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GPS SatellitesThere are 30 GPS satellites -- called NAVSTARs -- in place and the oldest one was launched in 1989. These are just the ones in operation now -- another 22 have been launched since the program started in 1978, but are no longer working.

The design of the satellites has remained essentially the same over the years; the differences have just been in their operations.

The first 11 satellites, known as Group I and designed by Rockwell International, were launched into orbit between 1978 and 1985 from Vandenburg Air Force Base in California. Each of these satellites contained one Cesium and two Rubidium atomic clocks and could provide navigation and standard positioning information. Continuous contact with the Ground Control Segment (CS) was required for their operation. They were designed to last five years, but most lasted much longer.

The next group of 9 satellites are called Group II and were also designed by Rockwell. These were the first to provide precision positioning information for military use and to be able to operate for 14 days without contact with the CS. Group II satellites contained four clocks two Cesium and two Rubidium and were launched between February 1989 and October 1990 from Cape Canaveral Air Force Station in Florida. They were designed to last 7.3 years and two currently remain in operation.

The Group IIA satellites were next group to be designed by Rockwell and numbered 19. They are similar to the Group II satellites, except they have the ability to operate 180 days without contact with CS. These were launched from Cape Canaveral between November 1990 and November 1997. All but three of these satellites are still in operation.

The most recent type, Group IIR, were designed by Lockheed Martin and each have three Rubidium clocks. They were designed to provide more accurate information through a combination of ranging techniques and communication between the satellites. They are also designed to last slightly longer (7.8 years) and to have improved independent controls. There are currently 12 such satellites in orbit the most recent launched in November 2004.

The satellites are launched via a Delta II rocket designed by Boeing. These are expendable launch vehicles (ELVs), meaning they are intended for one use only. Each of these ELVs consists of the following:

  • Stage I which contains fuel and oxygen tanks to supply the main engine during its climb;
  • Solid rocket booster motors to provide additional thrust during the first two minutes of flight;
  • Stage II which contains the fuel and oxidizer tanks that supply the engine needed to insert the ELV into orbit and the brains of the ELV, including its guidance system;
  • Stage III that has a solid rocket motor to provide any needed velocity change.

More input from others:

  • According to SMC Fact Sheet (URL, as well as Garmin (URL, there are 24 satellites in the system with an additional 4 on reserve.

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โˆ™ 2012-01-27 12:47:38
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Q: How many GPS satellites are there and when were they put in orbit?
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Related Questions

What orbit are monitoring satellites put into?

Polar orbit

How are satellites put into orbit?

by a rocket

Did they have GPS a hundred years ago?

No, there was no GPS in 1918. Neither the concepts on which GPS operates had occurred to anyone nor was the primitive electronics of the time able to support its requirements had anyone thought of it. Also in 1918 it was not possible to put satellites in orbit.The first satellite put in orbit was in 1957.The concepts on which GPS operates were not worked out until the late 1960s.The first launch of a GPS satellite was on February 1978; 39 years ago.The GPS requires 24 operating satellites and 6 functional spare satellites in orbit to operate.Early GPS receivers (available only to the military and large companies) cost tens of thousands of dollars and weighed from 20 to 100 pounds. This was all that was available until the very late 1980s.

Some satellites are put into an orbit around the earths poles what is this type of orbit called?

Circum polar satellites.

What is the difference between moon and satellite?

The word Moon is a name given to the natural satellite in orbit around the Earth. We attribute this name to most objects large enough to see in orbit around other planets. In this way Moons and Natural Satellites are one in the same. Artifical Satellites are what we put into orbit around the earth IE GPS Satellites, but are man made.

How are most artificial satellites put into orbit?

By rockets

What are some artificial satellites?

Artificial satellites are satellites that we put up ourselves. These include the international space station, hubble telescope, and the GPS network of satellites.

How many satellites did India sent to the space?

72 + 35 (foreign) satellites were put into orbit so far (till November 2013).

State two purpose for which artificial satellites are put into orbit?

Two main purposes for which artificial satellites are put into orbit are weather mapping and forecasting and long-distance communication.

What are man-made satellites?

They are the machines that we put in orbit. Natural satellites are things like the moon, that got into orbit without our intervention.

What are the names of some satellites currently in earths orbit?

Sutnick was the very first Satellite that was put into orbit.=)

How many satellites comprise the GPS and expand it?

There are at least 24 GPS satellites in operation at any given time with a number of on-orbit spares in case one fails. Each one is in a 12 hour orbit (meaning it takes 12 hours to orbit the earth). They are in a variety of six different orbits and are not just locked into a geosynchronous orbit (meaning they stay over roughly the same place on earth at all times, like your satellite TV and communications satellites) like some satellites.All GPS satellites are owned and operated by the US Air Force and are controlled specifically by the 2d Space Operations Squadron at Schriever AFB in Colorado Springs, CO. There is not an easy way to deny the GPS capability to our enemies without also denying our own capability, so it is a free system open to anyone that has the technology to utilize it.GPS satellites carry not only positional data but also extremely precise timing signals, which help the GPS receivers on the ground to triangulate their position and are even used to validate and secure financial transactions, etc. When the system was first created, artificial timing errors were put into the signal to try to reduce the effectiveness of the system for non-military users, but it was removed in 2000.The GPS satellites also have NUDET (Nuclear Detonation) sensors on them to detect nuclear detonations almost anywhere on earth.To use GPS you need to be in clear view of at the very least 3 satellites but you should be in view of 6 satellites at any given time unless some are blocked by objects, mountains, etc. So, GPS usually doesn't work well in-doors or even in a forrest or valley at times.

Could a small satellite orbit the moon?

Satellites have been put into orbit around the moon. A list of them is at the link.

What does the acronym GPS stand for?

GPS: Global Positioning System. is a satellite-based navigation and consists of 24 satellites placed into orbit by the Department of Defense of the United States. Originally, it was intended for military applications, but from the 80's the U.S. government put the navigation system available to civilians.

Why do satallites have to stay in the equotorial plane?

they don't. surveillance satellites almost all have polar orbits, GPS satellites have a variety of orbits, most satellites follow orbits that were easiest and cheapest to put them in from launch site.

What happens to satellites when they are no longer needed?

They continue to orbit the planet or star they were put in orbit around until they fall into the atmosphere and burn up.

How can we put a satellite past Mars but we can't land on Mars?

satellites orbit around the Earth and if they come out of orbit, they can never come back

Who is the inventor of the gps?

Roger L. Easton is credited as being the inventor of the GPS concept, but it was not until the US Air Force became interested that GPS satellite were put into Earth orbit.

How do artificial satellites get fuel?

Many satellites contain propellant tanks used for repositioning the satellite. They also use solar arrays to collect energy from the sun. When the satellite runs out of fuel it is said to have reached its end of life and will either burn up in the earths atmosphere or will be put in another orbit, such as super synchronous orbit. This allows a replacement satellite to be launched and put in the same orbit but prevents over population of that particular orbit.

What is a satellite that orbits the earth?

If by satellite you mean an object that orbits the earth, then the Moon is a satellite of the earth. There are thousands of other satellites put into orbit by both private and public organizations used for everything from GPS to communication and even you TV service.

What moves around a planet?

A Satellite. There are man made satellites (equipment or stations put into orbit by a rocket) and natural satellites, which are called moons if large enough.

How are satellites put in space?

Rockets, and then they just push them out the rocket door, and they adjust them with little rockets into orbit

Why did they make the canadarm?

one reason it is made is to fix other satellites and put them back to its proper orbit

Who paid to put GPS all into orbit?

Some telecommunication companies have paid and others were paid for by governments.

What was the first rocket to orbit the earth?

Normally rockets do not orbit the earth. Rockets lift/put satellites into space, some of which orbit the earth. The first satellite to orbit the earth was the Soviet Union's Sputnik-1