Israel REgional NAvigation Satellite System

09 Aug 2015

Year 2009

Student Team: 

Brookman Orly, Podolsky Tatyana, Azar Elad, Ben-Yaakov Ohad, Fligelman Eli , Ben Meleh David, Kfir Rafi
Faculty of Aerospace Engineering, Technion, Israel;

Advisors:
Dr. Alex Kogan, Asher Space Research Institute, Technion, Israel; 

The Concept 

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.

Irena1

Irena2

A daughter satellite:  folded (left and unfolded (right) configurations

Orbital Control

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

Irena3

Relative Motion orbit (the mother satellite is in the center)

Orbit Determination

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.

 

Irena4

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

Irena5

 Scattering cloud  of  user’s position error

Attitude control

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 %

Irena6

 Step response of the pitch control loop