SpaceX’s Big Falcon Spaceship: How to build an interplanetary rocket

Elon
Musk and SpaceX’s Big Falcon Rocket is designed to be 16 stories
tall, carry up to 100 people, and deliver 150 tons of cargo to
Mars.
SpaceX; NASA; Mark Brake/Getty
Images; Samantha Lee/Business Insider

• Elon Musk plans to blast a tourist
  around the moon in a ship made by his rocket company, SpaceX.
• The private lunar mission is meant to demonstrate a new
  two-part launch system called Big Falcon Rocket, which is
  designed to eventually bring humans to
  Mars.
• Engineers are said to be building a prototype of the BFR’s
  spaceship primarily out of carbon-fiber composites.
• Exactly how SpaceX is building that spaceship isn’t publicly
  known, but industry experts have some guesses.
• Aerospace engineers, astronauts, and Musk himself have said the first
  missions to Mars are likely to be perilous.

In December, a giant white tent appeared at the Port of Los
Angeles. A routine permit suggested that SpaceX, the rocket
company founded by Elon Musk, was using the roughly
20,000-square-foot, $500,000 facility as a “storage tent.”

But Musk revealed the tent’s true purpose a few months later.
Inside, his engineers are building
a colossal interplanetary spacecraft called BFR, the Big
Falcon Rocket (or, as Musk has said, Big F—ing Rocket).

On Thursday, SpaceX announced it had
selected the first private passenger to be launched in the
BFR. That person, whose identity is set to be revealed on Monday,
will fly around the moon, the company said.

The BFR project and its immediate lunar goalposts mark the
incredible and plainly unorthodox beginning of an effort by
SpaceX to
colonize Mars. Though Musk may announce a moon-mission launch
date on Monday, his larger goal, which he has described as
“aspirational,” is to launch an uncrewed cargo mission to the red
planet in 2022, followed by human missions in 2024.

“He wants to have two planets for humans to live on. Some people
call it crazy, but it kind of makes some sense,”
Marco Cáceres, a senior space analyst at the Teal Group, told
Business Insider. “If something were to happen to our planet, we
have an option.”

Based on Musk’s statements and peeks of hardware inside the tent,
experts say it’s clear that SpaceX workers are now building a
full-scale prototype there.

SpaceX
is said to be building a prototype Mars spaceship inside a
20,000-square-foot tent at the Port of Los
Angeles.
Google Earth Pro; Samantha
Lee/Business Insider

The two-part BFR, as described by Musk before his
private-lunar-voyage announcement, will consist of a
157-foot-tall spaceship sitting atop a 191-foot-tall rocket
booster. Together, such a system would be 35 stories — taller
than the Statue of Liberty.

When fully fueled, it’ll weigh
nearly 9 million pounds, lift up to 150 tons of cargo, and
ferry those supplies to Mars with as many as 100 passengers.

On top of all that, the entire system will be
100% reusable.

That’s something “we haven’t seen, ever,” Cáceres said. “This
would be the first entirely reusable launch vehicle.”

An illustration of a Big
Falcon Rocket launching toward space.

SpaceX/YouTube

Musk’s vision for the BFR places it among the most difficult
engineering projects ever attempted by humans.

“We’ve gone to the moon. But this is an order of magnitude at
least more ambitious than that — probably a couple,” Steve
Nutt, a materials scientist and aerospace engineer at the
University of Southern California, told Business Insider of
Musk’s Martian ambitions. “It just sounds like science fiction.”

Thus far, SpaceX has mostly kept secret whatever is going on
under that white tent. People who work there will not reveal
details of the project, nor will a few lucky outsiders who’ve
been given a tour. The company declined multiple requests to
provide interviews or on-the-record comments for this story.

So aerospace experts and the public are left asking how SpaceX
can possibly build the enormous spaceship Musk has envisioned on
the timelines he’s put forth.

To get as close as possible to an answer, we spoke to a handful
of aerospace industry experts who have ideas about how SpaceX
will construct the BFR — including potential building materials,
cutting-edge assembly processes, safety checks, and projected
costs.

But they also have big questions, perhaps the most important of
which is: Is society prepared to accept the high probability that
some of SpaceX’s missions to Mars will end in tragedy?

2019: Year of the first Mars spaceship?

Musk speaks at the
International Astronautical Congress last September in Adelaide,
Australia.

Mark Brake/Getty
Images

Musk has said the BFR system will eventually replace every rocket
and spaceship that SpaceX uses today, since it should be
inexpensive to launch; that is, relative to the
single-use rockets that dominate the industry.

To that end, the company recently
raised hundreds of millions of dollars, much of which may go
toward the BFR project. The newly announced moon voyage will also
go toward the spacecraft’s development, and more and more of

SpaceX’s 6,000 employees are also getting pulled into the
effort.

Engineers started with “by far the hardest” part of the system to
get right, as Musk has described it: the 16-story spaceship. The
first prototype should be completed in 2019, according to Musk.

Assuming construction began with the tent’s completion around
December — tools for making pieces of the fuselage, or body of
the spaceship, rolled through the tent’s flaps months ago — this
would mean a build time of about 18-24 months. By comparison,
NASA’s space shuttle orbiters (which are smaller than a BFR
spaceship) each took about five years to make.

“It’s typical SpaceX and Elon Musk stuff,” Nutt said. “You don’t
sit around. There’s a lot of pressure to do things quickly.”

Once built, the spaceship prototype will most likely ride on a
barge through the Panama Canal, get dropped off in Texas, and be
transported inland by truck to the company’s
rocket facility in southern Texas. There it would start a
series of short “hop” tests by late 2019, Gwynne Shotwell, the
company’s president and COO, indicated during a conference earlier in
September.

Around the same time, workers may finish constructing SpaceX’s
permanent BFR factory
in the Port of Los Angeles. That facility will be about

200,000 square feet, 10 times as large as the white tent.

According to SpaceX’s plans, when all the parts are ready, the
booster will heave the spaceship dozens of miles above Earth,
detach, then land itself for inspection and refueling. Meanwhile,
the spaceship will fire its engines to accelerate into orbit
around Earth. (Shotwell said this may happen as soon as 2020.)

A diagram showing how
SpaceX plans to establish a base and methane-fueling depot on
Mars.

Elon Musk/SpaceX;
New Space/Mary Ann Liebert, Inc.
Publishers

The ship will be nearly out of fuel by that point though, so
SpaceX plans to launch nearly identical tanker spaceships to meet
up with the first one in orbit. A series of rendezvous at about
17,500 mph would refill the spaceship’s tanks with liquid methane
fuel and the liquid oxygen required to burn it, though this may
take about a dozen tanker flights.

“That allows us to effectively reset the rocket equation,” Paul
Wooster, SpaceX’s principal Mars-development engineer,
said during a presentation to the Mars Society in August. “We
go from getting 100 tons or more into low-Earth orbit, then
refill, and we can take that payload pretty much anywhere —
including the surface of Mars.”

Musk’s vision of a city on
Mars.

SpaceX/YouTube

The BFR’s spaceship is also designed to be refilled with fuel on
Mars to power its return to Earth. SpaceX plans to manufacture
oxygen and methane fuel using water from Martian soil, carbon
dioxide in the planet’s thin air, and electricity from solar
panels.

A carbon-fiber emissary from Earth

An illustration of
SpaceX’s BFR spaceship landing on Mars.

SpaceX

To be able to launch, refuel in orbit, endure months of flying
through space, land on Mars, leave that planet, and safely return
to Earth — then do all that over again — the BFR can’t be an
ordinary spacecraft.

That’s why Musk is planning to build the entire spaceship
“primarily of an advanced carbon fiber,” he
said in 2016.

Carbon-fiber composites are
made out of many borderline-microscopic yet super-strong threads
of carbon. The filaments, which are often woven together into a
fabric, are then set in sticky, glue-like epoxy. When cured by
heat, the epoxy hardens into an ultra-tough resin around the
fibers.

A
carbon-fiber strand tied in a knot.

Tour
Group/Rice University

In this case, the whole is greater than the sum of its parts.
Many carbon-fiber composites can match or exceed the properties
of steel using one-fifth of the material. Some variants can also
meet the properties of aluminum — the aerospace industry’s go-to,
lightweight building material — at half that metal’s mass.

But it’s not easy to build huge structures from carbon fiber, and
what SpaceX is constructing is unprecedented in the history of
aviation and spaceflight.

The largest comparable vehicle ever made would be Boeing’s 787
Dreamliner commercial jet airplane, which is about 50% composites by weight.

Of the spaceship, Cáceres said, “It will be massive — much bigger
than anything we’ve ever seen.”

Musk revealed the first clues about how SpaceX would manufacture
a carbon-fiber vessel when he shared a photo on Instagram in
April of a 40-foot-long metal cylinder with a seemingly tiny
Tesla car next to it for scale.

“SpaceX main body tool for the BFR interplanetary spaceship,”
Musk
said on Instagram. (He has since
deleted his account.)

A tool roughly 30 feet in
diameter that SpaceX will use to build its Big Falcon Rocket
spaceship.

Elon Musk/SpaceX;
Instagram

Nutt and others suspect that the tool is a rotating machine
called a lathe or mandrel, which is used to apply carbon-fiber
materials.

“It’s a really, really big one,” Nutt said of the mandrel. “I’ve
never seen one close to that big.”

Mandrels work something like a thread spooler. A robot moves
along the length of a rotating mandrel, precisely unwinding rolls
of carbon-fiber tape and wrapping them around the cylinder.

“You lay layer upon layer of the material. If you’re going to
make a spacecraft part, you’d probably have dozens of layers of
material on top of each other,” Greg
Autry, the director of the Southern California Spaceflight
Initiative who’s a leading expert on the space industry, told
Business Insider. (Autry has a nondisclosure agreement with
SpaceX but offered to speak about the aerospace industry in
general.)

Only Boeing has ever used a mandrel close to the size of the tool
in Musk’s photo.

‘The complexity is daunting’

Though the exact materials and methods SpaceX is using aren’t
publicly known, Nutt said several big challenges loom if you’re
making carbon-fiber structures the size of apartment buildings.

One is that epoxy slowly cures on its own at room temperature.
Each epoxy has a different cure rate, but the kind used to
manufacture airplanes becomes unusable after about four weeks,
according to Federal Aviation Administration regulations. That
means SpaceX would get only about a month to build each major
section of the spaceship.

Another challenge is that carbon-fiber composites don’t really
like to touch super-cooled, or cryogenic, liquids. But to remain
a liquid, methane must be kept below -259 degrees Fahrenheit and
oxygen below -297 degrees Fahrenheit.

The stakes of that challenge became clear in 2016, when one of
SpaceX’s Falcon 9 rockets exploded on a launchpad while carrying
a roughly
$200 million satellite. The most likely cause: the
bursting of a carbon-fiber-wrapped tank filled with cryogenic
liquid.

“It’s subject to cracking and leaking,” Musk
said during a presentation after the explosion.

Inside SpaceX’s giant carbon-fiber
tank.
SpaceX/Elon
Musk

But Musk
said last year that SpaceX had “developed a new carbon-fiber
matrix that’s much stronger and more capable at [cryogenic
temperatures] than anything before.”

To demonstrate that technological breakthrough, SpaceX built the
biggest-ever carbon-fiber-composite fuel tank, which Musk’s staff
then tied to a barge, dragged to sea, filled with cryogenic
liquid, pressurized beyond its limits, and
made violently burst.

A carbon-fiber tank 40
feet in diameter that SpaceX made in 2016.

Elon
Musk/SpaceX

And there’s yet another major challenge in building most of a
spaceship out of carbon-fiber composites: If the material isn’t
cured correctly, hard-to-detect and potentially mission-ending
flaws might get cooked into the spaceship’s body.

To avoid such disastrous defects, carbon-fiber composites must
get squeezed under as much pressure as possible to push out
bubbles, collapse voids, and ensure strong bonds.

“That’s typically done with a giant pressurized oven, like a
pressure cooker, that’s called an autoclave,” Autry said. “But
these things are very expensive.”

Cáceres said an autoclave the size SpaceX might require would be
a similar size to the one used for 787 airplane fabrication, and
that custom-built device cost Boeing up to $300 million. So Nutt
thinks SpaceX is likely to go about it a different way.

“I think they’re going to cure it in an oven,” Nutt said. “You
can make an oven for one-half to one-tenth the cost of an
autoclave.”

A
forward fuselage of a Boeing 787 Dreamliner.

Tim
Kelly/Reuters

If he’s right, that means SpaceX would put each finished section
into a giant, heat-resistant plastic bag, suck out enough air to
smoosh the carbon-fiber layers together, and heat everything.

Workers might then disassemble the mandrel to free the cured and
hardened section. When all the big pieces are done — perhaps two
or three “barrel sections,” as Wooster calls them, plus one
pointy nosecone — SpaceX would somehow combine them all into a
single fuselage.

To join the sections of Boeing’s Dreamliner together, the company
uses about 50,000 metal fasteners. But initially this led to
major headaches, since thousands of fasteners had to be replaced

on about a dozen of the earliest planes after problems
appeared during pressurization tests.

Such a problem would only be worse for a spaceship. Temperature
differences in space can be hundreds of degrees, and various
aerospace materials expand and contract at different rates.

“There are so many different parts of this thing, the complexity
is daunting,” Nutt said. “There will have to be a variety of
materials and joining methods to accomplish everything this has
to accomplish.”

Nutt said this will be all the more reason for critics to laud
any triumphs by SpaceX.

“I think if he succeeds, then people should appreciate what he
had to overcome — what the company had to overcome,” Nutt said,
adding, “I wouldn’t recommend betting against Elon Musk.”

How to avoid death by defect or damage

Whatever is going on under that big white tent, one thing is
certain, Nutt said: SpaceX needs to very carefully check its
work.

That’s because carbon-fiber composite materials don’t easily
signal cracks, voids, or other defects.

“When a metal part gets damaged, there’s usually a dent or a
scratch or something like that,” Nutt said. “With composite
parts, there can be damage and no manifestations at the surface.
It’s all subsurface.”

Workers
look over carbon-fiber composite materials for Boeing’s 787
Dreamliner.
Boeing

To inspect carbon-fiber sections, SpaceX may need to
painstakingly cover every square inch with ultrasound scanners.

“You may have some structural problems on an aircraft, but the
aircraft won’t explode,” Cáceres said. “But on a rocket, leaks,
cracks, and instability — those things can be catastrophic. It
explodes and people die.”

Nutt thinks that to reduce that risk, SpaceX is likely to follow
an industry standard practice of making demonstration parts,
cutting out foot-long sample pieces, torturing those in stress
tests, then inspecting them. Engineers could feed that test data
into computer models and simulators to estimate how a full-size
spaceship might fare.

“It’s a fairly tedious process, and that’s one reason materials
in aerospace are introduced extremely slowly,” Nutt said.

Eventually, SpaceX will build and test a full-scale spaceship.
And there’s a good chance the first one will fail spectacularly.

“When you’re building something this big, the only real way to
test it is once you’ve completed it, and you launch it,” Cáceres
said. “You better have a lot of money, because you’re probably
going to go through a lot of big, big structures before you get
the one that works.”

A SpaceX Grasshopper
rocket explodes in midair in August 2014 after an engine sensor
failure.

SpaceX/YouTube

SpaceX is not under any delusions about avoiding snags. Many of
its experimental launches and landings have
ended in fiery explosions. The company has also weathered
failures with operational rockets that resulted in the loss of
expensive payloads. And earlier this year, Musk warned that
SpaceX’s largest-ever rocket,
Falcon Heavy, could
blow up during its maiden launch. (It
did not.)

“Knowing Elon, I think you can expect him to experiment and do
iterative testing — he always has — and it may work, or it may
not,” Autry said.

Once the spaceship is on a mission, however, in-flight
inspections and repairs will still be essential.

“It’s such a long mission,” Nutt said. “I think the chances of
some kind of damage or failure en route are much greater than a
mission of days or weeks that we’ve seen in our lifetime.”

Tiny pieces of rock or comet dust are extremely dangerous in
space, since they can impact a spacecraft at thousands of miles
per hour. One strike by a millimeter-long object could cripple a deep-space mission
if it doesn’t have repair capabilities.

“Those things can go right through any kind of structure and do a
lot of damage,” Nutt said. (The video below shows a 0.1-inch
aluminum sphere striking a carbon-composite material at 15,800
mph.)

Yet carbon-fiber composites are extraordinarily tricky to fix,
even on Earth. For example, Nutt said, when the Department of
Defense needs to repair carbon-fiber-composite jet fighters,
workers sand and sheen a damaged area, slather on layers of epoxy
using “fancy trowels,” put the damaged area under vacuum, and
heat it. And that’s what he calls the “crude” method.

“Things that you might be able to repair with some difficulty on
Earth are orders of magnitude more difficult to execute and
accomplish in space,” Nutt said. “It’s a big structure with a lot
of components. The chances of failure are not zero. So you have
to worry about those things and have contingency plans for all of
them.”

Spaceships don’t grow on trees

An
illustration of a BFR spaceship docked at the International Space
Station.
SpaceX/YouTube

Cáceres said each BFR launch might cost about $10 million, give
or take, with most of that going toward fuel (since the system is
designed to be reused many times). By comparison, the Falcon
Heavy rocket costs close to
$100 million per launch but can carry about half the payload
of a BFR spaceship.

However, Cáceres’ estimate doesn’t include the capital needed to
build and test the BFR in the first place.

“If I had to venture to guess, I would say it would be somewhere
in the $4 billion to $5 billion range,” Cáceres said of those
development costs, adding that if Musk “is really unlucky and
there continue to be setbacks, it could be more than that.”

Delays can add enormously to the final bill, Cáceres said.

“That’s why so many government space programs tend to be so
expensive — because they just go on and on, forever and ever, for
technical reasons as well as budgetary and political reasons,” he
said.

SpaceX’s
rendering of a Big Falcon Rocket spaceship carrying a passenger
around the moon.

SpaceX/Twitter

But Cáceres expects that if SpaceX shows enough progress, NASA
could become interested and invest in the system’s further
development, helping to offset the company’s costs.

“Ultimately, BFR could become a joint US government–SpaceX
program,” Cáceres said. “That would be my guess, eventually,
because as much as I admire the success of SpaceX, this just
seems like something too massive and too complicated for one
company alone to handle.”

If SpaceX successfully flies a tourist around the moon, that
could serve as an audacious advertisement to NASA and lawmakers
who control the government’s purse strings: “Buy me,” it would
tacitly say.

‘Rockets are going to explode, and people are going to die’

An
illustration of SpaceX’s Crew Dragon spaceship, also known as
Dragon 2 or Dragon V2, orbiting Earth.
Kennedy Space Center/SpaceX via
Flickr

Before BFR is built and a passenger is launched toward the moon,
SpaceX must ace a more immediate task.

For the first time in its 16-year existence, the company is about
to
launch NASA astronauts to the International Space Station.

“If BFR is going to work, then using Falcon 9 or Falcon Heavy
rockets to launch a crewed capsule has to be successful,” Cáceres
said. “SpaceX has got to get into a rhythm where launching people
to the space station becomes a matter of habit.”

But even if those
crewed flights go smoothly, the world must be prepared for an
uncomfortable and inevitable moment: death on or en route to
Mars.

When Musk presented his plan to reach the red planet to the
International Astronautical Congress in 2016, an audience member
asked who the first people to go on SpaceX’s Mars mission should
be.

“The first journey to Mars is going to be really very dangerous.
The risk of fatality will be high; there’s just no way around
it,”
Musk said, adding, “It would be basically: Are you prepared
to die? And if that’s OK, then you’re a candidate for going.”

Cáceres, who was watching the presentation, said he was struck by
Musk’s honesty.

“I immediately thought: That’s not something that any
representative, any CEO from a company, or any NASA administrator
would say,” Cáceres said. “That’s about as blunt as you can be,
and I think he was being very truthful.”

Is Earth ready for a trail of death leading to the red planet?

Mars
is about 140 million miles from Earth.

ISRO/ISSDC/Emily
Lakdawalla (CC BY-NC-SA 3.0)

A significant chunk of the US population now considers sending
people to the space station to be somewhat routine and fairly
safe, minus two deadly space shuttle accidents, Cáceres said. But
the early days of the commercial railroad, automobile, and
aviation industries were very deadly.

Cáceres said we should expect a similar outcome if SpaceX is to
achieve its goal of making interplanetary travel similarly
commonplace.

“SpaceX is going to fail in the future — rockets are going to
explode, and people are going to die,” he said. “That is what
everyone has to totally understand.”

Chris Hadfield, a retired astronaut,
has compared the dangers of using current technologies to
reach Mars to an even earlier period of human history, when
explorers circumnavigated Earth on perilous, yearslong ocean
voyages.

“The majority of the astronauts that we send on those missions
wouldn’t make it,” Hadfield told Business Insider of attempts to
reach Mars. “They’d die.”

Seasoned astronauts would be likely to attempt the trip
regardless — and already the first private lunar voyager has
signed up.

But Cáceres wonders how deep our enthusiasm for reaching toward
the stars runs.

“If we want to actually open space to average people rather than
government astronauts, then we’ve got to accept that there’s
going to be a lot of fatalities,” he said. “We can either decide
that that’s acceptable or it’s not, in which case we don’t
explore space any more than we have already.”