 ascended slowly on the thrust of three Raptor engines.
Two Raptors were shut down in sequence as the vehicle climbed, to keep velocity below
the speed of sound. The vehicle nearly hovered at its peak as it slid sideways for
some distance. Then the third Raptor shut down and SN8 nosed over to begin its
aerodynamicly controled descent.
The vehicle descended "sideways", under control of
its four moving fins. This was a successful test of the "belly flop" maneuver that
full scale Starships will use during reentry.
SN8's engines switched to the header tanks for the final
landing burn startup, which included two engines at first as the prototype rapidly
flipped back to a vertical orientation. The fuel header tank pressure was low during
the landing burn, causing low thrust and high touchdown velocity, which ended the flight
in a big explosion on the landing pad.
SpaceX webcast the entire test, including the destructive ending. Elon Musk quickly
tweeted an explanation for the ending, along with congratulations to his team for what
was a highly successful development test. The next prototype Starhip, SN9, was already
ready to move to the pad for the next series of tests.
Starship prototype SN9 had a rough start to its test campaign when it fell over against the side of its high bay near
the end of its construction after its
base appeared to collapse. After being set upright, damage was visible on its top and bottom fins.
The vehicle was subsequently righted, repaired, and on December 22, 2020 moved to launch pad. Its nose and tail
flaps had been replaced on one side.
The SN9 tanks were pressure tested by year's end. On January 6, 2021, SN9 performed a static fire test that
apparently cut off prematurely. Three Raptors were to have fired during the test. A second static fire try
was aborted on January 12. The Raptors did fire up on January 13, when three separate static firings took
After the testing, two Raptor engines had to be replaced and other repairs were needed in the engine section.
On January 22, 2021, SN9 finally completed a successful static firing.
Meanwhile, SpaceX crews rolled Starship prototype SN10 out to the launch site on January 29, where it stood
On February 2, 2021, the SN9 10 km test flight ended in a failed, explosive landing.
One of two Raptors meant to start for the landing failed upon restart as the vehicle was flipping
from horizontal to vertical. SN9 flipped and landed on its back and exploded.
Starship prototypes Mk1, SN1, and SN3 were all destroyed during tanking tests.
Starship prototypes SN4, SN8, and now SN9 were destroyed in explosions, the latter two during
landing attempts at the end of test flights.
SN10 Post-Landing, Before Exploding
Starship prototype SN10, like SN8 and SN9, exploded at the end of its subsonic 10-12 km test
flight, which took place on March 3, 2021 from Boca Chica. SN10 did manage a first mostly-successful
landing following a flip from horizontal to vertical and restart of all three Raptor engines, with two
quickly shut down to allow landing on one engine. A fire appeared to
have ignited at the base of the vehicle
shortly after the two Raptors shut down. The vehicle appeared to land without all of its landing legs
properly deployed, and leaned after landing. After standing upright for about eight minutes with a fire
and possible propellant leak underway in its engine section, it exploded.
SN10 had performed static firings on February 23 and February 25, with one Raptor being
replaced between the firings.
SN10. SN9. SN8. SN4. All exploded. SN3. SN1. MK1. All failed during cryo or tanking tests.
SN11 rolled to its pad on March 8, 2021. It aborted a static test fire attempt on March 15, cutting off
after less than one second. A static firing was performed on March 22, followed by a second firing on
March 27 after one of the Raptor engines was replaced. SN11 lifted off on March 30 for its 10 km test.
The flight was mostly invisible to ground observers thanks to heavy fog. The vehicle rose to apogee
and transitioned to horizonal for its downward path. When the Raptor restart was attempted just prior
to the planned flip to horizontal for landing, the vehicle exploded, fragmenting into thousands of
parts that rained and floated down over a wide area. Elon Musk subsequently revealed that a methane
leak during the ascent phase had resulted in a fire on one of the engines. The fire damaged part of
the avionics system, which resulted in a "hard start" of the engine methane turbopump at the start
of the landing burn ignition. The disentegrating turbopump punctured propellant tanks and lines,
causing the explosion.
SN15 Shortly After Landing on May 5, 2021
It was left to Starship prototype SN15 (SN12 through SN14 having been scrapped or canceled) to
complete the first successful 10 km test flight. This vehicle rolled out on April 8, 2021. It
was fitted with more belly heat shield tiles than previous vehicles. SN15 completed a cryoproof
test on April 12 and static test firings on April 26 and 27 before completing its 10 km test
flight on May 5. Two Raptor engines successfully reignited during the landing flip. SN15 then
lowered itself slowly to a soft landing on the landing pad near the launch site. A fire
ignited at the base of the vehicle during the final moments of the flight. It burned after the
landing for several minutes before being extinguished. SN15 survived the flight, the landing,
and the post-landing fire, an achievement that came 8 months after the initial, SN8 attempt
- followed by failed SN9, SN10, and SN11 attempts - and 2.5 years after Boca Chica testing began.
That testing saw the destruction of eight Starship prototypes during flight or on the ground.
Liftoff Thrust (metric tons)
||2 Stage Fully Recoverable
||12 x 122 m
|Super Heavy/Starship 2017
||2 Stage Fully Recoverable
||9 x 106 m
|Super Heavy/Starship 2019
||2 Stage Fully Recoverable
||9 x 118 m
||4,800 t to 6,200 t
Stage 1 (2017)
Stage 2 -(2017)
Stage 1 (2019)
Stage 2 -(2019)
|~120 t (est)
||~300 t (est)
(120 t goal)
|Propellant Mass (tonnes)
(~3,300 t goal)
|Total Mass (tonnes)
|ISP (SL sec)
Super Heavy/Starship Flight History
Date Vehicle No. Payload Mass Site Orbit (kmxkmxdeg)
NN/NN/NN AAAAA NNN AAA NN AA AA
LIST BY STAGE 1 SERIAL NUMBER
X = Expended
OL = Ocean Landing
DRL = Down Range Platform Landing
LZ1 = Landing Zone 1 Landing
-X = Failed Landing
-S = Successful Landing (Scrapped)
-D = Successful Landing (Saved for Display)
-M = Successful Landing (Mothballed)
STA = Structural Test Article
QTA = Qualification Test Article
No. Date Variant/No. Description Mass Site Stg1/Result Orbit
Draft Environmental Impact Statement, SpaceX Texas Launch
Site, Vol 1&2, April 2013
SpaceX web site www.spacex.com
Elon Musk Twitter feed