History

The first space mission, Sputnik 1, was an artificial satellite put into Earth orbit by the USSR on 4 October 1957. On 3 November 1957, the USSR orbited Sputnik 2, the first to carry a living animal into space – a dog.

The USA achieved its first successful space probe launch with the orbit of Explorer 1 on 31 January 1958. Explorer 1 weighed less than 14 kilograms compared to 83.6 kg and 508.3 kg for Sputniks 1 and 2 respectively. Nonetheless, Explorer 1 detected a narrow band of radiation surrounding the Earth, named the Van Allen belts after the scientist whose equipment detected it.

Only seven other countries have successfully launched orbital missions using their own vehicles: France (1965), Japan (1970), China (1970), the United Kingdom (1971), India (1981), Israel (1988).

Most American space probe missions have been coordinated by the Jet Propulsion Laboratory, and European missions by the European Space Operations Centre, part of the European Space Agency (ESA). ESA has launched many spacecraft to carry out astronomy, and is a collaborator with NASA on the Hubble Space Telescope. There have been many successful Russian space missions. There have also been a few Japanese, Chinese and Indian missions.

Design

In spacecraft design, the United States Air Force considers a vehicle to consist of the mission payload and the bus (or platform). The bus provides physical structure, thermal control, electrical power, attitude control and telemetry, tracking and commanding. The "flight system" of a spacecraft into subsystems. These include:

- physical backbone structure (provides overall mechanical integrity of the spacecraft; ensures spacecraft components are supported and can withstand launch loads);

- command and data subsystem. (responsible for command sequence storage, maintaining the spacecraft clock, collecting and reporting spacecraft telemetry data (e.g. spacecraft health), collecting and reporting mission data (e.g. photographic images);

- attitude control subsystem (responsible for the spacecraft's orientation in space and the positioning of movable parts);

- telecommunication subsystem (includes radio antennas, transmitters and receivers which are used to communicate with ground stations on Earth, or with other spacecraft);

- electrical power subsystem (includes solar cells and a radioisotope thermoelectric generator, batteries for storing power and distribution circuitry that connects components to the power sources);

- temperature control and protection from the environment subsystem (includes mirrors and sunshades for additional protection from solar heating).