A Falcon 9 launch costs about $3.000 per kilo. Starship promises to get that down to $500. Longshot Space aims for $10. How? By firing satellites from a hypersonic cannon 10 kilometers long, powered by compressed gas, capable of reaching Mach 23.
The prototype (36 meters, over 100 tests) has already exceeded Mach 4 in Oakland: now the startup is building a longer version in Alameda, California. If it works, it could redefine access to space. And if it doesn't? Well, the CEO Mike Grace he says that in that case he will sell everything to the defense sector and retire to an island. Win-win, at least for him.
Hypersonic cannon, the physics work
Grace didn't invent the idea from scratch. In 2009, he saw a TechTalk by John Hunter, the man behind the SHARP (Super High Altitude Research Project), which in the 90s fired projectiles beyond the Kármán Line1 using light gas cannons. Hunter spoke of submerged launch tubes mounted on oil platforms. Grace simply took that concept and lifted it out of the sea and placed it in the Nevada desert.
Technology is called shock-impingement thrustIt works a bit like when you try to hammer in a nail but hit it glancingly: the angled blow generates a lateral push that makes it fly away. Longshot applies this principle On an industrial scale. The "vehicle," which looks more like an artillery shell than a satellite, travels through a vacuum tube. Along the tube, pairs of compressed gas cylinders (about 3.000 psi) explode sequentially against a flat skirt mounted on the rear of the projectile. Each explosion adds velocity without the need to pump additional gas to the rear.
The trick is length. The longer the tube, the more time you have to accelerate the payload. The more time you have, the fewer g-forces the object experiences. A 300-meter launch generates thousands of g-forces. A 10-kilometer launch generates 500. With a 25-kilometer hypersonic cannon? It drops to 250 gStill too much for humans, but perfectly manageable for batteries, water, solar panels, or satellites.
Mass Ablation, Longshot's Hypersonic Cannon Trick
At Mach 23, the air turns to plasma. The surface temperature rises to 1.650°C in less than a second. How do you avoid vaporizing a delicate satellite? Simple: you stuff it inside 3.000 kilos of expendable materialThe outer mass burns up as it passes through the atmosphere. The satellite remains safely inside, protected from ablation. The larger the payload, the better the mass-to-surface area ratio. A 40-ton satellite only needs 4.000 kilograms of protection. This efficiency, of course, scales with size.
Grace has collected over 8 million dollars—venture capital plus Air Force contracts—to build a 500-meter cannon in Tonopah, Nevada. The town is known for two things: the Clown Motel (decorated with creepy clowns) and for hosting secret tests of the F-117 stealth bomber. Perfect for firing things at Mach 5 (for now) without worrying too much about the neighbors.
From the prototype to the Pentagon
Grace started in 2021 with $30.000 from friends and family, building a PVC prototype in her garage (which also reached Mach 1.8). Then came the first $750.000 contract from the Air Force through the SBIR (Small Business Innovation Research) program. From there, everything accelerated, literally. The 15-centimeter gun in Oakland reached Mach 4.6. The 75-centimeter gun in Alameda is ready for testing, awaiting FAA permits.
The progressive plan includes three phases: Mach 5 as a low-cost hypersonic test platform, Mach 10-15 for defensive applications, and Mach 25 for orbital insertion. The Pentagon is interestedTesting hypersonic vehicles costs millions per launch. Longshot offers an alternative for just a few tens of thousands of dollars.
In the meantime, SpaceX continues to dominate with Starlink and reusable launches. But Grace doesn't want to compete in human cargo or delicate satellites. It wants to dominate "only" the market for raw materials: steel, batteries, water, supplies for the ISS. Anything that can withstand acceleration and doesn't require sophisticated flight controls.
Grace plans to launch dozens of times a day. At $10 a kilo, the hypersonic cannon It could make access to space as mundane as shipping a container. Longshot won't replace rockets, but it could make them redundant for everything that doesn't breathe.
A bit like Jules Verne
The idea of shoot objects into space It has existed for 160 years. Jules Verne he imagined it in 1865. Gerald Bull He almost achieved this in the 60s with his HARP, sending projectiles to an altitude of 180 km (but only upward, never fast enough to stay in orbit). Because, you see, the difference between going up and going into orbit is enormous. You need 6 km/s vertically to touch space. and 7,8 km/s horizontally to stay there.
Longshot is aiming for that second number. And if it succeeds, it won't be with brute force but with cleverly applied physics: multiple injections, a vacuum in the tube, hydrogen instead of nitrogen, and a skirt that captures angled pulses like a hammer hitting a wedge.
If that fails, Grace already has a plan B ready: “I'll sell everything to Raytheon and cry on my cocaine island, wiping my tears with $100 bills.”. Said like that it seems like a joke. But considering that Italy is also developing electromagnetic cannons for defense and space with the HERAKLES project, perhaps the military industry would pay really well.
Physics works. Will anyone actually have the courage to pull the trigger on a 10-kilometer-long hypersonic cannon that fires satellites at Mach 23? Grace says yes. The rest of the world is watching.
- The Karman line is a symbolic and practical boundary between the sky and space, set at 100 km altitude, where planes can no longer fly as they normally do: from there onwards we enter "real" space. ↩︎
