Update for 4 p.m. EDT on Aug. 28: The launch window is now expected to open at 5:45 p.m. EDT (2145 GMT).
Update for 1:20 p.m. EDT on Aug. 28: Astra announced via Twitter that the next launch attempt will come today (Aug. 28), with the window expected to open at 5 p.m. EDT (2100 GMT).
Astra aimed to reach orbit for the first time ever today (Aug. 27), but the company's Rocket 3.3 aborted the liftoff at the last second.
The 43-foot-tall (13 meters) Rocket 3.3, also known as Launch Vehicle 006, was poised to lift off from the Pacific Spaceport Complex on Alaska's Kodiak Island today at 5:45 p.m. EDT (2145 GMT) on a milestone orbital test flight. And that very nearly happened: The countdown clock reached zero and the rocket's first-stage engines ignited, but they shut down almost immediately.
"It sounds like the abort was called by our guidance system near T-zero," an Astra team member said in a NASASpaceflight.com webcast of today's launch attempt. "It looks like the engines successfully lit but the guidance system called abort."
Video: Watch Astra's Rocket 3.2 launch on its 1st successful flight
There were still a few hours left in today's launch window, but Astra decided to stand down to investigate and troubleshoot the issue. There's no big rush to get the two-stage Rocket 3.3 off the ground; daily launch opportunities for the mission run through Sept. 11, and Astra announced the next try will come on Saturday (Aug. 28), with the launch window expected to open at 5 p.m. EDT (2100 GMT).
Astra, which is based in California's Bay Area, has attempted two orbital test flights to date, in September and December of last year. The company's Rocket 3.1 suffered a guidance problem during the first mission and crashed shortly after liftoff. Its successor, Rocket 3.2, reached space but ran out of fuel just before achieving orbital velocity.
Astra addressed these issues with tweaks and upgrades to Rocket 3.3, which stands about 5 feet (1.5 m) taller than its two immediate predecessors and features a more powerful upper stage, among other modifications. The new booster is also carrying a payload, a first for an Astra launch attempt.
That payload is a mass simulator for the U.S. Department of Defense's Space Test Program. It will not be deployed during the upcoming mission.
Astra builds mass-produced, flexible and cost-effective rockets designed to launch small satellites to orbit. The company has big ambitions, aiming eventually to launch on a nearly daily cadence from a variety of sites around the world.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.