Algorithms for Asteroid/Comet Gravimetry via Laser Ranging and Camera Tracking During a Hypervelocity Spacecraft Flyby

While investigating the potential to reduce the uncertainty of a small (50 - 200 meter) target's (asteroid/comet) GM value using retroreflectors at approach speeds of greater than 5 km/s, it was discovered that certain mission aspects may lead to mission infeasibility.  Firstly, small targets may not be first detected at a suitable time before the flyby (less than 1 day), requiring large retroreflector release velocities, fast targeting estimation, and fast spacecraft slew and settle times.  Secondly, the uncertainty of the target's state causes difficulty in targeting the correct location for retroreflector release. Lastly, due to the retroreflector release uncertainty, retroreflector state uncertainty, and the study's laser ranging device's beam width, it is difficult to point directly at the retro reflector, obtaining measurements.  At this stage of understanding, further investigation is needed to determine if gravimetry of small targets using retroreflectors is viable due to the difficulties in target acquisition, retroreflector release targeting, and retroreflector tracking.

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