FLOAT III

1. Space ADS-B Receiver Experiment (SABRE) Alex Cushley, RonVincent, Michael Baskey, José Castillo, Michael Earl, Richard Van Der Pryt, Daniel Stolzman, Malcolm Grieve Royal Military College of Canada (RMCC), Kingston, ON Payload Ground Segment Mission Summary Space Segment The Royal Military College of Canada (RMCC) plans to demonstrate a technology that has the potential to vastly improve the management of air traffic and reduce green house emissions produced by inefficient flight routes. RMCC proposes a microsatellite mission, SABRE, which will be equipped with an Automatic Dependent Surveillance - Broadcast (ADS-B) receiver. The primary mission will consist of the collection of ADS-B data and transmission of this data to a ground station. The ADS-B transmission is a 120 bit data packet transmitted on 1090 MHz that contains the aircraft identification, position, velocity, and status. The message is broadcast with a period that ranges randomly between 0.4 and 0.6 seconds. This randomization function is designed to prevent aircraft from having synchronized transmissions on the same frequency, and thus obscuring each other's transmissions. Required transmitter power for the ADS-B signal varies with the aircraft category. For smaller aircraft, a minimum transmission power of 75 W is specified while larger aircraft require a minimum power of 125 W or 200 W with a maximum output power for all classes of 500 W. Any aircraft that is capable of operating at altitudes greater than 15,000 ft (4570 m) above sea level, or with cruising speeds above 175 kts (324 km/h), are required to transmit at 125 W as a minimum. Aircraft use a quarter-wave monopole antenna for ADS-B transmissions that transmit vertically polarized signals. The proposed SABRE ADS-B receiver is a small (100 x 53 mm) PCB known as the Beast. The payload is the only non space proven component on SABRE, since an ADS-B receiver has never flown in space. The Beast has a maximum power consumption of 150 mA at 5 VDC (0.75W). Based on NAV CANADA data, a typical SABRE pass over the Hudson Bay region (180 to 240 seconds) will generate an estimated 300 kB of ADS-B data. This data will be stored on-board and subsequently downlinked to RMCC for analysis on the ground. SABRE is a 3U nanosatellite with deployable UHF/VHF antennae for ground station communications. Most of the SABRE components have been purchased and all the subsystems have a space heritage. Overview Current radar surveillance cannot track aircraft over the ocean or remote areas, requiring air traffic to use inefficient procedural techniques to provide safe separation. The North Atlantic region, which includes polar routes that fly over Canada’s Arctic, is the busiest airspace in the world with approximately 350,000 flights every year. Provision of continuous surveillance in this airspace would not only enhance air safety, but also allow aircraft to follow more direct routes, saving fuel and reducing engine emissions. An alternate method to radar surveillance is ADS-B, in which aircraft continually transmit their identity and GPS-derived navigational information. ADS-B signals are received by ground stations and relayed to air traffic services where this information is used to track aircraft with radar-like precision. ADS-B networks have already been implemented in areas around the world, including Canada’s Hudson Bay region; however, ground stations cannot be installed in mid-ocean and are difficult to build and maintain in the Arctic, leaving a coverage gap for oceanic and high latitude airspace. A potential solution for the accurate surveillance and tracking of aircraft anywhere in the world is through the monitoring of aircraft-transmitted ADS-B signals using satellite-borne receivers. To investigate this possibility, a high altitude balloon experiment was carried out by RMCC Space Science students in June 2009 to determine if ADS-B signals can be detected from near space. The Flying Laboratory for the Observation of ADS-B Transmissions (FLOAT) was the first stratospheric platform to collect ADS-B data. The FLOAT mission successfully demonstrated the reception of ADS-B signals from near space, paving the way to the development of a space-based ADS-B system. Work is currently underway at RMC to design a 3U nanosatellite (10 × 10 × 30 cm, 3 kg) to demonstrate that ADS-B signals can be received from space. The SABRE mission is designed for a low-Earth polar orbit. ADS-B transmissions will be collected over the Hudson Bay region and subsequently downlinked to RMCC for analysis. Hudson Bay is currently monitored by a series of ADS-B ground stations, so truth data will be available from Nav Canada to determine the effectiveness of the system. The future of air traffic control is ADS-B. A constellation of ADS-B satellite receivers could allow precision tracking of aircraft in any region, enhancing flight safety and promoting Canadian sovereignty. Such a system would also lead to more efficient air routes, thereby decreasing fuel consumption and carbon emissions. FLOAT III RMCC Space Science students recently conducted a third high altitude balloon mission to test the ADS-B receiver payload, which is intended to eventually fly on SABRE. The most recent balloon experiment was launched from Wingham, Ontario on 21 March 2012. Flight time for the mission was 2 hours and 19 minutes, with the balloon reaching a maximum altitude of 95,500 feet and landing approximately 30 kilometers south of the launch site. Over 51,000 ADS-B messages were received by the payload during the flight, representing 138 unique aircraft. This experiment, FLOAT III, is the third in a series of tests for the SABRE payload. *GENSO: ICOM computer Control Interface (ICOM CI-V) radios allow multiple radio control simultaneously and are required ground station hardware for participation in the Global Educational Network for Satellite Operations (GENSO). SABREPhysical Layout Future Work Two ADS-B related theses will be completed in the summer of 2012. One thesis will accurately model the neutral atmosphere and ionosphere. This model will be used in conjunction with NAV Canada air traffic data to run a simulation over the North Atlantic to determine expected signal density and strength for an ADS-B receiver in low-Earth orbit. The other thesis will form the basis to analyze electron content of the ionosphere by studying Faraday rotation of the ADS-B signal. FLOAT IV and V will be launched simultaneously in the summer of 2012 to assess and compare antenna configurations for the ADS-B receiver. The construction and systems integration phase of SABRE will begin in 2013, followed by environmental testing prior to launch. FLOAT III Ascent (Left) and Descent (Right) Conclusion The future of air traffic control is ADS-B. A constellation of ADS-B receivers will allow precision tracking of aircraft around the globe, enhancing flight safety while reducing carbon emissions due to decreased fuel consumption. NAV CANADA Vice president of operations stated, “If only 3% of flights can vary their speed and altitude in a manner that increases efficiency, we could save, each year, 2.7 million litres of fuel and avoid emitting about 7,200 tons of greenhouse gases.” SABRE is the initial step in the development of global space-based air traffic control. FLOATIII(L-R): Ocdt M. Baskey, OCdt M. Grieve, Mr. A. Cushley, Dr. R. Vincent, Mr. M. Earl, OCdt D. Stolzman & Maj. R. Van Der Pryt SABRE Ground Track (Red), RMCC Access (Green), and ADS-B Data Collection Zone (Blue) for a Typical 24-hour Period SABREMission Characteristics