On Friday afternoon, United Launch Alliance will attempt to launch a uniquely fitted Atlas 5 rocket from Cape Canaveral Space Force Station in Florida. You can watch the action live right here.
The window for today’s launch will open at 2:00 p.m. EST (11:00 a.m. PST), with forecasters predicting an 80% chance of good weather at Cape Canaveral.
The ULA Atlas V 511 rocket, with its extra-wide faring and lone side rocket booster, will blast off from Space Launch Complex-41. United Launch Alliance will use this unique configuration to launch two satellites for the U.S. Space Force, in a mission known as USSF-8. You can stream ULA’s webcast here, with coverage starting at 1:30 p.m. EST (10:30 a.m. PST):
The two identical satellites, GSSAP-5 and GSSAP-6, represent the fifth and six satellites of Space Force’s Situational Awareness Program. The satellites will go directly to geosynchronous orbit, some 22,300 miles (36,000 km) above the equator, where they will provide “neighborhood watch services” for the purpose of “improving flight safety for all spacefaring nations operating in that orbit,” according to ULA’s mission overview. Data from the GSSAP satellite network will allow for improved orbital predictions, such that satellite controllers can be alerted to possible collisions with space junk or other satellites. The previous four GSSAP satellites were delivered in pairs on Delta 4 rockets in 2014 and 2016.
ULA says this’ll be the first and only flight of the Atlas V 511 configuration, and it remains the only unflown configuration in the Atlas family of rockets. Since 2002, the Atlas V has flown in 10 different configurations, this being the 11th. Today’s launch will be ULA’s third direct-to-GEO mission, the previous two being AFSPC-11 in 2018 and STP-3 in 2021.
The “511” configuration is in reference to the fairing, side booster, and second stage booster. The “5” represents the width of the payload fairing, which is 5 meters, or 17 feet, across. The first “1” is the number of solid rocket boosters strapped to the side, and the second “1” refers to the number of engines on the second stage Centaur booster. ULA has previously flown an Atlas V 411 rocket, a configuration you should be able to figure out for yourself given my clear and concise explanation.
The single solid-fueled booster gives the rocket a distinctly asymmetrical appearance, but it will provide the additional power needed at liftoff: 371,500 pounds of thrust. The kerosene-fueled main booster will provide 860,200 pounds of thrust, for a total of 1.23 million pounds of thrust at liftoff. The Atlas V 511 is capable of delivering up to 11,570 pounds (5,250 kg) of payload to an elliptical geostationary orbit, according to SpaceFlightNow.
The Atlas V 511, in addition to looking off-kilter, will also exert asymmetrical thrust, as AmericaSpace explains in a post from last year:
Like its smaller cousin, the Atlas V 411—which carries a slightly smaller payload fairing, measuring 13 feet (4 meters) across, and which saw service most recently in February 2020 to launch Solar Orbiter—the 511 will exhibit an unusual “sideways-flying” perspective as it “slides” upward from the pad.
Steering actuators on the Atlas V’s RD-180 engine will counteract the asymmetrical thrust from the single solid and ensure that the rocket flies straight and true, but it will undoubtedly offer a disconcerting sight for spectators. And as [ULA CEO Tory] Bruno previously noted, all Atlas Vs have their own nicknames. With the 411 already dubbed “Slider”, the moniker for the bigger 511 is “Super Slider”.
The entire mission will take slightly less than eight minutes to complete. Key moments will include the jettisoning of the solid rocket booster at two minutes, the jettisoning of the payload fairing at the 3:30 mark, separation of Atlas/Centaur at 4:27, and the first main engine start of Centaur 10 seconds later. The two satellites will separate at marks 6:35 and 6:45. Fingers are crossed that the Super Slider will perform as expected.