Stoke Space has successfully landed its reusable second-stage missile system, Hopper2. An important demonstration of the company’s innovative engineering concepts. The launch vehicle lifted off to approximately 10 meters and safely returned to the targeted landing area after flying for about 15 seconds.
The test aimed to showcase the robustness of the rocket’s systems and design elements, including the hydrogen/oxygen engine, coolant-based thermal shield, and a propulsion system that maneuvers the rocket by throttling the engines.
Stoke Space is confident that the success of the Hopper2 test will propel them toward the goal of developing fully reusable rockets. “We have also demonstrated that our new approach to robust and rapidly reusable spacecraft is technically sound. We have obtained an incredible amount of data that will allow us to safely evolve the vehicle’s design” the company stated in a press release (ref.).
Among the tested features were the rocket’s differential butterfly valve. This is used for vehicle attitude control and is not widely used in the modern space industry. Also, its regenerative cooling thermal shield. The system uses pressurized coolant that passes through metallic pores in the rocket’s exterior to cool its surface during reentry.
The latter is particularly interesting because this type of shielding was the type of thermal shield Elon Musk originally wanted for SpaceX‘s spacecraft. Although the project has many supporters, no spacecraft has ever attempted reentry into Earth’s atmosphere using this technology.
A Long Road Ahead
However, Stoke Space claims that “although this vehicle did not directly experience the heat from hypersonic atmospheric reentry, it successfully handled 100% of the anticipated thermal load in a simulated environment”. Despite the success of this test, Stoke Space still has a long way to go before achieving the goal of building a 100% reusable rocket with a 24-hour turnaround time. However, the company states that it is encouraged by the results achieved so far and will now focus on developing a reusable first-stage rocket.