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.
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.
|Falcon 1 Versions||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|
| Initial thrust|
| Takeoff weight|
| Fairing diameter|
|570 (or less to SSO)||450 (or less to SSO)||700 (or 430 to SSO)|
| minimal Price/kg|
|11,754||15,556||12,687 or 19,767 to SSO|
| minimal Price/kg|
| Success ratio|
Period = from:-150 till:600 TimeAxis = orientation:vertical order:reverse ScaleMajor = unit:year increment:60 start:-120
id:S1 value:rgb(0,1,0) legend:Stage_1_Burn
id:S2 value:rgb(1,1,0.5) legend:Stage_2_Burn
Legend = columns:1 left:20 top:40 columnwidth:100
BackgroundColors = canvas:canvas
Define $dx = 25 # shift text to right side of bar
bar:Leaders color:Bar width:25 mark:(line,black) align:left fontsize:s
from:start till:-120 shift:($dx,2) text:Merlin on internal power.
from:-120 till:-45 shift:($dx,12) text:Internal sequencer engages.
from:-45 till:-30 shift:($dx,3) text:Tank pressurization.
from:-30 till:0 shift:($dx,1) text:Helium spin-up of turbine.
from:0 till:0 shift:($dx,-4) text:"Ignition." color:S1
from:0 till:7 shift:($dx,-15) text:"Falcon 1 clears pad (7 s)." color:S1
from:7 till:76 shift:($dx,-20) text:"Qmax." color:S1
from:76 till:169 shift:($dx,-20) text:"MECO, stage sep. (169, 170 s)." color:S1
from:169 till:170 shift:($dx,-12) text:"Kestrel ignition (174 s)." color:S2
from:170 till:194 shift:($dx,-18) text:"fairing separation (194 s)." color:S2
from:194 till:552 shift:($dx,-5) text:"Second-stage burn." color:S2
from:552 till:553 shift:($dx,-1) text:"Kestrel shut down (553 s)." color:S2
from:553 till:570 shift:($dx,-9) text:Satellite deployment (570 s).
from:570 till:600 shift:($dx,-12) text:Re-ignition (demonstration).
|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.
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.
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. 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. 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. 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. 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. 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.
SpaceX attempted the third Falcon 1 launch on August 3, 2008 (GMT) from Kwajalein. This flight carried the Trailblazer (Jumpstart-1) satellite for the US Air Force, the NanoSail-D and PREsat nanosatellites for NASA and a space burial payload for Celestis. The rocket did not reach orbit. However, the first stage, with the new Merlin 1C engine, performed perfectly.
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.
The SpaceX flight 3 mission summary indicated that flight 4 would take place as planned and that the failure of flight 3 did not make any technology upgrades necessary. A longer time between first stage engine shutdown and stage separation was declared to be enough.
The full video of the third launch attempt was made public by SpaceX a few weeks after the launch.
|Flight No||Date & Time (GMT)||Launch Site||Payload/Customer||Outcome||Remarks|
|1|| 24 March 2006, 22:30 |
(25 March, 09:30 local)
|Omelek||FalconSat–2/DARPA||Failure|| Engine failure at T+25 seconds|
Loss of vehicle
|2||21 March 2007, 01:10|
|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
|3|| 3 August 2008, 03:34|
|Failure||Residual stage 1 thrust led to collision between stage1 and stage 2|
|4|| 28 September 2008, 23:15|
(11:15 local/16:15 PDT)
|Omelek||Dummy payload - mass simulator, 165kg (originally intended to be RazakSAT)||Successful||Initially scheduled for 23-25 Sept|
|2010||Omelek||Unknown/Swedish Space Corp.||Scheduled|