Brookman Orly, Podolsky Tatyana, Azar Elad, Ben-Yaakov Ohad, Fligelman Eli , Ben Meleh David, Kfir Rafi
Faculty of Aerospace Engineering, Technion, Israel;
Dr. Alex Kogan, Asher Space Research Institute, Technion, Israel;
A formation of a mother satellite and 4 daughter NANO-satellites in near- GEO will provide permanent access to positioning and precise timing service within the Middle East region.
Daughters relay mother’s signals to the user thus providing
a user with a set of pseudo-range data.
The daughters (<9 kg each) will be built from ‘on the shelf’ components.
All satellites will be delivered in orbit in one launch.
A daughter satellite: folded (left and unfolded (right) configurations
Daughters form a ~ 1000 km large, non-degenerating tetrahedron whereas their orbits obey International Regulations and stay within the allocated slot on GEO .
Perturbations make the semi major axis drift and the orbital plane rotate. Orbital correction are required in order to keep daughters’ orbits in slot.
The amount of fuel required : 67 gram/year
Relative Motion orbit (the mother satellite is in the center)
High-precision estimates of relative positions of satellites are necessary for accurate terminal users’ positioning . Laser range meter and star tracker onboard the mother sat and corner retro reflectors onboard every daughter provide required navigation data. Kalman filtering assures STD of relative position estimation errors >3 cm in each axis.
A daughter’s relative position coordinates
Terminal User’s Positioning Errors
The satellites coordinates arrive to a users’ terminal with 3s noise up to 10 cm. This noise affects the error of the terminal user positioning (the output error).
These errors have been estimated with the Monte-Carlo method.
They are proven to be less than 10 m
Scattering cloud of user’s position error
Finding the angular position in which the received power of the on-ground beacon is maximum.
The pitch loop performance:
RT:2.63 sec,ST:2.89 sec ,OT: 4.8 %
Step response of the pitch control loop