Screenshot from ULA Webcast of the launch of Kuiper 1. Let’s go for the second time this year...
Mission Rundown: ULA - Atlas V 501 - Kuiper 1
Written: October 7, 2023
Lack in the Information Highway
This launch of an Atlas V marks United Launch Alliance’s 158th mission. It will launch the Project Kuiper Protoflight with two test satellites into a Low Earth Orbit (LEO). An Atlas V in a 501 configuration will launch from SLC-41, Cape Canaveral Air Force Station.
Atlas V tail number AV-104, a unique designation assigned to each individual Atlas rocket which began with Atlas-Centaur rockets in the 1960s. The Atlas-Centaur tail numbers (first with the AC-001) were continued by the Atlas I, Atlas II and Atlas III rockets which evolved the Atlas-Centaur design, before being replaced with the “AV” series for Atlas V.
ULA’s Atlas V 501 launched from SLC-41, CCAFS October 6, 2023 at 14:06 EDT
Atlas V 501 with Kuiper 1 launch in a 30 degree orbit from SLC-41 at Cape Canaveral
Kuiper 1 launched aboard United Launch Alliance’s Atlas V rocket, which flew in the 501 configuration for this launch. This was the ninety-seventh flight of an Atlas V rocket, one of the most proven and reliable rockets currently in service.
Atlas is a two-stage rocket, consisting of a Common Core Booster (CCB) and a Centaur upper stage. It can fly with up to five AJ-60A solid rocket boosters to provide additional performance for heavier payloads or where the rocket is targeting a higher-energy orbit.
However, with lightweight payloads like the Kuiper 1 Atlas flies without these additional motors. In the 501 configuration there's a 5 meter fairing and a single Centaur engine.
This launch will use the shortest version of the five-meter fairing, which is 5.4 meters (17.7 feet) wide and measures 20.7 meters (68 feet) in length. The composite structure is produced by Swiss manufacturer RUAG, who also makes a similar fairing for the European Ariane 5 rocket.
When Atlas V flies with a five-meter fairing, the fairing attaches to the interstage between the first and second stages, completely enclosing the Centaur upper stage as well as the payload. Because of this, the fairing must be jettisoned during first-stage flight.
By around three minutes, 40 seconds mission elapsed time mark Atlas reached space, and the fairing was no longer needed, so it could be safely discarded. A few seconds later the forward load reactor also separated. This device, which attaches at the forward end of the Centaur, helps to spread some of the payload’s weight across the lower half of the fairing.
Screenshot of Atlas V 501 with an X-37B as its payload. It's a tight fit for a space plane.
This inclosure of the Centaur 2nd stage makes the fairing far larger than necessary, and also make the fairing look too big. The fairing half is actually made of two ¼ sections, top and bottom bolted together in the middle.
Another reason for this design is the highly volatile Hydrogen gas ability to penetrate any material in fuel tanks, fuelpipes, valves and even the fairings themself.
The payload in the top compartment is pressurized with a dry nitrogen gas, preventing hydrogen gas from penetrating into the payload. With no oxygen there can be no fire or explosion so the payload is secure from this source of destruction.
The number of vent holes in the lower part of the fairings indicates that the hydrogen gas is present and abundant enough to cause a major accident. Liquid hydrogen tanks are in their supercooled state even more prone to hydrogen gas penetration and therefore even more dangerous around oxygen and electric spark sources.
The Centaur making a second burn to be disposed of into solar orbit has happened at least six times before with light payloads. The Atlas V Centaurs are being placed out of Earth's orbit despite the payload isn't going there.
The Kuiper 1 Payload
The Project Kuiper Protoflight Atlas V carried two prototype satellites for the upcoming Kuiper broadband satellite constellation, which needs to place half of its 3,236 satellites in orbit before July 2026. These satellites, known as Kuipersat-1 and Kuipersat-2, are set to be placed into a circular 500-kilometer low-Earth orbit inclined 30 degrees to the Equator.
Kuipersat-1 and Kuipersat-2 would finally reach orbit over five years after SpaceX launched its prototype Starlink satellites Tintin A and B. The Kuiper constellation, which got its name from the Kuiper Belt of objects orbiting beyond Neptune, is planned to provide broadband to unserved or underserved regions, and like Starlink, will be marketed to consumers.
Photo of X-37B in a fairing. The blue tiles are soundproofing. Maybe Kuiper 1 was in its cargo bay?
A good portion of Kuiper’s satellites are planned to fly on ULA Atlas V or Vulcan rockets, while Blue Origin and Arianespace have also received contracts to fly these satellites. A shareholder lawsuit has been filed by a pension fund that believes the Amazon board of directors acted in bad faith and did not properly consider flying the satellites aboard SpaceX and its Falcon 9.
This was only the 20th commercial mission for ULA, which has flown many national security and NASA missions aboard its rockets over nearly two decades. The Kuiper Protoflight mission was also the eighth and final flight of the Atlas V 501 configuration.
All future Atlas V flights will involve the 551 or N22 configurations. The N22 will be used for Starliner missions while the 551 configuration will be used by eight Project Kuiper missions, USSF-51, and ViaSat-3 EMEA.
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