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The UV LED mission demonstrates the precise control of the potential ofelectrically isolated test masses that is essential for the operation of spaceaccelerometers and drag free sensors. Accelerometers and drag free sensors wereand remain at the core of geodesy, aeronomy, and precision navigation missionsas well as gravitational science experiments and gravitational waveobservatories. Charge management using photoelectrons generated by the 254 nmUV line of Hg was first demonstrated on Gravity Probe B and is presently partof the LISA Pathfinder technology demonstration. The UV LED mission and priorground testing demonstrates that AlGaN UV LEDs operating at 255 nm are superiorto Mercury vapor lamps because of their smaller size, lower draw, higherdynamic range, and higher control authority. We show flight data from a smallsatellite mission on a Saudi Satellite that demonstrates AC charge control (UVLEDs and bias are AC modulated with adjustable relative phase) between aspherical test mass and its housing. The result of the mission is to bring theUV LED device Technology Readiness Level (TRL) to TRL 9 and the chargemanagement system to TRL 7. We demonstrate the ability to control the test masspotential on an 89 mm diameter spherical test mass over a 20 mm gap in a dragfree system configuration. The test mass potential was measured with an ultrahigh impedance contact probe. Finally, the key electrical and opticalcharacteristics of the UV LEDs showed less than 7.5 percent change inperformance after 12 months in orbit.

Ground Testing and Flight Demonstration of Charge Management of Insulated Test Masses Using UV LED Electron Photoemission