A massive "space cannon" can shoot payloads into space at hypersonic speeds

Alternative rocket launch firm Green Launch is developing a system to send small launch vehicles into space using a massive gas cannon, a press statement reveals.

With a 54-foot (16.5-meter) launch tube, the company was able to fire a payload into the stratosphere at a velocity exceeding Mach 3. 

If scaled, the company's explosive method could massively reduce the cost and carbon footprint of small satellite launches.

Space artillery can enable green rocket launches

The concept of an artillery gun used as a low-cost method for orbital payload launches dates back to the U.S. Army's High Altitude Research Project (HARP) of the 1960s. Around the time of NASA's highly successful, and highly expensive, Apollo missions, HARP set a record in 1966 by firing a projectile above the 100-kilometer Kármán Line —  considered by many to be the boundary between Earth and space.

During the 90s, Green Launch COO and Chief Science Officer Dr. John W. Hunter worked on an offshoot of the HARP program called SHARP – the 'S' representative of the program's ambition to reach "super" high altitudes. During his time at the SHARP program, Hunter led the development of the world's largest "hydrogen impulse launcher".

The hydrogen impulse launcher — described on the U.S. Army's website as a "space" gun — features a long thin barrel filled with hydrogen mixed with helium and oxygen. When these gases expand at immense speeds, a projectile is fired at velocities several times the speed of sound. The SHARP program's 400-foot (122-m) impulse launcher broke records during the 90s by launching payloads at speeds of up to Mach 9.

Green Launch aims to "revolutionize access to space"

Now, Green Launch wants to leverage that technology to disrupt the booming small satellite launch sector. Using a 54-foot-long version of the SHARP system, Green Launch has fired a projectile into the stratosphere (video below) on its first vertical attempt, in what the company calls a "quantum leap for space access and exploration". 

Green Launch says its "proof of concept" impulse launcher will allow it to attempt to send a projectile past the Kármán Line later this year. The company believes its method could also eventually be scaled to reach hypersonic speeds as high as Mach 20. And it will be able to achieve all of this with a minimal carbon footprint when compared to traditional rockets.

"The trick is using a light gas like hydrogen, which has a very low molecular weight," said Green Launch CTO Dr. John Hunter. "You can get very high velocities that aren't possible with railguns or other systems. This has zero carbon emission and will allow us to revolutionize access to space and open the solar system to manned exploration."

Green Launch's work draws comparisons to another alternative rocket system in development by space firm SpinLaunch, a recent recipient of a NASA Space Act Agreement contract. SpinLaunch is building a catapult-like system that will fire payloads into space at up to 5,000 mph using a spinning arm and a vacuum chamber. It also claims its low-emissions method will provide a much more affordable alternative to rocket launches.

In the same manner as SpinLaunch's system, Green Launch will eventually have to build a launch vehicle that fires a small amount of propellant for course correction and placement once in orbit. As Green Launch's impulse launcher has the capacity to fire its payloads at much higher speeds, it has the potential to send much lighter launch vehicles into space.

"Your satellites and supplies can be in orbit in 10 minutes," said Green Launch co-founder Eric Robinson. "We can be launching every 60 to 90 minutes. This will enable us to be the Next Day Air delivery to space."

If its upcoming launch tests prove successful, Green Launch says it first aims to deploy its system to send atmospheric sampling devices to space to collect data for climatologists. The company also believes it can be used to test hypersonic vehicles as well as deliver satellites to orbit, all at a fraction of the environmental costs of traditional space rockets.