Spacecraft systems

Maglev CubeSat Testbed

The Maglev CubeSat Testbed (MCT) was designed and built by MIT students to provide a realistic environment to test nanosatellite hardware. The MCT makes use of magnetic levitation to suspend a CubeSat-sized satellite inside the Astrovac vacuum chamber. Magnetic levitation allows rotational motion around the vertical axis. This motion is practically frictionless, such that the satellite can rotate freely without contacting chamber materials. The MCT is used to explore the way a small satellite will behave in space once it is equipped with thrusters, electronics, sensors, actuators, batteries, on-board computer, radio and payload. Spacecraft charging, rotational motion due to thrust, attitude control performance and integrity of all components in a vacuum environment can be investigated with the MCT.

Maglev CubeSat Testbed

 

Thrust measurements

By firing the thrusters over a period of time and measuring the angular velocity acquired by the satellite, thrust can be calculated.

Thrust measurements of electrospray thrusters as a function of emitted current

 

Video of electrospray thruster firings changing the attitude of a Maglev CubeSat Testbed satellite

F. Mier-Hicks, P. C Lozano, "Electrospray Thrusters as Precise Attitude Control Actuators for Small Satellites" Submitted to Journal of Guidance, Control and Dynamics.

 

Attitude control

The zero friction environment the magnetic levitation creates is ideal to test attitude control performance of the thrusters. A non-contact angular encoder capable of arcsecond resolution is used to monitor the angular position of the levitated CubeSat in real time. This information is provided to an attitude controller which then fires thrusters on the CubeSat to maintain attitude. The system has been proven to hold attitude within 22 arcsecond 3σ during a 10hour period

Precise attitude control demonstration using electrospray thrusters
 

Pointing control and achieved attitude accuracy for a CubeSat using iEPS thrusters on the Maglev Testbed

F. Mier-Hicks and P. Lozano. “Electrospray Thrusters as Precise Attitude Control Actuators for Small Satellites”. Journal of Guidance, Control, and Dynamics.

 

Spacecraft charging

Spacecraft charging can be monitored while the thrusters are firing thanks to a non-contact charge sensor placed in close proximity to the levitated CubeSat.  While firing the thrusters the satellite potential rises and after a brief transient stabilizes. The spacecraft charging induced by the thrusters is always bounded.

Satellite charging characteristics during multiple thruster polarity switching cycles

F. Mier-Hicks and P. Lozano. “Spacecraft Charging Characteristics Induced by the Operation of Electrospray Thrusters”. Journal of Propulsion and Power.

 

For further information, please contact Fernando Mier Hicks