SpaceX Falcon

Vehicle Configurations

Vehicle Components

In June, 2002, dot-com multimillionaire Elon Musk established SpaceX Corporation, setting up shop in a warehouse in El Segundo, California.  He staffed the tiny company with space vehicle engineering talent gleaned from nearby California aerospace companies that were, at the time, rapidly downsizing.  He poured at least $100 million of his own money into the company to develop not only the Falcon 1 space launch vehicle, but the rocket engines to propel it.  

Musk chose initially to attempt to develop the smallest practical space launcher.  At a time when other dot-com space startups were struggling with plans to develop complex reusable vehicles, SpaceX planned to build a relatively simple 21.3 meter tall, 1.7 meter diameter kerosene-fueled two-stage rocket capable of boosting about 0.6 tonnes to low earth orbit (LEO).  The company focused on providing the lowest launch price possible. 

SpaceX developed the 40-tonne-thrust-class Merlin engine to power the Falcon 1 first stage and the 3.17 tonne thrust Kestrel engine for the second stage.  Merlin was a gas generator cycle engine that used a pintle style injector, an injector design adapted from the Apollo Lunar Module engine.  Some Merlin features were similar to NASA's mothballed FASTRAC engine, including use of a similar turbopump manufactured by Barber Nichols.  Turbopump exhaust was used to provide roll control.  Kestrel, which also used a pintle injector, was a pressure fed design.  Kestrel had a radiatively cooled Niobium nozzle and an ablatively cooled chamber and throat. 

The first stage was a "pressure assisted stabilized" graduated monocoque aluminum design that used a common bulkhead between its aft kerosene tank and its forward liquid oxygen tank.   The stage was helium pressurized and  was designed to be recovered at sea after floating down beneath a 22.9 meter ringsail parachute.   SpaceX hoped to recover parts of the stage for reuse. 

The expendable second stage was fabricated from Aluminum.  The company originally planned to use lighter Aluminum-Lithium, but it was unable to secure a stockpile of the metal.  The stage was helium pressurized.  Helium cold gas thrusters were used to control roll during Kestrel burns and to provide three-axis control of the stage at other times. 

Falcon 1 development began quickly.  The first Merlin test firing took place at the company's McGregor, Texas test lab in March, 2003, and Kestrel testing began soon after. 


Falcon 1 Protovehicle

Fabrication of a "protovehicle" began in early 2003.  On December 3, 2003, after a cross-country drive on its custom-built transport trailer, SpaceX unveiled the protovehicle in Washington D.C., having parked it on the street in front of the FAA building.  During the ceremonies, Elon Musk announced that SpaceX planned to follow-up Falcon 1 with a more powerful 3.7 meter diameter Falcon 5 that would be powered by five Merlin engines.   Falcon 1 was initially priced at about $6 million while Falcon 5, designed to haul 4.5 tonnes to LEO, listed at $12 million.

During 2004, SpaceX completed its first Falcon 1 flight vehicle, which it erected at the company's SLC 3W launch pad at Vandenberg Air Force Base on October 5, 2004.  The rocket was transported and erected with a trailer-based system.  A second trailer contained a mobile control center.  Falcon 1 was equipped with a new carbon fiber composite interstage, replacing the protovehicle's heavier aluminum interstage. 

Meanwhile, the company struggled with Merlin development.  Cast aluminum manifolds cracked during tests, requiring replacement with heavier inconel manifolds.  The engines were not quite as efficient as planned, requiring thrust to be increased to offset the lower specific impulse.  The redesigned Merlin was testing by mid year. 

In September 2004, SpaceX won a DARPA contract that included a Falcon 1 space launch from 7-acre Omelek Island in Kwajalein Atoll in the Marshall Islands.  The company gradually built a backlog of missions, including one to launch TacSat-1, a $15 million U.S. Navy microsatellite, and another to orbit a test payload for Bigelow Aerospace.  The latter launch would use Falcon 5, a design that had been beefed up since its announcement to haul 6 tonnes to LEO when the original plan to power the Falcon 5 second stage with two Kestrels had been superceded by a plan to use a single Merlin.
 
First Fire

Merlin development was finally completed on January 14, 2005, when the first full run qualification test was performed.  Falcon 1 development was completed on March 31, 2005 with a series of structural qualification tests.  Merlin was integrated with the first flight vehicle in April, 2005 and on May 27, 2005, the first 5-second hot fire test occurred at SLC 3W.   Space reporters were surprised to see how quickly the 15 on-site SpaceX personnel packed up Falcon 1 and its mobile control center trailer after the hot-fire test.   The rocket was back in its Los Angeles area warehouse within hours of the test. 

SpaceX was ready to launch TacSat-1, but the Air Force did not want the launch to occur until the final Titan 4 flew from nearby SLC 4E.  Repeated delays pushed the Titan launch back until an exasperated Musk decided to fly the first launch from Kwajalein instead, on the DARPA mission with an Air Force Academy payload named Falconsat 2 .  In June, 2005, SpaceX packed up the Falcon launch equipment and sent it on a ship to the islands.  The first Falcon 1 vehicle followed a month later.

By late 2005, SpaceX had completed two Falcon 1 launchers and was fabricating a third. 
 

Inaugural Omelek Campaign

The first Falcon 1 launch attempt at Omelek on November 25, 2005 was scrubbed after a ground-supply LOX vent valve allowed the small LOX supply to boil off.  A second attempt on December 19, 2005 was delayed by high winds.   Then, the first stage fuel tank buckled during fuel draining when the fuel pressurization system suffered a controller failure.  The damaged first stage was shipped back to Los Angeles for repair.  The second flight vehicle's first stage was shipped to Omelek in its place. 

On February 9, 2006, SpaceX completed a hot-fire test at the Omelek pad with the new first stage, but a second stage propellant leak was discovered during the testing process, thwarting a February launch attempt.  The company shipped the second stage to Los Angeles, replacing it with the second flight vehicle's second stage.  On March 18 and 23, 2006, the reconfigured vehicle performed hot-fire tests in preparation for a fourth launch attempt. 

SpaceX Falcon 1 Inaugural Liftoff Failure

Elon Musk's Falcon 1 failed in its March 24, 2006 inaugural launch attempt from Omelek Island in Kwajalein Atoll, Marshall Islands, after a 22:30 GMT liftoff. The two-stage rocket rose from its pad and ascended for about 25 seconds before a fire in the area just above the engine cut into the first stage helium pneumatic system, causing an engine shut-down at T+34 seconds.  A downward looking on-board camera view showed a clean, stable ascent until the shutdown.  After the shutdown, the camera showed the vehicle rolling and falling toward the ocean. 

Falcon 1 is equipped with an engine cut-off range safety system rather than destruct charges.  As a result, when the failure occurred, the rocket fell more or less intact to impact on a reef not far from the launch site.   The Falconsat 2 payload, an experimental microsat built by U.S. Air Force Academy students, crashed through the roof of a shop building on the island.

According to Elon Musk, the fire, which began just a few seconds after liftoff, appeared to have been fed by a fuel leak.  In a March 31 NPR interview, company VP Gwynne Shotwell said that the leak had been caused by a "procedural error" rather than a launch vehicle hardware failure.  A fuel pipe fitting had been opened by a technician the day before the launch to provide access for other work.  The presumption was that the fitting had not been properly restored after work was complete. 

On July 25, 2006, SpaceX reported the findings of a DARPA “Falcon Return to Flight Board”.  The investigation discovered that a kerosene fuel leak began 400 seconds before liftoff, when the propellant pre-valves were opened.  The leak occurred on plumbing associated with the turbopump fuel inlet pressure transducer.  When the Merlin main engine started at liftoff, the leaking fuel ignited.  The precise cause of the leak was not determined, although initial reports that a pad processing error was responsible were ruled out.  One possible cause that could not be ruled out was stress corrosion cracking of an “aluminum B-nut” on the transducer plumbing. 

Merlin 1C

During 2006, Elon Musk announced that SpaceX had decided to begin work on a "Merlin 1C" engine with a regeneratively cooled thrust chamber.  In early February 2007, SpaceX updated its web site with revised design information for both Merlin and Falcon.  The data was said to be effective for vehicles launched in 2009 or later.  Merlin 1C was shown to produce 46.259 tonnes of sea-level thrust - a 32% increase over the thrust produced by Merlin 1A during the initial Falcon 1 launches.   

A revised Payload User's Guide was published in May 2007.   It provided details of the new Merlin 1C powered "Falcon 1e" rocket that would be about 5.53 meters taller and 11.36 tonnes heavier than the original Falcon rocket.  Falcon 1e, expected to enter service after 2009, would be able to haul 25-30% more payload than the original Falcon rocket.       

Second Launch

The second Falcon 1 launch, carrying only a dummy payload for DARPA, was planned to occur during the first quarter of 2007.  After being erected at Omelek and after having passed a wet dress rehearsal in mid-January, 2007, a planned late-January hot fire test had to be postponed when the vehicle's second stage engine failed a slew test during the countdown.  The vehicle was moved back into its Omelek hanger for work, halting the launch campaign until at least early March.

SpaceX performed a brief, successful static test ignition of the Falcon 1 first stage Merlin engine on March 15.  After a scrubbed launch attempt on March 19, 2007, Elon Musk's SpaceX Falcon 1 failed to reach orbit during its second flight on March 21, 2007.  Flight control was lost about 2 minutes 10 seconds into the vehicle's second stage burn, about five minutes into the roughly 10 minute planned ascent. It was the second Falcon 1 launch failure in two attempts.

Liftoff from Omelek Island, Kwajalein Atoll, Republic of the Marshall Islands occurred at 01:10 UTC. The flight achieved several milestones before the failure, including passing through "Max-Q", a complete first stage burn, stage separation, second stage ignition, and payload fairing jettison. 

On board video broadcast by SpaceX showed the second stage engine bell brushing against the side of the interstage at stage separation.    The video also showed an apparent "coning" motion developing during the last minute of controlled flight.  The magnitude of the oscillating motion increased during the final seconds of downlink, just before roll control and telemetry was lost. 

On March 27, Elon Musk reported that propellant sloshing had caused the oscillation.  LOX sloshing had been initiated by the contact during staging, specifically by the subsequent second stage "hard slew" required to restore its orientation after its Kestrel engine ignited.  The LOX slosh frequency coupled with the thrust vector control system in a way that gradually amplified the oscillation until flight control was lost.  The Kestrel engine continued to fire until the T+7.5 minute mark when roll rates increased sufficiently to cause propellant starvation.  Mr. Musk also reported that the first stage had not been recovered as planned.       

The "Demo 2" demonstration flight was performed for the Defense Advanced Research Projects Agency (DARPA) under the auspices of the DARPA/USAF Falcon program. Payloads, totaling about 50 kg, consisted of a small dummy payload that was to have been deployed and two non-deployable NASA experiments. They included the Autonomous Flight Safety System (AFSS) and the Low Cost Tracking and Data Relay Satellite System (TDRSS) Transmitter (LCT2), both developed by NASA. AFSS was to use LCT2 to telemeter data back to Kwajalein and to Wallops Flight Facility. AFSS and LCT2 were tests of low-cost space-based range services for communications, tracking, and on-board autonomous flight termination.   

The 27.526 tonne, two stage launch vehicle rose on 34.92 tonnes of liftoff thrust from its Merlin LOX/kerosene first stage engine. First stage burnout occurred 168 seconds after liftoff at an altitude of 75 km and a velocity of 2,600 meters per second. The second stage pressure-fed LOX/kerosene 3.l75 tonne thrust Kestrel engine ignited five seconds after first stage cutoff, beginning a planned burned of about 415 seconds duration intended to insert the stage into an initial 330 x 685 km x 9 deg initial orbit about 585 seconds after liftoff.  As it turned out, the second stage only achieved suborbital velocity (about 5,100  meters per second), reaching a 289 km apogee before falling back into the Pacific Ocean east of the Marshalls.

The launch occurred only 1 hour 5 minutes after a dramatic launch abort that stopped the main engine start sequence.  The abort was caused by a slightly low chamber pressure reading caused by lower than planned kerosene fuel temperatures. SpaceX crews drained and reloaded some of the first stage fuel before restarting the count.

New Falcon Details Emerge

In April 2008, SpaceX revealed new details for the higher-thrust Merlin 1C and for Falcon 1e. 

The upgraded Merlin 1C would produce 56.689 tonnes of sea-level thrust and 63.449 tonnes of thrust in vacuum, 1.5-1.6 times more than the original Merlin.  With more available liftoff thrust,

With the beefed-up Merlin 1C, Falcon 1e grew substantially heavier and more capable.  Falcon 1e LEO payload increased to 1 tonne, far more than the original Falcon 1, who's LEO payload had fallen to 0.42 tonnes.   An interim Falcon 1, the same size as the original but powered by the initial Merlin 1C model and able to lift 0.47 tonnes to LEO, would fly before Falcon 1e appeared.  

Third SpaceX Falcon 1 Launch Fails - Cause Announced (Updated 8/6/08)

The third SpaceX Falcon 1 rocket failed shortly after lifting off from Omelek Island, Kwajalein Atoll, on August 3, 2008.  Liftoff of the 21.3 meter tall, 27.67 tonne, two stage rocket occurred at 03:34 UTC.  According to a message from Elon Musk to NasaSpaceFlight.com, the failure occurred at staging, about 2 minutes 39 seconds after liftoff, following a nominal first stage burn.  A video feed of the launch provided by SpaceX was cut off about 2 minutes 11 seconds after launch, shortly before second stage pressurization, first stage cutoff, and stage separation would have occurred. 

On August 6, Musk announced that residual thrust produced by the Merlin 1C first stage engine had caused the stage to recontact the second stage immediately after stage separation.  Separation was timed to take place only 1.5 seconds after Merlin 1C shutdown - a timing that had worked with the original ablatively cooled Merlin 1 engine.  The pressure-fed Kestrel second stage engine had just started when it and its stage were damaged by the impact. 

Lost with the Falcon 1 were the U.S. Air Force Jumpstart mission's Trailblazer satellite, NASA's Nanosail-D solar sail experiment, and NASA's PreSat experiment.  Total payload mass was 170 kg. The payloads were expected to be boosted into a 685 x 330 km x 9 deg orbit.

The regeneratively cooled Merlin 1C engine flew for the first time on the flight, boosting Falcon 1 off its pad and downrange for its 2 minute 38 second burn.  The engine had aborted an initial countdown attempt 34 minutes before the launch, shutting down during its start sequence when one measured parameter was detected to be out of limit.  SpaceX crews recycled the count in 23 minutes.     

It was the third Falcon 1 failure in three attempts.  Musk said that the fourth Falcon 1 launch, which could occur within weeks, will now only carry a dummy payload.  Additional time will be added between the Merlin 1C shutdown and stage separation for the launch.

The third Falcon 1 was shipped to Kwajalein in early 2008.   After a delay to allow replacement of a defective Kestrel second stage engine nozzle, the rocket performed a Merlin 1C static test at Omelek on June 25, 2008. 

Falcon 1 Launch Succeeds on Fourth Try (Updated 10-4-08)

The fourth SpaceX Falcon 1 rocket carried a 165 kg payload mass simulator into space after a September 28 launch from Omelek Island, Kwajalein Atoll.  SpaceX reported that the vehicle's second stage and dummy payload reached an initial 330 x 650 km x 9 deg orbit about 9.5 minutes after a 23:14 UTC liftoff.  The company also reported that the Kestrel second stage engine subsequently performed a test of its restart capability in space. The stage was tracked by U.S. Space Command in a 621 x 643 km x 9.35 deg orbit after the Kestrel restart.

The reported initial orbit was less than the announced planned 330 x 685 km orbit.  Second stage shutdown occurred about 8 seconds earlier than the time listed in the SpaceX press kit.     

The flight took place less than two months after the third Falcon 1 suffered a staging failure.  That failure happened when Merlin 1C first stage engine residual thrust caused the stage to recontact the second stage immediately after stage separation.  Separation was timed to take place only 1.5 seconds after Merlin 1C shutdown - a timing that had worked with the original ablatively cooled Merlin 1 engine.  For the fourth flight the  separation time was extended to 5 seconds and the staging sequence was successful. 

Prior to the launch, on September 20, 2008, SpaceX crews briefly ignited the Falcon 1 first stage Merlin 1C engine in a static test on the Omelek pad.  After the test, crews decided to replace an unspecified second stage LOX supply component.   

It was the first Falcon 1 success in four attempts.  The regeneratively cooled Merlin 1C engine flew for the second time on the flight.

Falcon 1 Orbits RazakSAT for Malaysia

The fifth SpaceX Falcon 1 boosted RazakSAT, a Malaysian government earth observation imaging satellite, into orbit from Kwajalein Atoll, Republic of the Marshall Islands, on July 14, 2009.   The 180 kg spacecraft was aimed toward a 685 km x 9 deg low earth orbit.   Spacecraft separation was planned to occur 50-55 minutes after launch, following a brief restart of the second stage Kestrel engine to cirularize the orbit. 

The 27.67 tonne, two-stage Falcon 1 lifted from Omelek Island at Kwajalien Atoll at 03:35 UTC on 35.38 tonnes of thrust from the rocket's first stage Merlin 1C engine.  Following a 2 minute 40 second burn, the first stage fell away and the 3.175 tonne thrust second stage Kestrel engine ignited.  Kestrel completed its first burn about 9 minutes 40 seconds after liftoff, boosting the stage and payload toward an approximate planned 330 x 685 km parking orbit.  The engine reignited about 38 minutes after its first shutdown as the stack passed within tracking range of Ascension Island.

RazakSAT was designed and built by ATSB, a Malaysian satellite builder.

The launch, by the last original-size Falcon 1 on the SpaceX launch manifest, was the second consecutive Falcon 1 success.  It was also the first successful Falcon 1 launch of a live satellite.  Falcon 1 first flew in 2006.   Two "Falcon 1e" launches, by vehicles with stretched tanks and higher-thrust Merlin 1c engines, are projected to fly in 2010.

Vehicle Configurations

Vehicle Components

** Estimates extrapolated from SpaceX User's Guides or Data Sheets.

References

Falcon 1 Payload User's Guide, SpaceX, 2004
Falcon 1 Payload User's Guide, SpaceX, 2007
Falcon 1 Data Sheet, SpaceX, 2008
Updates at www.spacex.com

 Last Update:  7-18-2009