US startup Hop Aero has introduced Rook, an autonomous cargo rocket designed to launch from a standard shipping container. The company states the vehicle will carry 550 pounds (250 kg) of cargo up to 750 km in about 15 minutes.
Hop Aero says Rook will be fully autonomous and capable of landing on unprepared ground with no runway or fixed infrastructure. The reference mission for Rook is between Okinawa, Japan, and Taiwan, a distance of about 750 km.
The company pitches Rook as a way to put swarms of autonomous unmanned systems on a battlefield. Rook has not flown yet, but Hop Aero says it has completed one tethered test of a small-scale prototype at the Oklahoma spaceport.
Small team, limited funding
Hop Aero is a Y Combinator startup based in Orange, California, US, with a team of only six people. Its only government funding is a single $1.25 million US Air Force contract that expires in October.
No company has yet flown a licensed commercial point-to-point cargo delivery by rocket. The US Air Force Research Laboratory made Rocket Cargo a Vanguard program in June 2021, and awarded SpaceX $102 million in January 2022 to work on the concept with Starship.
The US Air Force renamed the Rocket Cargo effort Point-to-Point Delivery in its fiscal year 2025 budget request and asked for $4 million. A Johnston Atoll environmental review covering up to 10 reentry vehicle landings a year was suspended in July 2025.
Technical constraints and competitors
A minimum-energy ballistic arc covering 750 km needs roughly 2.64 km/s at burnout and peaks near 181 km. This arc puts Rook well above the 100 km Kármán line into space. The ballistic coast alone accounts for about six to seven minutes of the claimed 15-minute flight, leaving around eight minutes for boost, reentry, and landing.
Rook will launch from a standard 40-foot shipping container, which offers about 12.03 m of internal length and 2.35 m of width, capping the rocket's dimensions. Rocket Lab's Electron rocket stands 18 m tall and delivers about 300 kg to low Earth orbit.
Inversion Space, another Y Combinator company, raised $44 million in Series A funding and employs about 60 staff. Its Ray test vehicle failed to complete its mission in January last year due to a deorbit engine malfunction caused by a short circuit that prevented ignition.
Starship flew its 13th test on July 24, with the upper stage later splashing down in the Indian Ocean. Rocket Lab's AFRL reentry demonstration on Neutron has not flown yet. The US Navy's answer to the forward-supply problem is 3D printing spare parts at the deployment site.
Hop Aero co-founder Jacob Balaj previously worked at Masten Space Systems, which ran more than 600 vertical takeoff and landing flights over 18 years. Masten was developing its Xogdor vehicle for point-to-point payload transport when it filed for Chapter 11 in July 2022. Astrobotic bought Masten's assets for $4.5 million in September 2022.