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A sun-synchronous orbit is an orbit around the Earth, where the movement of the satellite always looks the same when viewed from the Sun. A satellite in a sun-synchronous orbit still orbits the Earth, but does so in such a way that over the course of the day, its distance to the Sun will change in a consistent pattern no matter the time of year. Summer vacation plans changed for many in 2020. Whatever your plans, Landsat can take you on a virtual road trip. Landsat 8, in its sun-synchronous polar orbit, views every national park in the U.S. Every 16 days and gathers more photographic data than the most ambitious of tourists. This video illustrates the principle of Sun-synchronous orbits used by EUMETSAT's Metop satellites. The satellite's orbital plane is indicated by the red tor. The mission concept involves two identical satellites that will orbit at a nominal altitude of 612km in a Sun-synchronous orbit with a 6 day repeat cycle. The two satellites will fly in the same orbital plane half an orbit apart. This configuration is capable of acquiring SAR interferometric data pairs with a 3. Sun Synchronous Orbits allow a satellite to pass over a certain point on the earth at the same time of every day. Since there are 365 days in a year and 360 degrees in a circle, the orbit changes about one degree per day to stay synchronous.

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(Files in red–history) Index 10a. Particle Drift 11. Explorers 1/3 11a. Geiger Counter 12. Rad. Belts 12H. Argus 1958 12a. Inner Belt 12b. Outer Belt 13. Fast Particles 14. Synch. Orbit 15. Energy 16. The Sun 16H. Schwabe, 1843 16a. Schwabe paper 16b. Carrington, 1859 17. The Corona

The orbital period of a satellite increases as its mean distance from Earth grows. The space shuttle in a low altitude circular orbit, just above the atmosphere, completes one circuit in about 90 minutes. It orbits some 6700 km from the Earth's center, while the moon, at 380,000 km, completes one orbit in 27.3 days. Intermediate distances go with intermediate periods, and somewhere between those two extremes is a distance where the orbital period is 24 hours. It turns out to be at about 42,000 km or 26,000 miles, some 6.6 Earth radii. (More precisely, the period is 23 hours 56 minutes: 24 hours is the mean interval from noon to noon, but noon is determined by the Sun's position in the sky, and the Sun's position among the stars shifts slightly during that time.) [The formula for the period T of a satellite orbiting the Earth in a circle of radius R Earth radii can be derived from Kepler's 3rd law (see here for the details) and is (x here denotes multiplication) T = 84 minutesx Rx √R If you have a suitable calculator, you can easily check the value of T for R=6.6] A satellite orbiting above the equator at that distance keeps its position above the same spot on the ground; hence this is known as the synchronous orbit, from the Greek syn--same, chronos--time. Such an orbit is useful first and foremost for communication satellites, because a ground station linked to the satellite will always be in touch with it, as long as its antenna points to a fixed spot on the sky.

The same holds for satellite dishes receiving TV broadcasts from such satellites, and of course, weather satellites designed to monitor (say) US weather will always have the proper view if parked in a synchronous orbit and facing the US. The NOAA agency of the US government ('National Oceanic and Atmospheric Administration') maintains in a set of GOES synchronous satellites to observe the weather and monitor the space environment. Images obtained by these satellites are available on the world wide web and are updated every 15 or 30 minutes. NASA's tracking network, too, uses the TDRSS Satellites (Tracking, Data and Relay Satellite System) in synchronous orbit to collect data from near-Earth spacecraft. Currently more than 200 spacecraft share this orbit, most of them commercial communication satellites. The synchronous orbit also happens to be the approximate boundary between the sheltered near-Earth magnetosphere and the outer portions where substorms and other active changes occur. For this reason many synchronous satellites have carried detectors for magnetic fields and for trapped or injected ions and electrons. Interest in that region is driven in part by the realization that the sudden arrival there of a large number of energetic particles, as happens now and then, can charge satellites to many hundreds of volts, can create false signals in their circuitry and can even, in extreme cases, cause serious damage.

(Above) The record of electrons intercepted by the synchronous satellite ATS 6 on 20 July 1974. The jagged peaks mark the arrival of electrons in substorms, and they gradually drift away again. The lower energies which persist belong to the plasma sheet of the magnetotail (described in a later section) in which the satellite is immersed for about half of its orbit.Questions from Users: *** Synchronous satellites

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Author and Curator: Dr. David P. Stern
Mail to Dr.Stern: education('at' symbol)phy6.org
Co-author: Dr. Mauricio Peredo
Spanish translation by J. Méndez

Last updated 25 November 2001
Re-formatted 3-12-2006

A Sun-synchronous orbit matches the rate at which the Earth goes around the Sun. It is a low-Earth orbit.

Advantage: consistent lighting conditions of the Earth’s surface enable us to compare images from the same season over several years

Altitude: typically 600–800 km

Satellite period: 96–100 minutes

Satellite examples: Landsat 7, CloudSat

Transcript

Sun Synchronous Polar Orbit In Hindi

Dr Allan McInnes

Sun-synchronous orbit is a special kind of orbit. Wow, this is where we get into the complexities or orbit mechanics. So orbits are not fixed in space, they tend to change over time, and one of the things that makes an orbit change is the shape of the Earth. And in the case of the shape of the Earth, one of the changes that we see with orbits is something called precession of the orbit, and precession basically means that the orbit moves relative to the Earth over time. So you’re not just orbiting around the Earth – the circle of the orbit is actually shifting in space as well.

Normally that’s something that we either ignore or counter the effects of by manoeuvring the spacecraft. But with a Sun-synchronous orbit, what we actually try to do is take advantage of that. If we pick the right altitude and the right inclination relative to the equator, we can actually get a precession rate at which that orbit changes that just happens to exactly match the rate at which the Earth goes around the Sun.

Sun Synchronous Orbit Animation

And what that means is that, if we put a spacecraft into an orbit where, when it initially takes off and is flying around the Earth, it spends part of its time directly over a point that’s seeing midday Sun and the other half of its orbit over the side of the Earth where it’s exactly at midnight, we’re going to maintain that all the way through the year, because as the Earth moves around the Sun, the orbit’s also shifting. If we weren’t in a Sun-synchronous orbit, then we might start out seeing noon and midnight and then later in the year we’d be seeing some other time of day, and it would change over time.

With the Sun-synchronous orbit, we’re locked to the Sun essentially, and so if we start out seeing noon and midnight, we’ll always see noon and midnight. And that can be quite useful for observation and scientific missions where we want to get consistent lighting conditions on the ground. So if we always want to be over something with nice bright midday Sun then we’ll make sure we always see that with the Sun-synchronous orbit.