Session
Session II: Where We're Going Section 1
Abstract
An approach of using a very low flying orbit for a microsatellite to achieve a low cost imaging mission, and its demonstration in the Israeli - French VENμS program scheduled to be launched in 2009, are presented. At low satellite altitude, a smaller and less expensive payload can be used to obtain the performance of another one that operates at a higher altitude. This is true for the optical payload (of the present concern), and is even much more conspicuous when an RF payload is involved. More savings in mission cost are achieved due to the impact of the payload size on the satellite and on the launch cost. The main problem of flying at such altitudes is the orbital rapid loss of energy due to the drag. This is compensated for by a fuel efficient Hall Effect electrical thruster, and by proper low-drag configuration design. The electrical thruster's high specific impulse (of about 1350 sec. in our case) can provide the microsatellite with several years of mission duration at the low altitude, using acceptable amount of Xenon propellant. This concept is scheduled to be demonstrated in the Israeli - French VENμS (Vegetation and Environment New μSatellite) program. The VENμS mission is composed of two portionsa scientific one and a technological one. The scientific mission consists of multispectral Earth monitoring for vegetation and water resources quality, from a Sun- Synchronous 2-day Earth repeating circular orbit, with a mean altitude of 720 km. The technological mission has several goals, one of which is to simulate a satellite flying in a high drag environment and performing an enhanced mission. In the VENμS program the enhanced mission is the same scientific mission mentioned before, only that it is carried out at a mean altitude of 410 km, thus providing a spatial resolution almost twice as good, while maintaining the 2-day repeating ground track. The required orbit corrections do not interfere with the Earth monitoring task. The VENμS platform, not designed to fly at high air density environment, has over 2.7 m2 average cross section area to the wind. Its mission at 410 km represents a mission at much lower altitude (less than 300 km) of a different microsatellite, configured especially for high drag environment. The paper describes the low altitude microsatellite concept and analysis, the VENμS mission with emphasis on its technological portions, and the Israeli Hall Effect thruster which is especially designed to be used by small satellites. Main design issues, such as electrical power supply and environment disturbances, are also addressed.
Presentation Slides
Microsatellites at Very Low Altitude
An approach of using a very low flying orbit for a microsatellite to achieve a low cost imaging mission, and its demonstration in the Israeli - French VENμS program scheduled to be launched in 2009, are presented. At low satellite altitude, a smaller and less expensive payload can be used to obtain the performance of another one that operates at a higher altitude. This is true for the optical payload (of the present concern), and is even much more conspicuous when an RF payload is involved. More savings in mission cost are achieved due to the impact of the payload size on the satellite and on the launch cost. The main problem of flying at such altitudes is the orbital rapid loss of energy due to the drag. This is compensated for by a fuel efficient Hall Effect electrical thruster, and by proper low-drag configuration design. The electrical thruster's high specific impulse (of about 1350 sec. in our case) can provide the microsatellite with several years of mission duration at the low altitude, using acceptable amount of Xenon propellant. This concept is scheduled to be demonstrated in the Israeli - French VENμS (Vegetation and Environment New μSatellite) program. The VENμS mission is composed of two portionsa scientific one and a technological one. The scientific mission consists of multispectral Earth monitoring for vegetation and water resources quality, from a Sun- Synchronous 2-day Earth repeating circular orbit, with a mean altitude of 720 km. The technological mission has several goals, one of which is to simulate a satellite flying in a high drag environment and performing an enhanced mission. In the VENμS program the enhanced mission is the same scientific mission mentioned before, only that it is carried out at a mean altitude of 410 km, thus providing a spatial resolution almost twice as good, while maintaining the 2-day repeating ground track. The required orbit corrections do not interfere with the Earth monitoring task. The VENμS platform, not designed to fly at high air density environment, has over 2.7 m2 average cross section area to the wind. Its mission at 410 km represents a mission at much lower altitude (less than 300 km) of a different microsatellite, configured especially for high drag environment. The paper describes the low altitude microsatellite concept and analysis, the VENμS mission with emphasis on its technological portions, and the Israeli Hall Effect thruster which is especially designed to be used by small satellites. Main design issues, such as electrical power supply and environment disturbances, are also addressed.
