Amazon’s Project Kuiper broadband communications mega-constellation, a future competitor to SpaceX’s Starlink service, is ready to launch its first operational satellites to low-Earth orbit. A United Launch Alliance (ULA) Atlas V 551, standing atop Space Launch Complex-41 at the Cape Canaveral Space Force Station (CCSFS), is set to fly Kuiper Atlas 1 (KA-01), the first of more than 80 Kuiper launches over the coming years.
The Atlas V is scheduled to launch on Wednesday, April 9, at 7:00 pm EDT (23:00 UTC), at the start of a two hour window ending at 9:00 pm EDT (01:00 UTC on April 10). The launch will fly on a northeast trajectory, which will take the 27 satellites on board to an initial 450 km altitude circular orbit inclined 51.9 degrees to the equator.
The current forecast from the U.S. Space Force’s 45th Weather Squadron at CCSFS shows only a 55 percent chance of acceptable conditions, with the cumulus cloud rule and the liftoff winds being primary concerns. The launch forecast improves to 90 percent favorable for the backup launch day on Thursday, April 10, with the cumulus cloud rule being the only concern.
The Atlas V rocket is equipped with five GEM-63 solid rocket boosters (SRBs) and the 5.4 meter wide medium-length payload fairing. This configuration allows the rocket to take as many Kuiper satellites as possible to orbit; the number of satellites for this flight is similar to the number of Starlink v2 Mini satellites taken to orbit by Falcon 9.
The Atlas V will ignite its two Russian-made RD-180 engines 2.7 seconds before liftoff. If all is in order, the five GEM-63 SRBs will ignite, and the vehicle will launch from CCSFS on 12 meganewtons of thrust. The Atlas will go through maximum dynamic pressure around 45 seconds after liftoff, and the SRBs will jettison around the T+1:46 minute mark.
Graphic showing the Atlas V 551 launch sequence. (Credit: ULA)
The payload fairing will be jettisoned just after three minutes of flight, and the RD-180 engines, using RP-1 highly purified kerosene and liquid oxygen as propellants, will continue burning until around T+4:23 minutes. After booster separation, the Centaur and its RL10A-4-2 engine, using liquid hydrogen and liquid oxygen as propellants, will burn until around T+18:14 minutes after liftoff.
Unlike SpaceX’s Falcon 9 first stage, the Atlas V boosters are not reused. The fairing is also expended, and the Centaur upper stage will be deorbited after satellite deployment to ensure it does not become space debris. ULA has done work on the possibility of returning booster engine sections to Earth using an inflatable reentry shield and parachute, a concept that could be used on a future version of ULA’s Vulcan rocket.
The Kuiper satellites, built in Kirkland, Washington, are equipped with optical inter-satellite laser communications links and are designed to deliver low latency broadband to users worldwide using small terminals in a manner similar to Starlink. The satellites are shipped to the dedicated Amazon satellite integration facility at CCSFS before they are processed for launch.
The fairing enclosing 27 Kuiper satellites is shown leaving Amazon’s satellite processing facility in Cape Canaveral. (Credit: Amazon)
Kuiper Systems LLC, the subsidiary of Amazon responsible for development and operation of the constellation, plans to launch up to 3,232 satellites to deliver this service. The satellites will be launched into three shells and 98 orbital planes. The three shells will be at altitudes of 590 km, 610 km, and 630 km, with the satellites controlled from a center in Redmond, Washington.
In contrast to Starlink, the initial Kuiper constellation will use Ka-band frequencies for communication with both user terminals and gateways. The constellation’s approved orbits have a maximum inclination of 51.9 degrees, concentrating coverage over Earth’s more populous areas and lacking service at high latitudes.
The KA-01 satellites will be boosted to an orbital altitude of 630 km prior to becoming operational, using their Hall-effect electric thrusters. Kuiper will start service once 578 satellites are in their operational orbits, with the full constellation deployment being done in five phases.
Launch of the Kuiper Protoflight mission on Oct. 6, 2023. (Credit: Amazon)
Kuiper Systems has faced delays in getting its satellites to orbit and is now working against upcoming deadlines. The Federal Communications Commission (FCC) granted the Kuiper constellation a license in 2020 to operate over 3,200 Kuiper satellites, with a stipulation that half of them be launched and operated by July 30, 2026.
In addition, this license requires that the remaining satellites must be launched and operated by July 30, 2029. If the July 2026 deadline for half of the constellation’s satellites to be operational is not met, it is possible the FCC could restrict the constellation to using just the satellites already operating by the deadline.
Two prototype satellites, KuiperSat 1 and 2, were launched aboard an Atlas V 501 on Oct. 6, 2023 from CCSFS to prove out the system’s technology. The operational Kuiper satellites have many upgrades to their systems compared to the prototypes, and also use a dielectric mirror film to scatter reflected sunlight and reduce their brightness in the night sky.
The KA-01 mission is the heaviest payload ever flown by an Atlas V, which in its 551 variant is capable of launching up to 18,850 kg to low-Earth orbit or 17,720 kg to the same orbit as the International Space Station. The ISS uses a 51.6 degree orbital inclination, which is very similar to the 51.9 degree inclination that the satellites launched by KA-01 will use.
The Centaur for the KA-01 flight shown before it was stacked atop the Atlas. (Credit: ULA)
KA-01 will also mark the 250th flight of a Centaur upper stage atop an Atlas rocket and the 275th overall flight for a Centaur stage. The next Kuiper flight, KA-02, will also use an Atlas V 551 and the satellites for that mission are being prepared in Florida. Eight operational Kuiper missions, including KA-01, will be flown by the Atlas V before the type winds down its career.
There are also 38 Kuiper missions booked aboard ULA’s Vulcan rocket, along with 18 on the Ariane 6 family, 12 launches aboard New Glenn with options for 15 more, and three launches aboard the SpaceX Falcon 9. The Falcon 9 launches were added a few months after a shareholder lawsuit was filed alleging bad faith in the original launch procurement strategy.
KA-01 is the first launch in 2025 for ULA, and the first launch this year of an Atlas V. ULA had planned up to 20 launches this year using Atlas V and Vulcan, but Vulcan has faced delays to its next flight after an anomaly that occurred with one of the rocket’s SRBs on its second flight.
(Lead image: The Atlas V 551 for KA-01 seen at SLC-41 before its launch. Credit: ULA)
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