7th Responsive Space Conference RS7-2009-1003

SpaceX Falcon 1: The First Privately-Developed Liquid Fuel Rocket to Achieve Earth Orbit

Brian Bjelde Falcon 1 Product Director

Dr. Hans Koenigsmann Vice President of GN&C

Gwynne Shotwell President

7th Responsive Space Conference April 27–30, 2009 Los Angeles, CA

AIAA-RS7-2009-1003

SpaceX Falcon 1: The First Privately-Developed Liquid Fuel Rocket To Achieve Earth Orbit

Brian Bjelde Falcon 1 Product Director 1 Rocket Rd. Hawthorne, CA 90250; 310-363-6248 brian@spacex.com

Hans Koenigsmann Vice President of Guidance, Navigation and Control 1 Rocket Rd. Hawthorne, CA 90250; 310-363-6228 [email protected]

Gwynne Shotwell President 1 Rocket Rd. Hawthorne, CA 90250; 310-363-6229 [email protected]

ABSTRACT

On September 28, 2008, SpaceX made history when its Falcon 1, designed and manufactured by SpaceX, became the first privately-developed liquid fuel rocket to orbit the Earth. This was the fourth flight of the Falcon 1 launch vehicle and it lifted off at 4:15 p.m. (PDT) / 23:15 (UTC) from the SpaceX launch site on Omelek Island at the U.S. Army Kwajalein Atoll (USAKA) in the Central Pacific, about 2,500 miles southwest of Hawaii. It achieved an elliptical orbit of 621 x 643 km, 9.34 degrees inclination, with full intended performance. The upper stage carried a 165 kg (364 lb) mass simulator, designed and built by SpaceX, into orbit. With this flight, SpaceX has successfully flight proven 100% of its subsystems including 1st stage ascent, stage separation, 2nd stage ignition, fairing separation, guidance and control accuracies, stage 2 engine shutdown and orbital insertion, payload separation signaling, and stage 2 engine restart capability. Furthermore, SpaceX was successful in demonstrating industry record breaking responsive operations. Including transportation, ground processing and licensing, Flight 4 occurred the month following the Flight 3 attempt on August 2, 2008. The successful flight of SpaceX’s Falcon 1 is both historically noteworthy and represents a major opportunity for the industry to finally have access to a low cost demonstrated launch capability.

This paper will cover the vehicle performance achieved and describe in detail the responsive elements that have been successfully demonstrated.

KEYWORDS: SpaceX, Falcon 1, Launch Vehicle, Responsive, C-17, Iridium, RATSAT, ORS, Flight 4

OVERVIEW inclination of 9.34 degrees based on the averaged NORAD data. As this was a test flight, the 2nd stage On September 28, 2008, Space Exploration Technologies (SpaceX) launched the fourth flight of the carried a spacecraft mass dummy – called RATSAT – Falcon 1 launch vehicle from the SpaceX launch site on and went into a slightly eccentric parking orbit, with an orbit-raising second burn demonstration over Ascension Omelek Island (Figure 1). This flight was a test flight, sponsored by SpaceX, and it made history when the Island. RF links were established with Kwajalein, Roi- Falcon 1 became the first privately developed liquid- Namur, a down-range vessel, and Ascension Island. The stage then made contact with Kwajalein again fuel rocket to achieve Earth orbit. The final orbit had a perigee of 621.55 km, an apogee of 643.21 km, and an during the first orbital pass overhead.

Bjelde 1 AIAA/7th Responsive Space® Conference 2009

Figure 1: F1-004 Liftoff on 9/28/2008 (CA date) 11:15 AM local time

The Falcon 1 is a two-stage launch vehicle This mission was conducted under a commercial launch approximately 70’ in height with a wet mass of about license issued by the FAA Office of Commercial Space 61,000 lbm. The 1st stage is powered by the Merlin 1C Transportation (FAA/AST). pump-fed RP-1/liquid oxygen (LOX) engine. The upper stage is powered by the pressure-fed Kestrel engine, The decision to fly this mission without a traditional also burning RP-1/LOX. This vehicle was developed customer and payload was made after the Flight 3 entirely by SpaceX under funding provided by separation failure, which occurred on 8/3/2008. In less SpaceX’s founder, Mr. Elon Musk. This mission was than 2 months, SpaceX finished the next Falcon 1 launched from facilities on Omelek Island, part of the vehicle, performed a thorough failure analysis, and Reagan Test Site (RTS) at Kwajalein Atoll in the implemented the corrective actions necessary to launch Marshall Islands. All launch and control facilities, again. Both the Range and the FAA supported the fast including the Mission Control Center, the launch pad turn-around with unprecedented short schedules, and and the vehicle and payload integration facilities were the U.S. Air Force provided the transportation to fly the developed entirely by SpaceX. 1st stage, 2nd stage, fairing, payload, and the launch team out to Kwajalein on a single C-17 (Figure 2).

Bjelde 2 AIAA/7th Responsive Space® Conference 2009

Figure 2: Both stages, the launch crew, and additional support hardware were all flown on a C-17 The Flight 4 mission showed that the stage separation Vehicle performance was within an acceptable range issue from Flight 3 was indeed the only anomaly that and the design fixes to account for the Flight 2 slosh required a correction following Flight 3 and while there failure and Flight 3 stage separation timing issue were were recorded observations and minor anomalies verified to be effective. experienced during Flight 4, none of them caused any risk to the success of this mission. The data recorded Significant achievements for the Flight 4 mission exceeded expectations in terms of content and quality include successful demonstration of: and will go far in continuing to ensure many more successful flights to come. • Ground control & support systems, including highly autonomous control & operations software MISSION OBJECTIVES • 1st stage performance and control from lift-off With Earth orbit achieved, all of the SpaceX Falcon 1 through Main Engine Cut-Off (MECO) launch vehicle programmatic and technical objectives have been met. This includes flight verification of • Vehicle structural performance & margins through subsystem performance involved in 1st stage ascent, lift-off, transonic & max-Q nd stage separation, 2 stage ignition, fairing separation, • Stage separation (Figure 3) guidance and control accuracies, stage 2 engine nd shutdown and orbital insertion, payload separation • 2 stage ignition (Figure 3) signaling, and stage 2 engine re-start capability. A • Fairing separation (Figure 3) secondary mission objective for SpaceX was to demonstrate operational responsiveness. SpaceX was • 2nd stage slosh baffle performance successful in demonstrating industry record-breaking nd responsive operations, which included transportation, • 2 stage engine performance in vacuum ground processing, and FAA licensing. Flight 4 • 2nd stage engine on-orbit restart succeeded in the month following the Flight 3 attempt. • Payload deployment signal sent and received

Bjelde 3 AIAA/7th Responsive Space® Conference 2009

• Guidance, navigation & control performance • Launch & flight environments: thermal, acoustic, through transonic, orbit insertion, coast and restart shock & vibration • Flight software through all flight domains • Aero-thermal and base-heating results for both stages • Store and forward data links

• RF links though orbit insertion, recontact for apogee burn, and recontact for first pass

Figure 3: Still frames from on-board camera showing stage separation, second stage ignition, and fairing separation events

This mission also demonstrated significant MISSION PROFILE breakthroughs in operational responsiveness. The Flight 4 (F1-004) Liftoff was at 11:15 AM local time entire launch campaign took less than 30 days with less and the second stage engine cut-off (SECO1) was at than 15 days taken to perform all vehicle processing. 11:24 AM. After a successful simulated payload The time from launch vehicle roll out until static fire deploy, the 2nd stage went into a coast orbit and took a total of 5 days. This was later improved on with performed an orbit raising burn maneuver over the second launch vehicle roll out until launch taking Ascension Island at 12:08 PM. This burn was only a less than 3 days. All of these times could be further few seconds long, enough to raise the perigee. During reduced by employing 24/7 work crews. SpaceX the coast, the orbital Iridium system experiment demonstrated its maturity in operating a launch site, sponsored by the Operationally Responsive Space with the Flight 4 launch occurring on the first attempt (ORS) Office sent telemetry messages, and the flight with zero aborts and no late countdown holds. computer stored these messages as a backup. To the

Bjelde 4 AIAA/7th Responsive Space® Conference 2009

best of SpaceX’s knowledge, this may bethe first time “depletion” burn so that we could quantify our an Iridium system has been used on orbit. After the propellant residuals after a coast period. The goal was second burn the flight computer transmitted the stored to burn all margin propellant with the exception of the telemetry data to the Ascension Island station. last 100 lb, thereby keeping the risk low to have the 2nd Following a venting sequence, the vehicle then waited stage stranded in an orbit with low (i.e. less than 500 for a telemetry contact with Kwajalein. At 12:55 PM, km) perigee. The second burn was performed at 70 data and video were received by the Kwajalein degree yaw angle and changed the inclination from 8.99 Telemetry Center. At 12:58 PM, the avionics battery to 9.34 degrees. With the information gained during expired and shut down vehicle functions, ending a very the second burn demonstration, SpaceX is confident successful mission after the first full orbit. that advertised orbit accuracies can be met.

The final orbit had a perigee of 621.55 km and an Figure 4 shows an overview of the mission timeline, apogee of 643.21 km with an inclination of 9.34 including the ground operations that were worked degrees, based on the averaged NORAD data. It should during on the day of launch. Figure 5, Figure 6, and be noted that the orbit is slightly lower than expected, Figure 7 show the events that took place during the because the shutdown transients of stage 2 were over- powered ascent and some additional trajectory data for estimated. In addition, the second burn was NOT the first stage after stage separation. designed to be a circularization burn, but rather to be a

Figure 4: Overview of the Mission Timeline

Bjelde 5 AIAA/7th Responsive Space® Conference 2009

Figure 5: Powered Ascent Profile – zoomed to show major events

Figure 6: Powered Ascent Profile

Bjelde 6 AIAA/7th Responsive Space® Conference 2009

Figure 7: Stage 1 Trajectory DEMONSTRATED RESPONSIVENESS no mission-critical hardware issues, the entire campaign Flight 4 was the shortest launch campaign to date for required only one trip to the launch site. It should also be noted, that the FAA Commercial Launch license SpaceX, and this was largely due to the continued improvements from an operational responsiveness took only 4 weeks to obtain, and for that SpaceX is very perspective. Significant progress in vehicle processing appreciative of the staff at the FAA/AST Office for their demonstration of responsiveness. Procedurally, times and operation of the vehicle manifested itself in the launch campaign schedule: there were few revision updates between flights as well as in-operation changes, so the team was very familiar • Launch campaign timeline <30 days with operations and there was much improved standardization in handling and operation. When o Integrated and flew a nearly identical vehicle from previous flight required, additional personnel were flown in for back- up and for maintaining schedule. One major procedural • 15 days to perform all Vehicle processing change, to split Pad Preps into Initial Pad Preps the day o Roll Out to Static Fire – 5 days before launch and Final Pad Preps the morning of o Final Roll Out to Launch – 3 days launch, allowed for ample time to chill helium and • Launch on 1st Launch Attempt prevented any holds on launch day. • Launch 15 minutes after initial T-0 time This responsiveness can be attributed to a number of factors. From a hardware perspective, there were very few changes to the vehicle and pad between F1-003 and PERFORMANCE OVERVIEW BY SYSTEM F1-004, and the payload on this flight required essentially no special handling. On the scheduling side, Ground Systems transporting the vehicle and most of the personnel The Ground Support Equipment (GSE) and Ground through non-commercial means via C-17 proved to be Control performed well during the Flight 4 mission very efficient. Normally, the transportation of the 1st campaign. LOX and RP-1 were loaded nominally. stage takes 3 weeks and the second stage takes just Following the F1-003 helium load delays, the procedure under 1 week. Also with swift anomaly resolution and Bjelde 7 AIAA/7th Responsive Space® Conference 2009

was altered to allow the load to begin the day before • Updated stage separation timing proven in launch. This procedure alteration worked well and flight. 100% helium mass was achieved at approximately 8:00 • Post separation tank pressure management for AM on the day of launch. safe recovery. • Post-flight TEA/TEB flush behaved All other gas and fluid support systems performed nominally. nominally as well. The engine purge, engine bay purge, All auxiliary components of the Stage 1 propulsion thrust vector control, water and tank pressurizations systems were exercised and performed well enough to also showed nominal pressures. Lastly, the payload accomplish mission objectives. A/C performed as expected.

Ground Control proved very stable for Flight 4. There nd were also a number of improvements which made the Stage 2: This mission success presented the 2 stage of control system more flexible to reconfigurations. The Falcon 1 with its first opportunity to fully demonstrate majority of auto-sequences performed as expected, and its mission capabilities including the following system the few exceptions were easily explained and capabilities: addressed. No ground control aborts occurred, and there was sufficient margin on each. All voice and • Completely successful stage separation network communication performed nominally, and • Multiple successful vacuum ignitions there was a great improvement in webcast video data • Kestrel engine mission performance and from the previous flight. stability demonstration Propulsion • Niobium alloy nozzle skirt performance • Helium heat exchanger performance in Stage 1: F1-004 represented the second flight of the vacuum regeneratively cooled Merlin engine (M1), a member of the M1C engine family. Flight data reveals that this • Stable and controlled guidance and navigation engine, S/N M50302, performed quite well, verifying • Stable and controlled vehicle operation during the performance realized during Flight 3, the inaugural a long-duration coast period M1 engine flight. In particular, the goal of proving the • Propellant and helium margin M1 engine to have repeatable, robust flight • Engine restart capability ( ) performance was realized. As a result of accomplishing Figure 8 this goal, no changes will be required to the engine • Post-mission vehicle depressurization and prior to future flights. safing

The following Merlin engine and first stage operations Overall the 2nd stage propulsion systems demonstrated were demonstrated and/or proven during the F1-004 excellent operational capability. A small set of mission: anomalies and observations have been identified but all are minor. • Repeatable engine behavior between flights shown: o Total impulse delivered was within 0.16% between flights. o Mission actual Isp was within 0.29% between flights. • Nominal Merlin ignition and startup to adequate thrust level for liftoff. This includes the active engine computer monitoring system that detects minimum liftoff levels and aborts if those levels are not achieved. It also includes passing through all pad abort criteria. • The updated engine alignment procedure was verified. • In-flight steady state Merlin operation and performance. • Main engine cutoff detection and engine Figure 8: SpaceX Stage 2 with payload performing shutdown based on acceleration. orbit raising maneuver at Apogee Bjelde 8 AIAA/7th Responsive Space® Conference 2009

Structures, Mechanisms, & Environments oscillations drove a vibration response at ~35 Hz at All structures and mechanisms performed nominal for nearly all locations on the vehicle for approximately two seconds before main engine cutoff. Cavitation this mission and no anomalies were identified. Some of the highlights include the successful operation and data also appeared to be the cause of the high amplitude collection for: shutdown transient. These excitations did not cause any failures but SpaceX has already implemented a • Hydraulic Vehicle Release corrective action where the LOX transfer tube will be • 1st stage electrical/propellant quick disconnects redesigned to eliminate cavitation on subsequent flights. • 2nd stage propellant/electrical/AC quick disconnects st nd The flight acoustic environment, as measured in the • 1 and 2 stage tank pressures payload fairing (Figure 9), has been determined to be • Strain gage data fine as-is with flight levels from liftoff through the • Stage separation system entire ascent being far less than the existing Falcon 1 • Fairing separation system maximum predicted environment (MPE). • Avionics Bay Skin temperature • Fairing internal temperature • Fairing Venting The hydraulic release system operated properly and all vehicle quick disconnects disengaged properly. Post- flight inspection of the ground side quick disconnects found no damage, and all quick disconnects were holding pressure after launch.

Tank pressures on 1st and 2nd stages remained within their limits throughout flight, including through 2nd- stage coast.

Strain gages were installed on the mid-barrel of the interstage. The gages all functioned properly and produced axial force and bending moment around the y and z axes of the vehicle. Loads all appeared within Figure 9: Flight Acoustic Environment operational constraints and matched the predicted loads Avionics from the coupled loads analysis. Falcon 1 Flight 4 demonstrated several significant The stage separation system and fairing separation "firsts" for the avionics system. Helium was loaded system functioned nominally. overnight to allow for greater mass, thus requiring vehicle power and control for the entire 24-hour period Skin mounted thermocouples were attached to the prior to launch, but greatly reducing the operational interior wall of the avionics bay. During flight these requirements on personnel. By achieving orbit and measured a peak temperature of just under 130ºF. acquiring telemetry lock over Kwajalein on the first Fairing internal temperature sensors closely followed orbital pass, power margin and power models were the behavior of the avionics bay skin thermocouples, verified for the upper stage. Additionally, a simulated and measured a minimum temperature of 62ºF at payload deploy signal was sent and verified after 2nd- t=100s. The fairing internal temperature at fairing stage first burn. Except for a few non-critical separation was 68ºF. A pressure sensor was mounted on anomalies and observations, the avionics systems the payload adaptor cone and measured a peak pressure performed exceptionally well. above ambient of 0.75 psi. Flight Software Dynamics: High speed accelerometer and microphone data have been collected and processed for F1-004 No evidence of software issues or anomalies were seen during launch. Data quality was good on all during the Flight 4 mission. In addition, corrective accelerometers and microphones. actions stemming from the Falcon 1 Flight 3 mission were verified during this flight. Liftoff and ascent environments were nominal at all locations on the vehicle. Unexpected cavitation

Bjelde 9 AIAA/7th Responsive Space® Conference 2009

Flight Termination System anomalies found, however, none posed any risk for this The flight termination system performed nominal mission, and none poses any risk for future missions. during pre-launch, launch, 2nd burn and Kwajalein first pass. No command signal carrier was brought up at Ascension Island or Kwajalein during the first orbital pass as Range Safety was only concerned with having command authority during the first burn of the 1st and 2nd stage. During the first pass, the battery voltage was still above 28 V, indicating plenty of battery margin for the FTS batteries.

Telemetry Falcon 1 contains one S-band telemetry link on each stage and a video downlink on the 2nd stage. The first stage was tracked by Roi Namur Island’s (ROI) 3m dish, Kwajalein’s 3m dishes, and by two mobile telemetry stations on the recovery boat. The second stage video and telemetry was tracked by ROI’s 5m dish, Kwajalein’s 5m and 7m dishes, and Ascension Island’s receiving station assets. All data links and ground stations performed nominally during Flight 4. Figure 10: SpaceX Falcon 1 Flight 4 Mission Logo Guidance, Navigation and Control

The GNC system successfully provided attitude stability and navigation control of the vehicle into a The complete success of this mission and the large stable orbit. It showed that the implementation of the nd st amount of flight data obtained have greatly reduced 2 stage slosh filter was successful, and that the 1 risks for all future Falcon 1 missions and for the larger stage azimuth accuracy is excellent. Both of these sister vehicle, the Falcon 9. verify corrective actions from previous mission anomalies. Flight data showed the ground track to be ACKNOWLEDGEMENTS within 0.001 degree latitude and the instantaneous impact point (IIP) within 1 km (0.01 degrees latitude). SpaceX wishes to acknowledge the many people and organizations that have contributed to this historic The original perigee altitude for the parking orbit was achievement. Specifically, the entire team at SpaceX excellent, hitting 331 km versus a target of 330.5km. whose technical expertise and drive have led to not only Initial inclination accuracy was also excellent hitting making history, but also to doing it in record time with 8.99 degrees versus a target inclination of 9.00 degrees. the Falcon 1 being one of the fastest rocket As mentioned before, the apogee altitude was slightly developments in history. Special thanks to our many low due to the previously untested second stage engine customers for their patience, support and partnership. on-orbit shutdown thrust transients, however the values These customers include, but are not limited to: obtained on Flight 4 will be applied on all subsequent DARPA, ORS, ATSB, NASA, USAFA, NRL, missions providing increased accuracy. SpaceDev, and Space Access Technologies. Thanks to the FAA/AST office for their hard work and coaching SUMMARY through the commercial launch licensing process during Flights F1-003, -004, and -005. A big thanks to the On September 28, 2008, SpaceX made history when its United States Army Kwajalein Atoll and Reagan Test Falcon 1, designed and manufactured from the ground Site personnel for their professional and responsive up by SpaceX, became the first privately developed mission support during the various launch campaigns liquid-fuel rocket to orbit the Earth. This launch proved conducted at Kwajalein. Finally, thanks to the out all vehicle technology, including fixes to previous excellent SpaceX vendors, suppliers and fans. We flight anomalies, and succeeded in verifying all major greatly appreciate the support and look forward to flight events. SpaceX was also successful in sharing many more significant milestones in the near demonstrating industry record breaking responsiveness. future in our continuous attempt to revolutionize access Even for such a successful mission, a number of to space. observations and minor anomalies are to be expected, and some were experienced. Of the observations and Bjelde 10 AIAA/7th Responsive Space® Conference 2009