• ULA Atlas V rocket configuration graphic: Credit: ULA
  • ULA Atlas V at Sunset at pad 41 on Cape Canaveral Air Force Station, Fla that will deliver SBIRS GEO Flight 4 to geosynchronous orbit for the USAF on Jan. 19, 2018. Credit: Ken Kremer/SpaceUpClose.com

ULA Atlas V Liftoff with USAF SBIRS GEO 4 Missile DetectionSatellite Reset to Jan 19 after Launch Pad Scrub: Live Webcast

Ken Kremer -- Space UpClose -- 19 Jan 2018

CAPE CANAVERAL AIR FORCE STATION, FL – Thursday nights (Jan. 18) Atlas Vlaunch ofthe SBIRSGeo Flight 4 infrared imaging missile warning and detection satellite for the U.S. Air Force was scrubbed shortly before the planned liftoff due to a ground hardware valve issue with the “booster liquid oxygen system” announced rocket provider United Launch Alliance.

Blastoff of the ULA Atlas V rocket carrying the USAF the SBIRSGeo Flight 4 satellite has been rescheduled to Fri., Jan. 19 at 7:48 p.m. EST, fromseaside Space Launch Complex-41 at Cape Canaveral Air Force Station in Florida.

“The launch of a United Launch Alliance Atlas V carrying the SBIRS GEO Flight 4 mission was scrubbed today due to a ground issue associated with the booster liquid oxygen system,” ULA said in a statement.

SBIRS GEO Flight 4 is part of a constellation of satellites that will detect incoming nuclear and conventional missiles in case of an enemy attack on the US and its allies.

As the countdown entered its final phases under perfect weather conditions and crystal clear evening skies the launch team encountered technical troubles with the fill-and-drainvalve used for the first stage liquid oxygen propellant.

Meanwhile the launch team continued loading the second stage propellants as they worked the balky first stage valve issue.

The team finally called the scrub at 7:06 pm EST after loading the second stage liquid hydrogen propellant.

Flocks of excited spectators had gathered at beaches and lined causeways ringing the Florida Space Coast for the especially convenient dinnertime blastoff.

The issue has apparently been resolved and ULA and the USAF announced launch for a reset to Friday.

You can watch the Atlas launch live via a ULA webcast.

The launch window opens at 7:48 p.m. EST (0048 GMT).

The launch window extends for 40 minutes from 7:48-8:28 p.m. EST.

The live launch broadcast will begin about 20 minutes before the planned liftoff at 7:28 p.m. EST. here:

The current launch weather forecast for Friday, Jan. 18, calls for a 90 percent chance ofacceptable weather conditions at launch time. The primary concern is for cumulus clouds.

The backup launch opportunity is on Saturday.

In case of a scrub for any reason, technical or weather, the weather chances remain highly favorable.

The U.S. Air Force satellite will provide vital early warnings on incoming enemy missiles that are critical to the defense of our homeland and allies.

The Space Based Infrared System (SBIRS) satellite will be launched to geosynchronous transfer orbit some 22,000 miles (36,000 kilometers) over the equator.

The 194-foot-tall commercial Atlas V booster will launch in the 411 rocket configuration with approximately 860,000 pounds of sea level first stage thrust powered by the dual nozzle Russian-built RD AMROSS RD-180 engine. There is one thrust augmenting solid attached to the first stage generating approximately348,500 pounds of thrust.

The SBIRS team is led by the Remote Sensing Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Lockheed Martin is the prime contractor, with Northrop Grumman as the payload integrator. Air Force Space Command operates the SBIRS system, according to a ULA description.

Watch for Ken’s continuing onsite coverage of Falcon Heavy, ULA and NASA and spacemission reports direct from the Kennedy Space Center and Cape Canaveral Air Force Station, Florida.

Stay tuned here for Ken's continuing Earth and Planetary science and human spaceflight news: www.kenkremer.com – www.spaceupclose.com – twitter @ken_kremer
Nighttime view of ULAAtlas V rocket poised for liftoff carrying the SBIRS GEO Flight 4 mission to geosynchronous orbit for the U.S. Air Force from Space Launch Complex-41 on Cape Canaveral Air Force Station, Fla., on Jan. 18, 2018. Launch reset for Jan. 19, 2018. Credit: Ken Kremer/SpaceUpClose.com