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(Redirected from Ofek-4)
Israeli reconnaissance satellites
The satellite launches made Israel the eighth nation to gain an indigenous launch capability. Both the satellites and the launchers were designed and manufactured by Israel Aerospace Industries (IAI) with Elbit Systems' El-Op division supplying the optical payload.
Description
While exact technical details and capabilities are classified, it is assumed that the Ofeq satellites have an effective operational lifespan of 1–3 years and ultraviolet and visible imaging sensors, except Ofeq-8 and -10 which utilize synthetic-aperture radar (SAR) for all-weather and nighttime reconnaissance. Some reports place the imaging resolution at 80 cm for Ofeq-5.
Most satellites are launched eastward to gain a boost from the Earth's rotational speed. However, Ofeq satellites are launched westward, in retrograde orbits, over the Mediterranean to avoid flying over, and dropping spent rocket stages over, populated land areas. Other Israeli satellites, such as the AMOS series, are launched from locations in other countries.
Orbital characteristics
Ofeq's east-to-west orbit of 143.0° orbital inclination is phased to give good daylight coverage of the Middle East. Some American and Russian observation satellites have near-polar orbits and make between 14 and 16 orbits per day, but pass over Israel on fewer orbits. Spacecraft need to reach roughly 27,000 km/h (7,500 m/s) to achieve low Earth orbit.
At 31.88°N, the latitude of Palmachim Airbase, where the angular velocity of the Earth is around 1,420 km/h (390 m/s) to the east, westward launched Ofeq satellites must use more fuel to counter starting going 1,420 km/h the opposite direction. Many other observation satellites with prograde orbits have the same maximum latitude and cover the same areas of the Earth. However the retrograde orbit of Ofeq increases the relative speed to the surface of the Earth and thusly increases the average number of times they pass over Israel on each revolution.
Ofeq satellites make a half-dozen or so daylight passes per day over Israel and the surrounding countries, whereas non-Israeli observation satellites in Sun-synchronous orbits get one or two passes per day from their lower inclination orbits.
Since its launch in 2002, Ofeq-5's orbital inclination of 143.4 has been the most-inclined orbit of all of Earth's artificial satellites.
Ofeq-7 launch on the Shavit 2 Launch vehicle.
