Gravity and history
Everything thrown up the earth's surface (except tantrums) comes down. It's as if some force pulls everything down to the ground. This is what we call gravity. Space travel is only possible is if we escape the Earth's gravitational field. For defying gravity, a spacecraft must reach a velocity of 11.2 km/sec or 39,600 km/hr. It was only by the middle of the 20th century that mankind understood this, finally, and worked to make such a speed attainable.
The earliest evidence of rocket dates back to 1045 A.D. when Chinese made and used them in warfare. By World War II, liquid propulsion technology revolutionised rockets. The 1942 launch of a rocket by Germans that hit a target 120 miles away marked the beginning of the space age. Rockets made space travel possible and today after what one can say, honing of the rocket talent, spacecrafts and shuttle came into being. Shuttles carry spacecrafts, which are released while in orbit. After it clears the Earth's gravitational pull, the spacecraft uses small on-board thrusters to navigate.
In 1957, the Soviet Union launched Sputnik 1, the world's first satellite, which was followed by the US satellite, Explorer 1, a year later. For the next few decades, the US space programme included Ranger, Lunar Orbiter, and Surveyor (Moon), Viking (Mars), Mariner, Voyager, Magellan, Galileo, and Pioneer (Venus and the outer planets). The Russian space programme included Luna to the Moon and Venera to Venus. By the eighties, Europe and Japan had joined the space race with unmanned missions to Halley's comet.
The nineties was another successful period for space exploration. The launch of the Hubble Space Telescope rocketed off that decade. Then came Ulysses and ACE spacecrafts sent to study the sun, specifically. The Deep Space 1 spacecraft was the first of NASA's New Millennium programme to be launched. Cassini, NEAR (Near Earth Asteroid Rendezvous), and Stardust are just a few of the other missions currently underway.
Putting a satellite in geosynchronous orbit was yet another major breakthrough. This takes place at 35,800 km above the equator, where a satellite keeps up with the Earth's spin. From the ground, the satellite appears to be standing still.. This way, it is able to beam images of a particular area, continuously. Latest work on spaceology has created spacecraft that have become satellites to other planets. Like Galileo spacecraft that, after six years of travel to Jupiter, is now that planet's newest satellite.
Asking for the Moon
The Moon, since ages remained the object of desire for mankind. Globally, space programmes initially hovered around the conquest of moon. It all started after Sputnik 2 (1957), which carried the first animal to space, convinced mankind that it was indeed possible for live beings to go to zilch beyond earth without actually being harmed. Luna II, a Russian unmanned craft, impacted the Moon's surface on September 13, 1959, becoming the first man-made object to reach another body in the universe. In 1961, the Russian cosmonaut, Yuri Garagin, became the first human to go into space. It was followed a month later by the US astronaut, Alan Shepard.
This inspired astronauts-in-wings and paved the way for launching man on the Moon and predictably, for all space missions, Moon became the target number one. That famous "one step by man and one big leap for mankind" came in 1969, finally.
Apollo 11 became the first manned mission to land on the Moon. Neil Armstrong and Buzz Aldrin took the first 'human' steps on another planetary body on July 20, 1969. Apollo 13 was the third mission to land on the Moon and Apollo 17 was the last Apollo mission to land men on the Moon. It carried the only trained geologist to walk on the lunar surface, lunar module pilot Harrison Schmitt. This happened in December,1972.
USA vs Russia
After the success of landing on the Moon, the US government's interest waned in space programmes and they became more science-based. In 1973, the first American space lab was put into orbit and scientific tests began to take place. Between 1973-1981, the USA scheduled only one or two manned missions. Finally in 1981, the USA revamped their manned mission programme with several new missions and brand new spacecraft design, the space shuttle. One of the most significant missions included the deployment of the Hubble Space Telescope in 1990. In the meantime, the Russians tested new spacecraft and became the first to create a space station. Throughout the sixties, the cosmonauts sent many manned and unmanned spacecraft.
Near the end of the Apollo space programme, NASA officials were looking at the future of the American space programme. At that time, one-shot disposable rockets were in vogue. A reliable, but less expensive, reusable rocket was the need of the hour and thus the idea of space shuttle that could launch like a rocket, deliver and land like an airplane and could be used again was born. In 1972, President Nixon announced that NASA would develop a reusable space shuttle or space transportation system (STS). Then that was not an easy issue to sort out as re-entry into Earth's atmosphere involves large amount of heat generation by way of friction. Re-entry temperatures can reach as high as 1,650 oC. At that time, spacecrafts used ablative heat shields that would burn away as the spacecraft re-entered the Earth's atmosphere (as in Apollo). The designers of the space shuttle came up with an idea to cover the space shuttle with many insulating ceramic tiles that could absorb the heat of re-entry without harming the astronauts. This insulating tile technology is different from ablative technology. In ablative technology, the surface of the heat shield melts and vapourises, and in the process, carries away heat. In insulating technology, special silica tiles protect the outer surfaces of the hardware. The tile insulates so well that no heat makes it out to the edges. This technology is used in the space shuttle. Four shuttles—Columbia, Discovery, Atlantis, Challenger—were then made. The first flight was in 1980 with the space shuttle Columbia, piloted by astronauts John Young and Robert Crippen.
Ever since the first sounding rocket was launched on November 21, 1963, India has come a long way in space missions. On April 1, 1975, Aryabhatta, the first Indian satellite, was launched. Then came Bhaskara-I, an experimental satellite for Earth observations that was launched on June 7, 1979. In April 1984, Rakesh Sharma became the first Indian to go to space under the joint Indo-Soviet manned space mission. After a failed mission in March 24, 1987 when the first developmental launch of ASLV with SROSS-1 satellite on board could not place in orbit, GSLV launch was successfully completed on April 18, 2001. Now, Indian space scientists are eying the Moon. The Indian Space Research Organisation (ISRO) has already sent a report to government officials saying they have the technical capability to launch an expedition to the Moon by 2007. The organisation says it expects the project to cost nearly $ 82.5 million.
Failures propel success, to twist the cliché, the starry way. The space trip saga has its share of numerous failures, many of them being fatal.
Nearly 30 per cent of unmanned spacecrafts went astray and are now moving in other orbits. Russia's Luna 1, missed lunar surface in 1959 and is now in solar orbit. The latest non-fatal miss was when on June 4, 1996, Ariane 5, broke up 40 seconds after the lift-off. The reason: The flight parameters of Ariane 4 were fed for Ariane 5 leading to a software error. This took along $500 million worth of launch vehicle and satellites. (See table for some mishaps that impacted the manned space mission).
The recent loss of seven astronauts, notwithstanding, space missions continue to remain high on many countries agenda. USA has in mind CONTOUR (Comet Nucleus Tour) and MESSENGER (Mercury Surface Space Environment, Geochemistry Ranging Mission) for taking images of comets and orbiting Mercury to study its atmosphere, surface and crust. Already, some vital pieces of information from Mars are being joined together on the basis of images being sent through Odyssey, put into orbit by the USA in 2001. Chemical analyses of Maritan meteorites have supported the theory of water on Mars.
If ever, in future, any colony on space by human kind will be possible, all credit will go to zillions of money spent on space research and those who lost their lives in probing the yet unexplored.
Recently, a man in UK was convicted of fraud as he sold off plots on Moon to gullible customers. Right this day, Websites like www.scottishmultimedia.co.uk/moon.htm and www.moonplot.com/system/index.html are offering plots on moon. Who knows that may become a reality soon. Going by all endeavours, future may not be as void as the zilch beyond our planet!