Formation Autonomy Spacecraft with Thrust, Relnav, Attitude, and Crosslink
Encyclopedia
Formation Autonomy Spacecraft with Thrust, Relnav, Attitude and Crosslink (or FASTRAC) is a pair of nanosatellites developed and built by students at The University of Texas at Austin. The project is part of a program sponsored by the Air Force Research Laboratory
(AFRL), whose goal is to lead the development of affordable space technology. The FASTRAC mission will specifically investigate technologies that facilitate the operation of multiple satellites in formation. These enabling technologies include relative navigation, cross-link communications, attitude determination, and thrust. Due to the high cost of lifting mass into orbit
, there is a strong initiative to miniaturize the overall weight of spacecraft. The utilization of formations of satellites, in place of large single satellites, reduces the risk of single point failure and allows for the use of low-cost hardware.
In January 2005, the University of Texas won the University Nanosat-3 Program
, a grant-based competition that included 12 other participating universities. As a winner, FASTRAC was given the opportunity to launch its satellites into space. The student-led team received $100,000 from AFRL for the competition portion of the project, and another $100,000 for the implementation phase. FASTRAC is the first student-developed satellite mission incorporating on-orbit real-time relative navigation, on-orbit real-time attitude determination using a single GPS antenna, and a micro-discharge plasma thruster.
FASTRAC launched on 19 November 2010 aboard a Minotaur IV
rocket from the Kodiak Launch Complex
in Kodiak, Alaska
. Separation of the satellites from each other and cross-link communication were successfully carried out.
FASTRAC was developed under the US Air Force Research Laboratory University Nanosatellite Program, and was ranked number 32 in the Space Experiments Review Board's list of priortised spacecraft experiments in 2006. The spacecraft were expected to demonstrate Global Positioning System relative navigation and micro-charge thruster performance.
The third phase will begin once the two nanosatellites are ejected from the rocket. During this phase, there will be a 30 minute period where the satellites will go through a check out and initialization process. After this period, the satellites will begin transmitting beacon messages containing telemetry information that will help determine each satellite's status. During this phase the ground station will attempt to establish first contact with the satellites and perform a check out procedure to make sure all the subsystems on board are working correctly. It is expected that this checkout procedure will take several hours or even a few days depending on the duration of the communication passes with the ground station. Once the operators are satisfied with the status of the satellites, the satellites will be commanded from the ground to separate, finalizing the third phase of the mission.
When the satellites have successfully separated, the primary mission will begin, signaling the start of fourth phase. First, the satellites will autonomously establish a cross-link, or in other words, they will communicate with each other through UHF
/VHF
bands. The satellites will then exchange GPS data through this cross-link in order to calculate on-orbit real time relative navigation solutions.
The fifth phase will activate a micro-discharge plasma thruster with a command from the ground that will autonomously operate when the thrusting vector is within a 15 degree cone of the anti-velocity vector. The thruster operation will be dependent on the on-orbit real-time single antenna GPS attitude determination solution. After this phase is over, a command from the ground station will disable the thruster on FASTRAC 1.
The final phase of the mission will start once the communication architecture of the satellites is reconfigured from the ground to work with the Automatic Packet Reporting System (APRS) network. This will make the satellites available to amateur radio users all around the world. Once the ground station loses all communication with the satellites, the mission will be terminated and the satellites will passively de-orbit, burning up in the atmosphere. The FASTRAC team has estimated that it will take six months to successfully achieve its mission objectives.
. The FASTRAC implementation consists of two receivers, one transmitter, a terminal node controller (TNC), a transmitter relay board, and a receiver relay board. On FASTRAC 1 “Sara Lily”, two R-100 VHF receivers and one TA-451 UHF transmitter from Hamtronics are used. On FASTRAC 2 “Emma”, two R-451 UHF receivers and one TA-51 VHF transmitter from Hamtronics are used. The TNC used is a KPC-9612+ from Kantronics. Both the transmitter and receiver relay boards were designed and manufactured in house.
s which were developed by Santa Clara University
. Each AVR has an Atmega 128 microcontroller and controls an individual subsystem on the satellite (i.e.: COM, EPS, GPS, and THR or IMU). The AVRs communicate with each other through the I2C bus.
(SNR) and 3-axis magnetometer
measurements to provide estimates of position, velocity, and attitude. Each satellite will have redundant ORION GPS receivers, dual cross-strapped antennas with RF switching and splitting hardware.
provided to the team by AFRL. Both the solar panels and the VREG board were designed and made in-house. On each satellite, the VREG board distributes power from three VICOR VI-J00 voltage regulators, and also charges the batteries with the power collected from the solar panels.
(IMU) MASIMU01 from Micro Aerospace Solutions is used to measure the separation of the two satellites.
Air Force Research Laboratory
The Air Force Research Laboratory is a scientific research organization operated by the United States Air Force Materiel Command dedicated to leading the discovery, development, and integration of affordable aerospace warfighting technologies; planning and executing the Air Force science and...
(AFRL), whose goal is to lead the development of affordable space technology. The FASTRAC mission will specifically investigate technologies that facilitate the operation of multiple satellites in formation. These enabling technologies include relative navigation, cross-link communications, attitude determination, and thrust. Due to the high cost of lifting mass into orbit
Orbit
In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System...
, there is a strong initiative to miniaturize the overall weight of spacecraft. The utilization of formations of satellites, in place of large single satellites, reduces the risk of single point failure and allows for the use of low-cost hardware.
In January 2005, the University of Texas won the University Nanosat-3 Program
University Nanosatellite Program
The University Nanosat Program, a satellite design and fabrication competition for universities jointly administered by the Air Force Office of Scientific Research , the Air Force Research Laboratory , the American Institute of Aeronautics and Astronautics , and the Space Development and Test Wing,...
, a grant-based competition that included 12 other participating universities. As a winner, FASTRAC was given the opportunity to launch its satellites into space. The student-led team received $100,000 from AFRL for the competition portion of the project, and another $100,000 for the implementation phase. FASTRAC is the first student-developed satellite mission incorporating on-orbit real-time relative navigation, on-orbit real-time attitude determination using a single GPS antenna, and a micro-discharge plasma thruster.
FASTRAC launched on 19 November 2010 aboard a Minotaur IV
Minotaur IV
Minotaur IV, also known as Peacekeeper SLV and OSP-2 PK is an active expendable launch system derived from the Peacekeeper missile. It is operated by Orbital Sciences Corporation, and made its maiden flight on 22 April 2010, carrying the HTV-2a Hypersonic Test Vehicle...
rocket from the Kodiak Launch Complex
Kodiak Launch Complex
The Kodiak Launch Complex is a commercial rocket launch facility for sub-orbital and orbital space launch vehiclesowned and operated by the Alaska Aerospace Corporation, a public corporation of the State of Alaska....
in Kodiak, Alaska
Kodiak, Alaska
Kodiak is one of 7 communities and the main city on Kodiak Island, Kodiak Island Borough, in the U.S. state of Alaska. All commercial transportation between the entire island and the outside world goes through this city either via ferryboat or airline...
. Separation of the satellites from each other and cross-link communication were successfully carried out.
FASTRAC was developed under the US Air Force Research Laboratory University Nanosatellite Program, and was ranked number 32 in the Space Experiments Review Board's list of priortised spacecraft experiments in 2006. The spacecraft were expected to demonstrate Global Positioning System relative navigation and micro-charge thruster performance.
Operations
The main mission sequence is composed of six distinct phases: Launch, Launch Vehicle Separation, Initial Acquisition, GPS Onboard Relative Navigation, Onboard Single Antenna GPS Attitude Determination and Micro-discharge Plasma Thruster Operation, and Amateur Radio Operations. In the first phase, the two nanosatellites will be launched on the Department of Defense Space Test Program STP-S26 Mission from Kodiak Launch Complex (KLC) in Kodiak, Alaska. They will be transported to a 72 degree inclination circular low Earth orbit with an altitude of 650 km by a Minotaur IV rocket. Initially, the two nanosatellites will be in a stacked configuration. Once the rocket reaches the desired orbit, the satellites will be powered on by the launch vehicle before finally separating from the launch vehicle.The third phase will begin once the two nanosatellites are ejected from the rocket. During this phase, there will be a 30 minute period where the satellites will go through a check out and initialization process. After this period, the satellites will begin transmitting beacon messages containing telemetry information that will help determine each satellite's status. During this phase the ground station will attempt to establish first contact with the satellites and perform a check out procedure to make sure all the subsystems on board are working correctly. It is expected that this checkout procedure will take several hours or even a few days depending on the duration of the communication passes with the ground station. Once the operators are satisfied with the status of the satellites, the satellites will be commanded from the ground to separate, finalizing the third phase of the mission.
When the satellites have successfully separated, the primary mission will begin, signaling the start of fourth phase. First, the satellites will autonomously establish a cross-link, or in other words, they will communicate with each other through UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
/VHF
Very high frequency
Very high frequency is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency , and the next higher frequencies are known as Ultra high frequency...
bands. The satellites will then exchange GPS data through this cross-link in order to calculate on-orbit real time relative navigation solutions.
The fifth phase will activate a micro-discharge plasma thruster with a command from the ground that will autonomously operate when the thrusting vector is within a 15 degree cone of the anti-velocity vector. The thruster operation will be dependent on the on-orbit real-time single antenna GPS attitude determination solution. After this phase is over, a command from the ground station will disable the thruster on FASTRAC 1.
The final phase of the mission will start once the communication architecture of the satellites is reconfigured from the ground to work with the Automatic Packet Reporting System (APRS) network. This will make the satellites available to amateur radio users all around the world. Once the ground station loses all communication with the satellites, the mission will be terminated and the satellites will passively de-orbit, burning up in the atmosphere. The FASTRAC team has estimated that it will take six months to successfully achieve its mission objectives.
Structure
The structure of the FASTRAC satellites is a hexagonal iso-grid design that is composed of two titanium adapter plates, aluminum 6061 T-6 side panels, six hollow outer columns with inserts and six inner columns. The mass of the two nanosatellites is approximately 127 lbs with all of the components included.Communication Architecture
The communications architecture is based on a system flown on PCSat2PCSat2
PCSat2 is an amateur radio satellite created by the US Naval Academy.It was installed on the International Space Station on August 3, 2005. PCSAT2 was recovered from the outside of the ISS by astronauts on the 3rd EVA of mission STS-115 and was return to Earth.PCsat2 transmitted packet bursts every...
. The FASTRAC implementation consists of two receivers, one transmitter, a terminal node controller (TNC), a transmitter relay board, and a receiver relay board. On FASTRAC 1 “Sara Lily”, two R-100 VHF receivers and one TA-451 UHF transmitter from Hamtronics are used. On FASTRAC 2 “Emma”, two R-451 UHF receivers and one TA-51 VHF transmitter from Hamtronics are used. The TNC used is a KPC-9612+ from Kantronics. Both the transmitter and receiver relay boards were designed and manufactured in house.
Command & Data Handling
The command & data handling (C&DH) system is composed by four distributed AVRAVR
AVR may refer to:* Avon Valley Railway, a heritage railway in the United Kingdom* Atmel AVR, a family of microcontrollers* Assiniboine Valley Railway, a minimum gauge railway in Winnipeg, Canada...
s which were developed by Santa Clara University
Santa Clara University
Santa Clara University is a private, not-for-profit, Jesuit-affiliated university located in Santa Clara, California, United States. Chartered by the state of California and accredited by the Western Association of Schools and Colleges, it operates in collaboration with the Society of Jesus , whose...
. Each AVR has an Atmega 128 microcontroller and controls an individual subsystem on the satellite (i.e.: COM, EPS, GPS, and THR or IMU). The AVRs communicate with each other through the I2C bus.
GPS Subsystem
The GPS position and attitude determination system was designed and built by student researchers at The University of Texas' GPS Research Lab. The system utilizes GPS code measurements, as well as antenna signal-to-noise ratioSignal-to-noise ratio
Signal-to-noise ratio is a measure used in science and engineering that compares the level of a desired signal to the level of background noise. It is defined as the ratio of signal power to the noise power. A ratio higher than 1:1 indicates more signal than noise...
(SNR) and 3-axis magnetometer
Magnetometer
A magnetometer is a measuring instrument used to measure the strength or direction of a magnetic field either produced in the laboratory or existing in nature...
measurements to provide estimates of position, velocity, and attitude. Each satellite will have redundant ORION GPS receivers, dual cross-strapped antennas with RF switching and splitting hardware.
Power System
The power system for each satellite is composed of eight solar panels, a VREG box, and a battery box. The battey box is made from black anodized aluminum and holds 10 Sanyo N4000-DRL D-cellsD battery
A D battery is a size of dry cell. A D cell is cylindrical with electrical contacts at each end; the positive end having a nub or bump...
provided to the team by AFRL. Both the solar panels and the VREG board were designed and made in-house. On each satellite, the VREG board distributes power from three VICOR VI-J00 voltage regulators, and also charges the batteries with the power collected from the solar panels.
Separation System
There are two separation systems for the FASTRAC satellites, both designed and manufactured by Planetary Systems Corporation (PSC), which will be used to separate the satellites in their stacked configuration from the Launch Vehicle and then to separate the two satellites while they are in orbit. The PSC Lightband Separation System is composed of two spring-loaded rings and a motorized release mechanism.Micro-Discharge Plasma Thruster
The micro-discharge plasma thruster was designed and built at UT-Austin. The thruster channels and superheats an inert gas through a micro-channel nozzle producing a micro-Newton level of thrust. It uses a custom made composite tank from CTD. The operation of the thruster will be automated by the spacecraft C&DH using the attitude measurements provided by the GPS attitude determination system. After enabling the operation of the thruster from the ground, it will be only be active when one of the two nozzles is within a 15 degree cone of the anti-velocity vector. The thruster subsystem is only present on FASTRAC 1 "Sara Lily".Inertial Measurement Unit (IMU)
On FASTRAC 2 “Emma”, instead of using a thruster, an Inertial Measurement UnitInertial measurement unit
An inertial measurement unit, or IMU, is an electronic device that measures and reports on a craft's velocity, orientation, and gravitational forces, using a combination of accelerometers and gyroscopes. IMUs are typically used to maneuver aircraft, including UAVs, among many others, and...
(IMU) MASIMU01 from Micro Aerospace Solutions is used to measure the separation of the two satellites.
Amateur Radio Participation
The FASTRAC satellites transmit and receive data (GPS, Health, etc.) on amateur radio frequencies. All amateur radio operators are encouraged to downlink data from either satellite and upload the data to the radio operator section on the FASTRAC Website.Operation Frequencies
| FASTRAC 1 "Sara Lily" | FASTRAC 2 "Emma" | |
|---|---|---|
| Downlink | 437.345 MHz FM | 145.825 MHz FM |
| Beacon Radio propagation beacon A radio propagation beacon is a radio beacon, whose purpose is the investigation of the propagation of radio signals. Most radio propagation beacons use amateur radio frequencies. They can be found on HF, VHF, UHF, and microwave frequencies... |
437.345 MHz AX.25 1200 AFSK | 145.825 MHz AX.25 1200 AFSK |
| Uplink Uplink A telecommunications link is generally one of several types of information transmission paths such as those provided by communication satellites to connect two points on earth.-Uplink:... (1200 Baud Baud In telecommunications and electronics, baud is synonymous to symbols per second or pulses per second. It is the unit of symbol rate, also known as baud rate or modulation rate; the number of distinct symbol changes made to the transmission medium per second in a digitally modulated signal or a... ) |
145.980 MHz FM | 435.025 MHz FM |
| Uplink (9600 Baud) | 145.825 MHz FM | 437.345 MHz FM |