Elon Musk hopes to make SpaceX’s Falcon, Dragon fleet obsolete with Mars rocket
Just a year after unveiling a design for a mega-booster four times the size of the Saturn V, SpaceX founder and CEO Elon Musk presented an updated version of the Mars rocket his company hopes will enable colonization of the Red Planet. The Sept. 29, 2017, presentation occurred during the 68th International Astronautical Congress in Adelaide, Australia.
The new design is a scaled-down version of the Interplanetary Transport System (ITS) design announced in 2016. The biggest change is that the two-stage, fully reusable rocket and spaceship would be 30 feet (9 meters) in diameter instead of 40 feet (12 meters) and would be 348 feet (106 meters) tall. Moreover, the spaceship, which also serves as the system’s second stage, has been modified to have a delta wing.
The Mars rocket, which Musk is continuing to call the “BFR” until a better name is thought up, would be able to send 150 tons to low-Earth orbit in its fully reusable mode. The booster stage, which would be 190 feet (58 meters) tall, would use 31 of the currently in-development Raptor engines (compared with 42 that was planned for ITS) that will consume liquid methane and oxygen to produce a liftoff thrust of 5,400 tons.
The 157-foot (48-meter) long spaceship would have six Raptor engines, four of which would be vacuum Raptors. Additionally, it would have a pressurized volume of 29,100 cubic feet (825 cubic meters), enough space for 40 cabins, a large common area, central storage, galley, and a solar storm shelter for transits to Mars.
“The most important thing that I want to convey in this presentation is that I think we’ve figured out a way to pay for it,” Musk said. “This is very important.”
Making Falcon and Dragon ‘redundant’
Last year, Musk joked about using Kickstarter and collecting underpants as a way to fund the ITS. Needless to say, those “plans” didn’t pan out. Instead, he said that by scaling the system back, it could be designed to do any activity around the Earth-Moon system.
“We want to make our current vehicles redundant,” Musk said. “We want to have one system – one booster and one ship – that replaces Falcon 9, Falcon Heavy and Dragon.”
Musk said if the company can achieve that, then all the resources that are being used for current systems can be applied to the Mars rocket. The new design could be used for anything ranging from sending satellites into space, servicing the International Space Station, sending astronauts to the Moon or Mars, or even point-to-point travel for destinations on Earth.
Additionally, Musk said SpaceX will be building ahead to have a stock of Falcon 9 boosters in order to begin turning its attention toward the Mars rocket. He said he believes the company can pay for the development of the new booster with revenue from existing satellite and space station contracts.
Musk said the current Falcon 9 system can achieve about 70–80 percent reusability with a recovery of the first stage and eventually the fairing. The second stage of the Falcon system isn’t being designed for reuse, but according to Teslarati.com, SpaceX President and Chief Operating Officer Gwynne Shotwell said during a presentation at the Massachusetts Institute of Technology that SpaceX hopes to soft the upper stage before the end of 2018.
Development already underway
Regardless, it appears that SpaceX wants to prioritize the development of the BFR system to replace the Falcon and Dragon systems altogether. In fact, Musk said during the presentation that the company has already started building a facility for the rocket and tooling has been ordered. He expects to start building the vehicle as early as six to nine months from now for a completed first ship in five years: 2022.
The whole system would be built out of carbon fiber. SpaceX has already tested a 40-foot (12-meter) diameter tank to its designed pressure and then performed a destructive test.
“We developed a new carbon fiber matrix that is much stronger and more capable at [cryogenic temperatures] than anything before,” Musk said. “We successfully tested it up to its design pressure and then went a little further. We wanted to see where it would break.”
Musk said that when the development tank broke, it shot up 300 feet (90 meters) in the air and then landed in the ocean.
“We’ve now got a pretty good sense of what it takes to create a huge carbon fiber tank that can hold cryogenic liquid,” Musk said.
Another key element that Musk said will make the new system fully and rapidly reusable is supersonic retro-propulsion. SpaceX has demonstrated that technique 16 times over the last 21 months with the first stage of the Falcon 9 rocket.
“In order to land on a place like the Moon where there is no atmosphere, and certainly no runways, or on Mars where the atmosphere is too thin to land with a wing, you really have to get propulsive landing perfect,” Musk said.
While the Falcon 9 lands on a single engine, meaning there is no redundancy in case of a failure, Musk said the Mars rocket would have an engine-out capability during landing. With enough practice, he believes SpaceX could get to a landing reliability that is on par with the safest commercial airliners. Also, like last year’s ITS, Musk said BFR’s landing would be precise enough to land back on the launch mount.
An ambitions timeline
Musk said SpaceX hopes to be able to send the two spaceships to Mars by 2022, although he admitted that was optimistic. If all goes according to plan with no delays, which is almost unheard of in the space industry, four more ships would launch in 2024 with two of them crewed.
The spaceship’s journey to Mars would be similar to the ITS’s Mars mission profile. First, the spaceship would arrive in Earth orbit empty. Then fuel tankers based on the spaceship design would be launched to refuel the Mars-bound spaceship. Finally, once full, it would be able to send and land 150 tons of payload the surface of Mars.
However, in order to return to Earth, the spaceship would need to be refueled on Mars using a chemical reaction that converts the Martian atmosphere into methane and oxygen. Additionally, the return trip to Earth would only net about 20 to 50 tons of payload.
Other ‘interesting’ applications
Once fully operational, the Mars rocket system would also be able to support low-Earth orbit missions. With a 30-foot (9-meter) wide payload bay, Musk said the rocket could launch telescopes, large space station pieces, or even large numbers of commercial satellites. It could even service the International Space Station.
Additionally, it could be used to support lunar exploration efforts. If the spaceship were refueled in a highly elliptical Earth orbit, it could go to the surface of the Moon and return to Earth without further refueling.
However, probably the most surprising spin-off of the system was point-to-point travel for destinations on Earth. Musk said the BFR would be safe and reliable enough to send paying customers anywhere on the planet in less than an hour with most destinations being under 30 minutes.
“If we’re building this thing to go to the Moon and Mars,” Musk said, “then why not go to other places on Earth as well.”
Video courtesy of SpaceX
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.
This scaled down BFR seems almost feasable, particularly as they have already successfully built an enormous tank and the Raptor development is going well. I watched Elon’s speech live and I liked the idea of transferring propellant from the tanker by firing thrusters so that it would just run ‘downhill’. So much simpler than pumps and dealing with liquids floating around mid-tank. Not mentioned was how to avoid the propellant from boiling away en route to Mars. Solar powered refrigeration? Super insulation?
He plans to top off the fuel tanks in low Earth orbit before leaving for Mars. Space is colder than the fuel. Remember how the Apollo 13 astronauts nearly froze inside the capsule after they had to power down nearly everything. Shading the tank with the engines should do it.
Why would the propellant boil away? That would seem to require leaks in the tank (and escaping gases), since in a closed pressure vessel, an equilibrium is established between a liquid and its gas phase.
Concerning temperature control, a simple sunshade at a reasonable distance from the tank should allow you to achieve pretty much any temperature in the tank.
Tank isn’t designed to take arbitrarily high pressure. Main tanks have vents to maintain pressure of around ~30 PSI. So of it’s boiling you will need to vent. A tank with the volume of an A380 is not a scuba tank that goes to 1000s of PSI.
Above the critical temperature of the gas no amount of pressure will keep it from boiling off. You need to keep the liquid oxygen & methane below the critical T to keep it from boiling off. Shade and insulation will work, except for liquid hydrogen with a critical T near absolute 0.
Very promising. Mars aside, even ‘just’ having a reusable super heavy lift vehicle for telescopes and other equipment as well as opening up more affordable missions to the Moon would be a huge improvement on current capabilities.
Sonic booms & rocket noise will prevent Earthly use. It could finally make a Moon base affordable. Giant telescopes & sats too. Maybe missile defense stations. And orbiting fueling depots. Gas stations in the sky. We could repair satellites, and clean up big space junk. It might change the world.
When you fly in the atmosphere you get a sonic boom. Flying above it, there’s no boom. Hence, no problem.
Both the returning first stage booster and landing second stage transporter stage will make loud sonic booms when reentering the atmosphere until the go subsonic near the landing site.