After three disappointing failures, Space Exploration Technologies Corp. finally tasted success with its Falcon 1 launch vehicle Sunday. With the fourth Falcon launch, SpaceX becomes the first private company to orbit a satellite with a liquid fueled rocket designed and manufactured entirely in-house. The flight also sets the stage for the larger Falcon 9 vehicle which is on track to have its inaugural rocket delivered to Cape Canaveral by the end of the year.
READ: FALCON 1 FLIGHT 4 PRESS KIT VIDEO: WACH A CLIP OF HIGHLIGHTS FROM THE FALCON LAUNCH VIDEO: FALCON LAUNCH, T-90 SEC. TO FAIRING SEPARATION VIDEO: OVERVIEW OF THE FALCON 1 LAUNCH VEHICLE (COURTESY: SPACEX) ALL-ACCESS SUBSCRIBERS: WATCH THE ENTIRE FALCON 1 FLIGHT 4 LAUNCH WEBCAST. 57 MINUTES "This is a great day for SpaceX and the culmination of an enormous amount of work by a great team," said Elon Musk, CEO and CTO of SpaceX. "The data shows we achieved a super precise orbit insertion—middle of the bull's-eye — and then went on to coast and restart the second stage, which was icing on the cake." The seven story tall rocket placed a 364 pound payload simulator into orbit 10 minutes after launch from the tiny South Pacific island of Omelek in the Kwajelein Atoll. The mission marks the first time a private U.S. company has successfully orbited a payload with a launch vehicle designed and manufactured completely in-house. The journey to the historic success has been long and sometimes fraught with disappointment for SpaceX. After its founding in 2002, SpaceX planned an aggressive development schedule with hopes of a first flight for the Falcon rocket in 2004. That goal proved elusive because of difficulties developing the Merlin first stage engine. The company finally conducted its first launch in 2006 but lost the vehicle less than a minute after liftoff when a corroded nut led to a fuel leak in the engine compartment. The resulting fire caused a premature shutdown of the first stage engine and the rocket plummeted into the ocean near the launch site. The second Falcon launch nearly made it to orbit, but once again SpaceX's hopes were dashed in a heartbreaking failure. After a perfect first stage and separation, fuel in the second stage began sloshing back and forth in the tanks. The control system was unable to counteract the effects of the sloshing, which resulted in another early engine cutoff. The Falcon upper stage and payloads burned up in the atmosphere before completing a single orbit. The third mission was especially disappointing. The rocket was equipped with an upgraded Merlin engine for the first time. The Merlin 1C engine features regenerative cooling versus the ablatively-cooled Merlin 1A. Regeneratively cooled engines cycle fuel through tubes around the engine to keep it cool before the fuel is routed into the combustion chamber. One side-effect of this is that some fuel remains in the plumbing after the engine shutdown command and results in a short transient thrust even after the engine has cutoff. "The problem arose due to the longer thrust decay transient of our new Merlin 1C regeneratively cooled engine, as compared to the prior flight that used our old Merlin 1A ablatively cooled engine," said Musk. "Unlike the ablative engine, the regen engine had unburned fuel in the cooling channels and manifold that combined with a small amount of residual oxygen to produce a small thrust that was just enough to overcome the stage separation pusher impulse." The post-shutdown transient thrust is longer with regenerative engines than for ones that are ablatively cooled. The thrust is very small and the pressure in the engine is less than 10 psi. At sea-level it is masked by normal atmospheric pressure, and as a result, SpaceX engineers failed to take it into full account when designing the ascent profile. "We were aware of and had allowed for a thrust transient, but did not expect it to last that long. As it turned out, a very small increase in the time between commanding main engine shutdown and stage separation would have been enough to save the mission," Musk claimed. The payload originally manifested for this flight, a commercial satellite from Malaysia, has been pushed back to the fifth Falcon flight. In its place was a dummy payload and mass simulator weighing approximately 364 lbs. The simulator was designed and built by SpaceX in the wake of the loss of flight three. Manufactured from an aluminum alloy, the simulator is shaped like a 5 foot tall hexagonal chamber that fits on top of the second stage payload mounting adapter. The payload did not separate and entered orbit attached to the second stage. After a smooth countdown, the Merlin engine blazed to life. After being held back for several seconds while the engine built up full thrust and all operating parameters were verified normal, Falcon 1 lifted off at 7:15 p.m. EDT and quickly rose into the sky. Tere were none of last-minute holds or launch aborts that bedeviled the previous three launches. Two and a half minutes after liftoff, the first stage exhausted its fuel supply and was cast free to fall back to the ocean. The modifications to the separation sequence made after the third Falcon failure paid off, and, five seconds after cutoff, the first stage separated cleanly and fell away, followed by the ignition of the Kestrel second stage engine. Thirty seconds later, the 11.5 foot long clamshell protective fairing over the payload separated in two and also fell away. The Kestrel burned for about 7 minutes, placing the upper stage and payload simulator into an orbit with a low point 205 miles above Earth and 404 miles at its highest. Before launch, SpaceX had targeted an orbit with an apogee of 426 miles, but the company is happy with the accuracy of insertion. The orbital inclination is tiled 9.3 degrees to the Equator, precisely as planned. Several minutes later, Kestrel restarted for a short burn to circularize the orbit at an altitude of almost 400 miles. "Restarting rocket upper stages is not a trivial matter, so there was definitely a big icing on the cake there," Musk said. "I would have been happy if we just made it to orbit, but the restart was definitely great." The Falcon 1 is approximately 70 feet tall with a maximum diameter of 5.5 feet. The rocket's first stage is powered by a single Merlin 1C regeneratively cooled engine. This will be the second fligbht of the Merlin 1C engine. It burns refined RP-1 (highly refined kerosene) with liquid oxygen oxidizer. At liftoff, the rocket produces 78,000 pounds of thrust, enough to lift the 61,000 pound rocket. At ignition, the rocket is held down until nominal operating conditions are verified before the vehicle is released to begin its ascent from the island launch site. The Falcon 1 first stage is comprised of a structure also made from an aluminum allow with a common bulkhead between the fuel and oxidizer tanks. The stage represents a combination of a rigid self-supporting structure as used in the Delta II and a structure that is pressure-stabilized, such as on the now-retired Atlas II launch vehicle. A fully prssurized design benefits from the weight savings over a rigid structure but is unable to support itself or maintain its shape unless it is kept contantly pressurized. The Falcon 1 is designed to blend elements of both design philosophies to achieve a vehicle with a high vehicle mass fraction but enough strength to support itself without more expensive handling systems. The first stage of Falcon is designed to be recoverable. A thermal protection system protects the stage as it re-enters the atmosphere and then it descends into the ocean by parachute downrage, where a recovery boat stands by waiting to retrieve it for cleaning and re-use. Unfortunately, it appears the stage was destroyed upon re-entry this time. After the launch, Musk said engineers didn't have enough time to beef up the insulation outside the rocket so it would survive the stress of re-entry. "It most likely did not survive re-entry, but we knew that before liftoff," Musk said. "When it comes to Flight 5, we are going to improve the thermal protection and I think that's going to give us a decent chance of recovering the stage." A single SpaceX Kestrel engine powers the Falcon 1 upper stage. The second stage engine produces a vacuum thrust of 6,900 pounds and powers the vehicle for the remainder of ascent to orbit. Kestrel is pressure fed, eliminating the complexity and risk of using urbopumps. Unlike the Merlin 1C, the engine is ablatively cooled in the thrust chamber and nozzle throad. The nozzle bell employs radiative cooling whereby the heat that's generated passes through the nozzle wall and is radiated into the vacuum of space. The successful launch marks a milestone in the commercial space industry. Since the early 1980's numerous companies have tried to develop their own low-cost launch vehicles. History is painted with names like Starstruck, Space Services, Inc., American Rocket Company, Rotary Rocket and others who tried to reach the "holy grail" of the launch business but fell short. "Getting to orbit - that's just a huge milestone," Musk said. "There are only a handful of countries on Earth that have done it. It's normally a country thing, not a company thing." Now that SpaceX has a first success under their belts, the company must work to build a long-term track record of reliability, beginning with the next flight, a commercial mission with the Malaysia RazakSat, which may fly next January or February. Then it's on to the much larger Falcon 9, a heavy-lift vehicle featuring 9 Merlin engines in the first stage. The inaugural Falcon 9 is on track for delivery to SpaceX's launch site at Cape Canaveral, FL. by the end of the year. The company is in the midst of renovating the former Titan IV launch pad, SLC-40, to accomodate the Falcon 9. Renovations include liquid oxygen and hydrogen storage facilities and a hangar for horizontal prelaunch integration of the vehicle and payloads. The first Falcon 9 is expected to liftoff from the Cape sometime in the 2nd quarter of 2009. (The Spacearium / Space Media Corporation) 
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