Falcon 1

Falcon 1

Falcon 1 rocket.
Function	Orbital launch vehicle
Manufacturer	SpaceX
Country of origin	United States
Size
Height	21.3 m (70 ft)
Diameter	1.7 m (5.5 ft)
Mass	38,555 kg (85,000 lb)
Stages	2
Capacity
Payload to LEO	670 kg (1480 lb)
Payload to SSO	430 kg (990 lb)
Launch history
Status	Active
Launch sites	Omelek Island Vandenberg AFB
Total launches	4
Success(es)	1
Failure(s)	3
Partial failure(s)	0
First flight	March 24, 2006 22:30 GMT
First stage
Engines	1 Merlin 1C
Thrust	454 kN (102,000 lbf)
Specific impulse	255 s (sea level) (2.6 kN·s/kg)
Burn time	169 seconds
Propellant	RP-1/LOX
Second stage
Engines	1 Kestrel
Thrust	31 kN (7,000 lbf)
Specific impulse	327 s (vacuum) (3.2 kN·s/kg))
Burn time	378 seconds
Propellant	RP-1/LOX
[edit on Wikidata]

The Falcon 1 is a partially reusable launch system designed and manufactured by SpaceX. The two-stage-to-orbit rocket uses Lox/RP-1 for both stages, the first powered by a single Merlin engine and the second powered by a single Kestrel engine.

The Falcon 1 achieved orbit on its fourth attempt. It was designed by SpaceX from the ground up and is the first successful liquid-propelled launch vehicle developed with private funding.

According to SpaceX, the Falcon 1 is designed to minimize price per launch for low-Earth-orbit satellites, increase reliability, and optimize flight environment and time to launch.^[1] It is also intended to verify components and structural design concepts that will be reused in the Falcon 9.

At launch, the first stage engine (Merlin) is ignited and throttled to full power while the launcher is restrained and all systems are verified by the flight computer. If the systems are operating correctly, the rocket is released and clears the tower in about seven seconds. The first-stage burn lasts about 2:49 minutes. Stage separation is accomplished with explosive bolts and a pneumatically actuated pusher system. The first stage returns by parachute to a water landing and is recovered for reuse, while the second stage is not reusable. The second stage Kestrel engine burns for about six minutes, inserting the payload into a low Earth orbit. It is capable of multiple restarts.

The first stage is made from friction-stir-welded aluminum alloy. It employs a common bulkhead between the LOX and RP-1 tanks, as well as flight pressure stabilization. It can be transported safely without pressurization (like the heavier Delta II isogrid design) but gains additional strength when pressurized for flight (like the Atlas II, which cannot be transported unpressurized). The resulting design has the highest propellant mass fraction of any current first stage. The parachute system, built by Irvin Para­chute Corp­oration, uses a high-speed drogue chute and a main chute.

The second stage tanks are built with a cryogenic-compatible aluminum–lithium alloy. The helium pressurization system pumps propellant to the engine, supplies pressurized gas for the attitude control thrusters, and is used for zero-g propellant accumulation prior to engine restart. The Kestrel engine includes a titanium heat exchanger to pass waste heat to the helium, thereby greatly extending its work capacity.^[2] The pressure tanks are made by Arde corporation and are the same as those used in the Delta IV. They consist of an inconel shell wrapped by a composite.

The Falcon 1 rocket was developed with private funding. The only other orbital launch vehicle to be privately funded and developed is the Pegasus, first launched in 1990; however, it requires a large aircraft as its first stage.^[3] The Falcon 1 is also the first partially reusable orbital rocket to be developed without public funding.^[4] While the development of Falcon 1 was privately funded, the first two Falcon 1 launches were purchased by the U.S. Department of Defense under a program that evaluates new US launch vehicles suitable for use by DARPA.^[5]

SpaceX is one of the few launch system operators that communicate launch prices to the public. Falcon 1 was advertised as costing $5.9 million as early as 2005.^[6] In 2006 until 2007 the quoted price of the rocket when operational was $6.7 million.^[7] Most recently SpaceX has announced new prices for the Falcon 1 and the Falcon 1e as $7 million and $8.5 million. SpaceX notes that small discounts may be available for multi-launch contracts.^[1]

The first four launches were conducted at Kwajalein Atoll using the SpaceX launch facility on Omelek Island and range facilities of the Reagan Test Site. All upcoming Falcon 1 flights shown on the SpaceX manifest are also planned for Kwajalein. Other launch sites which have been discussed for Falcon 1 flights include:

• Vandenberg Air Force Base, Pad 3W. According to Elon Musk, SpaceX may be be evicted from Vandenberg because of safety concerns expressed by United Launch Alliance, which launches the Atlas V rocket from neighboring site SLC-3W.^[8]

• Cape Canaveral Air Force Station Launch Complex 40.^[9]

Falcon 1 Versions[10][11][1]	Merlin A; 2006–2007	Merlin C; 2007–2009	Falcon 1e; 2010
Stage 1	1 × Merlin 1A	1 × Merlin 1C	1 × Merlin 1C
Stage 2	1 × Kestrel	1 × Kestrel	1 × Kestrel
Height (max; m)	21.3	22.25	26.83
Diameter (m)	1.7	1.7	1.7
Initial thrust (kN)	318	343	454
Takeoff weight (tonnes)	27.2	33.23	38.56
Fairing diameter (Inner; m)	1.5	1.71	1.71
Payload (LEO; kg)	570 (or less to SSO)	450 (or less to SSO)	700 (or 430 to SSO)
Payload (GTO; kg)	—	—	—
Price (Mil. USD)	6.7	7	8.5
minimal Price/kg (LEO; USD)	11,754	15,556	12,687 or 19,767 to SSO
minimal Price/kg (GTO; USD)	—	—	—
Success ratio (successful/total)	0/2	1/2	—

Launch sequence (maiden flight example); time scale is in seconds.

The maiden flight of the Falcon 1 was launched on Saturday, 24 March 2006 at 22:30 UTC. It ended in failure about a minute into the flight due to a fuel line leak and subsequent fire. The launch took place from the SpaceX launch site on Omelek Island in the Marshall Islands.

The launch was postponed several times due to various technical issues with the new vehicle. Scheduling conflicts with a Titan IV launch at Vandenberg AFB also caused delays and resulted in the launch moving to the Reagan Test Site in the Kwajalein Atoll. The first launch attempt on 19 December 2005 was scrubbed when a faulty valve caused a vacuum in the first stage fuel tank which sucked inward and caused structural damage. After replacing the first stage, Falcon 1 launched Saturday, 25 March 2006 at 09:30 local time. The DARPA payload was the United States Air Force Academy’s FalconSAT–2, which would have measured space plasma phenomena.

The vehicle had a noticeable rolling motion after liftoff, as shown on the launch video, rocking back and forth a bit, and then at T+26 seconds rapidly pitched over. Impact occurred at T+41 seconds onto a dead reef about 250 feet from the launch site. The FalconSAT–2 payload separated from the booster and landed on the island, with damage reports varying from slight to significant.^[12]

SpaceX initially attributed the fire to an improperly tightened fuel-line nut. A later review by DARPA found that the nut was properly tightened, since its locking wire was still in place, but had failed due to corrosion.

SpaceX implemented numerous changes to the rocket design and software to prevent this type of failure from recurring, including stainless steel to replace aluminum hardware (which is actually cheaper in cost although the trade off is being a little heavier in weight) and pre-liftoff computer checks that increased by a factor of thirty.^[13][14]

The second test flight was originally scheduled for January 2007, but was delayed due to problems with the second stage. Before the January launch date, SpaceX had stated earlier potential launch dates, moving from September 2006 to November and December. In December the launch was rescheduled for 9 March, but delayed because of range availability issues caused by a Minuteman III test flight which would re-enter over Kwajelen. The launch attempt on 19 March was delayed 45 minutes from 23:00 GMT due to a data relay issue, and then scrubbed one minute and two seconds before launch at 23:45 due to a computer issue, whereby the safety computer incorrectly detected a transmission failure due to a hardware delay of a few milliseconds in the process. The 20 March attempt was delayed 65 minutes, from an originally planned time of 23:00 due to a problem with communications between one of the NASA experiments in the payload, and the TDRS system.

The launch attempt on March 21, 2007 was aborted at 00:05 GMT at the last second before launch and after the engine had ignited. It was however decided that another launch should be made the same day. The rocket was launched successfully at 01:10 GMT on 21 March 2007 with a DemoSat payload for DARPA and NASA. The rocket performed well during the first stage burn. However, during staging, the interstage fairing on the top of the first stage bumped the second stage engine bell.^[15] The bump occurred as the second stage nozzle exited the interstage, with the first stage rotating much higher than expected (a rotation rate of about 2.5 deg/s vs. expected rate of 0.5 deg/s maximum), thereby making contact with the niobium nozzle of the second stage. Elon Musk reported that the bump did not appear to have caused damage, and that the reason why they chose a niobium skirt instead of carbon-carbon was to prevent problematic damage in the event of such incidents. Shortly after second stage ignition, a stabilization ring detached from the engine bell as designed.^[16] At around T+4:20, a circular coning oscillation began that increased in amplitude until video was lost. At T+5:01, the vehicle started to roll and telemetry ended. According to Elon Musk, the second stage engine shut down at T+7.5 minutes due to a roll control issue. Sloshing of propellant in the LOX tank increased oscillation. This oscillation would normally have been dampened by the Thrust Vector Control system in the second stage, but the bump to the second nozzle during separation caused an overcompensation in the correction.^[16] The rocket continued to within one minute of its desired location, and also managed to deploy the satellite mass simulator ring. While the webcast video ended prematurely, SpaceX was able to retrieve telemetry for the entire flight.^[17] The status of the first stage is unknown; it was not recovered due to problems with a nonfunctioning GPS tracking device. The rocket reached a final altitude of 289 km (156 miles) and a final velocity of 5.1 km/s, compared to 7.5 km/s needed for orbit.

SpaceX characterized the test flight as a success, having flight proven over 95% of Falcon 1's systems. Their primary objectives for this launch were to test responsive launch procedures and gather data.^[18] According to Musk, the SpaceX team intends to have both a diagnosis and solution vetted by third party experts. Musk believes the slosh issue can be corrected by adding baffles to the second stage LOX tank and adjusting the control logic. Furthermore, the Merlin shutdown transient can be addressed by initiating shutdown at a much lower thrust level, albeit at some risk to engine reusability. The SpaceX team intends to work the problem to avoid a recurrence as they change over into the operational phase for Falcon 1.^[19]

SpaceX attempted the third Falcon 1 launch on August 3, 2008 (GMT) from Kwajalein.^[20] This flight carried the Trailblazer (Jumpstart-1) satellite for the US Air Force,^[21] the NanoSail-D and PREsat nanosatellites for NASA and a space burial payload for Celestis.^[22] The rocket did not reach orbit. However, the first stage, with the new Merlin 1C engine, performed perfectly.^[23]

When preparing for launch, an earlier launch attempt was delayed by the unexpected slow loading of helium onto the Falcon 1; thus exposing the fuel and oxidizer to the cryogenic helium, rendering the vehicle in a premature launch state. Still within the specified window, the launch attempt was recycled, but aborted half a second before lift-off due to a sensor misreading. The problem was resolved, and the launch was again recycled. With twenty-five minutes left in the launch window, the Falcon 1 lifted off from Omelek Island at 03:35 UTC. During the launch, small vehicle roll oscillations were visible.

Stage separation occurred as planned, but due to residual fuel in the new Merlin 1C engine evaporating and providing transient thrust, the first stage recontacted the second stage, preventing successful completion of the mission.^[24]

According to the SpaceX flight 3 mission summary flight 4 will take place as planned and the failure of flight 3 does not make any technology upgrades necessary. A longer time between first stage engine shutdown and stage separation was declared to be enough.^[25]

The full video of the third launch attempt was made public by SpaceX a few weeks after the launch.^[26]

The fourth flight of the Falcon 1 rocket successfully flew on September 28 2008.^[27] A fifth Falcon 1 vehicle will be ready for launch by January 2009, with Falcon 1 vehicles currently being produced at the rate of one every four months. By 2010 it is expected that production rate will be increased to one every two or three months.^[28]

Flight No	Date & Time (GMT)	Launch Site	Payload/Customer	Outcome	Remarks
1	24 March 2006, 22:30 (25 March, 09:30 local)[citation needed]	Omelek	FalconSat–2/DARPA	Failure	Engine failure at T+25 seconds Loss of vehicle
2	21 March 2007, 01:10 (13:10 local)	Omelek	DemoSat/DARPA	Failure	Successful first stage burn and transition to second stage, maximum altitude 289 km Harmonic oscillation at T+5 minutes Premature engine shutdown at T+7 min 30 s Failed to reach orbit Failed to recover first stage Claimed to be a "Partial success" as it gathered enough data for operational flights[18]
3	3 August 2008, 03:34[29] (15:34 local)	Omelek	Trailblazer/ORS PRESat/NASA NanoSail-D/NASA Explorers/Celestis[30]	Failure	Residual stage 1 thrust led to collision between stage1 and stage 2[25]
4	28 September 2008, 23:15[31][27] (11:15 local/16:15 PDT)	Omelek	Dummy payload - mass simulator, 165kg (originally intended to be RazakSAT)	Successful[31]	Initially scheduled for 23-25 Sept
Scheduled Launches[30]
	2009	Omelek	Unknown/SpaceDev	Scheduled
	2010	Omelek	Unknown/MDA Corporation	Scheduled
	2010	Omelek	Unknown/Swedish Space Corp.	Scheduled

• "Damage puts first SpaceX rocket launch on hold". Spaceflight Now. 19 December 2005. {{cite news}}: Check date values in: |date= (help)
• "SpaceX rocket fails first flight". BBC News. 24 March 2006. {{cite news}}: Check date values in: |date= (help)

• SpaceX Falcon 1 Overview
• Spaceflight Now Mission Status Center for Flight 1
• SpaceX Falcon 1 Rocket Reaches Orbit on 4th Try