Screenshot from ULA Webcast of the launch of USSF-8. It’s clouded but it’s go for launch
Mission Rundown: ULA - Atlas V 511 - USSF-8
Written: November 26, 2022
Two small’s for the price of one
United Launch Alliance (ULA) will, with an Atlas V 511 rocket, launch the USSF-8 mission for the U.S. Space Force. Liftoff will occur from Space Launch Complex-41 at Cape Canaveral Space Force Station, Florida on January 21, 2022 at 14:00 EST - 19:00:00 UTC.
USSF-8 will launch two identical Geosynchronous Space Situational Awareness Program (GSSAP) satellites. GSSAP-5 and GSSAP-6, directly to a near geosynchronous orbit approximately 22,300 miles (36,000 km) above the equator.
Upcoming in the Atlas V 511 stacking work, a GEM 63 solid rocket booster and the Centaur upper stage will be hoisted into place. The USSF-8 payload attachment occurs early in the new year. Liftoff on January 21st will be the 75th Atlas V launch from Cape Canaveral and ULA's 148th mission.
The tail number for USSF 8 is seen as AV-084. This mission was originally known as AFSPC 8. Link
When flying from SLC-41, Atlas rockets are assembled atop the mobile platform in the VIF (Vertical Integration Facility), which is located 550 meters south of the pad. AV-084’s Common Core Booster and Centaur arrived at Cape Canaveral aboard ULA’s RocketShip transport vessel in September 2020, with launch then slated for March 2021.
Various factors resulted in subsequent delays to this date, with the CCB finally arriving at the Vertical Integration Facility on December 18th, less than a fortnight after SLC-41 had been vacated by the previous Atlas V launch with STP-3.
The encapsulated payload in its fairings was hoisted on its launch vehicle on Monday, January 10th to begin integrated operations. Final pre-launch readiness reviews and rollout to the launch pad will happen next.
The photo of the mission patch on the fairing suggests that four ‘Owls’ are in place on their geostationary ‘perch’ after two successful launches, and this is the last launch with two ‘Owls’. The GSSAP satellites are represented as ‘Owls’ and the launches are represented as the two Gold Stars and one Silver Star. link
USSF-8 will be the one and only mission to fly on Atlas V 511 in this unique configuration that will provide just the right amount of thrust to deliver the twin spacecraft directly to near-geosynchronous orbit. It’s known as "Big Slider" named by GEO Tory Bruno because the SRB’s offset thrust will move Atlas V sideways during its launch.
ULA will launch USSF-8 on an Atlas V 511 configuration rocket, that includes a 5-meter short payload fairing and stands 196 ft. (59.7 m) tall. The Atlas booster for this mission is powered by the AMROSS RD-180 engine. Aerojet Rocketdyne provided the RL10C-1 engine for the Centaur upper stage and Northrop Grumman provided the single Graphite Epoxy Motor (GEM) 63 solid rocket booster.
1st stage AV-084’s Common Core Booster is powered by a RD-180 engine manufactured by Russia’s NPO Energomash, and is a two-chamber version of the four-chamber RD-170 developed for the Soviet Union’s Zenit and Energia rockets. See or read about it here.
Alerting observers and astro-photographers
Friday evening a fuel dump from a Centaur rocket may be visible as a bright nebula in the sky for observers in North, Central and South America. The fuel dump will occur at 18:11 PST - 21:11 EST for the planned 19:00:00 UTC launch of the Atlas V 511 rocket.
The Atlas V 511 rocket will place 2 satellites in geostationary orbit above the Galapagos Islands and after separation of the satellites the rocket stage will dump the remaining fuel. This cloud of fuel will be visible as a bright nebula, possibly as big as the Full Moon.
The cloud should be visible to the naked eye, and with binoculars or telescopes it should be possible to see the cloud grow and change shape. See Marco Langbroek's blog.
https://sattrackcam.blogspot.com/2016/06/muos-5-gto-insertion-and-centaur-fuel.html
With binoculars and telescopes, it may also be possible to see the exhaust plume of the rocket burn that circularizes the elliptical transfer orbit at geostationary altitude, as well as plumes while the rocket maneuvers to deploy the satellites before it moves away to begin dumping its remaining propellant reserves and emptying its gaseous residues.
The circularization burn is scheduled for 6h31m after launch, with separation of the satellites at 6h36m and 6h45m after launch. Check the ULA mission overview for more information. https://ulalaunch.com/missions/next-launch/atlas-v-ussf-8
In 2016, two similar satellites were placed in a similar orbit and @coastal8049 link managed to capture the circularization burn, maneuvering plumes and fuel dump in this video. The burn starts at the 8 second mark on the right hand side.
For Friday's Atlas V 511 launch, the timing is perfect as the Sun has set for North, Central and South America, with the events occurring some 36 000 km above the Galapagos Islands with the rocket still lit by the Sun.
The GSSAP Payload
The GSSAP (Geosynchronous Space Situational Awareness Program) is a US Space Force project using small satellites to inspect other spacecraft operating in geostationary orbit. Friday’s launch, which is designated USSF-8 (US Space Force 8), is carrying the fifth and sixth satellites in this series. Links to GSSAP launch one and two.
Graphic with two GSSAP satellites with a small red hydrazine thruster and solar wings unfolded
The six GSSAP spacecraft operate in near-geosynchronous orbits, which means they are slower or faster depending on their altitude allowing observations of other spacecraft from above and below. This means strutting with camera’s and a lot of antennas.
GSSAP satellites are manufactured by Northrop Grumman, formerly Orbital ATK, and are based on the lightweight GeoStar-1 bus. This is a three-axis stabilized platform incorporating the systems that enable the satellite to carry out its mission. Each satellite is powered by a pair of deployable solar arrays and are capable of maneuvering on-orbit to set up inspection passes of other spacecraft.
Each GSSAP spacecraft must have a mass of less than 1,000 kilograms (2,204 pounds) in order for the selected rocket configuration to be able to deliver them directly into a near geosynchronous orbit.
The USSF-8 launch comes shortly after the retirement of the first two GSSAP satellites, with GSSAP-1 being decommissioned and moved to a “graveyard” orbit above the geostationary belt around the start of last February. GSSAP-2 retired in October.
It would be logical for the US Space Force to use Hall Effect plasma thrusters in order to conserve propellant in orbit. The GSSAP satellites are too small to extend their service life beyond 5-10 years. Extensive orbit maneuvering going from satellite to satellite in deep space is time and propellant consuming.
The arrival of GSSAP-5 and 6 will restore the constellation to four satellites, although it is not clear for how much longer GSSAP-3 and 4 will be able to remain in service as they are only one year younger than GSSAP-1 and 2 was when they were withdrawn.
In addition to their own names and their launch designations, all military spacecraft in orbit have also been assigned numbers under the series of USA designations.
The first pair was designated USA-253 and 254, while the second pair was designated USA-270 and 271. USA designations are assigned sequentially, and the most recently announced example was USA-319, given to the GPS-III-05 satellite launched last June.
Assuming no unannounced numbers have been assigned in the meantime, this means that GSSAP-5 and 6 will most likely be given the designations USA-320 and USA-321.
