This paper describes initial results on the use of a laser radar (LADAR)system to measure the rotational properties of a spinning sphere coated with two different surface materials. Numerical simulations were carried out using the Time-Domain Analysis Simulation for Advanced Tracking (TASAT) toolkit and a specialized laser ranging module included within the toolkit. Assuming some of the surface materials on the sphere's surface depolarize the incident radiation from the laser, the rotational properties of the object can be deduced. Futhermore, polarization properties of materials can enhance the ability to extract information about the sphere's rotational rate and relative orientation in the case where speckle noise and tracking jitter is significant. Future work will involve the creation of a large database of simulated return signatures for many orientations and rotation rates. The database will be correlated against actual LADAR measurements in order to determine the rotational and orientation properties of spinning objects in low earth orbit.
The Air Force Research Laboratory (AFRL) has initiated the LARRA (Laser Radar for Recognition and Assessment) program to investigate the use of laser radar signatures for identifying and determining the pose of satellites. The algorithms will use the 1-D range-amplitude information in the returns. To determine the identification and/or pose, the field returns will be correlated over a library of simulated returns. It is critical that the algorithms that produce the simulated returns do so accurately. AFRL has previously sponsored the development of TASAT (Time-Domain Analysis Simulation for Advanced Tracking), which has the capability to simulate the returns from satellites, to include the effects of atmospheric propagation. In this paper, we describe the modification and verification of TASAT using returns from mock satellites placed on the ground at a distance of 1 km from the laser. The laser is a mode-locked CO<SUB>2</SUB> (10.6(mu) ) and the FWHM of the micropulses is 1.4 ns.