TAMPA, Fla. — SpaceX is proposing to use Starship to rapidly deploy its second-generation Starlink constellation, providing denser rural coverage without needing more than the 30,000 satellites it previously envisioned for the follow-on network.

The proposal is one of two revised configurations that SpaceX filed Aug. 18 with the Federal Communications Commission for Starlink Gen2, updating a plan submitted in 2020. 

The other configuration envisages continuing to use Falcon 9 rockets for launching Starlink satellites, and also does not involve a larger constellation or require more spectrum than what SpaceX outlined last year.

Instead, the revised scenarios for Starlink Gen2 aim to spread satellites more evenly across nine to 12 inclined orbits to provide denser polar coverage for rural subscribers, as well as national security and first responder customers, to make the network’s performance more consistent.

SpaceX said it prefers the configuration that uses its heavy-lift Starship rocket because it would allow satellites to enter service “within a matter of weeks after launch, rather than months.” The company recently accelerated work at its Starbase test site in Boca Chica, Texas, to prepare for Starship’s first orbital flight.

The Starship-enabled Starlink configuration comprises 29,988 satellites at altitudes of between 340 and 614 kilometers, across nine inclined orbits.

“By targeting multiple inclinations, these revised orbital parameters will more evenly distribute capacity by latitude ensuring better, more consistent global coverage,” SpaceX said in an FCC filing.

“SpaceX will also nearly double the number of satellites deployed in sun-synchronous orbit optimized for key throughput demand times and service to polar regions like Alaska, resulting in additional capacity for those chronically underserved areas. 

“The revised orbital planes enable ‘direct to station’ launch campaigns that capitalize on the ability of Starship to deliver satellites at a faster pace.”

The Falcon 9-launched configuration would spread 29,996 satellites across 12 orbital inclinations at altitudes between 328 and 614 kilometers altitude.

Although the Gen2 satellites will be “somewhat larger and generate more power than originally contemplated,” SpaceX said its analysis shows they would not interfere with other constellations, or increase the risk of debris-causing collisions in space.

As with the more than 1,600 Starlink satellites SpaceX currently operates in low Earth orbit at an altitude of around 550 kilometers, Gen2 spacecraft will rely on collision-avoidance software and on-board propulsion to mitigate debris threats.

The increasingly crowded space environment is a growing concern for businesses and regulators worldwide, as a rising number of megaconstellations plan to deploy thousands more LEO satellites in the coming years.

Satellite broadband operator Viasat has launched legal action against SpaceX in an attempt to compel an environmental review into its Starlink expansion plans.

“As the Commission has recognized, because SpaceX has invested in advanced propulsion capabilities for its satellites, collision risk with large objects is considered to be zero while the spacecraft are capable of maneuvering,” SpaceX said in the FCC filing.

“While SpaceX expects its satellites to perform nominally and deorbit actively, in the unlikely event a vehicle is unable to finish its planned disposal maneuver, the denser atmospheric conditions at the low altitudes proposed herein for use by the Gen2 System provide fully passive redundancy to SpaceX’s active disposal procedures.”

Even in a “worst-case scenario” where a Starlink satellite loses maneuverability and attitude control in operational orbit, a satellite in either proposed Gen2 configuration would reenter the atmosphere within four years and burn up.

At lower altitudes than satellites in the first-generation Starlink constellation and other megaconstellations including OneWeb, Gen2 spacecraft would spend less time illuminated by the sun, posing less of a reflection problem for astronomers.

SpaceX is asking the FCC for waivers to proceed with either configuration. 

One of the waivers concerns power flux density Ka-band downlink limits set by the International Telecommunication Union (ITU).

These limits rely on flawed calculations, according to SpaceX, because they were devised without the capability to scale up for non-geostationary constellations with more than 840 satellites.

The FCC had told SpaceX to get a “favorable” or “qualified favorable” finding from the ITU on its equivalent power flux-density (EPFD) limits before initiating services.

“Given the volume of pending EPFD filings, the ITU is unlikely to complete its evaluation of the Gen2 System and render an EPFD finding on a time frame that will match SpaceX’s aggressive constellation deployment schedule,” SpaceX said in a related FCC filing.

Without a waiver from the FCC, SpaceX warned it “would have to postpone providing the more capable and efficient service contemplated under this new constellation until the ITU completes its analysis, with many gigahertz of valuable spectrum remaining underutilized in the interim.”

Quelle: SN

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Update: 24.08.2021

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SpaceX Starship factory breaks ground on an even bigger ‘high bay’

 

SpaceX appears to have more or less broken ground on a new, even bigger ‘high bay’ assembly facility at its Boca Chica, Texas Starship factory.

Barely one year ago, SpaceX erected the first prefabricated steel sections of what eventually become its Starship factory ‘high bay’ – a spartan 81m (~265 ft) tall designed at the most basic level to shield final Starship and Super Heavy booster assembly from the elements. Situated near the southernmost tip of Texas and just a few miles west of the Gulf of Mexico, those “elements” can be less than pleasant at SpaceX’s primary Starship factory, ranging from sauna-like heat and humidity and mosquitoes the size of quarters to regular downpours, thunderstorms, tropical conditions, and even hurricanes.

While a great deal of work at Starbase is still done out in the open with little more than an umbrella as protection, SpaceX has nevertheless worked to find a middle ground where the most sensitive work (mainly structural welding) can be mostly shielded from wind and rain. First, SpaceX built a (relatively) tiny ‘windbreak’ too small for much of anything. Two years later, the windbreak is partially used for Starship nose section assembly – when a nose cone is stacked on and welded to a separate stack of four steel rings.

A few months after the triangular windbreak was fully finished, SpaceX started work on a larger box-like building that would eventually be known as the Starship factory’s ‘midbay.’ Standing around 45m (~150 ft) tall, the midbay was designed to support the process of assembling Starship tank sections from several stacks of 2-4 steel rings but was – for whatever reason – left too short to support the full Starship assembly process.

Instead, once Starship tank sections were finished, they would have to be rolled out of the midbay for nose installation. Eventually, in July 2020, SpaceX began assembling an even larger ‘high bay’ that would ultimately measure 81m (~265 ft) tall and 20-25m (65-80 ft) wide and deep – easily big enough to fit the company’s existing Falcon 9 or Falcon Heavy rockets with room to spare. More importantly, of course, the high bay was built to be large enough to support Super Heavy assembly from start to finish, giving SpaceX teams a sheltered place to build the largest rocket boosters in history.

As of August 2021, SpaceX’s midbay has supported the assembly of 10 Starship prototypes, 5-6 propellant storage tanks, and several ‘test tanks,’ while the newer high bay has helped SpaceX build three (mostly) complete Super Heavy boosters in 2021. However, working at full speed, SpaceX’s midbay is really only capable of supporting the assembly of one Starship tank section (and more general work on two) at a time and the high bay – while offering at least twice the covered surface area – appears to be limited to simultaneous work on two or three different stacks (boosters, ships, tanks, etc.).

As SpaceX slowly but surely treks towards the end of approximately two years almost exclusively dedicated to building ever-changing prototypes, it’s been clear for a while that the company would need to drastically expand its production facilities to produce the dozens of Starships and boosters CEO Elon Musk has been publicly dreaming of. Even at lower volumes, those existing facilities – while great for producing a dozen or more prototypes per year – would still become a chokepoint for the near-term production of a small fleet of operational Starships and Super Heavies.

In turn, Musk revealed that SpaceX was about to start building “a much larger high bay” adjacent to the existing structure in late July. On August 20th, a little over a year after assembly of the original high bay kicked off, SpaceX began the process of tearing up existing concrete for the even larger bay – breaking ground, at least in a sense. According to Musk, the newest addition to Starbase’s Starship factory will be about 10% taller (~90m vs 81m), substantially wider, and likely a bit deeper than the existing high bay, allowing for the installation of two side-by-side bridge cranes with tracks running the full width of the building.

With at least 2-3 times more surface area than the high bay, the new wide bay should give SpaceX enough space to simultaneously assemble something like 4-8 Starships or Super Heavy boosters. Depending on which direction SpaceX goes, the wide bay could also potentially be large enough for SpaceX to create the first true Starship and Super Heavy assembly lines, though that would be a substantial departure from Starbase’s existing approach to manufacturing.

Quelle: TESLARATI