Small satellites could provide high visibility of the enemy
Rafael Advanced Defense Systems is developing a new microsatellite concept optimized for operationally responsive space (ORS), offering tactical users rapid access to near-real-time, high-resolution satellite imagery to augment aerial reconnaissance obtained by aircraft and UAVs.
The core of the system is based on Rafael's LiteSat design, a new microsatellite platform with a maximum weight of 100 kg (220 lb.). The satellite is configured with small, compatible airborne launch methods. This concept would, supposedly, offer a low-cost alternative to satellite launchers on the ground. An airborne launch from a fighter such as thecould be performed at high altitude, high speed and a steep angle, enabling a relatively small launcher such as Rafael's Sparrow ballistic missile target to place a light payload in low Earth orbit (LEO).
Theoretically, such miniature satellites packed into Silver Sparrow-type missiles—in development for the testing of Arrow 3 interceptors—could be maintained byreconnaissance units to be deployed in times of crisis to fill any intelligence gaps required for operations.
Deployed as single microsatellites or satellite constellation of nanosatellites, these assets would enable nearly continuous coverage of areas of interest, with high-revisit frequency, offering ORS deployment.
Rafael's LiteSat concept is based on a small platform packed in a 5-ft.-long, 1-ft.-wide envelope. The company is proposing two types of satellites: a 100-kg hydrazine-propelled and an 85-kg electrically propelled platform. The latter employs a state-of-the-art Hall-Effect propulsion system, also produced by Rafael, to be launched on the first mission in 2014 with the Israeli-French Venus satellite. This propulsion system converts solar energy into ionic-charged thrust, sustaining the satellite in LEO for extended missions that would have been prohibitive for hydrazine-propelled satellites, given the large volumes of propellants needed to keep the satellite in orbit.
According to Yaaqov Sharony, microsatellite programs manager in Rafael's Space Systems Directorate, the satellite is designed to operate in LEO at an altitude of 400 km for missions lasting up to seven years. The payload will comprise a panchromatic and thermal-imaging system offering “sub-metric” resolution from that altitude. Payload control and image processing will utilize the company's Imilite imagery intelligence processing, management and dissemination systems that are supporting aerial reconnaissance and UAVs.
The LiteSat platform is designed with ultra-light structures manufactured by Rafael's space-qualified composite material labs. The company has also developed lightweight propulsion methods, based on cold gas and electrical propulsion facilitating long operation with minimal fuel storage. One of the critical aspects of low-orbit satellites is their relatively short lifespan.
One such system is the company's Hall Effect Thruster (HET), a new-generation hybrid-electric satellite propulsion driven by electrical power. The system also has eight backup hydrazine thrusters employed when higher impulse is required. The first deployment of HET is scheduled for early 2014, when it is slated to power the Venus mini-class satellite, designed byas part of the joint French-Israeli scientific vegetation Earth-monitoring program. Tal Inbar, Fisher Institute director for space and UAV programs, says the Rafael initiative could be used to establish Israel's position in a new era of formation flying for various applications.
In 2015, a constellation of three nanosatellites will be placed in orbit as part of a project headed by Pini Gurfil, an aerospace engineering professor at the Asher Space Research Institute at Technion-Israel Institute of Technology. The project will demonstrate that multiple satellites can keep formation in orbit in order to triangulate and locate a radio beacon on the ground. High-precision formation-keeping is a prerequisite for interferometry processing using multiple sensors mounted on micro- or nanosatellites.
Such processing would enable future nano-satellite formations to carry out signals intelligence, search-and-rescue, electro-optical or radar-imaging missions.