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Atlas V 511 sends up USSF-8

January 21st at 2:00 PM Est atop an Atlas V 511 rocket from SLC-41 at CCSFS

Space Force’s first launch of the year was used to deliver space surveillance assets to expand the capabilities of U.S. Space Force in support of national security, according to Gary Wentz, ULA vice president of Government and Commercial Programs. The USSF-8 mission launched two satellites of the Geosynchronous Space Situational Awareness Program. GSSAP-5 & GSSAP-6 will go to a near geosynchronous orbit that is approximately 22,300 miles above the equator.

These GSSAP satellites operating in a near geosynchronous orbit are a space-based capability in support of the U.S. Space Command space surveillance operations as a dedicated SSN (Space Surveillance Network) sensor. They will provide neighborhood watch services and improve flight safety for all spacefaring nations operating that orbit. With enhanced position knowledge of satellites at that distance the ability to warn a spacecraft owner/operator if another object is approaching too closely becomes improved. Data from these GSSAP satellites will contribute to timely and accurate orbital predictions which will further our knowledge of the GEO (Geosynchronous Earth Orbit) environment and also enable enhanced space flight safety.

This mission, the ninety-first launch of an Atlas V rocket will be the first of its kind. The Atlas V 511 configuration dubbed, “Big Slider” by ULA (United Launch Alliance) CEO Tory Bruno. Stating it’s a reference to how it will power slide off the pad due to its asymmetric torque. The 511 configuration simply means it includes a five-meter short payload fairing and is powered by the RD-180 engine, with Aerojet Rocketdyne’s RL10C-1 Engine for the Centaur upper stage and a Northrop Grumman GEM 63 (Graphite Epoxy Motor) as the solid rocket booster. In its entirety the rocket wills stand 196ft tall, and weight 858,115 pounds when fully fueled.

With 1.2 million pounds of thrust at take off the Atlas V 511 is capable of carrying 11,570 pounds to an elliptical geostationary transfer orbit, or 24,250 pounds to a low Earth orbit with its single solid rocket booster and RD-180 main engine, according to ULA. The Atlas V, designed by Lockheed Martin was designed to fly in up to twenty different configurations. This gives them the ability to dial in the rocket’s power and payload volume to meet the needs of every specific mission. Mission planners also have the option of flying a four-, or five-meter fairing depending on the size of the payload.

In 2006 Lockheed Martin merged the Atlas rocket program Boeings Delta family, which created United Launch Alliance (ULA). To date the most used Atlas V configuration is the “401” or a four-meter fairing and zero solid rocket boosters. This variant has flown forty times now, including the first Atlas flight back in 2002. There have been six flights of the Atlas V in the 411 configuration but never a flight in the 511, until now. With asymmetrical thrust countered by steering from the Atlas V’s RD-180 engine the single solid rocket booster allows customers to pay for just enough capacity for their payloads rather than buying the larger, more expensive variant of the Atlas V.

Currently in development is the Vulcan Centaur rocket, which will replace the Atlas V and Delta rockets and all their variants. With the one on the pad there are now twenty-six Atlas V launches, all for future missions for the U.S. Space Force, NASA, and Amazon’s Kuiper satellite constellation. There also are only three more Delta IV Heavy launches, all of which will carry classified satellites into orbit for the National Reconnaissance Office, which is the U.S. governments spy satellite agency.

Once the GSSAP satellites are in orbit they will unfurl their solar panels and begin to contact ground stations to allow military personnel to confirm the health of each spacecraft. But first they had to get to orbit. Once launched the rocket took around fifty-eight seconds to reach the speed of sound and at the T plus two-minute mark the SRB will be released from the main booster. At three minutes and thirty seconds the payload fairings jettisoned, followed by the shutdown of the RD-180 first stage main engine. Just after four minutes and twenty-one seconds the Atlas V will separate the first and second stage to clear the way for Centaur upper stage ignition at the four minute thirty-seven second mark. That burn will last four eight and a half minutes to reach the parking orbit with the twin satellites. After coasting almost fully around the world the RL10 engine will re-ignite for a four-minute burn over the Pacific Ocean which will bring the satellites into an elongated transfer orbit as far as 22,000 miles away from Earth. This will result in one final burn of that RL10 engine, which lasts nearly two full minutes, but won’t take place until six-and-a-half hours into the mission. That final burn will bring the satellites into the proper altitude for deployment.

With China and Russia bringing more sophisticated military spacecraft to orbit the U.S. Space Force needs these GSSAP satellites to add a new dimension to its tracking of objects in orbit. Cataloguing satellites and space debris has been a chief goal of the military’s space effort for decades. These fifth and sixth satellites will provide additional capacity for the GSSAP network to better cover the large volume of space in the geosynchronous orbit belt.

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