It began with a tweet (as so many things do when Elon Musk is involved).
On Nov. 17, the SpaceX CEO announced he's terminating efforts "to upgrade [the currently expendable second stage on Falcon 9 rockets] for reusability," and instead "accelerating" development of a fully reusable, two-part rocket known as the "BFR."
Two days later, Musk clarified that BFR is actually not going to be called "BFR" any longer, but rather will have two separate names for its two separate parts. The new, mondo-sized rocket's reusable first stage will henceforth be known as the "Super Heavy" booster, and the rocketship that sits on top of it, which will carry cargo and passengers to the moon, Mars, and elsewhere, will be dubbed "Starship."
Fast-forward two more weeks, and we got our next clue about what could possibly become the most important mission that the Super Heavy-Starship pairing will be asked to do: Deploy dozens of small satellites into orbit in a single launch.
All aboard the SmallSat Express
SpaceX's SSO-A mission, which was contracted in its entirety by Spaceflight Industries and then sold piecemeal to multiple customers seeking to send smallsats to orbit, launched (and landed) successfully on Monday, Dec. 3. (This was before SpaceX's second Falcon mission this week, which successfully delivered cargo to the International Space Station on Wednesday, ended up splashing down in the Atlantic because of an equipment malfunction that prevented a successful land-landing.) Dubbed the "SmallSat Express," the rocket carried and deployed to carefully calibrated orbits 64 separate payloads from 34 separate customers.
In so doing, SpaceX gained invaluable experience that will come in handy as it begins, sometime next year most likely, a smallsat delivery project of its own.
A foreshadowing of missions to come
We discussed this project at length last week. Beginning in 2019, SpaceX plans to start assembling a constellation of nearly 12,000 "Starlink" satellites with which to provide broadband internet access from space.
SpaceX hopes Starlink will evolve into a business capable of generating massive profits -- and in excess of 75% of SpaceX's annual revenue -- within just a few years of deployment. But here's the thing: First, those satellites have to be deployed, and 12,000 satellites is more than six times the current complement of active satellites in orbit. It's going to take a ton (actually, many, many literal tons) of payload capacity to get them into orbit.
Luckily, BFR -- that is to say, Super Heavy and Starship -- can help with that.
We're going to need a bigger (space) boat
Prototypes of the Starlink broadband internet satellites that SpaceX proposes to put into orbit around Earth have a mass of 400 kilograms each. That's small for a comsat, but times nearly 12,000 satellites, it amounts to 4,800 metric tons of payload that SpaceX must put into orbit (and because satellites don't live forever, SpaceX will need to replace defunct comsats from time to time as well).
That's an incredible amount of mass -- more than 10 times the mass of the International Space Station. United Launch Alliance's Delta IV Heavy lift vehicle would need to conduct 170 missions (more missions than ULA has conducted in its entire lifetime) to lift that much mass into orbit.
Fortunately, though, SpaceX isn't restricted by the Delta IV's lift capacity. Boosted by the Super Heavy, SpaceX's own Starship will have the ability to lift 150 tons to low earth orbit. And that means that once Super Heavy and Starship are operational, SpaceX should be able to do the job in just 32 missions, or about 18 months' work at current launch rates.
Massive capacity, tiny cost
Of course, payload capacity is just one constraint on SpaceX's ability to create its Starlink satellite internet network. Cost is another limiting factor. When he first floated the idea back in 2015, Musk estimated that building out Starlink could ultimately cost as much as $10 billion. While that sounds like a lot of money, when you consider the sheer number of satellites Musk plans to launch, it actually isn't. It averages to less than $1 million per satellite. And SpaceX's Starlink budget looks even tighter when you consider that that $10 billion is supposed to pay for launching the satellites as well as just building them.
So, how does SpaceX keep launch costs down?
Once again, the answer is BFR -- er, Super Heavy and Starship. SpaceX explains that because both the Super Heavy lift vehicle and the Starship transport are built to launch, land, and relaunch over and over again without discarding any parts, "BFR provides lowest marginal cost per launch, despite vastly higher capacity than existing vehicles." Crucially, SpaceX is saying that the launch itself is cheaper than any other launch vehicles (Falcon 9 and Falcon Heavy included) -- not just the cost per ton of payload.
With no parts to replace, the cost of each Super Heavy-Starship launch will basically be the cost of the fuel consumed to launch and land the rocket (plus refurbishment costs, employee salaries, and other overhead, of course).
How much does that cost? SpaceX says fueling a Falcon 9 mission, for example, costs "$1 million or less." With 6.6 times Falcon's payload capacity, it makes sense that a Super Heavy-Starship launch should therefore cost no more than $6.6 million. If that launch can carry 375 Starlink satellites (150 tons divided by 0.4 tons per satellite), then each satellite's launch cost should be a mere $17,600.
Assuming SpaceX's numbers are accurate, then, it really does look like Starlink could be affordable to implement. And once implemented, it could evolve into the profits-driver for SpaceX that Musk hopes it will become. The only question remaining at that point will be: How does any other space company, lacking low-cost reusable rockets and lacking a high-margin satellite internet business with which to subsidize its space launch business, hope to compete with SpaceX?
I honestly don't know the answer to that.