NEPTUNE — USA, ...I’m guessing never

Interorbital Systems is yet another startup with a little rocket for launching cubesats and such... but their approach is different. They’ve designed a simple disposable booster core which cuts lots of corners to be super cheap — it burns turpentine hypergolically with nitric acid, it uses pressurized tanks instead of pumps, it uses ablatively cooled nozzles, and so on — and then they designed them to be used in parallel. Tell us how big your payload is and we’ll tell you how many booster cores to put under it. Like real-life Kerbal players, they just stick more and more side boosters on until your payload flies. Common configurations they describe include five in a plus-sign layout, and seven in a hexagonal one. More recently they tested with four in a square pattern. They have planned a setup with five clusters of seven; by adding up thirty-five little boosters, they might be able to put a whole ton in orbit. These rockets could be launched at sea, hence the name. Or, with smaller bundles, a flimsy little trailer is all that’s needed. They claim the whole system is so simple that two people and one laptop could perform a launch.

The whole idea is derived from a German company called OTRAG, which tried to put together a similar rocket made of cheap disposable pressurized modules back in the seventies and eighties. One of the designers was none other than Werner von Braun. Their venture didn’t fail: it was forced to quit by political pressure from neighboring countries which didn’t want Germany to have rockets. The remnants of OTRAG are now advisers to Interorbital. But the new group is led by people unaffiliated with the earlier effort, most notably CEO Randa Milliron, one of very few women to run a rocket outfit, and someone familiar with doing things in a cheap DIY way from experience playing in a punk rock band. Her husband Roderick, who was also in the band, is the company’s CTO. As amateur hobbyists they once built a cryogenic engine for under a thousand bucks.

The company has announced ambitious plans to put an instrument package on the moon, as part of the competition for the Lunar X Prize. But unfortunately, they seem to be having plenty of trouble just getting the damn thing to fly. Their target dates just keep slipping, year after year, and as yet they’re still working on mastering the shortest suborbital hops. Very little of substance has been heard from them lately, but they still make noises like they’re trying to compete with the likes of Astra for DARPA prizes.

After years of apparently moribund inactivity, their website now says that after the Neptune they plan to make something bigger called Triton, which would apparently be just a scaled-up version of the same crude technology. They even mention a Triton Heavy. And they claim to be working on a tourist crew capsule to ride on it! In 2022 they tweeted that they’re about to announce yet another forthcoming rocket. But I have not seen evidence that the company has made any progress at all on real hardware since about 2018, when they tested an upper stage. In short, though this company sounded cool when I first added it here, over time the smell of fertilizer has become quite evident.

Neptune N5: mass unknown, diam 1.9 m (0.6 per core), thrust 1300 kN? (330? per core), imp unknown, pressure-fed (turpentine), payload 0.03 t, cost unknown, record 0/2/0 through 2023.