On Sunday afternoon, Virgin Orbit joined the rare club of companies that have privately developed a rocket and successfully launched it into orbit. Moreover, with its LauncherOne rocket dropped from a 747 aircraft, the California-based company has become the first to reach orbit with an air-launched, liquid-fueled rocket.
"This magnificent flight is the culmination of many years of hard work and will also unleash a whole new generation of innovators on the path to orbit," said Sir Richard Branson, the founder of the company. "Virgin Orbit has achieved something many thought impossible."
Sunday's flight, which included multiple firings of LauncherOne's upper stage engine and successful deployment of several small satellites for NASA, caps a development program that has spanned about eight years and myriad technical challenges.
An air-launched rocket has some advantages over traditional boosters launched from the ground, most notably flexibility in reaching different orbits and the ability to take off in fairly inclement weather. However, to obtain these benefits, Virgin Orbit had to design a liquid-fueled rocket that could be dropped horizontally from an aircraft, ignite its engines, and rapidly orient itself into a more vertical trajectory. (Although Orbital Sciences developed the Pegasus rocket to drop from a carrier aircraft in the late 1980s, it was a more straightforward design using solid propellant.)
A rocket dropped from an aircraft cannot ignite its engines immediately due to the proximity of the plane and its pilots. In the case of LauncherOne, the rocket's NewtonThree engine is ignited 3.25 seconds after being dropped. Main engine start comes at 5.2 seconds. During this time, the rocket is falling and losing the velocity it gained from the aircraft at about 30,000 feet.
Technical challenges
Due to this drag, a negative acceleration acts on the booster, causing all sorts of problems for both the rocket's structure and its propulsion system. One problem is that this begins to force the liquid oxygen and kerosene propellants to the top of the tanks and the ullage gas—which fills the tanks as propellant is expended—toward the engine inlet.
The ignition process itself is also a challenge in the air. On the ground, a rocket typically ignites its engines, and the onboard computer performs a final, quick check to make sure everything is healthy, before the rocket is released. This is why liftoff typically follows ignition by a few seconds. There is no margin for error with Launcher One, because if ignition does not happen, the rocket simply falls into the ocean.
The company and its engineers were able to overcome all of these issues and more with the design of their rocket. But it took time and a lot of money. Branson has acknowledged that he and other investors have put about $1 billion into Virgin Orbit, which is a lot of money to invest in a small satellite launcher, however innovative it could be. Ars explored Virgin Orbit's pathways toward profitability last year, and the road will not be easy.
But those are discussions for another day. On Sunday, Virgin Orbit reached orbit on just its second flight, with what appeared to be a pretty much flawless mission. Few companies have done this with privately developed vehicles—very few indeed beyond Orbital Sciences, SpaceX, and Rocket Lab. It was a good day.
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