Space Slingshot

This past October, a team of  engineers at a facility in the New Mexico desert watched excitedly as a launch timer began to count down. Their attention was focused on a large structure, taller than the Statue of Liberty. Within the device, a flight-test vehicle was starting to spin faster and faster. When the timer hit zero, the vehicle was released. It shot out of a vertical tube attached to the structure and soared into the air at more than 1,600 kilometers (1,000 miles) per hour. As everyone cheered, they heard the thunder of a sonic boom, an explosive noise created by the vehicle moving at 1.3 times the speed of sound.

The event marked the first successful test of a new launch system created by the California-based tech company SpinLaunch. It uses kinetic energy, or the energy of motion, to launch objects into Earth’s atmosphere. Right now, the company is testing a scaled-down version of this launch system, called the Suborbital Accelerator (see Reaching New Heights). Next, the company plans to build a larger version capable of flinging objects, like satellites, all the way to the edge of Earth’s atmosphere. By harnessing the power of physics, this new launch system could become a simpler, less expensive, and more sustainable way to send spacecraft into orbit.

Last October, a launch timer began to count down at a facility in the New Mexico desert. A team of engineers held their breath. They focused on a large structure, taller than the Statue of Liberty. Inside the structure, a flight-test vehicle spun faster and faster. When the timer hit zero, the vehicle was released. It shot out of a vertical tube on the structure. The vehicle soared into the air at more than 1,600 kilometers (1,000 miles) per hour. As everyone cheered, a sonic boom thundered. The vehicle created this explosive noise as it moved at 1.3 times the speed of sound. 

This was the first successful test of a new launch system. The California-based tech company SpinLaunch created it. The system relies on kinetic energy. It uses the energy of motion to launch objects high into Earth’s atmosphere. Right now, the company is testing a smaller version of the launch system. It’s called the Suborbital Accelerator (see Reaching New Heights). Next, the company plans to build a larger version. It will be able to fling objects, like satellites, all the way to the edge of Earth’s atmosphere. By using the power of physics, this new launch system could become a simpler way to send spacecraft into orbit. It could also be less expensive and more sustainable.

For decades, there has been only one way to get an object to space: Strap it to a rocket and blast it up into the atmosphere. This works because of Newton’s third law of motion, which states that for every action, there is an equal and opposite reaction. A rocket’s engine burns fuel to produce a hot, fast exhaust. This fiery jet of gases creates a downward force that pushes the spacecraft upward.

This requires a tremendous amount of rocket fuel. To reach space, a rocket must generate enough thrust, or forward force, to overcome the downward pull of Earth’s gravity. The rocket must also fight against drag, a slowing force caused by air molecules pushing against its surface as it hurtles through the atmosphere. “The fuel weighs more than the rocket itself,” says Sandy Barker, a rocket scientist at the University of Texas, Austin. “And the bigger the rocket, the more fuel it needs,” she adds. That doesn’t leave much room for the payload, or cargo, it will carry. Rocket fuel is also very expensive. That’s why companies like SpinLaunch have been developing new ways to get to space that don’t solely rely on rockets.

For decades, we’ve had only one way to get an object to space: Strap it to a rocket and blast it up into the atmosphere. This works because of Newton’s third law of motion. It states that for every action, there is an equal and opposite reaction. A rocket’s engine burns fuel to produce a hot, fast exhaust. This fiery jet of gases creates a downward force. It pushes the spacecraft upward. 

This requires a great amount of rocket fuel. To reach space, a rocket must overcome the downward pull of Earth’s gravity. It must generate enough thrust, or forward force, to do this. The rocket must also fight against the slowing force of drag. Air molecules push against the rocket’s surface as it shoots through the atmosphere. That causes drag. “The fuel weighs more than the rocket itself,” says Sandy Barker, a rocket scientist at the University of Texas, Austin. “And the bigger the rocket, the more fuel it needs,” she adds. That doesn’t leave much room for the rocket’s payload, or cargo. Rocket fuel is also very expensive. That’s why companies like SpinLaunch are developing new ways to get to space. These methods don’t rely only on rockets (see Up, Up, and Away).

At the core of SpinLaunch’s Suborbital Accelerator is a giant spinning machine called a centrifuge (see Launch System, above). That’s what gives the device its flinging power. It’s like launching a stone with a sling, says Juan Alonso, an aerospace engineer at Stanford University in California. If you spin the sling around and around before releasing it, you can accelerate the stone to a much higher speed than if you simply threw it by hand. “SpinLaunch is a sling for space-going cargo,” says Alonso.

SpinLaunch’s Suborbital Accelerator contains a giant spinning machine called a centrifuge (see Launch System). The centrifuge gives the technology its flinging power. It’s like launching a stone with a sling, says Juan Alonso. He’s an aerospace engineer at Stanford University in California. A person spins a sling around and around before releasing it. That accelerates the stone to a much higher speed than just throwing it by hand. “SpinLaunch is a sling for space-going cargo,” says Alonso.

Inside the structure’s circular centrifuge, there’s a long mechanical arm called a tether. The end of the tether is attached to a rocketshaped launch vehicle. An electric motor rotates the tether to generate kinetic energy. The tether spins faster and faster, accelerating the vehicle before shooting it upward through a launch tube.

To allow the vehicle to reach high-enough speeds, engineers designed the inside of the centrifuge to be a near-vacuum chamber—a space containing almost no air. Otherwise, friction created by air molecules rubbing against the tether would generate high heat. “The tether would burn up,” says David Wrenn, SpinLaunch’s vice president of technology.

To maintain the near-vacuum conditions, the release of the vehicle must be timed precisely. When the launch tube doors open, the vehicle has just a few thousandths of a second to sail through the doors before they are sealed again. This prevents air from rushing into the chamber while the tether is still spinning. “We developed the fastest doors on Earth,” says Wrenn. “They close about two to three times faster than the blink of an eye.”

A long mechanical arm called a tether is inside the circular centrifuge. The end of the tether is attached to a rocket-shaped launch vehicle. An electric motor spins the tether to generate kinetic energy. To accelerate the vehicle, the tether spins faster and faster. Then it shoots the vehicle upward through a launch tube.

The vehicle needs to reach high speeds, so engineers made the inside of the centrifuge a near-vacuum chamber. This space contains almost no air. Otherwise, air molecules would rub against the tether and create friction. That would generate high heat. “The tether would burn up,” says David Wrenn, SpinLaunch’s vice president of technology.

To maintain the near vacuum, the vehicle must be released at exactly the right time. When the launch tube doors open, the vehicle must sail through in just a few thousandths of a second. Then the doors are sealed again. That way, air doesn’t rush into the chamber while the tether is still spinning. “We developed the fastest doors on Earth,” says Wrenn. “They close about two to three times faster than the blink of an eye.”