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  2. Sun-synchronous orbit - Wikipedia

    en.wikipedia.org/wiki/Sun-synchronous_orbit

    An orbit will be Sun-synchronous when the precession rate ρ = ⁠ dΩ / dt ⁠ equals the mean motion of the Earth about the Sun n E, which is 360° per sidereal year (1.990 968 71 × 10 −7 rad/s), so we must set n E = ⁠ ΔΩ E / T E ⁠ = ρ = ⁠ ΔΩ / T ⁠, where T E is the Earth orbital period, while T is the period of the spacecraft ...

  3. Synchronous orbit - Wikipedia

    en.wikipedia.org/wiki/Synchronous_orbit

    A synchronous orbit is an orbit in which an orbiting body (usually a satellite) has a period equal to the average rotational period of the body being orbited (usually a planet), and in the same direction of rotation as that body.

  4. Polar orbit - Wikipedia

    en.wikipedia.org/wiki/Polar_orbit

    The half-orbit on the Sun side then takes only 50 minutes, during which local time of day does not vary greatly. To retain a Sun-synchronous orbit as the Earth revolves around the Sun during the year, the orbit must precess about the Earth at the same rate (which is not possible if the satellite passes directly over the pole).

  5. Wide-field Infrared Survey Explorer - Wikipedia

    en.wikipedia.org/wiki/Wide-field_Infrared_Survey...

    The mission was planned to create infrared images of 99% of the sky, with at least eight images made of each position on the sky in order to increase accuracy. The spacecraft was placed in a 525 km (326 mi), circular, polar, Sun-synchronous orbit for its ten-month mission, during which it has taken 1.5 million images, one every 11 seconds. [19]

  6. Terminator (solar) - Wikipedia

    en.wikipedia.org/wiki/Terminator_(solar)

    Low Earth orbit satellites take advantage of the fact that certain polar orbits set near the terminator do not suffer from eclipse, therefore their solar cells are continuously lit by sunlight. Such orbits are called dawn-dusk orbits, a type of Sun-synchronous orbit. This prolongs the operational life of a LEO satellite, as onboard battery life ...

  7. Soil Moisture Active Passive - Wikipedia

    en.wikipedia.org/wiki/Soil_Moisture_Active_Passive

    An animation of SMAP 's trajectory around Earth from 31 January 2015 to 19 August 2015: SMAP · Earth. Soil Moisture Active Passive (SMAP) is a NASA environmental monitoring satellite that measures soil moisture across the planet. It is designed to collect a global 'snapshot' of soil moisture every 2 to 3 days.

  8. Terra (satellite) - Wikipedia

    en.wikipedia.org/wiki/Terra_(satellite)

    Terra (EOS AM-1) is a multi-national scientific research satellite operated by NASA in a Sun-synchronous orbit around the Earth.It takes simultaneous measurements of Earth's atmosphere, land, and water to understand how Earth is changing and to identify the consequences for life on Earth. [1]

  9. Synodic day - Wikipedia

    en.wikipedia.org/wiki/Synodic_day

    As viewed from Earth during the year, the Sun appears to slowly drift along an imaginary path coplanar with Earth's orbit, known as the ecliptic, on a spherical background of seemingly fixed stars. [5] Each synodic day, this gradual motion is a little less than 1° eastward (360° per 365.25 days), in a manner known as prograde motion.