A screengrab from SpaceSpecialists' Twitter account on May 31, 2020, shows the photos illustrating the moments of the "successful docking of (the) Crew Dragon with the International Space Station (ISS)" on Sunday. (Xinhua)

"It's been a real honor to be a small part of this nine-year endeavor since the last time a United States spaceship docked with the International Space Station," says astronaut Doug Hurley.

WASHINGTON, May 31  -- SpaceX has completed the first part of its historic crewed flight to the International Space Station (ISS) Sunday morning, when its Crew Dragon spacecraft successfully docked with the orbiting laboratory.

In a first for a commercial spacecraft, Crew Dragon docked with the ISS at 10: 16 a.m. Eastern Time Sunday, a few minutes earlier than planned, carrying astronauts Bob Behnken and Doug Hurley. The two astronauts entered the ISS at 1:22 p.m. Eastern Time, after hatch opened.

The docking was a delicate and dangerous part of the mission. The spacecraft performed a series of phasing maneuvers to position itself for rendezvous and docking with the ISS.

The two astronauts onboard worked with SpaceX mission control to verify that the spacecraft was performing as intended by testing the environmental control system, the displays and control system, and maneuvering the thrusters, among other things.

"It's been a real honor to be a small part of this nine-year endeavor since the last time a United States spaceship docked with the International Space Station," Hurley said after docking completed.

"We have to congratulate the men and women of SpaceX, at Hawthorne McGregor and at Kennedy Space Center. Their incredible efforts over the last several years to make this possible can not go overstated," the astronaut added.

The mission went smoothly, ground officials said.