Update for Monday, May 25: Virgin Orbit is now targeting its first LauncherOne launch for May 25 between 10 a.m. and 2 p.m. PDT (1-5 p.m. EDT/1700-2100 GMT). Our original delay story is below.
Virgin Orbit postponed the launch debut of its new rocket for small satellite missions today (May 24) due to a sensor glitch on the booster.
The rocket, an air-launched vehicle called LauncherOne, was expected to make its first test flight over the Pacific Ocean during a four-hour window that opened at 10 a.m. PDT (1 p.m. EDT/1700 GMT). But after fueling the rocket late Saturday, an issue popped up.
"Everything has been proceeding smoothly: team, aircraft, & rocket are in excellent shape. However, we have one sensor that is acting up," Virgin Orbit wrote in a Twitter update. "Out of an abundance of caution, we are offloading fuel to address."
In photos: Virgin Orbit's LauncherOne rocket for satellite missions
Virgin Orbit may try again on Monday (May 25), its backup date for LauncherOne's debut.
"Currently, it appears we've got a straightforward path to address this minor sensor issue and recycle quickly," the company wrote. "The crew are already hard at work putting that plan into action."
LauncherOne is a small-satellite booster designed to loft payloads of up to 1,100 lbs. (500 kilograms) to low Earth orbit. The liquid-fueled rocket is about 70 feet long (21 meters) and uses the rocket-grade kerosene RP-1 and liquid oxygen as propellant.
Virgin Orbit plans to launch LauncherOne from the air using a carrier plane called Cosmic Girl, a Boeing 747 jumbo jet modified for rocket missions. Under the plan, the carrier plane will take off from the Mojave Air and Space Port in Mojave, California, fly over the Pacific Ocean and drop LauncherOne from an altitude of 35,000 feet (10,700 m).
For this test flight, LauncherOne is carrying a dummy payload that will be sent into a low orbit to ensure it falls back to Earth quickly and burns up in the atmosphere, Virgin Orbit Vice President Will Pomerantz told reporters in a press conference Saturday.
"It is essentially a nice-looking inert mass that allows us to practice with it," Pomerantz said.
Virgin Orbit CEO Dan Hart stressed that LauncherOne is a brand-new vehicle in Saturday's press conference, adding that it likely would not launch on the first try.
"There is certainly a significant likelihood that we don't get to countdown on our first pass," Hart said. "This is a test flight. The purpose of this flight is to incrementally test the rocket and the airplane."
Virgin Orbit was founded in 2012 by British billionaire Sir Richard Branson and aims to launch missions for customers at $12 million per flight. The company has since secured a three-launch deal worth $35 million to launch missions for the United States Space Force.
Branson also has another space company, Virgin Galactic, which aims to fly passengers on a suborbital space plane called SpaceShipTwo. Tickets for those flights cost $250,000 per seat.
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Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik. Follow us @Spacedotcom, Facebook and Instagram.
