Enter the MEGA Constellation
Part IV in an exploration of the promise and perils of Starlink and planetary-scale internet service providers
IIridium and similar generations of satellites constellations that were deployed in the late 1990s and early 2000s consist of 25 to 75 satellites operating at an orbital height of 780 km to 1400 km, which allowed these network to provide low-bandwidth data and voice connections with relatively high latency (60ms to 120ms) using just a small number of satellites (see part II of this series for details).
At the time, deploying and managing a network of 75 satellites in constant communications seemed like an engineering marvel. Fast forward twenty years to today, and the scale of the deployed and planned satellite constellations has increased by several orders of magnitude to thousands and even tens of thousands of satellites!
These so-called Mega-constellations are designed to provide low-latency, high-bandwidth data service to consumers (potentially tens of millions of customers). To accomplish these goals, the orbital height of the satellites is lowered to 550km or even 340km. This lower orbit results in a much lower travel time for the signals between satellites and the earth, substantially reducing the connection's latency.
But reducing the orbital height comes with a cost: the area that each satellite can cover is also reduced substantially. More satellites are needed in each orbit to compensate for the reduced service area, and the number of orbits must also be increased. More satellites are also needed as the number of users increases, as each satellite has a limited amount of throughput.
Mega First Mover: Starlink
Not all future mega-constellations will be designed the same way, nor will they try to compete to deliver data services to consumers (several others will target defense or industrial users). However, the implications for our planet will be similar. Therefore it is worth examining Earth's most successful mega-constellation, SpaceX's Starlink, in detail.
After an initial test of three Starlink satellites in 2018, SpaceX developed a satellite production facility and started planning for the first phase of their networks. The figure below shows the orbits for the first phase. Starlink's configuration provides coverage for most of the earth's population without having many satellites flying over the uninhabited areas of the poles (there are a few in an elliptical orbit to provide coverage for the poles).
Starlink satellites orbiting at 550 km high travel at 27,000 km per hour or more, circling the globe every 90-110 minutes. The lower the orbit, the faster the satellite moves to maintain its height. The Table below shows Starlink's plan for their network and the status of the Starlink Constellation.
Rather than launch LEOs individually, Starlink satellites are typically launched in large batches (except when just a few are hitching a ride on a ride-share mission). Currently, SpaceX's Falcon 9 rocket can launch 60 Starlink satellites simultaneously. Once operational, SpaceX's Starship system might launch as many as 400 at a time.
Before takeoff, the satellites are loaded into a carrier that holds them securely during the strains of launch and releases them once in space. The satellites are "flat packed" with solar panels and antennae unextended to minimize the space they take up.
Once the rocket and its payload are in an "injection" orbit (very close to the desired final orbit but not quite there yet), the individual satellites are released from the carrier attached to the front of the delivering stage of the rocket (usually the second stage).
To save fuel, thereby extending the useful life of the satellites, the devices slowly space themselves out and lift themselves (via onboard rockets) into the final operational orbit. Typically, a Starlink satellite will come into service three months after it is launched.
Living in LEO
There is no hard line between where earth's atmosphere ends and space begins. Even past the Kármán Line, there is a thin atmosphere, especially for objects traveling tens of thousands of miles per hour. The small amount of atmosphere these objects encounter makes them slow down, thereby losing altitude until they eventually fall back to earth. The lower the orbit, the worst the problem of atmospheric drag becomes.
The International Space Station has been in Low Earth Orbit for over two decades and has a lot of surface area, so its orbit is constantly decaying. To solve this problem, the ISS is periodically lifted back into higher orbit using either the ISS's two main rocket engines or the engines of docked spacecraft. Yearly, the ISS burns about 7.5 tonnes of fuel to maintain its orbit, costing $210 million to sustain its orbit (the fuel cost is minimal, but getting it to the ISS is very expensive).
While fuel can be delivered to the ISS, it is impractical to refuel an LEO satellite, so once it uses up the fuel it is launched with, a satellite in LEO will experience orbital decay until it burns up on reentry (hopefully within 5-10 years after its useful life). So no matter how robust the electronics and other components are, the useful life of a LEO satellite is limited. As such, spare and replacement satellites must be delivered into orbit to maintain a satellite constellation.
The need for constant replacement is one significant difference between satellite internet infrastructure and fiber optic cable installed on earth. Fiber optic cables deployed in the 1990s along the highways of my home state are still in use today and just as fast (the electronics that connect to the fiber is the "slow" part of any fiber connection, and this part of the system has been upgraded many times since 1990).
Satellite to Satellite Communications
The first generation of Starlink satellites act as a relay between users and ground stations and can communicate via radio between satellites (similar to the Iridium constellation described in part II). Newer generations of the Starlink satellite use light from small lasers to communicate with one another, increasing the connection's bandwidth and speed.
New satellites are being added to the Starlink network monthly, if not weekly. Several excellent websites track the development of Starlink and similar systems (OneWeb, for example) and provide the current status and location of each satellite in the network up to the second. The image below shows a screenshot of the status of the Starlink network from one of these websites, satellitemap.space. Here are some of the sites for tracking Starlink and the development of other mega-constellations.
Back on Earth
Starlink customers use a terminal with an antenna for communicating with the network overhead. The form factor can vary, but the smaller terminals use an antenna on a motorized mount and beamforming technology to focus on the satellites as they zoom overhead. Other designs are large, flat antennas for mounting on an aircraft, recreational vehicle (RV), or ship.
Starlink systems have been authorized for use in various applications besides residential and commercial use. They are especially popular with people who spend a lot of time traveling or living in an RV.
Commercial aircraft are also an emerging customer for Planetary ISPs. Commercial airlines that offer onboard internet access often do so via a connection to ground stations, which offer spotty and slow connections (the plane essentially acts as a high-flying hotspot) or through existing satellite systems. Starlink and similar services can substantially increase the bandwidth and reduce the latency for in-flight Wifi. Starlink has signed a contract to deliver onboard WI-FI for JSX airlines (a short-haul carrier in the southwest) and has conducted several tests with Delta airlines.
Quality of Service
Connection quality is directly related to the number of satellites over an area, the number of ground terminals those satellites have to service, and the usage of the service by end users. As such, bandwidth and latency experienced by Starlink customers vary with location and time. As more customers come online, the bandwidth can decrease, and latency can increase since the limited number of satellites overhead have to service more terminals. Likewise, when more satellites come online, the network capacity increases.
Adjustments to the constellation can also change the quality of the connections. Currently, the orbital height of Starlink satellites is 550 km, but the next generation of Starlink satellites will operate at a shallow orbit (340 km), dramatically reducing users' latency.
As of the end of 2022, Starlink has over 1,000,000 customers in 40 countries, with more customers and countries coming online quickly. SpaceX can't launch satellites fast enough to meet the demand for service, and as of this writing, they are floating the idea of data caps in some locations to limit high-volume users during peak demand times; data caps are already used for RV customers since they might roam into a geographic area that is already saturated with users.
Applications Beyond Internet
Besides providing internet access, there are several other services that Planetary ISPs can provide.
SpaceX has received approval from the FCC to deploy “direct-to-cellular” technology in its satellite fleet and has signed a deal with T-Mobile to deliver cellular services (at least data services) using existing smartphone handsets. This service might not include voice services at first, but would be allow for texting and low-bandwidth data services. Specialized handsets would allow for more applications.
In addition to allowing the passengers to keep up with their slack messages and emails, Planetary ISPs will allow better tracking of airplanes in uninhabited or sparsely inhabited parts of the world. When Malaysia Airlines Flight 370 disappeared in 2014, it was well outside any radar tracking and was initially presumed to have crashed somewhere in the South China Sea. Eventually, data from an Inmarsat satellite in GEO orbit indicated that it was last in the southern Indian Ocean, a vast area that is not monitored.
Even though there are no Internet consumers in the southern Indian Ocean, that area is now well covered by mega constellations like Starlink. These mega constellations could be used as a transponder network to locate aircraft and boats of all sizes.
In an interesting development, researchers from University of Texas at Austin have been able to use the radio emissions from Starlink satellites to determine one's location on planet earth. Lead researcher Todd Humphreys had originally approached SpaceX in attempt to co-develop an alternative GPS system based on Starlink, but was rebuffed, perhaps understandable as such a project was a distraction for Starlink. However Mr. Humphreys continued his work sans Starlink and has developed a basic GPS system based on Starlink.
Hundreds of Millions of dollars are spent by high-frequency traders to improve the speed of long-distance networks between exchanges. The Wall Street Journal reports that several trading firms are looking at Starlink as an alternative to land-based microwave and fiber networks. One startup is looking to launch a satellite constellation just for high-speed trading.
J Cooke, founder of London-based startup Azuries Space Mission Studios Ltd., has designed a satellite constellation that he projects will typically be about 20% faster than subsea fiber. Unlike Starlink, which plans to launch tens of thousands of satellites, Azuries’ proposed Angel network would have just 111 satellites. Mr. Cooke’s stripped-down constellation would be optimized to deliver data from New York to London, from Chicago to Tokyo and on several other routes important to traders.
The total price tag, he estimates, would be $155 million. Mr. Cooke, who is still raising money and has yet to launch any satellites, says his network could be up and running within three years of the startup closing its seed round.
—High-Frequency Traders Eye Satellites for Ultimate Speed Boost, WSJ
Can we put the Internet in Space?
Content Delivery Networks or CDNs are ways for platforms and providers of streaming, photo sharing, and other high-bandwidth services to buffer or store content at locations closer to the user. For example, a popular Netflix movie will be automatically stored on a CDN, whereas a rarely watched film will be stored only in the platform's primary data center.
Currently, all the servers and services that a Starlink customer is accessing (including content on a CDN) are located back on earth, requiring an eventual connection to the land-based Internet and incurring the delay needed for the signal to travel back to earth. Placing CDNs in space would bypass the need to return to earth for the content.
It might seem far-fetched, but "unmanned" data center technology already exists. In 2018 Microsoft placed a data center in a waterproof container and sunk it off Scotland's Orkney Islands as an experiment to see if cooling costs for a data center could be reduced by placing it in the ocean and if data centers could be operated entirely remotely, after two years of operation, the project has been deemed a success. Microsoft wants to expand this idea into production data centers for its Azure cloud service.
Such a system could be deployed in space and would not need to be particularly complex—lots and lots of fast storage is required, not high-performance computing. Placing CDNs in space would save bandwidth and enhance the user experience. And in countries with many Starlink or other mega constellation users, using a data center directly tied to the network would be a logical choice. [Note: You might also have seen that there are several efforts to return humans to the moon. One company is already trying to figure out how to put data centers on the moon: Florida Startup Moves Closer to Building Data Centers on the Moon.]
Next Post: Mega Motivations: Current Projects.
And ICYMI here is the previous post in this series.
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