A privately built rocket blasted past the atmosphere on Monday and landed safely, becoming the unofficial winner of a $10-million US award for the first craft to complete two flights to space.

SpaceShipOne reached an altitude of 100 kilometres above Earth, the internationally recognized entry point to space, according to radar measurements that should be confirmed later in the day.

The craft took off from California's Mojave desert under the belly of a specially adapted jet at about 7 a.m. local time.

SpaceShipOne followed by chase plane at touch down.
SpaceShipOne followed by chase plane at touch down.

Former U.S. navy test pilot Brian Binnie then flew SpaceShipOne to the target altitude and returned safely to the California desert.

If the altitude is confirmed, Binnie, 51, and his U.S. team will win the Ansari X Prize, and he'll earn his wings as a commercial astronaut.

To win the Ansari X prize, a team had to safely complete two trips to space within 14 days while carrying the weight of three people.

The U.S. team, funded by Microsoft billionaire Paul G. Allen, took the lead in the race in June with a test flight, followed by a successful attempt last week to reach the limits of space.

The $10-million US award is modelled after the prize Charles Lindbergh won in his airplane Spirit of St. Louis for the first solo New York-to-Paris flight across the Atlantic in 1927.

Two Canadian teams were among the more than two dozen competitors vying for the international prize.

The Toronto-based team da Vinci Project, sponsored by internet gambling site Golden Palace.com, plans to launch from a balloon in October, according to team leader Brian Feeney.

Another contestant, the Canadian Arrow team from London, Ont., is using a vehicle based on a Second World War V2 missile.

Both Canadian teams have always said that even if they didn't win the prize, they would continuing pursuing their goal of developing commercial spaceflights.