Access to the internet is essentially a requirement for all gerbils. Most of us here on TR get our home internet delivered via a wired connection. Usually, that means copper in the form of cable or DSL. Others are fortunate enough to have the option of fiber. For those not using a wire, some may choose to use a cellular connection, while a small percentage might take advantage of fixed wireless to exchange bits. Each option comes with their own plusses and minuses both technical and economic. Very few, however, would make the choice of going with a satellite-based ISP—unless that is their only option. SpaceX is looking to change that with Starlink, and it all starts now.
A brief history of SpaceX
SpaceX’s rocket launches and the clients that pay for them have created a financially stable and sustainable business. SpaceX has successfully launched 17 missions that supplied cargo to the International Space Station (ISS), including the first demonstration mission of the new Dragon2 capsule. This capsule is expected to launch humans to the ISS within a year. The company has also launched dozens of communication satellites for private businesses, along with multiple US government satellites. That’s all well and good, but SpaceX’s long-term goal is to take the next steps of reaching out into (and beyond) the solar system to send payloads, scientific or human, to other planets—most immediately, Mars. Admittedly, this is a pretty ambitious goal, but this way-out-there thinking is what’s driven the company to do things others thought impossible, or never seriously considered.
The second Falcon Heavy flight. Source: Me!
The company has pioneered various space-tricks, many of which revolve around the re-use of components. Starting with the 11th ISS cargo mission, SpaceX started re-using the Dragon capsule instead of building new ones each time. In 2015, SpaceX pulled a card from sci-fi novels and accomplished what most considered to be impossible by landing the first stage of their rocket on a landing pad. In 2016, SpaceX upped the game again by landing in the middle (figuratively speaking) of the ocean onboard a large floating barge. In 2018, during the Falcon Heavy test flight, it accomplished another milestone by successfully landing two first-stages on land. Earlier this year, on the second Falcon Heavy flight, SpaceX was able to successfully land all three first-stages, two by land and one by sea.
The goal of component re-use is primarily to bring down the cost of space travel. For reference, the cost of a Space Shuttle launch was about $1 billion each trip. Granted, the Shuttle could deliver about 28 metric tons to low-earth orbit (LEO) while the standard Falcon 9 can only do 23 tons, but SpaceX’s own website lists the price of a basic Falcon 9 launch at just $62 million. Access to LEO is good, and being able to lob huge satellites toward a Geosynchronous Earth Orbit (GEO) is great too. Going to Mars is a whole other ballgame, though.
Back in 1969-1972, the mighty Saturn V powered the historic Apollo missions to the moon. The combined mass of the CSM & LEM was around 30,000kg. SpaceX’s largest currently operational rocket, the Falcon Heavy, can only launch about 17,000kg to Mars. Of course, the trip to the Moon only took about three days. The duration of a trip to Mars varies depending on the orbital distance between the planets and how much fuel is available, but it would be something more like nine months. Today, no rocket exists that can lift enough mass to make a manned Mars mission feasible.
However, SpaceX has a plan. It’s called Starship—formerly known as BFR, MCT, and ITS. Starship will be powered by 38 Raptor engines and is expected to offer almost twice the thrust of the Saturn V. SpaceX also intends to refuel the rocket in orbit. That will purportedly allow it to carry around 100,000kg to Mars.
All of that is some pretty ambitious technology, but research and development isn’t cheap. There’s no government footing the bill to get human butts to Mars. That means Elon Musk and SpaceX must find another avenue to pay for the development of this plan, and that avenue is Starlink.
Look to the Stars…for Internet?
Back in 2015, SpaceX announced plans to develop a global satellite-based internet service. It won’t be alone in that space; HughesNet, along with some other options in partnership with Dish Network or DirectTV, are established players in the satellite internet provider game. Frankly, satellite-based internet is unacceptable for most consumers—especially for those gerbil in nature—owing to its extremely limited bandwidth and incredibly high latency. Because of the extreme latency, anything that needs near-real-time communication is pretty much out the window. That mostly affects online gaming, but even things as simple as VOIP can fail. Some services, like the PlayStation Network, will simply refuse to operate with ping times in the four-digit range. The reason for the extra latency is simple physics.
Satellites that provide internet are largely based way out in GEO. This means that the satellite is at roughly the same place in the sky relative to a single point on the ground. That’s a good thing for most use-cases. A consumer will have a dish located somewhere on their property that is pointing to a specific place in the sky, because that’s where the satellite is orbiting. The trade-off for maintaining a fixed place in the sky is that you have to be pretty far away above the surface of the earth: around 36,000km, to be semi-specific.
Falcon Heavy demo flight. Source: Me again!
So, why not put satellites in LEO? The upside to LEO-based satellite internet is that the latency is around an order of magnitude lower. Instead of talking 100’s of ms, you’re talking 10’s of ms. In fact, by some calculations, it may be faster to communicate long distances via satellite than fiber due to fiber’s approximate 30% speed of light slow down (by my quick math, if the linear distance is greater than four times the satellite’s height, satellite would be faster). That all sounds great, but of course there’s a catch: LEO is far from stationary, so you need a lot of fast-moving satellites to maintain coverage. This setup is called a “satellite constellation.”
From a ground-tracking standpoint, a single dish pointed at a fixed point in the sky won’t cut it for constellation communication. Instead, the receiver would have a much wider view, something like 45° of the sky. Over time, multiple satellites would pass in and out of that cone. Such a client device would have logic built-in that would let it know where the satellites are, where they’re going, and handle seamless handoffs between them. Those of you who have worked with Wi-Fi zero-handoff know how tricky this was, until recently.
In addition to the latency benefits, Starlink could offer significantly higher bandwidth. Rather than having a handful of satellites serving the entire continental United States, you might have a couple hundred that are covering that same area. As a result, the bandwidth isn’t spread nearly as thin, so more is available to any individual client.
SpaceX has worked toward deploying such a satellite infrastructure for a while now. The company’s intent is to have thousands of satellites in LEO, between 500-700km about the earth, with a user-base of a million clients. So far, Starlink is still in the development phase, but that’s about to change. Back in February 2018, SpaceX launched 2 prototypes, called Tintin-A and TinTin-B. They were proof-of-concept satellites that piggybacked on a large communication satellite launch (Paz, a Spanish imaging satellite). For the last 15 months, SpaceX has been testing various aspects of their system. While many details of the overall project are still unknown, 2019 is supposed to be the year that SpaceX launches a 1.0 version of their communication hardware.
Future Starlink satellites are expected to make their way to space on dedicated SpaceX launches, rather than as secondary payloads. Most of SpaceX’s payloads have been either two small or medium size satellites or, more commonly, a single large satellite. These are mounted on top of the second stage of the rocket and are kept protected inside a fairing.
Most communication satellites, which rest in GEO, tend to be big and fill up the mass and volume restrictions of a rocket by themselves. A larger satellite dish is required to receive signals in GEO, and more onboard fuel is needed for station keeping. For most launches, the chief limitation is the rocket’s mass-lifting ability, rather than volume-carrying capacity. Along those lines, a SpaceX Falcon 9 rocket can deploy a payload with three times the mass if it is going to LEO instead of GEO. The farther in orbit your payload is meant for, the more energy it takes to launch the same payload. The same math means that the further out your payload is going, the less mass you can launch with the same energy.
SpaceX designs its own rockets, and the company knows exactly what their capabilities are. Instead of large communication satellites, what SpaceX has done instead is develop small satellites. SpaceX can clearly optimize the dimensions, the center of mass, and other physical properties of the rocket to suit the needs of launching Starlink. It can also intentionally design the shape of the individual satellites to maximize the amount of space inside the rocket fairing. SpaceX’s current fairings are 5m in diameter and 13m in length; for the initial Starlink launch, SpaceX found a way to Jenga sixty satellites inside the fairing.
Another difference between LEO and GEO is the rate of decay. A typical GEO satellite can stay in its orbit for over ten years before it runs out of the fuel it uses to stay still. Most LEO satellites have a lifespan closer to five years. There are negatives and positives to this limitation. The positive is that a LEO satellite will de-orbit itself at the end of its life, or, in the event of a complete failure, will deorbit after a few years with no input needed. In GEO, reserve fuel must be kept until end-of-life, at which time the satellite burns its thrusters to put the satellite in a “graveyard orbit” where it is out of the way, and can’t interfere with other satellites. Of course, the big negative to LEO is that five-year lifespan.
Let’s get ready to tumble
As of the time of writing, SpaceX is scheduled to launch the first dedicated Starlink mission on Thursday, May 23 2019 at 22:30 EDT (0230 GMT on May 24). This will be a Falcon’s heaviest payload, even including the two Falcon Heavy launches. It doesn’t need to go quite as fast as other payloads, though: since it’s going to LEO, it only needs to get up to 26,000 km/hr.
As you may recall, SpaceX also has a knack for landing its boosters after they have launched so the company can reuse them. Fittingly, the booster flying this mission has already been used twice. For lighter payloads, there’s enough fuel left-over to land the booster on a concrete pad south of the launch pad, but given the enormous mass of this launch, the booster will instead land on a drone ship used for down-range landings. That barge will be sitting off the coast of North Carolina, about 680km away from Cape Canaveral here in Florida.
Booster being offloaded from the Drone ship after launching Beresheet satellite to the moon. Source: Still me.
The deployment of the satellites will be unique. Over the course of about one hour, the second stage will begin to rotate like a rotisserie. As it comes up to speed, it will eject the individual satellites at specific times. This rotation will give it centrifugal force and will assist in spreading out the satellites using minimal onboard propulsion. One of the risks of deploying so many satellites is that there’s a good chance that some of the satellites may bump into each other after they are deployed. According to SpaceX, this has been accounted for in the design and they are made to handle some bumper-car-ing.
In a way, Starlink is the pinnacle in satellite vertical integration. SpaceX controls everything, from the rocket, to the launch, the payload, and the fairing. Obviously, this reduces the cost compared to outsourcing. While the company has been tight-lipped regarding the cost of the satellites, Musk said that the rocket and launch costs were more than the satellite manufacturing costs. If you’ll indulge me while I speculate, I would estimate a cost of around $35 million for the launch, and maybe another $25 million for manufacturing and setup of the individual satellites. That puts the per-satellite cost at around a million bucks, according to my back-of-the-napkin math. For perspective, the Iridium NEXT satellites have a per-satellite cost around $12 million, all-inclusive.
SpaceX is estimating that around 1,200 satellites will provide “good” coverage over the whole globe. The inclination of the satellite’s orbit determines how much of the earth it covers. The ISS is at a 52° inclination which means that during its orbit, it passes 75% of the globe. As with most things space-related, the lower the inclination, the more fuel-efficient it is to get to orbit. The higher the inclination, the greater percentage of the globe is covered and the more useful the satellite is. Starlink’s satellites are going to be placed at a 53° inclination which will cover 75% of the earth’s surface, but 95% of the world’s population.
From a bandwidth standpoint, Elon said SpaceX are estimating about one terabit of bandwidth for the 60 satellites that are launching. Hypothetically, 10,000 simultaneous test users would each get 100 Mbps at that rate. As the number of satellites increase, the available bandwidth increases as well. For a lot of people served by Starlink, it will be the highest-throughput transfer option available. By the way, instead of a dish, the Starlink receiver will be roughly the size of a pizza box. Inside, there will be an electronically phase-controlled array of antennas.
As we said, on the first launch there would be 60 Starlink satellites. This will get the testing started. According to SpaceX, about six launches would be enough to provide salable coverage. Because SpaceX can build them as fast as it can afford and launch as frequently as it can allocate rockets, the company completely controls the roll-out timing. While SpaceX hasn’t given a specific timeline, six launches could be done every month or two, in theory. That could work out to moderate-volume testing somewhere in the next six months to a year.
The long-term plan is for the number of satellites to be over 10,000. A few different scenarios are speculated as options for orbital arrangement. The one I personally like is a plan of multiple constellations at different orbital heights. In this scenario, users would be connected to one of a thousand or so satellites at the lowest height, say 500km. Beyond that, there might be 50 satellites in a 700km orbit which would serve as the trunk and would talk to the ground stations. Each of the 500km satellites would use lasers to route traffic through to the 700km satellites before being sent back down to earth. This would allow for redundancy and simplify the satellite-satellite links. This is all speculation, as SpaceX hasn’t announced specific plans on how or when it will roll that out. We do know that this initial launch does not have the hardware to do satellite to satellite cross communication, though.
There are multiple technical curiosities that will be answered following the launch. The satellites are currently inside the payload folded up like origami. It’ll be very interesting to finally see their final shape. They’ll have to open their wings like a butterfly to deploy the solar planes for power. Speaking of solar panels, the information SpaceX has given is that each satellite would have around 2kW of solar power generating potential. Mathematically, all 60 combined would generate 50% more power than the eight arrays on the ISS (or about six times fish’s house).
Most satellites have onboard thrusters and reaction wheels used for various purposes: getting to final orbit post-deployment, ejection and separation from the rocket, staying where they’re supposed to, and moving to an end-of-life orbit. The Starlink satellites are making use of Hall-effect ion thrusters. That means they use electricity to generate a magnetic field which accelerates the onboard propellant out a nozzle, pushing the satellite in the opposite direction. Normally xenon is used as the propellant, but to cut costs SpaceX is going with krypton—useful should we ever need to deploy a planetary shield against an evil Superman.
Making Space personal
I have a personal love (ok, obsession) with all things Aerospace. I love rockets, launches, and orbital mechanics. However, my love for airplanes and airports is a much more tangible thing than my love for grown-up space toys. I was very excited following the design of the Boeing 787 and that got to come full-circle with the couple business trips I’ve flown on them. Space doesn’t have that same connection. A random communication satellite doesn’t directly impact my life, especially since I don’t have satellite TV. Maybe if you are someone that uses a satellite phone, watching a rocket launch that carries an Iridium satellite would provide that connection. It may mean more that you could be talking to that very satellite at one point down the road.
SpaceX DM1 launch. Source: This lucky guy.
The technology and science of space flight is the part that is inspiring and motivating for my engineering brain. Living in Florida, it is convenient for me to go over and watch launches. While I very much enjoy it, the payloads are usually the least-interesting part because they are not personally relevant. With Starlink, the payload is just as exciting as the launch for the first time in a while.
Of course, people are more interested in things that impact them personally. Well, the internet is something that touches everyone. By the end of 2020, the rocket that carries these first nodes might be your gateway to the internet. Starlink could help bridge the gap and bring space into the thoughts of the everyman. This is a case where people can say, “I watched this rocket go up, I saw the payload deploy, and I’m currently using that payload to connect to the internet.” I think it’ll be very interesting to see how this all goes.
Even for those who aren’t rabid space fans, Starlink should be a win-win. For those without good options for broadband—particularly in rural areas—it could be a godsend. That market would be SpaceX’s to lose. It should basically come down to speed, pricing, and a lack of data usage caps (well, I can dream). For those of us who already have decent options, Starlink may still work out to be a better choice.
Adding a competitor to the market will probably make the existing players up their game to compete. It was no coincidence that, when Google Fiber was announced and started to roll out, the cable and telco providers started offering higher speeds and decreased their prices for premium tiers. Competition is usually a good thing. It’s also worth mentioning that 5G cellular service will be rolling out soon. In fact, the initial test markets in the US are being done in stationary settings with users using it as their home connection. I very much look forward to all of these new options reaching the hands of us users.
Hopefully in the next few months we’ll get some more details, specifically with regards to timeframe and constellation setup. I have to give major kudos to the team over at SpaceX for being willing to put themselves out there and develop something completely new. Of all the various companies that have attempted this idea, most have either given up or gone bankrupt trying. I wish the best to Elon, Shotwell, and their team, and I’m looking forward to being on the beach to watch this historic launch.