Spaceflight fosters international cooperation among government agencies scientific bodies industries and organizations Some large-scale projects such as the Inter national Space Station ISS would not have been possible without collaboration Space exploration and research serves as an arena in which countries work together peacefully toward shared goals even when they may be at odds con cerning other issues The space race between the Soviet Union and the United States during the twentieth century contributed to many milestones in space exploration Today the United States and Russia cooperate on many missions especially those involving the ISS The Outer Space Treaty of 1967 established that nations cannot claim outer space as sovereign territory and forbade installing weapons in space Spaceflight isn’t a sure thing Successful missions will be countered by occasional failures and even tragedies But the unexpected setbacks will be matched by unexpected benefits As long as human beings set their eyes and ambi tions toward space the resulting discoveries and break throughs will make the effort worthwhile 6 the BenefIts of spaCeflIght and spaCe exploratIon
Keeping the World ConneCted The space age began on October 4 1957 when the Soviet Union launched the first artificial satellite to orbit Earth Sputnik 1 weighed 184 pounds 84 kilo grams Its maximum distance from Earth was 584 miles 940 kilometers It circled Earth every ninety-six minutes and remained in orbit until early 1958 when it fell back and burned in Earth’s atmosphere Today nearly 1,500 operational artificial satellites orbit Earth Many more satellites now dead are classified As this model of Sputnik 1 shows the first artificial satellite was about the size of a basketball It was launched into Earth orbit by the Soviet Union in 1957 7 Chapter tItle runnIng head goes here Chapter 1
as space debris More than five hundred of the operational satellites were launched by the United States Most satellites orbit Earth in low Earth orbit LEO between one hun dred and one thousand miles 160 km and 1,600 km above Earth or geostationary orbit GEO 22,236 miles 35,786 km above Earth PHONING HOME AND TUNING IN The major application of artificial satellites in the modern world is to provide long-distance communication links In addition to launching the space age Sputnik 1 ushered in a new era in communications technology For its first twenty-two days in orbit before its battery ran down the satellite transmitted signals back to Earth In 1962 the United States launched Telstar 1 the first satellite capable of two-way communication It transmitted live television images between the United States and Europe as well as the first phone call transmitted by satellite A satellite consists of three main components The communications system receives a signal from Earth ampli fies the signal and retransmits it back to Earth where it can be received over a wide geographic area The propulsion system includes the rockets that propel the satellite and is capable of adjusting the satellite’s position in space Finally solar panels provide power to the satellite A communica tions satellite can function for up to twenty years Many communications satellites operate in GEO meaning that they are fixed over one specific location 8 the BenefIts of spaCeflIght and spaCe exploratIon
KeepIng the World ConneCted above Earth’s surface These sat ellites provide a signal to a vast geographical area Three GEO satellites can provide global cov erage But a signal from a GEO satellite is very slightly delayed Therefore mobile and voice ser vices usually utilize satellites in lower orbits Telstar 1 was launched by NASA on July 10 1962 Two days later it transmitted the first live television signals across the Atlantic Ocean between the United States and Europe Today communication satellites provide various services to broadcasters internet service providers ISPs governments the military and other sectors These include three types of com munication services telecommu nications broadcasting and data communications Telecommuni cation services include telephone calls and services provided to telephone companies as well as wireless mobile and cellular network providers Broadcast ing services include radio and television delivered directly to households as well as programming received by cell phones and other mobile devices Data communications involve the transfer of data A significant amount of internet traffic goes through satellites making ISPs one of the largest customers for satellite services 9
