Spaceflight

Question 0

Explain Artificial Satellites

Answer 0

1. Artificial satellites are spacecraft in Earth orbit (or probes orbiting another planet or the Moon).
2. Today, there are more than 900 operational Earth satellites for purposes such as communications, navigation, or weather forecasting.
3. Satellites are placed into orbit with a fixed speed—not so fast that they escape the Earth’s gravitational pull, and not so slow that they fall back to Earth.
4. Many satellites, such as military reconnaissance satellites, are placed in low Earth orbits to get a close-up view of the Earth’s surface.
5. Most communications satellites orbit in the geostationary ring about 22,236 miles (35,786 km) above the Earth’s equator. At this altitude, an orbit takes twenty-four hours, so a satellite hovers over a fixed point on the ground as the Earth rotates, maintaining a fixed communications link.
6. More than 5,000 tons of technology circles above our heads today. But most of it is useless “space junk,” such as discarded rocket stages, which threatens to damage operational satellites through collisions.

Question 1

Explain Rocketry

Answer 1

1. Rocketry is the technology that enabled all the feats of the space age, including satellite launches, planetary probes, and astronauts landing on the Moon.
2. All rockets work by the principle of action and reaction in Newton’s third law of motion, they push forward by ejecting propellant backward extremely fast. Most rockets burn liquid or solid fuel to achieve this.
3. The Second World War and the Cold War were driving forces for military rocket development and the subsequent space race. The German V-2 rocket, developed as a ballistic missile, is often considered the first object to have reached space on a suborbital flight, while a Soviet rocket launched the first satellite, Sputnik 1, in 1957. Human spaceflight began in 1961.
4. A rocket has to attain a specific speed, the so-called escape velocity, to overcome Earth’s gravity and travel beyond our planet. From Earth’s surface, the necessary escape velocity is about 25,000 mph (11.2 km/s)—roughly ten times faster than the record speed for a jet aircraft.

Question 2

What are planetary probes

Answer 2

1. Interplanetary spacecraft missions began in earnest in 1959, when the Soviet Union successfully crashed a probe, Luna 2, into the Moon.
2. The Soviet Venera 7 probe was the first to beam back data from another planet after landing on Venus in 1970, while NASA’s Mariner 9 spacecraft became the first to orbit another planet, arriving at Mars in 1971.
3. Several missions have robotically gathered extraterrestrial samples and returned them to Earth for analysis. Between 1970 and 1976, three Soviet missions returned samples of lunar soil.

Other sample-return missions include NASA’s Stardust project, which returned dust samples from a comet in 2006, and

the Japanese Hayabusa mission, which returned asteroid samples in 2010.

4. Most of the Mars missions attempted in the late twentieth century flopped, but success rates in the past decade have dramatically improved.

NASA’s robotic rovers Spirit and Opportunity operated on Mars for more than six years—more than twenty times longer than expected.

Question 3

Short note on human space flight

Answer 3

1. Human spaceflight began in April 1961 with the flight of YURI GAGARIN on the Soviet Union’s VOSTOK 1 spacecraft, which orbited the Earth once in 108 minutes. Gagarin’s safe return laid to rest worries that spaceflight might be fatal for humans.

Alan Shepard became the first American in space the following month. NASA’s extraordinary Apollo program followed, landing the first men on the Moon in 1969. In total, twelve men walked on the Moon between 1969 and 1972.

2. The Soviet Union (later the Russian Federation) developed a strong track record for orbiting space stations, operating the Mir space station from 1986 until 2001. Astronauts often worked on Mir for nearly a year or more at a time.

NASA’s Space Shuttle has flown crews into space more than 130 times. Five reusable shuttles originally existed, but accidents destroyed two in 1986 and 2003, claiming the lives of fourteen astronauts.

3. China became the third nation to independently launch astronauts into space in 2003, and many nations are collaborating on the current International Space Station.