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One of SpaceX’s many ambitious projects apart from colonizing Mars and achieve rapid rocket reusability is to build Starlink, a huge satellite constellation in low Earth orbit, which will provide fast internet connectivity around the world. The constellation could also represent a significant source of revenue that SpaceX would like to use to finance development of more advanced rockets and spacecraft.
Last Update: June 26, 2019
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- Starlink’s history and purpose
- Constellation parameters
- User terminals
- Project schedule
- Project financing
- Launching the satellites
- List of launches
- Safety and space debris
- Impacts on astronomy and astrophotography
Starlink’s history and purpose
In January 2015, SpaceX announced plans to build a large internet constellation, but the company did not talk about it much for a long time afterwards. It didn’t lift the veil of secrecy until May 2019 when the first batch of satellites for this project were scheduled to launch. However, even before that, a number of things could have been gleaned from various FCC filings. The design of the entire constellation has also undergone significant changes over the years. Eventually, the project became known as Starlink, the name inspired by the novel The Fault in Our Stars, according to Elon Musk.
SpaceX originally planned a constellation consisting of 4,425 satellites at altitudes around 1,200 km, which would later be supplemented by a set of 7,518 satellites located in orbits at an altitude of about 320 km. The FCC granted a license to SpaceX to operate the first 4,425 satellites in March 2018, which triggered an important countdown. The FCC requires satellite companies to deploy half of the planned number of satellites within 6 years of receiving the initial authorization. On top of that, the FCC requires all satellites to be in orbit within 9 years. If companies fail to meet these deadlines, they’ll be allowed to operate only as many satellites as had been deployed before the deadline.
In November 2018, SpaceX also received permission from the FCC to launch and operate the remaining 7,518 satellites. At the same time, SpaceX asked for the previous license to be modified. Instead of operating all 4,425 satellites at an altitude around 1,100 km, the company now plans to operate only 2,825 satellites there, while adding 1,584 satellites that would orbit at 550 km. As currently planned, the complete constellation would consist of 11,924 satellites in total:
- 1,584 satellites positioned at altitude of 550 km, split into 24 orbital planes with 66 satellites each, with 53° inclination (these satellites will be deployed first)
- 2,825 satellites positioned between 1,110 km and 1,325 km, split into several different planes with different inclinations (see table below)
- 7,518 satellites positioned at an altitude of 320 km (these will most likely be the last ones to be deployed)
The internet connection provided by Starlink will be particularly useful in remote areas and developing countries where people do not have access to the Internet, however Starlink will also compete with internet providers in areas where people might have slow or expensive access. According to the UN, currently about 57% of the world’s population does not have internet access, so the potential market is enormous.
SpaceX hopes Starlink will become a major source of revenue, which the company can then use to develop more advanced rockets and spacecraft and eventually enable the colonization of Mars. SpaceX’s annual revenue from its launch business is expected to max out at about 3 billion USD, while the revenue from Starlink could be around 30 billion. Elon Musk says SpaceX would like to control about 3% of global telecommunications revenue, which reaches approximately 1 trillion USD a year. However, SpaceX says it is not trying to replace existing telcos, but rather to cooperate with them.
The planned constellation will be huge, consisting of nearly 12,000 satellites when completed. For comparison, in 2019, there were only about 1957 functional satellites in orbit around Earth in total. Therefore, the SpaceX constellation would increase the number of active satellites in orbit sevenfold.
These satellites will be in orbits at altitudes between 340 km and 1,300 km and will eventually be interconnected using lasers (the first generation will not yet utilize lasers) and their signal will cover the entire Earth surface in the Ku (12–18 GHz), Ka (26.5–40 GHz) and V (40–75 GHz) bands.
The V and Ku bands will be used by the network’s users, while the V and Ka bands will be used to connect to gateways and for tracking, telemetry and control purposes. The 7,518 satellites located in very low Earth orbit will use V-band for all purposes. Here is a breakdown of the specific frequency bands used by Starlink:
- Transmissions from satellite to user terminals: 10.7 – 12.7 GHz
- Satellite to gateway transmissions: 17.8 – 18.6 GHz and 18.8 – 19.3 GHz
- Transmissions from terminals to satellites: 14.0 – 14.5 GHz
- Transmissions from gateways to satellites: 27.5 – 29.1 GHz and 29.5 – 30.0 GHz
- Tracking, telemetry and control (downlink): 12.15 – 12.25 GHz and 18.55 – 18.60 GHz
- Tracking, telemetry and control (uplink): 13.85 – 14.00 GHz
- V-band space-to-Earth transmissions: 47.2 – 50.2 GHz
- V-band Earth-to-space transmissions: 50.4 – 51.4 GHz
Satellites will communicate either directly with user terminals (see the section below) or with gateways, which will be typically located near major Internet nodes. SpaceX is currently authorized to operate the first six gateways that will be located in different places around the US:
These test gateways will operate in Ku band and SpaceX will use them “to deliver broadband data between the first-generation satellites of its NGSO system and terrestrial Internet exchange points”. Reddit user daedalus_j managed to photogragh these antennas near North Bend. They are located next to Level 3 Communications, a Tier 1 network.
In addition, SpaceX plans to initially operate two ground stations for telemetry, tracking and control – one on the US West Coast and one on the East Coast (in Brewster, WA).
And what kind of connection parameters will this constellation offer? According to SpaceX, users can expect “gigabit speeds” and very low latency at around 20 milliseconds, which is more than sufficient even for playing latency-sensitive online games. In contrast, the current satellite internet services are much slower and their main disadvantage is the high latency in hundreds of milliseconds due to the placement of satellites in the geostationary orbit at 35,000 km. This delay is noticable even during normal use, let alone when playing an online shooter.
Compared to conventional networks, satellites in low Earth orbit have some advantages. For one, light travels slower through fiber optic cables than it does in free space (in addition, the terrestrial data must be routed through many intermediate points which may not represent the physically shortest route). This means that Starlink should enable faster long distance communication, which might be useful for high-frequency trading and other applications. However, until Starlink is up and running, we do not know what kinds of plans will SpaceX offer and what kinds of limits it will set, and we do not yet know the actual speeds and latency that will be achieved in practice.
Elon Musk also revealed that Starlink’s network protocol “will be simpler than IPv6 and have tiny packet overhead”. Additionally, the network will provide “end-to-end encryption encoded at firmware level“.
The development and production of Starlink satellites takes place in Redmond, Washington, and SpaceX is not currently planning to move production elsewhere. The production of the first 60 satellites took a couple of months, but due to the total number of satellites required to finish the constellation, the production rate can be expected to accelerate over time.
They are the world’s first operational satellites equipped with ion engines that use krypton gas. Krypton is less efficient than the more traditional xenon, so bigger tanks are needed, but krypton is 10 times cheaper. The engines have a specific impulse of about 1500 seconds and will be used to move the satellites to their target orbit, then maintain it and eventually deorbit.
Satellites can track their position using GPS and a SpaceX-developed star tracker system. That enables the satellites to steer its antennas more precisely and also automatically avoid orbital debris and other satellites. Information about these objects from NORAD’s database is uploaded to the satellites.
Deployment of Starlink satellites is very unique. Falcon 9 upper stage starts rotating slowly along its Y axis and then the whole stack of 60 satellites separates. The system does not contain any springs, only the moment of inertia causes the satellites to slowly spread out over time. The satellites might even lightly bump into each other during deployment, but they are designed to handle it.
Each of the 60 satellites launched during the Starlink-1 mission has a mass of 227 kg, according to SpaceX. However, this is the first generation of satellites and the design is constantly changing, so the mass may be different on future missions.
The satellites have a very flat design so that SpaceX can fit as many of them as possible inside the rocket’s fairing. Each satellite is equipped with a single folding solar panel made of standardized cells.
Starlink satellites are equipped with one solar array instead of two, minimizing potential points of failure pic.twitter.com/bJirVr67fF
— SpaceX (@SpaceX) May 24, 2019
Each satellite is equipped with 4 powerful phased-array antennas. The satellites launched during the Starlink-1 mission are missing Ka antennas, but otherwise they are said to be essentially the same as future first-generation satellites. Next generations should eventually get laser interlinks. At the moment, the satellites are only interconnected via gateways on the ground, and Elon Musk said some gateways may also need to be placed on ships at sea to ensure global coverage.
Every 60 satellites represent about 1 terabit of useful capacity, but the total capacity might actually be 2-3 terabits. That means each satellite should have a capacity between 16 and 50 Gbps.
Elon Musk said that the cost to launch the satellites is currently higher than the cost to make them, which suggests that the production of one satellite costs no more than $500,000. Satellites are relatively inexpensive because SpaceX self-produces them and with so many satellites being made, economies of scale reduce the production costs.
Satellites are expected to be outdated after 5 years of operation and will have to be periodically replaced by newer-generation satellites. The short lifespan reduces the production cost of each satellite and also enables faster innovation. The company can also respond more quickly to changing customer demands.
The end-user will be able to connect to the Starlink satellites using a special terminal that looks like a flat disc the size of a medium-sized pizza. This device will have a phased-array antenna that can be steered electronically and therefore does not have to physically rotate to follow the satellites in the sky. Switching between satellites should be imperceptibly quick. The terminal will need a unobstructed view of the sky and SpaceX is aiming for the terminal’s price to be no more than $200. The antenna works even while moving, so it can be placed on a car, boat or plane.
In February 2019, SpaceX filed an application with the FCC for permission to operate up to a million of these user terminals in the United States.
The communication between satellites and terminals will be influenced by weather (rain, heavy clouds, etc.), but it is not clear at the moment how much of a problem this will be in practice.
Two test satellites, named Tintin A and Tintin B, were launched by SpaceX in February 2018 as a secondary payload on the Paz mission. With these two satellites, the company tested laser links between them along with communications with several ground stations that were deployed at various SpaceX facilities in Hawthorne, McGregor, Brownsville and Redmond. Another station was located in the Tesla building in Fremont and there were also three mobile stations placed on vans. These test satellites orbit at an altitude of 514 km.
SpaceX then began launching a larger number of first-generation satellites onn May 24, 2019, launching the first 60 units on the Starlink-1 mission. The FCC requires the entire constellation consisting of 11,924 satellites to be completed by November 2027 (and at least half of all satellites must be launched by March 2024). But even after the constellation is completed, SpaceX will not stop launching new satellites, because by that time it will be necessary to start replacing old satellites that were deployed at the beginning.
The company claims that a commercial service for Canada and northern parts of the United States after six launches are completed. If everything goes well, SpaceX said it could start providing Starlink services to telcos and other customers as early as late 2019.
SpaceX President Gwynne Shotwell estimates that completing the Starlink constellation might cost about 10 billion USD or more.
In 2015, Google and Fidelity invested a billion dollars in SpaceX and it is believed that the main reason was the Starlink project. US Air Force also contributed 28.7 million dollars for “connectivity demonstrations to Air Force ground sites and aircraft for experimental purposes”.
Elon Musk says SpaceX has enough capital to build a functional constellation of several hundred satellites. Obtaining additional capital would only be needed if something went wrong. But he said that SpaceX had no problem getting more capital – he said that in the last investment round there had been more interest from investors than needed.
SpaceX has not yet signed any customers, but negotiations are ongoing with strategic partners such as telecommunications companies in countries with poor internet access.
Launching the satellites
How does SpaceX plan to launch several thousand satellites in just a few years? The company announced that it intends to do so with its Falcon 9 rocket and the key to success will be its rapid reusability enabled by the much improved Falcon 9 variant called Block 5. Each Falcon 9 booster should be reusable at least 10 times and the company even wants to eventually achieve a 24-hour turnaround of a single booster.
If SpaceX’s plans come to fruition, the rapid reusability of Falcon 9, combined with several active launch pads designed for fast turnaround, could enable a large number of satellites to be launched every year relatively cheaply. On the first launch, 60 satellites will be deployed but the numbers might be different on future missions. Elon Musk expects to launch 1,000–2,000 satellites per year using Falcon 9 rockets. At least 12 launches are needed to cover the US and at least 24 launches for moderate global coverage. For uninterrupted service worldwide, there need to be operational satellites in at least six orbital planes.
Starlink will connect the globe with reliable and affordable high-speed broadband services pic.twitter.com/dWVvPwVWU4
— SpaceX (@SpaceX) May 24, 2019
The main limiting factor when launching the Starlink satellites is currently the size of the rocket’s fairing, not the rocket’s payload capacity. That means that using Falcon Heavy would not allow SpaceX to launch more satellites at a time because the fairing is the same size as the one on Falcon 9. Interestingly, the fairings used on Starlink launches aren’t equipped with acoustic tiles that normally protect the payload from vibrations and noise during launch. They might have been removed in order to increase available space inside the fairing in order to fit in as many satellites as possible.
SpaceX is developing the Starship vehicle which has a significantly larger payload bay, but according to Elon Musk, Starship is not required to complete the constellation. That said, Musk hopes that Starship will begin flying long before SpaceX launches all 12,000 satellites. Compared to Falcon 9, Starship launch costs are expected to be at least 5 times lower due to its complete reusability.
Elon Musk said that Starlink can start providing services after 400 satellites are launched but he added that at least 1,000 satellites are needed for the constellation to be economically viable.
List of launches
|Feb 22, 2018||Paz||2||512 km||Two test satellites, Tintin A and B, were launched on this mission as a secondary payload|
|May 24, 2019||Starlink-1||60||550 km||First batch of 60 Starlink satellites|
(More specific launch dates can be found on the Launch Manifest page.)
Safety and space debris
There are more and more objects in orbit around Earth – not just active satellites, but also spent rocket stages, various small and large pieces of debris, broken satellites, etc. Depending on the debris’ orbit, it can take months or even thousands of years for the objects to deorbit on their own. Thus, governments, companies and many experts are rightly concerned about the threat that space debris represents (see Kessler syndrome) as a result of deploying multiple large-scale satellite constellations planned by SpaceX and others.
However, SpaceX claims that the increased risk is not nearly as high as it might seem. Starlink satellites are small and there is an incredible amount of space around the Earth. In addition, the constellation is designed in a way to minimize the risks of creating space debris:
- Starlink satellites have their own engines and will be able to avoid a possible collision with other objects, whether they’re another satellite, a piece of space debris or a non-functional Starlink satellite.
- Satellites reaching their end of life (expected to be about 5 years) will be moved proactively to such an orbit that they will reenter the atmosphere within 1–5 years and the satellite will burn up. This process is much faster than the 25 years currently required by international standards.
- In the case of the 7,518 satellites operating at very low Earth orbit constellation, the problem of space debris kind of solves itself. The satellites will orbit at such a low altitude that they will need to actively maintain the required altitude using engines, otherwise they’d deorbit within weeks due to atmospheric drag. So even if a satellite’s propulsion fails or it stops responding to commands, the satellite will burn up in the atmosphere within a short period of time and will not contribute to the problem of space debris.
On top of that, Starlink satellites are designed to completely disintegrate after deorbiting. That means no part of them will hit the Earth’s surface where it might hurt someone or damage property. The exception are the first few dozen satellites that use an older design where certain components may not completely burn up.
Impacts on astronomy and astrophotography
Soon after launching the first sixty satellites during the Starlink-1 mission, it became apparent that the slowly spreading satellites were creating an interesting phenomenon in the night sky in the form of a moving string of lights. As this unusual phenomenon was very visible, it raised concerns among amateur and professional astronomers and astrophotographers. In addition, some radio frequencies used by Starlink satellites could have a negative impact on radio astronomy.
Elon Musk responded to the concerns by saying: “Starlink won’t be seen by anyone unless looking very carefully & will have ~0% impact on advancements in astronomy”. He also said that he sent a note to the Starlink team regarding albedo reduction, or the degree of reflectivity of the satellites. He also said that it shouldn’t be a problem to “tweak satellite orientation to minimize solar reflection during critical astronomical experiments”. Later, SpaceX issued a press release saying: “The observability of the Starlink satellites is dramatically reduced as they orbit greater distance and orient themselves with the phased array antenas toward Earth and solar arrays behind the body of the satellite.”
Additionally, Elon Musk said that SpaceX avoids using “certain lower Ku frequencies specifically for radio astronomy”. The National Radio Astronomy Observatory issued a statement, saying that the organization is working with SpaceX to analyze and minimize the potential impacts of the Starlink constellation on radio astronomy. For example, the creation of exlusion zones around current and future radio astronomy facilities is being considered.
SpaceX is not the only company operating or planning to create a global internet constellation, but most of them are designed for other purposes (Iridium, Orbcomm) or have a very limited capacity due to low number of satellites (HughesNet, Viasat).
The biggest potential competitors for Starlink are constellations from OneWeb, Telesat and Amazon, as well as the LeoSat project. However, SpaceX, OneWeb and Telesat are currently the only companies that have launched any test satellites for their large constellations.
SpaceX, unlike other companies, can launch its satellites to orbit using its own rockets, which provides considerable savings and gives them a great competitive advantage. However, Elon Musk said that SpaceX will never refuse to launch satellites for a competing constellation if they express interest in their launch services.
- June 26 – Added a new section about potential impacts of Starlink on astronomy and astrophotography
- May 26 – Added a list of past and future Starlink launches, added new pictures and information about the satellites’s design from the official website
- May 23 – Fixed incorrect information about Telesat not launching any test satellites
- May 22 – Article first published