CAPE CANAVERAL, Fla — United Launch Alliance (ULA ) is working to conduct its third Atlas V launch of the year on Thursday, April 10. Liftoff is slated to take place at 1:45 p.m. EDT. The payload for this mission is the NROL-67 satellite with the launch site being Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) in Florida. If everything goes as advertised, it will mark the first launch since a short circuit with the Eastern Range’s caused a delay of all flights scheduled to take place at the Cape. Current weather conditions provide a 90 percent chance of favorable conditions for launch.
NROL-67 is a classified mission for the National Reconnaissance Office (NRO), the government department in charge of the nation’s surveillance satellites. The NROL-67 mission motto is “In Scientia Opurtunitas” which is Latin for “In knowledge there is opportunity.” While little is known about the satellite or its destination, the 541 Atlas V variant it sits atop is capable of carrying payloads weighing up to 7,800 pounds to Geostationary transfer orbit (GTO).
The launch had been slated to take place last month – but s short circuit with one of the Eastern Range’s radar stations caused the postponement of both the NROL-67 mission and SpaceX’s launch of a Dragon spacecraft atop one of the company’s Falcon 9 v1.1 rockets. The United States Air Force’s 45th Space Wing has since repaired/replaced the damaged equipment and both launches have since been rescheduled.
Assembly of the Atlas V launch vehicle began on February 7 – with the first stage being erected at the Vertical Integration Facility (VIF) which is adjacent to SLC-41. Over the following two weeks, the solid rocket boosters and the Centaur upper stage were attached. The payload was mated to the upper stage on March 14. Details about the length of launch window were not announced as this is a classified mission.
The 541 designation means that the Atlas V rocket has a five meter fairing, four solid rocket boosters and a single engine in its Centaur upper stage. The first stage is powered by an RD-180 main engine manufactured by Russia’s NPO Energomash. The RD-180 is capable of producing 860,000 pounds of thrust at liftoff. The Atlas V 541 is the second most powerful configuration of the Atlas family of launch vehicles. The Atlas V rocket has been used for some of the more high-profile NASA missions as well, including the launches of the Mars Science Laboratory rover Curiosity and Mars Reconnaissance Orbiter spacecraft.
Current weather conditions appear to be the primary issue which could cause a slip or delay for the launch. If everything proceeds according to schedule however, the following is what should take place:
At about an hour and 43 minutes prior to launch, the Centaur engine in Atlas’ upper stage will start to be filled with its LO2 fuel. Three minutes later and the Atlas core booster itself will start to be filled with its liquid oxygen fuel. Some 45 minutes prior to launch and Atlas’ Pneumatic System will be brought up to flight pressure.
Ten minutes before the mission begins, the Atlas weather officer will give a briefing on the atmospheric conditions and if they are suitable to conduct the launch. With just five minutes until the Countdown Clock hits “zero” – the Atlas is fully fueled. The water deluge system which will counter the extreme acoustics of launch will have its pressure adjusted. One minute later, with just four minutes left until launch the “go” “no-go” poll will be held to see if everything is ready for the launch to proceed. If so, the flight team will move out of the 4-minute built-in hold and move forward with the launch.
At three minutes before liftoff the Atlas’ tanks will be brought to flight pressure. A minute later and the rocket is running on internal power. Less than three seconds before launch and the RD-180 engine with its two nozzles will announce its presence to the surrounding marshlands.
About a minute into the flight and the rocket and its secretive cargo will be passing through the region of the atmosphere known as maximum dynamic pressure or “max-q.” This is the point in the mission where the Atlas is placed through the greatest amount of stress, caused by both the launch vehicle’s speed as well as the pressure of the atmosphere.
At this point in the mission, the RD-180 will be throttled back. After the Atlas passes through max-q it will again be brought back up to full capacity.
Not long after, some 30 seconds, the four solid rocket boosters will be spent. At this point they are little more than dead weight and as such – they will be jettisoned, where they will tumble back to the Earth to splash down in the Atlantic Ocean. These engines are produced by Aerojet Rocketdyne and can be affixed in different numbers to the Atlas V – dependent on the needs of the particular mission.
About three-and-a-half minutes into the flight, the five-meter fairing will have finished its mission of shielding the NROL-67 spacecraft through Earth’s turbulent atmosphere. As such, it will be jettisoned and allowed to fall back to Earth.
The launch comes at a busy time for Cape Canaveral Air Station which could possibly see two launches this week with the recently-rescheduled SpaceX CRS-3 launch now planned for April 14 over at the nearby launch pad – SLC-40. For Colorado-based ULA, 2014 is shaping up to be a busy year with 15 launches on the manifest.