LACE was the First Department of Defense Satellite Launched on a Commercial Launch Vehicle
LACE was the First Department of Defense Satellite Launched on a Commercial Launch Vehicle

The Strategic Defense Initiative Organization (later renamed the Ballistic Missile Defense Organization, or BMDO) asked the Naval Research Laboratory's (NRL) Naval Center for Space Technology (NCST) to build a simple, spaceborne target with a single sensor to characterize a laser beam emitted from a ground-based laser site. As the program evolved LACE became a full satellite instead of a set of sensors on a host satellite, and SDIO added an instrument to take video images of the UV emission from rocket plumes.

The SED designed and built the LACE satellite's electrical power subsystem, telemetry and tracking subsystem, radio frequency subsystem, attitude control subsystem, and mechanism subsystem; integrated and tested the spacecraft; and calibrated the Sensor Array Subsystem. SED also designed and built two transportable ground stations to allow the LACE experimenters to review the data and assess the progress of the experiments in real time. LACE was built, integrated, and tested at NCST's Payload Processing Facility in Building A-59.

LACE included three separate sensor arrays with a total of 210 sensors capable of characterizing ground-based laser beams with continuous wave or pulsed emission in the visible, ultraviolet, and infrared bands and the Ultraviolet Plume Instrument (UVPI).

On 14 February 1990, the LACE satellite was launched from Cape Canaveral.

The "simple, spaceborne target" proved that techniques to compensate for atmospheric distortion of laser beams actually work. The UVPI succeeded on all four of its opportunities to make video images of the UV emission from rocket plumes.

Calibrating the LACE Sensor Array Subsystem
Calibrating the LACE Sensor Array Subsystem
UVPI Image of Ultraviolet Emission from a Launching Rocket
UVPI Image of Ultraviolet Emission from a Launching Rocket

Sensor Array Subsystem

LACE Sensor Array Subsystem
LACE Sensor Array Subsystem

The original purpose of the LACE satellite was to design the sensor array subsystem (SAS) experiment to measure the intensity of laser emissions over the 4- by 4-m target board on the LACE satellite. The SAS consisted of three sensor arrays with 210 sensors and a leading retroreflector array comprising 252 cornercube retroreflectors.

The SAS measured the absolute distributed intensity of low-energy ultraviolet, visible, and infrared laser beams transmitter from ground laser sites. All of the SAS sensors were carefully calibrated before launch and were built to match the requirements and characteristics of specific ground-based lasers.

The sensors determined the effectiveness of various methods of compensating for the distortion caused by the passage of a laser beam through the atmosphere. The sensors also gave measurements of the absolute power received at the spacecraft.