FASTRAC: Formation Autonomy Spacecraft with Thrust, Relnav, Attitude, & Crosslink

Mission Objectives

The purpose of the FASTRAC (Formation Autonomy Spacecraft with Thrust, Relnav, Attitude and Crosslink) mission is to investigate enabling technologies for satellite formations, including relative navigation, crosslink communications, attitude determination and thrust. This will be achieved by downlinking data from one or more ground stations and processing the data for evaluation.

The FASTRAC mission will be a technology demonstration mission for:

On-orbit real-time GPS relative navigation solution via real-time crosslink data exchange
On-orbit real-time attitude determination using a single frequency, C/A-code, reprogrammable GPS receiver
Micro-discharge plasma thruster

The FASTRAC mission objectives are:

Test two-way intersatellite crosslink with verified data exchange
Perform on-orbit real-time GPS relative navigation to an accuracy matching ground simulations (compared to post-processed)
Demonstrate autonomous thruster firing using accurate, single-antenna on-orbit real-time GPS attitude determination

As a secondary mission objective, FASTRAC will utilize a minimum of two distributed university ground stations.

GPS On-orbit Real-time Relative Navigation and Attitude Determination

The University of Texas GPS Laboratory, under the guidance of Dr. E. Glenn Lightsey, developed a space-capable GPS receiver based on the Zarlink/Mitel GPS chipset. Named the Orion, the GPS receiver has been outfitted with a software package designed at the university, which allows the receiver to calculate the satellite's position, velocity and attitude in real-time. With data exchange from another Orion receiver, the relative position, velocity and attitude between the two satellites can be computed and reported in each receiver's output data stream. The use of a three-axis magnetic sensor will be employed together with the GPS receiver's single antenna signal-to-noise ratio measurements to produce the spacecraft attitude estimates. A cross-strap antenna design will be used along with dual GPS patch antennas to ensure greater GPS constellation visibility.

Micro-discharge Plasma Thruster

The University of Texas Satellite Propulsion Laboratory, under the guidance of Dr. L. Raja, developed a new satellite propulsion system which is capable of sustaining a micro-Newton level of thrust. The device works by channeling a superheated gas through a micro-discharge plenum. The method of superheating the gas is an innovation in the field of satellite propulsion. The thruster effectiveness will be qualitatively demonstrated by firing the thruster on FASTRAC 1. The thruster will be used to extend FASTRAC 1's lifetime in orbit by trying to counteract atmospheric drag perturbations. A noticeable difference in the nominal altitude and respective lifetimes of the two satellites will be used as a metric for the thruster's effectiveness in nanosatellite applications. The thruster operation will require autonomous control.

Distributed Ground Station Network

The University of Texas at Austin, in conjunction with Santa Clara University (SCU) in California, and Leeward Community College in Pearl City, Hawaii, are developing a distributed ground station network. The network will be remotely scheduled and controlled via the RACE ground station network control system developed by SCU. Use of the network will allow for increased downlink opportunity and for the first civilian satellite tracking network of its kind.