If you want to go to space anytime soon, you’re going to need a massive rocket.
Since Sputnik, it has remained standard to blast a highly expensive metal tube off Earth with the help of a controlled explosion. But one company thinks it can change that age-old paradigm with an electric motor, a vacuum chamber, and an arm that spins really, really fast.
The aptly named startup SpinLaunch is building a launch system inspired by the centrifuge, a lab device that spins fluids, such as blood, to separate their components. Now, a massive version will spin payloads inside a vacuum-sealed chamber before flinging them upward.
With enough speed (around 5,000 miles per hour), the launcher could send small satellites dozens of miles above the planet’s surface, where a small rocket would finish the job and usher them to low-Earth orbit.
The system offers a radically cheaper and more sustainable launch method compared to today’s rockets, according to David Wrenn, SpinLaunch’s vice president of technology.
“Space launch is an incredibly expensive endeavor,” he says, with launches costing in the tens of millions of dollars. Meanwhile, SpinLaunch could yeet something into space for around $250,000, Wrenn estimates. “It can be done more inexpensively, dramatically more inexpensively.”
The concept sounds pretty zany, and experts have questioned the basic science behind SpinLaunch’s ideas ever since the company took off in 2014. For example, can objects survive the immense g-forces that come from being spun that fast? Will they turn into raging fireballs as soon as they hit the atmosphere?
But a series of test launches using a small-scale version of its device over the past year has countered some of the criticism by showing the technology can at least work at lower speeds.
And a recent $71 million in funding from partners such as Google Ventures and Airbus adds some gravity to the company’s efforts. SpinLaunch is currently exploring commercial partnerships and recently inked a deal with NASA to test and potentially launch payloads, Wrenn says.
If everything goes according to plan, the full-size SpinLaunch system will be operational by 2026, Wrenn says.
A new spin on liftoffs
The basic idea behind SpinLaunch is simple. First, space cargo is encased in a dummy rocket. This rocket attaches to a carbon-fiber arm powered by an electric motor that accelerates to around 5,000 miles per hour.
When the payload whizzes up to maximum speed, the arm releases the cargo at precisely the right moment. Then, it barrels through a series of airlocked doors.
At this point, the dummy rocket ascends through the stratosphere at hypersonic speed until it’s high above the Earth, where small rockets take over to propel the payload the rest of the way to orbit.
The system isn’t meant to shoot out humans, but it could take payloads weighing as much as 440 pounds to space, the company says. That’s more than enough for the increasingly popular mini satellites called CubeSats, which are being used by projects like Elon Musk’s Starlink, as well as for small-scale space experiments.
An electric motor means there’s no need for fuel inside the spacecraft.
While SpinLaunch hasn’t sent anything to orbit yet, tests over the past year have launched payloads up to tens of thousands of feet, according to the company. A video from its eighth launch, which happened in April, gives some idea of what it’s like to get shot out of a centrifuge at high speed.
A launch system that relies on pure velocity neatly sidesteps one of the most vexing problems with spaceflight. Launching a rocket takes a lot of fuel — but the more fuel you carry, the heavier your rocket is, which means you need even more of it to reach space.
Today, the mass of a given rocket sitting on a launchpad may comprise 90 percent fuel (or an even higher percentage).
By contrast, an electric motor means there’s no need for fuel inside the spacecraft, and it could be powered by renewable fuels. Because it can get up to speed more slowly, an electric motor can also be more efficient.
And with no boosters to discard or return to the ground, successive launches could potentially happen much more quickly.
Failure to launch?
Even with successful test launches in the books, the concept runs head-on into multiple challenges.
For one, SpinLaunch may face a major obstacle up in the air because it does the opposite of a standard rocket, says Julián Rimoli, a professor of aerospace and mechanical engineering at the University of California, Irvine, who isn’t involved with the company.
“A regular rocket starts at [0 velocity] and accelerates and goes faster and faster,” he says. “So by the time you get to 5,000 miles per hour, you are pretty high.”
This matters because the air high up in the atmosphere is far less dense than at sea level. So launches powered by rocket boosters don’t usually struggle with air resistance by the time they hit maximum velocity in the upper atmosphere.
“I would expect this to get really hot.”
By contrast, SpinLaunch’s payloads start out at their fastest and slow down as they climb, meaning they’ll slam into the thickest air right away. This could cause the vehicle to drag — along with another worrisome possibility.
“I would expect this to get really hot,” Rimoli says, similar to how space capsules create mini-fireballs upon reentering the Earth’s atmosphere. That heat could prove disastrous for SpinLaunch’s precious cargo.
Another big issue comes from the massive g-forces slamming payloads inside the SpinLaunch centrifuge as it’s speeding up. Those forces could reach the thousands of G’s, far higher than a standard rocket launch.
“When you have G’s in the thousands, the structural solutions are not trivial,” Rimoli says. He compares it to putting an egg in a slingshot — whirl it around and you’ll probably end up with a sticky mess. It’s not a pretty picture, especially if you’re debating sending a multimillion-dollar spacecraft full of sensitive instruments to orbit.
A (possibly) rocket launch-free future
David Wrenn of SpinLaunch acknowledges the technical barriers with a centrifuge launcher. But the company has done extensive testing with a smaller 40-foot diameter system to see how potential payloads might fare: Even at thousands of G’s, he says, most do fine.
“It sounds like a really big number, but it turns out that the vast majority of spacecraft components are really compatible with the environment, or can be readily modified to operate in the environment,” Wrenn says.
The bigger issue: convincing potential customers that their payloads will be safe and sound, and finding ways to adapt existing technology to the high g-force conditions when necessary.
Many existing satellites, like those used for communications, GPS, and imaging, should work with SpinLaunch’s centrifuge, Wrenn says.
Heat shouldn’t pose a major issue either, Wrenn says. The payloads travel so quickly that they’ll only fly through the thicker, lower parts of the atmosphere for a few seconds, which isn’t long enough for them to catch fire.
He also points to existing military tests with hypersonic projectiles, as well as computer simulations, as evidence that a capsule can successfully hurl at high speeds into the dense sea-level atmosphere.
Indeed, tests so far have seemed promising. Since November 2021, SpinLaunch has been shooting test capsules from a one-third-scale prototype of its centrifuge at Spaceport America in New Mexico. Ten launches in, its system has sent payloads as high as 30,000 feet into the air and recovered them in one piece.
Spinlaunch could hit uncharted territory.
“It really was a dream come true at the end of last year to turn the system online and to see a flight test vehicle enter the atmosphere and disappear into the sky for the first time,” Wrenn says.
Its most recent test, which took place on Sept. 27, included test payloads from a few partners, including NASA, Airbus, Cornell University, and the satellite company Outpost.
NASA’s payload held a suite of sensors including two accelerometers, a gyroscope, and a magnetometer, along with sensors for pressure, temperature, and humidity. Results from that test are still being analyzed, SpinLaunch says.
SpinLaunch is continuing to work with commercial partners as it irons out the kinks in its system, and should be on track to start building its full-scale launcher within a year or two, Wrenn says.
That centrifuge, projected to measure more than 300 feet in diameter, will dwarf the current models. And it will mark the final testing step for SpinLaunch, which is now working to dispel doubts about its unconventional approach to space launches.
One of the biggest current unknowns: how SpinLaunch payloads will fare at much higher speeds, Rimoli says. Current tests have only spun them up to 1,000 mph.
“The problem in physics many times is how things scale,” he says. For example, the g-forces an object experiences increase exponentially. So when increasing velocity by a factor of five, it results in a far larger boost in g-forces. Ultimately, SpinLaunch could hit uncharted territory when bringing its full-scale device online.
But if all goes to plan, the company could soon be twirling payloads fast enough to blow them out of Earth’s atmosphere — (nearly) no rockets required.
Editor's note: On October 24, 2022, this post was updated to clarify that SpinLaunch hasn’t sent any payloads to orbit yet.