Date of Award


Document Type


Degree Name

Master of Science in Space Systems


Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD.


The world relies on encryption to perform critical and sensitive tasks every day. If quantum computing matures, the capability to decode keys and decrypt messages becomes possible. Quantum key distribution (QKD) is a method of distributing secure cryptographic keys which relies on the laws of quantum mechanics. Current implementations of QKD use fiber-based channels which limit the number of users and the distance between users. Satellite-based QKD using free-space channels is proposed as a feasible secure global communication solution. Since a free-space link does not use a waveguide, pointing a transmitter to receiver is required to ensure signal arrival. In this thesis, a scenario consisting of five ground sites is used to compare the amount of raw key material that can be received from four different orbits when perfect pointing is assumed. A second scenario utilizing one ground site is used to model the effect of pointing accuracy for the four orbits. The data from the first scenario indicates that lower altitudes produce higher key rates and sun-synchronous orbits don’t always produce the longest or most consistent keys. Data from the second scenario reveals a pointing bias of 1.3 μrad or less is most desirable and that with 1.3 μrad of pointing bias, a pointing jitter of 0.4 μrad will have no significant effect on key rates.

AFIT Designator


DTIC Accession Number