LIVE: ULA Atlas V launches WGS-2 for USAF

by William Graham

United Launch Alliance (ULA) has launched the WGS-2 satellite on an Atlas V rocket, with lift-off from Launch Complex 41 at Cape Canaveral at 21:33 EDT, Friday. The launch was realigned following an issue with the Centaur LOX pump led to the termination of tanking and put pay to the March 17 launch attempt.


The scrub was called following a leakage of LOX from the inlet valve on the RL-10 engine – related to the Centaur LOX pump. The vehicle was rolled back to the Vehicle Integration Facility (VIF) for a replacement valve.

“The launch of the Atlas V carrying the WGS-2 satellite was scrubbed tonight after the launch team detected an anomalous leak rate in the Centaur upper stage oxidizer valve,” added a ULA release. 

“The operation was secured for the evening and the team commenced the standard detanking procedure. Once the cause of the leak is understood, the team will begin planning for a new launch date in coordination with the U.S. Air Force and Eastern Range. “

Mission Preview:

The rocket will fly in the 421 configuration, with two solid rocket motors and a four metre diameter payload fairing.

WGS-2 is a communication satellite which will be operated by the United States Air Force. It is the second of six planned Wideband Global Satcom spacecraft, which will replace the Defense Satellite Communications System in providing communications for the United States military in Iraq and Afghanistan. The Australian Defence Force is also participating in the programme.

The first Wideband Global Satcom satellite, USA-195, was launched in October 2007, also on an Atlas V. It entered service on 16 April 2008, and is capable of providing ten times the capacity of the entire DSCS system. The next WGS satellite is currently scheduled for launch on a Delta IV on 29 July.

The Atlas V rocket will fly in the 421 configuration. The first stage main engine, a Russian-built RD-180, will ignite three seconds before launch, and will propel the rocket for the first four and a quarter minutes of flight. This will be augmented by two Aerojet SRMs, which will burn out and separate two minutes and twenty seconds after launch.

After the first stage shuts down the vehicle will coast for six seconds before staging. Following another ten seconds of coasting, the single RL-10 engine Centaur upper stage will ignite. Eight seconds after Centaur ignition, the fairing will separate. The first burn will last a little over ten and a half minutes, after which it will shut down and coast for nine minutes. It will then restart for its second burn, lasting four an a half minutes.

Once it has shut down, the WGS-2 spacecraft will separate into a 400 by 67,000 kilometre geosynchronous transfer orbit with 21 degrees of inclination, just under 32 minutes after launch. The spacecraft will then use its onboard propulsion system to place itself into geosynchronous orbit.

The rocket rolled out to the launch pad on Thursday, with the rocket departing the Vertical Integration Facility at 13:10 GMT, and arriving on the pad 30 minutes later. Complex 41 was originally built for the Titan rocket, and was first used for a Titan IIIC launch in December 1965.

During the mid 1970s, it was used by the Titan IIIE, with a Centaur upper stage, and was the launch site for the Helios, Viking and Voyager probes. Following this, several Titan IVs were launched from LC-41, including the type’s maiden flight. Work to convert the complex for the Atlas V began in 1999, and the towers were demolished that October.

The Atlas V first flew in 2002. The launch of WGS-2 will be the its fifteenth flight, and the third to use the 421 configuration. The fourteen previous launches were all successful, with one exception. In June 2007 the Centaur shut down early due to a valve problem, resulting in the USA-194 or NRO L-30R payload being delivered to an incorrect orbit. The payload was able to correct its own orbit, and the launch is considered a partial failure.

This is the second flight of an EELV this year, following January’s launch of NRO L-26 on a Delta IV Heavy. The next EELV launch is planned for 28 April, when a Delta IV will launch GOES-O for America’s National Oceanic and Atmospheric Administration. The next Atlas launch is scheduled for 20 May, with the LRO and LCROSS spacecraft for NASA.

Including the launch of LRO, five more Atlas rockets are scheduled to fly by the end of the year. ULA has also just been awarded four Atlas launch contracts for NASA, which will carry two Tracking and Data Relay Satellites, the Radiation Budget Storm Probes, and the Magnetospheric Multistage spacecraft. These launches will be conducted between 2011 and 2014.

Proton-M/W2A Launch

Earlier on Friday, International Launch Services (ILS) successfully launched a Proton-M launch vehicle from the Baikonur Cosmodrome in Kazakhstan, carrying Eutelsat Communications’ W2A communications satellite.

The path to orbit is taking nine hours, via five burns of the Breeze-M Upper Stage.

The W2A satellite, built by ThalesAleniaSpace, is a Spacebus 4000 C4 model, similar to the Ciel II satellite just launched. The W2A spacecraft is carrying three payloads, including the first S-band payload for Europe.

This feature will launch the Solaris Mobile communications service across the continent. Solaris Mobile is a joint venture between SES ASTRA and Eutelsat Communications.

The W2A C-band and Ku-band payloads will provide Europe and North Africa with an array of direct-to-home and business services.

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