The objective of this project is to develop a highly reliable smallsat class micro propulsion guidance, navigation, and control (GN&C) actuator that will be used as a component of the Goddard science-class SmallSats. To achieve this objective, we will partner with the George Washington University to jointly advance the technology readiness level of their Micro-Cathode Arc Thruster (μCAT) system. A version of the μCAT, jointly developed by the GWU/GSFC team, will be flying on the CANYVAL-X cubesat mission in the summer of 2017. The system is a modified version of the 1st test unit flown by USNA on the BRICSAT mission. These μCAT units are protoflight units intended to provide basic on-orbit performance data, but are not designed for reliable, long duration, precision applications. We propose to build upon the performance data collected during these flight demonstrations to develop a fully-functional, flight-ready μCAT that meets the specific needs of proposed Goddard science-class SmallSats. Specific goals of this research will be to improve reliability, thrust to power efficiency, scalable architectures for higher thrust levels, and precision of impulse bits. Our team will be leveraging our experience developing the CANYVAL-X unit and our relationship with GWU to develop a flight system to meet the needs of many proposed GSFC SmallSat missions.
The μCAT is a novel variation of a vacuum arc thruster. The thruster exhaust is plasma, an ionized electrically neutral gas. The μCAT works similar to a spark plug creating an electric arc between an anode and cathode. The arc forms a localized region of high temperature plasma at the “cathode spot”. A magnetic coil is used to cause the cathode spot to follow a circular path along the circumference of the cathode, resulting in uniform burning of the cathode over the operational life. The electric arc ablates some of the material off the cathode as high velocity plasma providing efficient, low-thrust. Each charge-discharge pulse of the electric arc creates a plasma exhaust or “impulse bit”. Thrust levels are controlled by increasing or decreasing the number of pulses each second. μCAT protoflight units have ~1 mN impulse bit, and 25 mN thrust per head.
The μCAT is a scalable technology and thrusters can be utilized in point configurations or combined in various array configurations for primary propulsion. The μCAT propulsion system includes the thruster, an inductive power processing unit (PPU) and a control unit. The thruster geometry is a simple concentric design using a spring-driven cathode feed, making it highly reliable and efficient. The cathode is the propellant, and can be any conductive or even semi-conductive material. Using the cathode as propellant reduces thruster mass and eliminates build-up of discharge by-products associated with other vacuum arc propulsion technologies. Continuous thruster tests over several weeks indicate a cathode of 6cm length operating at 10 pulses-per-second would last about a year.
The following tasks will be required for this effort
As the demand for SmallSats to become more capable and have farther reaching scientific goals, the need for them to have propulsion also becomes ever more vital. Mission paradigms looking to use the SmallSat platform include low-Earth orbit, but also higher altitude orbits, as well as lunar and interplanetary. These missions require precision orbit control and/or extended low-thrust maneuvers implying high performance (ISP and thrust precision) micro-propulsion technology. The current state-of-the-art for the majority of SmallSat propulsion systems, particularly for high-performance, low cost micro-propulsion, is at relatively low TRL. The main obstacles to any SmallSat technology are reliability, maturity, cost, ease of configuration customization and system safety.More »
|Organizations Performing Work||Role||Type||Location|
|Goddard Space Flight Center (GSFC)||Lead Organization||NASA Center||Greenbelt, MD|
The purpose of the Goddard Space Flight Center’s Internal Research and Development (IRAD) program is to support new technology development and to address scientific challenges. Each year, Principal Investigators (PIs) submit IRAD proposals and compete for funding for their development projects. Goddard’s IRAD program supports eight Lines of Business: Astrophysics; Communications and Navigation; Cross-Cutting Technology and Capabilities; Earth Science; Heliophysics; Planetary Science; Science Small Satellites Technology; and Suborbital Platforms and Range Services.
Task progress is evaluated twice a year at the Mid-term IRAD review and the end of the year. When the funding period has ended, the PIs compete again for IRAD funding or seek new sources of development and research funding or agree to external partnerships and collaborations. In some cases, when the development work has reached the appropriate Technology Readiness Level (TRL) level, the product is integrated into an actual NASA mission or used to support other government agencies. The technology may also be licensed out to the industry.
The completion of a project does not necessarily indicate that the development work has stopped. The work could potentially continue in the future as a follow-on IRAD; or used in collaboration or partnership with Academia, Industry and other Government Agencies.
If you are interested in partnering with NASA, see the TechPort Partnerships documentation available on the TechPort Help tab. http://techport.nasa.gov/helpMore »
|Closeout Document: Closeout Report 11/06/2017||Download|