SpaceX Mega-Starship
What comes next after a rocket with 3X the power of Saturn V
Starship is a prodigiously powerful vehicle, with three times the thrust of a Saturn V moon rocket and twice the payload – plus fully reusable! However, even this enormous vehicle lacks the lifting power necessary to create a city on Mars, Elon Musk’s enduring vision. Hence he is already planning the next evolutionary step in SpaceX’s rocket building program.
“Starship will lengthen in the next few years. 10 years from now, there will probably be a much wider diameter Starship too.” ~ Elon Musk/X
“Probably 18m [diameter] for next gen [launch] system” ~ Elon Musk/X
Elon has yet to name this behemoth vehicle, although ‘Starlifter’ seems appropriate considering its capabilities and antecedence. An 118m high x 18m diameter vehicle could carry four times more than Starship, putting it at ~1,000 tons payload with 4,000 cubic meters of pressurized volume. This would allow extremely large pieces of equipment to be launched fully assembled, e.g. a full scale propellant production plant or nuclear reactor core, significantly reducing the installation work required on Mars. More importantly it would reduce the launch cadence from 135 per month for Starship, down to 33 for Starlifter, a far more manageable figure.
Of course engineering such a beast would be challenging to say the least. For example Starship will have 44 Raptor engines in total, which suggests Starlifter would need 176, if the same engines were used. SpaceX always seeks to reduce the complexity of their systems, so it seems likely they will produce a significantly more powerful engine specifically for the Starlifter vehicle.
“Raptor [version] 2 has significant improvements in every way, but a complete design overhaul is necessary for the engine that can actually make life multiplanetary. It won’t be called Raptor.” ~ Elon Musk/X
Ideally this new engine would be around ten times more powerful than Raptor, i.e. produce ~2,800 tons of thrust, reducing the engine count to roughly 17 in total. This would provide adequate redundancy in case of an engine out, plus minimize the amount of pipework, hence reduce the overall complexity and increase reliability. Conventional wisdom suggests big engines suffer from combustion instability, certainly the case for the F1, the main engine used on Saturn V. Fortunately SpaceX employs powerful computational fluid dynamics to model the combustion process and will likely use some form of staged combustion to help minimize any instability. While the technical challenges are enormous for Starlifter, it would raise the bar for what is possible in space, opening myriad new possibilities...
Science vessel
Due to its huge payload capacity, Starlifter could be fitted with a small propellant production plant powered by a miniature nuclear reactor, similar to those used on nuclear submarines. This would allow Starlifter to explore our entire solar system, with a portable laboratory onboard and sizable crew. To illustrate: a trailblazer science mission could launch from Earth and refuel in low Mars orbit (using Mars colony tankers), allowing it to journey to the outer solar system. First stop would likely be Jupiter, where it could land on a Galilean moon i.e: Io, Europa, Ganymede, or Callisto. During the exploration process Starlifter could produce enough propellant to hop to the next major moon, until it had visited everything of interest in the Jovian subsystem. Then on to Saturn…
Asteroid mining
If Starlifter can be refueled at Mars or Ceres, it could reach anywhere in the main asteroid belt with propellant to spare. An ore refinery plant could be carried on Starlifter, allowing it to return with high value materials instead of unprocessed ore. In fact some materials might be so valuable it would be more profitable to offload the refinery plant to make room for additional cargo. Comparatively little propellant is needed to leave an asteroid and descend towards the sun, assuming atmospheric braking can be used at the destination. Overall Starlifter could haul 1,000 tons of noble metals or rare elements to wherever needed, e.g. Earth, Mars, orbital construction yards etc, at more than reasonable profit. For example, a thousand tons of Palladium would be worth ~$30bn, assuming industrial applications can be found for this extremely rare metal.
Mars city
“To build a city on Mars that can grow by itself likely requires at least a million tons of equipment, which would therefore require >$1000 trillion, an obviously impossible number, given that US GDP is only $29T. However, if rocket technology can be improved by 1000X, then the cost of becoming sustainably multiplanetary would drop to ~$1T, which could be spread out over 40 or more years, so <$25B/year... Starship is designed to achieve a >1000X improvement over existing systems and, especially after yesterday’s booster catch and precise ocean landing of the ship, I am now convinced that it can work.” ~ Elon Musk/X
Elon wants to build a Mars settlement that’s big enough to become self sustaining, which will probably take a city of a million people. Constructing accommodation on a virtually airless world would be difficult – except SpaceX has a work-around. Many more Starlifters will land on Mars than depart, because producing the enormous amount of propellant needed to return all these vehicles is hardly a priority. Most of the colonists and colony building equipment will remain there indefinitely, so the amount of return payload should be minimal. Hence, every time a Starlifter lands on Mars they are essentially emplacing a stainless steel skyscraper in a municipal area, ready for human habitation. Roughly twice as many cargo Starlifters will be sent compared to crew vehicles, which should provide plenty of room for a growing population. Hence by reusing Starlifter on the surface they could build Mars city in only a few short decades. So the plan is to mass produce Starships/Starlifters and keep pushing them to Mars until the city is complete – ready for the next evolutionary step in space technology...
Mars express
“We can certainly see a way to get to Mars in under three months and I think ultimately you'll be able to get to Mars in under a month.” ~ Elon Musk/Recode
No doubt Elon wants to transition to nuclear propulsion to speed the Mars transport process. Starlifter could be used to construct a sizable transport vehicle in Low Earth Orbit (LEO), because it can carry all the structural beams, sheet metal, welding equipment etc with comparative ease. To give some idea of scale, the Nuclear Transporter’s engines could mass 1,000 tons each, and multiple engines would be required for redundancy. Once the Transporter is complete, it could be loaded with people and cargo in LEO, transit to Mars orbit in less than a month then use Starlifter to shuttle everything down to the surface. Likely this will increase the Mars transport capability by an order of magnitude, because such a powerful vehicle could operate continuously, instead of waiting for Hohmann transfer windows.
Big prize
“This Starship is designed to traverse our entire solar system and beyond to the cloud of objects surrounding us. A future Starship, much larger and more advanced, will travel to other star systems.” ~ Elon Musk/X
SpaceX want to make us multiplanetary, but that’s just part of the iterative process on the way to interstellar. If a nuclear transport can reach Mars in a month, more powerful vehicles could reach the nearest stars in under a decade, fulfilling Musk’s vision of an inspiring sci-fi future.
In conclusion
SpaceX will make hay while the sun shines with Starship, until they overcome all the challenges with Starlifter. This more powerful vehicle is an evolutionary step that promises to provide the additional lift required to transition from Mars landings to full-scale colonization. Overall the Starship – Starlifter – Transporter iterative process plots a clear path to the stars and a far brighter future.