Ofeq

Ofeq, also spelled Offek or Ofek (Hebrew: אופק, lit. Horizon) is the designation of a series of Israeli reconnaissance satellites first launched in 1988. Most Ofeq satellites have been carried on top of Shavit 2 launch vehicles from Palmachim Airbase in Israel, on the Mediterranean coast. The low Earth orbit satellites complete one Earth orbit every 90 minutes. 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.

Ofeq
Ofeq-7 launch utilising the Shavit 2 Launch vehicle.
ManufacturerIsrael Aerospace Industries
Country of originIsrael
OperatorIsraeli Ministry of Defence / Tsahal
ApplicationsReconnaissance
Specifications
RegimeLow Earth orbit
Production
StatusActive
Built13
Launched13
Maiden launch19 September 1988 (Ofeq-1)
Last launch29 March 2023 (Ofeq-13)

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.[1]

Orbital characteristics

Ofeq's east-to-west orbit of 143.0° orbital inclination is phased to give good daylight coverage of the Middle East.[2] Some American and Russian observation satellites have near-polar orbits and also make between 14 and 16 orbits per day, but pass over Israel on fewer orbits. Spacecraft need to reach roughly 27,000 km/h to achieve low Earth orbit. At 31.88°N, the latitude of Palmachim Airbase, where the angular velocity of the Earth is around 1420 km/h to the east, westward launched Ofeq satellites must use more fuel to counter starting going 1420 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.[3]

Launch history
  • Ofeq-1, was launched on 19 September 1988, possessed a weight of 155 kg and circled the Earth on an orbit with a perigee of 249 km and an apogee of 1149 km on a course bent around 142.9°. It accomplished mainly solar cells and radio transmission tests.
  • Ofeq-2, was launched on 23 April 1990, on a course with a perigee of 149 km and an apogee of 251 km, bent around 143.2°. It also accomplished communication tests.
  • Ofeq-3, the launch of Ofeq-3 was initially postponed from 15 September 1994 to 5 April 1995,[4] was launched on 5 April 1995, was the first operational Israeli satellite with reconnaissance (photography) capabilities. It weighed 225 kg and had a perigee of 369 km and was launched on a new version of Shavit 2.
  • Ofeq-4, was launched on 22 January 1998, did not achieve Earth orbit due to a launcher failure and was lost.
  • Ofeq-5, was launched on 28 May 2002. The 300 kg Ofeq-5 orbited the Earth on a course with a perigee of 262 km and an apogee of 774 km, bent around 143.5°. During the course of its mission, its perigee was raised to 369 km and its apogee was lowered to 771 kilometers, in an attempt to prolong the satellite's lifespan. Some observers believe that the 300 kg weight of the satellite, combined with the additional propulsive requirements of the retrograde orbit, constitute a de facto demonstration of the Shavit's Intercontinental ballistic missile (ICBM) potential.
  • Ofeq-6, was launched on 6 September 2004, encountered another launcher failure, failed to achieve low Earth orbit and crashed to the sea. The launcher failure was due to the third stage of the Shavit 2 launcher.
  • Ofeq-7 was successfully launched on 11 June 2007 using the Shavit 2 launcher.[5]
  • TecSAR (Ofeq-8) designation is used for the synthetic-aperture radar satellite launched by an Indian launch vehicle on 21 January 2008.[6]
  • Ofeq-11 was successfully launched on 13 September 2016 from Palmachim Airbase using the upgraded Shavit 2 launcher.[8]
  • Ofeq-16 was successfully launched on 6 July 2020 from Palmachim Airbase using the upgraded Shavit 2 launcher.[9]
  • Ofeq-13 was successfully launched on 28 March 2023 from Palmachim Airbase using the upgraded Shavit 2 launcher.[10]

References
  1. "AMOS-1 → Intelsat 24". space.skyrocket.de. 18 November 2019. Retrieved 8 May 2021.
  2. Stephen Clark (10 April 2014). "All-weather surveillance satellite put in orbit by Israel". Spaceflight Now. Retrieved 12 April 2014.
  3. "UCS Satellite Database - Union of Concerned Scientists". Union of Concerned Scientists. Retrieved 23 May 2022.
  4. Shavit Archived 9 April 2016 at the Wayback Machine Federation of American Scientists
  5. "Israel successfully launches Ofeq-7 satellite". Israel Ministry of Foreign Affairs.
  6. Opall-Rome, Barbara (22 June 2010). "Israel Launches Ofeq-9 Satellite". Defense News. Archived from the original on 7 September 2012. Retrieved 22 June 2010.
  7. Greenberg, Hanan (23 June 2010). "Israel launches spy satellite". Ynetnews. Retrieved 6 July 2020.
  8. "Israel Launches New Spy Satellite, Ofeq-11". Haaretz.
  9. Anna Ahronheim (6 July 2020). "Israel successfully launches Ofek 16 spy satellite into space". The Jerusalem Post. Retrieved 6 July 2020.
  10. @Israel_MOD (28 March 2023). "The Israel Ministry of Defense, IAI & IDF successfully launched the "Ofek 13" satellite at 02:10 IST today (Wednesday). The satellite entered orbit, has begun transmitting data, and completed an initial series of inspections in accordance with original launch plans" (Tweet). Retrieved 29 March 2023 – via Twitter.
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