Shooting Payload to Orbit in a 10km Space Gun

On Episode 57 of S3 we didn't have to travel far from our San Francisco studio to film in Oakland, CA with @LongshotSpace

— a company aiming to build a multi-kilometer "space gun" to fire mass to orbit at $/kg costs never before though possible.

In the episode you meet CTO @natosaichek

and CEO Mike Grace. Nato takes us behind the scenes during a test of their proof of concept gun and you'll see the moment they fire a projectile from 0 MPH to Mach 4.2. You'll also hear details about their next 500 meter system they're preparing to build in Nevada later this year.

However, in this article, we'll go deeper on the following:

• The past challenges of getting payload on orbit

• Longshot's previous milestone systems and their upcoming 500 meter gun build

• Issues around G forces effects on payloads

Rockets are great, but space guns could significantly lower $/kg

With the bevy of recent advances in aerospace, many dreams that were once relegated to the territory of science fiction seem more and more plausible by the day. At the forefront of those one-time fantasies is space colonization.

With private companies like SpaceX drastically reducing the cost of launching payload to orbit, the barriers to cheaply putting mass in space have gradually been knocked down. But not all of them, and out in Oakland, California, Longshot hopes to break through another wall, by building the biggest gun humanity has ever seen.

Before we get into the fascinating specifics of Longshot's proposed space cannon, let’s further dissect the need.

Getting to space is expensive. It always has been, and though it is getting cheaper by the day, it still is pricey. In 1969, the launch of Apollo 11 was estimated to cost $185 million ($1.62 billion when adjusted for inflation). The Saturn V rocket that took the crew into orbit could carry up to 260,000 pounds into low-Earth orbit, which adjusts to around $6,300 per pound today. As we entered the space shuttle era, those costs boomed. The last shuttle launch in 2011 would cost around $2.1 billion when adjusted for inflation ($1.5 billion at the time), and with the relatively small carrying capacity of 60,500 pounds, the cost of sending cargo into space landed at an unfeasible $25,000 per pound. (Source)

The advancements in the private sector have done wonders for these costs. Rocket Lab’s electron rocket has a payload capacity of 660 pounds, but with an average launch price of only $7-7.5 million, the per pound cost comes out to $11,000. 

Finally, there’s SpaceX, whose Falcon 9 has a carrying capacity of 50,000 pounds and a launch cost of $67 million. The per pound costs vary depending on the size of the payload, but at $1,200-$2,500 it’s clear that Falcon 9 offers the most economically sensible option we’ve seen to date.

Elon has given projections on Starship that it could cost only $10/kg ($5 per pound), but these are still only projections and ones that are still dependent on a variety of factors and advancements.

So yes, while private breakthroughs in rocketry have gone a long way in cutting orbital transportation costs, it is still far from cheap.

Enter, Longshot.

If CEO and Founder Mike Grace was raised on a foundation for one thing, it was outlandish innovation. Growing up as a sci-fi enthusiast, cherishing the likes of Star Wars, Star Trek, and the pool of creativity that is hack science fiction, Grace was acutely aware that the realm of possibility extended beyond what had been done. Then, around 2000, he saw a talk from Dr. John Hunter. Hunter was discussing his idea of building a light gas gun, suspended below an oil derrick.

The idea would stick with him. In part, due to the potential for $/kg to be as low as $5 according to CTO and Cofounder @natosaichek: 

Launch a pool noodle in 6 months

Years would pass, and while trying to avoid working on his Master's thesis, Grace would call his close friend and eventual cofounder, Nathan "Nato" Saichek, with a frenzied tone and one simple phrase:“I’ve got an idea”. That phone call born out of procrastination would be the genesis of Longshot, the idea that rather than sending cargo to space on a rocket, we could do it with a kinetic launch system that will quickly (7-8 km/s) accelerate payloads to orbital velocities.

Of course, building a system capable of accelerating payloads to 7-8 km/s is going to be an expensive, time-consuming, and hard task. Longshot is still at least 4 years away from building anything capable of putting stuff in orbit — but in the meantime, they've come up with a solid dual use strategy to fund their business and solve engineering problems needed for an orbital system.

It began with Grace’s wife giving him 6 months of financial support. This gave him 180 days to prove his idea was something of substance. In those 6 months, Grace raised $20,000 allowing him to build a modest prototype that in his words was “basically a piece of irrigation equipment that can put a pool noodle up to Mach 1.8”.

After that proof of concept, Longshot would land a $750,000 contract with the Air Force, turning this half-a-year gamble into a real possibility. With that money in hand, Longshot was able to raise an additional $2.5 million in venture capital, allowing them to build their current prototype out in Oakland.

In short — by eliminating the need for onboard fuel and complex propulsion systems that traditional rockets require, Longshot's kinetic launch system could theoretically achieve incredibly low costs per kilogram to orbit. This approach also presents unique advantages in terms of rapid launch capabilities. Even if Starship achieves its ambitious $10/kg cost target, Longshot's system aiming for $5/kg could open up new possibilities for frequent, high-volume cargo launches that could accelerate space development and exploration in ways that traditional rockets may not be able to match.

Building a demo space gun in... Oakland, CA

There are certain limitations that come with building a demo version of a cannon designed to launch cargo into orbit, in an industrial and highly populated city like Oakland, CA.

The first is space. With only a 60-foot-long shed, Longshot had to be intentional with what they could build, designing the demo system to be 15 meters long.

The second is gas. In an ideal world, Longshot would use hydrogen to propel the projectiles inside of their device, but there are some obvious risks to doing something like that in a highly populated area.

So instead, the company has been using helium. The goal with these limitations was to shoot a projectile at Mach 4 or above, which Longshot achieved by reaching speeds of Mach 4.6, but on a more consistent basis, Mach 4.2.

Building a 500 meter gun in... Nevada.

Okay, that makes a bit more sense than Oakland.

Longshot is now looking to expand the design of their next gun from 15 meters, to 500 meters out in the deserts of Nevada. This proposed gun would be larger than any gun ever made by roughly a factor of 30. Rather than the small payloads they have been experimenting with so far, this latest system will be propelling payloads of 100 kilograms to speeds up to Mach 5, with Mike Grace even being hopeful that it could eventually reach Mach 15, which would be ~half of orbital velocity (though he notes it will not reach those speeds immediately).

The potential customer for this enormous cannon is, of course, the Department of Defense, who at minimum has uses for hypersonic test systems. But of course, the ultimate goal of Longshot is not to test missiles for the DoD, it is to send payloads into space, and in order to do that the system will have to be significantly bigger than the one they are building in Nevada.

Rather than the half-a-kilometer-long, biggest gun ever made that will rest in the desert, the final evolution of the project will be a system that is between 10-15 kilometers long, allowing the payloads to reach speeds up to Mach 25. In their most conservative estimates, assuming they are constricted financially, they could build a projectile that is 2 meters in diameter and would weigh roughly 3,000 kilograms, with around 500 kilograms of payload. But in an ideal world, Longshot would like to see that 500 kilograms of payload reach 40,000 kilograms of payload.

Obviously, there’s a long way to go before anything capable of that is built, but Mike Grace aims to have Longshot trying to send get payload into space by 2028 or 2029. If they manage to pull it off, there will be a future in which you can fire off enormous payloads into space, for $10 per kilogram, or roughly $5 per pound.

An obvious concern with this system is the effect such high G forces would have on payloads — a viewer of the episode commented:

Nato shared his thoughts on electronics being more resilient than people would suspect in his @1stPrinciplesFM interview and in a response provided under our episode:

Longshot’s journey in redefining how we get mass to orbit is far from complete, and there will certainly be many more hurdles in their future, but we wouldn't write them off.

From sending a pool noodle to speeds up to Mach 1.8, to their prototype in Oakland capable of sending projectiles out at speeds up to Mach 4.2, Longshot has hit every benchmark they’ve set so far. Their latest challenge will be faced in the scorching deserts of Nevada.

We can’t tell you what comes next, but whatever it is, we’ll be there to film it.

Keep on building the future.