Why do satellites orbit above 150 km

Since then the design of satellites has changed considerably and their lifetime has increased. Satellites can be launched into circular or elliptical orbits.

Once the chosen orbit is reached, small engines on board the satellite thrust it into its precise position. The main stages of a launcher separate once they have fulfilled their purpose. The engines, other equipment and residual propellant are vented or burned to depletion to preclude later explosions and avoid accidental creation of debris.

Stages then burn up on re-entry into the atmosphere or land in uninhabited areas, usually the ocean. The powerful Ariane-5 boosters provide the main thrust at liftoff. To avoid floating parts a breach is made in the tanks during their descent so that they sink on impact with the water.

On some flights, boosters are equipped with a parachute so that they can be recovered for technical inspection. At the end of its operational lifetime, a spacecraft is de-orbited above the geostationary arc and the controlled venting of pressure vessels and residual fuel takes place.

Batteries are discharged and the power is shut down to eliminate any chance of explosion. In this committee adopted a set of guidelines designed to reduce the growth of orbital debris. One method is the careful design and operation of space vehicles.

This depends on whether the surface is in sunlight or darkness. EU citizens can enter the country with a valid passport while non-EU citizens need a valid visa. All visitors need to provide proof of vaccination against yellow fever.

Vaccination should take place at least 20 days prior to their visit. I am going to French Guiana, do I need protection against malaria? The risk of malaria from mosquito bites in the coastal area around Kourou is minimal and no special medical precautions are needed.

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Even though this 1 kg mass has reached space, it would still fall back to Earth because there is still a very strong pull of gravity attracting it towards the centre of the Earth. To balance the strong gravitational pull, the 1 kg mass must be given additional energy to place it in orbit around the Earth. An object will fall back to Earth unless it has enough orbital speed. The net result of this is an equation of the form.

To keep the 1 kg mass in orbit at an altitude of km, an orbital speed of 7. The extra energy needed to make an object travel fast enough to stay in orbit is more than 30 times as much as the energy needed to lift it to an altitude of km.

This means that, even though it takes nearly a million joules of energy to lift a 1 kg mass to an altitude of km, it takes over 30 million joules of extra energy to give it enough speed to stay in orbit around the Earth. Rockets need to be big enough to carry enough fuel to provide all of the energy needed to reach the correct altitude and speed.

Rockets that carry satellites into orbit need to be incredibly large. Learn about the Rocket Lab orbital launch site at Mahia Peninsula in New Zealand and why they've chosen this site to launch rockets into orbit.

At the correct orbital velocity, gravity exactly balances the satellite's inertia, pulling down toward Earth's center just enough to keep the path of the satellite curving like Earth's curved surface, rather than flying off in a straight line. The orbital velocity of the satellite depends on its altitude above Earth.

The nearer to Earth, the faster the required orbital velocity. At an altitude of miles kilometers , the required orbital velocity is a little more than 17, mph about 27, kph. To maintain an orbit that is 22, miles 35, kilometers above Earth, the satellite must orbit at a speed of about 7, mph 11, kph.

That orbital speed and distance permit the satellite to make one revolution in 24 hours. Since Earth also rotates once in 24 hours, a satellite at 22, miles altitude stays in a fixed position relative to a point on Earth's surface.

Because the satellite stays right over the same spot all the time, this kind of orbit is called "geostationary. In general, the higher the orbit, the longer the satellite can stay in orbit. At lower altitudes, a satellite runs into traces of Earth's atmosphere, which creates drag. The drag causes the orbit to decay until the satellite falls back into the atmosphere and burns up. At higher altitudes, where the vacuum of space is nearly complete, there is almost no drag and a satellite like the moon can stay in orbit for centuries.

A launch window is a particular period during which it will be easier to place the satellite in the orbit necessary to perform its intended function.