WASHINGTON, Feb 28 (Reuters) - Virgin Galactic Holdings Inc has completed a lengthy upgrade period for its centerpiece tourist spacecraft, with commercial service on track to begin in the second quarter of 2023, the company said on Tuesday.

The company, founded by billionaire Richard Branson, had suspended flights of the spaceplane VSS Unity and its carrier plane in 2021 to make various spacecraft enhancements, delaying the company's debut customer mission to the edge of space.

"Our near-term objective for commercial spaceline operations is to safely deliver recurring flights with our current ships while providing an unrivaled experience for private astronauts and researchers," Virgin Galactic Chief Executive Michael Colglazier said in a statement on the company's Q4 and year-end 2022 earnings.

This month, VSS Unity's twin-fuselage carrier plane VMS Eve made its first flight since 2021. The company is planning "two or three" verification flights before its first commercial mission, involving a research trip to the edge of space for the Italian Air Force, Colglazier said during an earnings call.

Virgin Galactic is targeting monthly commercial missions after the Italian Air Force flight, a long-awaited cadence to handle the company's some 800 customers in line to fly.

The company in February re-opened ticket sales to the public for spacecraft flights, setting prices at $450,000 per person with an initial deposit of $150,000.

Each flight in space, over 50 miles (80 km) above ground, lasts roughly 10 minutes in microgravity, with VSS Unity launching mid-air from the center of its VMS Eve carrier plane. The spacecraft glides back for a landing much like commercial airliners. (Reporting by Joey Roulette; Editing by David Gregorio and Stephen Coates)