The NASA Ames Feature Innovative Propulsion System Gets Ready to Help Study Moon Orbit for Artemis says:
CAPSTONE’s journey to the Moon will take about three months, starting with its launch to low-Earth orbit on a Rocket Lab Electron. Rocket Lab’s Photon spacecraft will take over next and conduct a series of orbit-raising maneuvers to prepare the CubeSat for its transfer path to the Moon. After separating from Photon, CAPSTONE will utilize an energy-efficient ballistic lunar transfer using its onboard propulsion system and enter into a near rectilinear halo orbit in the vicinity of and around the Moon. There, it will maintain the orbit to inform future spacecraft and demonstrate new technologies.
CAPSTONE’s propulsion system is designed and built by Stellar Exploration Inc. of San Luis Obispo, California. Initially funded by NASA’s Small Business Innovation Research program, the system is approximately 8-inches square by 4-inches deep. The system’s eight thrusters are fed hydrazine propellant from an unpressurized tank. CAPSTONE’s super small, high-performance thrusters integrate proven NASA technology with state-of-the-art industry fabrication techniques.
Question: What makes CAPSTONE-1's eight hydrazine thrusters so "super small, high-performance"? How to they work without any tank pressurization?
Do they have higher ISP than other hydrazine thrusters, or is it that they have similar performance to other high performance hydrazine thrusters but fit into a smaller volume? Without any pressurization in the tank, how does liquid hydrazine reliably get into to the thruster?
What is CAPSTONE? links to many resources, including this image:
The CAPSTONE mission is planned for launch in 2021. Rocket Lab’s Photon satellite bus will deliver CAPSTONE into a trajectory toward the Moon. Credits: NASA/Rocket Lab/Advanced Space/Tyvak Nano-Satellite Systems