The launch of an Atlas 5 rocket from Cape Canaveral with an infrared surveillance satellite from the US Air Force. UU It was cleaned on Thursday night after the engineers found an exhaust valve associated with the liquid oxygen system of the first stage.
Alliance, a 50-50 joint venture between Boeing and Lockheed Martin, said the problem was reduced to a ground system on the launch pad of Complex 41 at Cape Canaveral. The countdown was paused to allow members of the Atlas 5 launch team to study a stagnant fill and drain valve needed to fill the first stage of the rocket with liquid oxygen.
Engineers investigated the problem before suspending Thursday's launch attempt, which had a 40 minute window to take off with the fourth Infrared System satellite based on the Air Force space in the direction of a geosynchronous orbit of more of 22,000 miles (almost 36,000 kilometers) over the equator.
ULA said in a statement that the flight today due to a ground problem associated with the liquid oxygen booster system. "
The company said another launch attempt was possible on Friday, with another 40-minute opening at 7:48 pm EST (0048 GMT), assuming the valve problem is resolved in time.
There is a 90 percent chance of favorable weather for the launch window on Friday night, with a slight concern of cumulus clouds that could pass over the launch pad.  The SBIRS GEO Flight 4 satellite of $ 1.2 thousand million aboard the Atlas 5 rocket will complete the initial deployment of the new generation of missile warning network of the Air Force.When completed, the constellation will include a minimum of four SBIRS ships stationed in geosynchronous orbit and at least two infrared charges in egg-shaped orbits on board the spy satellites of the National Reconnaissance Office, providing polar coverage.
Built by Lockheed Martin, the SBIRS satellites carry infrared sensors with sharp eyes to detect the heat feathers of rocket launchers, supplying data to the military on the origin and trajectory of missiles that could be directed to EE territories. UU Deployed troops, or allies.
Infrared payloads are provided by Northrop Grumman.
Three previous SBIRS satellites launched in Atlas 5 rockets in 2011, 2013 and 2017. The fourth will give the SBIRS fleet global coverage, replacing the missile detection capabilities. currently provided by the oldest satellites of the Defense Support Program of the previous generation.
Four "SBIRS HEO" link sensor packets were launched on the NRO classified spy satellites. Two are needed in operation at any time.
The Air Force has ordered two more SBIRS satellites to launch in 2021 and 2022 to improve coverage, and ultimately replace the first two SBIRS geosynchronous spacecraft.
"The successful launch and operation of this fourth SBIRS GEO satellite will mark the completion of the SBIRS reference constellation," said Col. Dennis Bythewood, director of remote sensing systems management at the Space and Missile Systems Center Air Force. "SBIRS intends to replace the old Defense Support Program satellites that have been providing missile warning for missile launches worldwide since 1970.
" The SBIRS constellation delivers timely, reliable and accurate warning and surveillance information. missiles to the president, the defense secretary, combatant commanders, the intelligence community and other key decision-makers throughout our nation, "Bythewood said in a pre-launch report with reporters.
Atlas 5 flight with SBIRS GEO Flight 4 will mark the first of the year for ULA's Battlehork rocket and the 75th Atlas 5 were released in general since it was released in August 2002.
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