Economical Reentry Capsules for Hypersonic Testing

Advanced strike, surveillance, interceptor, orbital transfer, and orbital reentry vehicles need to travel at hypersonic speeds for at least a portion of their trajectory. This hypersonic flight regime can generate flow energies in excess of 24MJ/kg, molecular excitation, and chemical dissociation. In turn, these thermo-chemical processes affect vehicle aerodynamic coefficients, heat transfer rates, and effectiveness of onboard sensors. Despite its importance, this flight regime remains poorly understood due to the difficulty in generating flight-accurate hypersonic flows in the lab or ground test facilities. Modern ground test facilities cannot simultaneously match all the hypersonic flow parameters leading to a compromise on test conditions (Reynolds number, free stream chemistry, test time, etc). Likewise, modern state-of-the-art hypersonic fluid dynamics codes are not fully validated because flight-relevant validation data does not exist. The resultant uncertainties associated with hypersonic flows lead to vehicle failures, increase development costs, and lengthen development timelines.   The best way to study hypersonic flows and test hypersonic materials is to fly at hypersonic speeds. Unfortunately, modern dedicated hypersonic flight test programs can cost over $100 M per flight and adapting additional sensors to qualified or crewed reentry vehicles for flight testing introduces unacceptable risks. Alternatively, Varda is designing a reentry vehicle for its commercial business that can be leveraged for readily available and cost-effective hypersonic environment and material testing.  Varda Space Industries is an in-space manufacturing company that is building on-orbit factories to manufacture ZBLAN fibers and reentry capsules to return ZBLAN to Earth. The first test flight is expected in 2023. Varda is optimizing these capsules for cost and repeatability to support Varda’s primary business of selling products produced in orbit. These optimization targets also make Varda’s capsules an ideal candidate for the Air Force’s hypersonic validation and test efforts. Once the capsules are produced the Air Force and other DoD customers will be able to buy capsules off Varda’s production line for flight testing and data collection.  This Phase 2 SBIR proposal will develop a high heat flux torch test and evaluate a range of thermal protection systems (TPS) for Varda’s capsule. This work will reduce reentry flight risk, characterize Varda’s capsule TPS, and accelerate Varda’s capsule development roadmap. An increased understanding of the capsule’s TPS will be critical when Varda’s capsule is utilized for hypersonic flight testing — either for testing material coupons during re-entry or while embedding new sensors though this TPS for environment sensing. The same test rig will also be used to qualify components and sensors that the Air Force may choose to install on Varda’s capsule for future flight test.