The booster was released from under the wing of one of the UK entrepreneur’s old jumbos which had been specially converted for the task.
The rocket ignited its engine seconds later but an anomaly meant the flight was terminated early.
Virgin Orbit’s goal is to try to capture a share of the emerging market for the launch of small satellites.
It’s not clear at this stage precisely what went wrong but the firm had warned beforehand that the chances of success might be only 50:50.
The history of rocketry shows that maiden outings very often encounter technical problems.
“Test flights are instrumented to yield data and we now have a treasure trove of that. We accomplished many of the goals we set for ourselves, though not as many as we would have liked,” said Virgin Orbit CEO Dan Hart.
“Nevertheless, we took a big step forward today. Our engineers are already poring through the data. Our next rocket is waiting. We will learn, adjust, and begin preparing for our next test, which is coming up soon.”