SpaceX was due to launch four more astronauts to the International Space Station for NASA (File)Cape Canaveral:
Elon Musk's private rocket company, SpaceX, was due to launch four more astronauts to the International Space Station for NASA on Wednesday, including a veteran spacewalker and two younger crewmates chosen to join NASA's forthcoming lunar missions.
The SpaceX-built launch vehicle, consisting of a Crew Dragon capsule perched atop a two-stage Falcon 9 rocket, was set for liftoff at 9:03 p.m. (0200 GMT Thursday) from NASA's Kennedy Space Center in Cape Canaveral, Florida.
If all goes smoothly, the three U.S. astronauts and their European Space Agency (ESA) crewmate will arrive about 22 hours later and dock with the space station 250 miles (400 km) above the Earth to begin a six-month science mission aboard the orbiting laboratory.
But rain and heavy clouds over the Cape on Wednesday cast renewed doubt on prospects for the launch proceeding as planned, although NASA said its latest forecasts called for a 70% chance of favorable weather conditions for liftoff.
A string of weather delays has confounded the mission since its original launch window on Oct. 31. One postponement earlier this month was attributed to an astronaut's unspecified medical issue, which has since been resolved.
Joining the SpaceX mission's three NASA astronauts - flight commander Raja Chari, 44, mission pilot Tom Marshburn, 61, and mission specialist Kayla Barron, 34 - is German astronaut Matthias Maurer, 51, an ESA mission specialist.
Chari, a U.S. Air Force combat jet and test pilot, Barron, a U.S. Navy submarine officer and nuclear engineer, and Maurer, a materials science engineer, are all making their debut spaceflights aboard the Dragon vehicle, dubbed Endurance.
The three rookies will become the 599th, 600th and 601st humans in space, according to SpaceX.
Both Chari and Barron were also among the first group of 18 astronauts selected last year for NASA's upcoming Artemis missions to the moon.
Spaceflight experience in low-Earth orbit and aboard the space station "is a great training ground for those kind of skills that we'll need for return to the moon on Artemis," NASA commercial crew manager Steve Stich told reporters during a preflight briefing late on Tuesday.
Marshburn, a physician and former NASA flight surgeon, is the most experienced astronaut of the crew, having logged two previous spaceflights and four spacewalks. He was part of a 13-member team that helped assemble the space station in 2009 and returned to the orbiting outpost in a 2012-2013 mission.
Wednesday's liftoff, if successful, would count as the fifth human spaceflight SpaceX has achieved to date, following its "Inspiration 4" launch in September that sent an all-civilian crew to orbit for the first time.
The latest mission would mark the fourth crew NASA has launched to orbit aboard a SpaceX vehicle in 17 months, building on a public-private partnership with the rocket company formed in 2002 by Musk, also founder of electric maker Tesla Inc.
Their collaboration helped usher in a new era for NASA leading to last year's first launch of American astronauts from U.S. soil in nine years, since it quit flying space shuttles in 2011.
The team set for blastoff on Wednesday has been designated "Crew 3" - the third full-fledged "operational" crew NASA and SpaceX have flown to the space station after a two-astronaut trial run in May 2020.
The four astronauts of "Crew 2" safely returned to Earth late on Monday from a record 199 days in orbit, splashing down in the Gulf of Mexico off Florida after an eight-hour voyage home from the space station.
The latest mission also follows a flurry of recent high-profile astro-tourism flights. In July, two SpaceX rivals, Blue Origin and Virgin Galactic Holding Inc, launched back-to-back flights with their respective billionaire founders, Jeff Bezos and Richard Branson, riding along.
Last month, 90-year-old actor William Shatner, famed for playing Captain James T. Kirk in the original 1960s "Star Trek" TV series, rode aboard a Blue Origin rocket to become the oldest person to fly in space.
Crew 3 will be welcomed aboard the space station by its three current occupants - two cosmonauts from Russia and Belarus and a U.S. astronaut who shared a Soyuz flight to the orbiting platform earlier this year.
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)