Teams from ULA have returned the #Starliner and Atlas V rocket to its integration facility to replace a valve on the rocket’s upper stage.

NASA’s Boeing Space Crew Flight Test is targeted to launch no earlier than 6:16pm ET May 17.

More: go.nasa.gov/3Uy58wz

#Starliner launch update:

NASA, Boeing Space and @ULALaunch are now targeting no earlier than 6:16pm ET May 17 for the launch of the agency's Boeing Crew Flight Test to International Space Station, following a valve replacement on ULA's Atlas V rocket: go.nasa.gov/3ycJneo

Out of an abundance of caution for the safety of the flight and pad crew, we scrubbed the Crew Flight Test (CFT) launch attempt today due to an observation on a liquid oxygen self-regulating solenoid relief valve on the Centaur upper stage. The team needs additional time to…

Live now: Officials from NASA, Boeing Space, and @ULAlaunch discuss today’s scrubbed #Starliner launch attempt. twitter.com/i/broadcasts/1…

Tune in at 10:30pm ET to hear from NASA, Boeing and United Launch Alliance leaders as they discuss tonight's scrub and future launch attempts: go.nasa.gov/4bK30ZR

ULA Launch Director Tom Heter III has made the decision to the launch team that launch operations will not continue tonight for #AtlasV and #Starliner .
bit.ly/av_cft

Now boarding #Starliner is #CFT mission pilot Suni Williams, a retired U.S. Navy captain and veteran of two previous spaceflights as a long-duration resident aboard the space station.

Did you know? Today is the 100th launch of an #AtlasV , which has demonstrated reliability spanning more than 20 years and successfully launched scientific spacecraft to Mars on five different occasions, plus the Sun, the Moon, Jupiter, the Asteroid Bennu and Pluto -- all with…

Commander in his #Starliner seat for launch.

Watch live: bit.ly/av_cft

First to board #Starliner tonight is #CFT mission commander Butch Wilmore, a retired U.S. Navy captain and veteran of two previous spaceflights to the space station.

The astronauts walk the Crew Access Arm to the ULA white room — the area just outside #Starliner . While in the white room, they'll each make a phone call, sign the Crew Flight Test patch and then begin ingress into the spacecraft.

This will be the most exciting moment of the day. We will make sure their ride to space will be as boring as possible…. :). #AtlasV #Starliner

We are now exactly three hours away from liftoff. Blue Team operations continue to progress smoothly at the pad following hatch opening while launch team members monitor the health and status of rocket and pad systems. bit.ly/av_cft

The astronauts have left the building!

Friends, family and colleagues are gathered outside the Operations and Checkout Building at NASA's Kennedy Space Center to see off Butch Wilmore and Sunita Williams as they head to Space Launch Complex-41.

.NASA Astronauts commemorate their historic NASA Commercial Crew missions by signing the wall of the Neil Armstrong Operations & Checkout Building. Butch Wilmore and Sunita Williams left their mark beside #Starliner 's Crew Flight Test patch during an earlier mission dress rehearsal.

The Blue Team has arrived on Level 12 of the Crew Access Tower to resume their work on #Starliner following #AtlasV fueling operations. All three cryogenic tanks on #AtlasV have been topped off to flight level.

.NASA Astronauts Butch Wilmore and Sunita Williams are in the Neil Armstrong Operations and Checkout Building at NASA's Kennedy Space Center, suiting up for today's #Starliner Crew Flight Test. Our engineers and David Clark technicians will perform suit-up checks.