MAHADEVAN Krishnan, Alameda Applied Sciences Corporation
MAHADEVAN KRISHNAN, president, Alameda Applied Sciences Corporation
The Metal Plasma Thruster (MPT) is a new class of electric propulsion technology suitable for CubeSats and Small Sats. The thruster uses inert, solid metal pucks as propellant. It uses 45V/~100A/~1ms pulses to convert ~10 µg/pulse of the metal into high velocity (~17km/s) jets of quasi-neutral plasma. The MPT technology does not require gas or liquid propellants, neutralizers, heaters, high voltage electronics, high electric or magnetic fields to operate. Furthermore, the design itself needs no special manufacturing or high precision components, making it more easily scaled for higher volume needs..
A unit module has 1.2kg mass, 96mm x 96mm x 60mm (0.6L) volume and gives 10µN/W thrust over a wide range of input power, limited only by spacecraft thermal management. The MPT is pulsed, with a wide dynamic range of impulse bits from 0.1 mNs up to the maximum total impulse of 5 kNs. The small impulse bits enable precision maneuvers such as fine positioning and attitude keeping. The comparatively simple pulsed operation is amenable to closed loop control, which provides for fine thrust control and spacecraft directed impulse on demand. Furthermore, the technology can use any metal as propellant, opening unique opportunities for In-Situ Resource Utilization (ISRU) as well as customizability of performance for meeting specific mission needs.
Supported by NASA SBIR grants, and with the aim of rapidly achieving a mature design ready for commercialization, design development and flight qualification were driven in parallel through the SBIR Phase I, Phase II and Phase II Sequential programs. Our process of rapid iteration coupled with an aggressive test-to-fail approach to development was able to take the technology from initial proof of concept to a first flight unit delivery and launch into LEO (OSS/USSF EWS RROCI mission) in only 4 years. The first launch in January 2023 failed to deploy the satellite. A second launch on March 04, 2024 inserted the satellite into LEO and awaits flight test of the MPT. A third launch is planned for early 2025.
The technology has continued to mature and drive towards scalability, with an emphasis on reliability, including direct impulse and thrust measurements of multiple metal propellants at NASA GRC# and over 9000 hrs of in-vacuum operation. Thirty two thrusters are schedule for shipment by early 2025.
# Journal of Propulsion and Power: Impulse Bit Measurements from Metal Plasma Thruster, Mahadevan Krishnan, John Frankovich and Jonathan A. Mackey; https://doi.org/10.2514/1.B38191.
# Qualification of a Pulsed, Millinewton Class Metal Plasma Thruster for Broad Mission Applications, Presented at the 38th International Electric Propulsion Conference, June 23-28, 2024, John Kent Frankovich, Mahadevan Krishnan, Jonathan Mackey and Hani Kamhawi