Image copyright MarsScientific.com/Trumbull Studios

Virgin Galactic has pushed its Unity rocket plane faster and higher than it's ever been.

Chief pilot, Scotsman Dave Mackay, and co-pilot, American Mike Masucci, took the vehicle to almost 90km in altitude above California's Mojave Desert before gliding back down to Earth.

The test flight edges Virgin that bit closer to its goal of introducing commercial passenger flights.

More than 700 people are signed up for a trip on Unity to suborbital space.

It's not clear when precisely this service will begin, but Virgin Group boss, Sir Richard Branson, believes it will be very soon.

Image copyright VIRGIN GALACTIC Image caption Chief pilot Dave Mackay (L) and co-pilot Mike "Sooch" Masucci (R)

Mr Mackay, from Helmsdale, Sutherland, becomes the first Scottish-born pilot to travel to space, by Virgin's preferred definition of that term.

"It was thrilling yet smooth and nicely controlled throughout, with a view at the top, of the Earth from space, which exceeded all our expectations," he said after landing back at Mojave airport.

Friday's mission followed the usual flight procedures.

Unity was carried aloft by the WhiteKnightTwo aircraft, before being released to ignite its rocket motor and climb high over the desert.

It's only the fifth time Unity has conducted a powered ascent, and should have provided valuable data on engine performance and the overall handling of the vehicle.

The big difference with previous flights is that there was a third person onboard. Beth Moses is Virgin's chief astronaut instructor and she was present on the mission to get a better understanding "of the customer cabin and spaceflight environment from the perspective of people in the back".

Unofficial data indicates Unity climbed to a maximum altitude of 89.9km (55.85 miles; 294,9007ft), travelling at Mach 3 (three times the speed of sound) on the way up.

In December, Unity reached an altitude of 82.7km (271,330ft), which was enough for the pilots on that occasion - Mark Stucky and CJ Sturckow - to earn commercial astronaut wings from the US Federal Aviation Authority. Mackay, Masucci and Moses should now receive the same honour.

Sir Richard commented: "I am immensely proud of everyone involved. Having Beth fly in the cabin today, starting to ensure that our customer journey is as flawless as the spaceship itself, brings a huge sense of anticipation and excitement to all of us here who are looking forward to experiencing space for ourselves. The next few months promise to be the most thrilling yet."

Image copyright Virgin Galactic Image caption Passengers would get to see the black of space and Earth's curved horizon

Sir Richard's Virgin Galactic company is vying with Amazon.com founder Jeff Bezos's Blue Origin outfit to be the first to introduce a sub-orbital passenger spaceflight service.

Mr Bezos is pursuing a different technological route. He has a booster and capsule system that goes straight up from a launch pad in West Texas.

The two components separate at altitude before then both making their way back to Earth under control.

The Amazon entrepreneur's New Shepard system regularly flies over 100km - the height most widely recognised as the lower boundary of space (although there is currently a lively scientific debate over whether this is the best classification).

Image copyright VIRGIN GALACTIC Image caption WhiteKnightTwo, with Unity carried at the centre, takes off from Mojave

Jonathan.Amos-INTERNET@bbc.co.uk and follow me on Twitter: @BBCAmos