Answers

What is a launcher?

A launcher is the vehicle used to carry satellites, space probes, and/or elements of space stations into space. Launchers also protect payloads during liftoff and during the critical stage of leaving the Earth’s atmosphere.

Why are the European launchers called Ariane?

Initially named LS3 for "Lanceur trois étages de substitiution", in 1971 it was decided to find a less technical name for the European launcher. Three names were proposed: Penelope, Phoenix and Ariane ESA chose the latter. Its origin goes back to "Ariane’s thread" and the mythological legend of Thesee.

What happens at liftoff into geostationary orbit?

The launcher lifts off vertically, powered by the main stage engine and the boosters. After approximately five seconds it banks progressively towards the east to put it into geostationary transfer orbit. It takes about 2 mins to reach a height of around 60 km, at which point the two boosters separate and fall into the sea.

The main stage burns for about 12 mins. During this time the launcher continues its ascent in preparation for the horizontal trajectory which is handled by the upper stage. As the launcher is now above the Earth’s atmosphere the fairing, which protected the satellites, is no longer needed and is jettisoned.

It is during the upper stage burnout lasting approximately 13 mins. that the launcher reaches its highest velocity of around 8 km/s. At this point the launcher’s upper stage engine is cut and the computer on board commands the satellites(s) to spin on their axis. This puts them into the correct position to continue their journey into space alone.

The launcher is steered from the ‘brain’ in the Vehicle Equipment Bay, placed above the cryogenic main stage. Data stored on position, velocity and acceleration enables the onboard computers to estimate the best trajectory and make any necessary corrections. Once the satellite(s) are on their way the upper stage is sent into what is called a ‘graveyard orbit’ where it can do no damage to other orbiting satellites and vehicles.

How can I see a launch?

For more information on how to see a launch check Attend a launch

What is a launch window?

This is the precise period of time, in hours and minutes, within which a launch must take place if the spacecraft onboard is to be placed into the correct orbit.

Who keeps track of the launcher once it lifts off?

As a launcher rises into the sky, ground stations scattered along its path take over and check that it remains on track. Computers onboard the launcher transmit data to ground stations for instant forwarding to Europe’s Spaceport in French Guiana.

The number of ground stations used depends on the type of launcher and the mission itself. For instance, the Galliot ground station in French Guiana tracks the first five minutes of an Ariane-5 launch into geostationary transfer orbit. Then, a tracking station in Natal on the coast of Brazil takes over for the next 3 minutes, during which the main stage separates and the second stage ignites. The next ground station to follow the track of the Ariane 5 is on Ascension Island, in the middle of the Atlantic Ocean. From here the launcher is tracked for approximately 9 minutes until the satellites are injected into geostationary transfer orbit.

There are many other ground stations scattered around the world, as well as transportable tracking stations that allow more flexibility. These are used to track launchers, and also to gather and transmit data from satellites in orbit.

 What are orbits

Orbits are the path followed by a satellite around a celestial body. The point of the orbit further away from the Earth is referred to as the apogee while that nearest to the Earth is called the perigee. Which orbit a satellite is place into depends on the job it is going to do in space. For more information see Types of orbits.

How fast does a launcher travel?

To escape from the Earth’s atmosphere a launcher has to reach an altitude of more than 150 km and travel at a speed of more than 7.9 km per second.

What is a satellite?

A satellite is any small body that orbits a larger one, either natural or artificial. The Earth’s natural satellite is the Moon. Artificial satellites are used for science, telecommunications, weather forecasting, navigation, defence, reconnaissance and Earth observation.

The first artificial satellite was the Russian Sputnik 1, launched in 1957. Since then the design of satellites has changed considerably and their lifetime has increased. Today’s satellites may remain in space for as long as 15 years and have large solar panels to supply power to the onboard electronic equipment that receives and transmits data from and to the Earth.

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. These engines are also used to correct the satellite’s trajectory during orbit and to maintain its nominal orbital position.

What happens to the stages of a launcher after launch?

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.

After the upper stage has released the satellite(s) it is sent into what is called a disposal or ‘graveyard’ orbit above the geostationary arc, where it can do no damage to other orbiting satellites and vehicles.

What happens to the boosters?

The powerful Ariane-5 boosters provide the main thrust at liftoff. Once the launcher reaches a height of around 60 km the boosters’ work is over and they separate from the launcher and fall into the sea. 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.

What happens to old satellites?

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.

What is being done about space debris?

The space agencies of 10 countries, as well as ESA, are members of the Inter-Agency Space Debris Coordination Committee (IADC). In 2002 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.

What is the external temperature of spacecraft in space?

This depends on whether the surface is in sunlight or darkness. In sunlight, near the Earth and the Moon, the external temperature of an object can reach over 150°C whereas in the shade the temperature can fall below –150°C.

How do I get to French Guiana?

There are daily flights from Orly, Paris to the airport at Cayenne Rochambeau, 65 km from Kourou in French Guiana. The flight takes approximately 8 1/2 hours. There are also regular flights from Martinique and Guadeloupe, Paramaribo in Surinam, and Belem and Macapa in Brazil.

Do I need a visa to go to French Guiana?

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.

Do I need any vaccinations to visit French Guiana?

Yellow fever: vaccination is required a minimum of 20 days before leaving
Tetanus: vaccination recommended
Diptheria: vaccination recommended
Polio: vaccination recommended
Hepatitis A+B: vaccination recommended
Typhus: vaccination recommended

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. However, preventive medicine is strongly recommended for visitors to Oyapock, Maroni, Cacao and Regina.

 What is there to see in French Guiana?

One of the main attractions is Europe's Spaceport but there are many other things to see in French Guiana. For more information look at Visit Europe's Spaceport and Tourism.

Last update: 30 October 2013

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