YUMA PROVING GROUND, Ariz.-- The world record for the highest altitude artillery shot—which reached past the Karman Line into space-- was set at U.S. Army Yuma Proving Ground (YPG) in 1966.The test fire more than 50 years ago proved the concept of ballistic suborbital space access, but funding for the program was cancelled the following year.Yet the idea of using artillery as a low-cost alternative to rockets to launch payloads into Earth orbit lives on. Currently, a private industry customer called Green Launch is conducting testing here to launch a projectile into space with an innovative new propellant technology.Using a hydrogen and oxygen gas propellant whose only byproduct is water vapor, the company has achieved four mega joules of energy with horizontal fires at YPG, and approached the velocities reached in the vertical shot that set the world record in 1966.“Last year, we launched a three kilogram test projectile at about 1.6 kilometers per second,” said Brad Tower, Green Launch CEO. “It proved our ignition system and we discovered some challenges with our release mechanism.”The successful shot that propelled the payload at nearly Mach Five resulted in more venture capital, and the team believes that later this year it will achieve the same velocities as the record-breaking shot. At present the team is firing horizontally into a newly-constructed catch box, and preparations are underway to fire vertically at YPG later this year. For these shots, the team will utilize their newly-constructed hydraulic gun mount, which will allow them to elevate the barrel to the necessary 87 degree angle.“We are getting ready to test where we can go up to 20 to 22 mega joules, which will build up enough energy to get our vehicle to 105 to 110 kilometers of altitude.”The projectile will land about 20 kilometers downrange from its firing point, which is easily accomplished within YPG’s 1,200 square miles of land area and 2,000 square miles of restricted airspace that in places reaches to outer space.The test fires at YPG are meant to serve as a technology demonstration, said Tower. The final device will achieve 160 mega joules of energy, roughly eight times more powerful than what is being fired this year. Eventually, the company’s ambitions for the technology will force than to test elsewhere.“Ultimately we want to go orbital, so that will require getting away from a landlocked facility like YPG. YPG has the unlimited vertical air space and a large enough range to get us into space and back down with a very, very high level of certitude that we would land back on the range, but if you want to get orbital, you have to have essentially unlimited downrange. We will probably end up somewhere in the South Pacific to do the kind of orbital shots we want to do.”Tower says that using YPG as a test facility has greatly helped the start-up company in their efforts to rigorously control costs, and characterizes the support his team receives from YPG personnel as unparalleled.“I don’t think we could do this anywhere else in the United States. We’ve gotten support all along that is incalculable in its value. These guys really put their back into it, and the professionalism has been exceptional.”