[It is 9.55 pm local time now. The countdown clock at NASA's website is showing 2 hours 40 minutes to liftoff. Another journey of the space shuttle Discovery will begin soon, marking the 18th US flight to the International Space Station. Commanded by Steven Lindsey, a crew of 5 American astronauts and 1 European astronaut will participate in the mission. It somehow seems appropriate recapping the events that marks the history of space missions.]

MICHAEL Collins called it "Carrying the Fire." In Greek mythology, Apollo carried the sun in a chariot across the sky. Collins, who took Apollo 11 to the moon, found a striking similarity between the myth and the flights of the modern space vehicles powered by raw, raging, and scorching fire. "How would you carry fire?" Collins contemplates in his memorable memoirs, "Very carefully, that's how, with lots of planning and at considerable risk."

After 35 years, on August 9, 2005, another Collins, Commander Eileen, who was flying the space shuttle Discovery round the Earth at an altitude of 329 km, radioed to Mission Control: "We are ready for whatever we need to do." With that, she actually accepted an alternate option to land in the Edwards Airforce Base in California, which NASA was compelled to select as the weather was not improving in Kennedy Space Centre, Cape Canaveral, Florida -- the primary site for Discovery's landing.

As the shuttle crew decided to land at Edwards, a series of complex maneuvers by Discovery started. Shuttle pilot, James Kelly,

fired the two Orbital Manoeuvring System engines, positioned at the base of the vertical tail abaft the fuselage, with extreme care. The risk loomed large on manifold accounts. Failure was not an option in any of the operations that would follow.

Earlier, during lift off, foam fillers from the fuel tank had dropped, though NASA maintained that the half kg. chunk of the loose foam did miss the orbiter and no harm was done to its heat shield. But why was the ceramic filler material protruding? Were the bonds failing in any other place? If a single piece of thermal tile, 6 by 6 inches in size, gets displaced during re-entry, it would simply unleash the firebreathing dragon loose on Discovery, and there were 20,000 pieces to worry about. A similar kind of impact damaged Columbia's heat shield and caused it to burn up during re-entry on February 1, 2002.

The two ceramic impregnated strips of cloth discovered during inspection in space, were sticking out an inch or so, from between the thermal tiles under the heat shield. They were eventually ripped off clean and the possibility of their generating excess heat was thus minimised. It took an unprecedented space-walk by astronaut Steve Robinson, the first of its kind in the history of shuttles program, assisted by Soichi Noguchi, who operated the robotic arm of the International Space Station (ISS). Steve succeeded in pulling out the strips of cloth, though it took seven. That was because the job warranted extreme care. If the robotic arm, or any of Steve's tools, came in contact with the fragile tiles on the shield, disaster would be inevitable.

Another damaged section on the

thermal blanket near the cock-pit window was left unattended, obviating the need for the fourth spacewalk, as NASA thought it was not posing any risk to the safe landing of Discovery. The pieces of cloth sticking out were part of the filler materials -- taking up gaps between the thermal tiles -- to provide cushioning during the most arduous transit through the Earth's atmosphere which makes its temperature rise sharply.

The landing was being postponed due to inclement weather in Florida. It almost reached a must-land situation as the provisions, i.e. food and water, were running short. They had barely one days provision left on Tuesday and the capacity of the lithium hydroxide/carbon scrubbers to remove carbon dioxide from the living space of Discovery was diminishing rapidly. A normal trip of the space shuttle spanned 5 days. But this time it was in space for 14 days, out of which it remained docked with ISS for 9 days.

As discovery fired its Orbital Manoeuvring System engines, the vehicle slowed down in its inverted position, moving tail first into orbit. Then it used its Reaction Control System nozzles to swing back to the normal position, taking the nose through an arc of 180 degrees and running it nose first, up-side-up. As it slowed down, the journey to the Earth began. The art of bringing back an orbiter is incredibly simple. In space it moves at a velocity constantly trying to break away from the pull of the Earth but always held back by an invisible tether called gravity. The shuttle's centrifugal momentum is checked and balanced constantly by the centripetal pull of the Earth. And they remain at an equilibrium, without having to expend extra energy by way of

running a propulsion engine. But if the orbiter slows down, Earth's gravity prevails and forces it to fall, literally.

The reason for using the OMS engines is to slow down the orbiter so that it could fall gradually towards the Earth. It started falling from the sky, from an altitude of 329 kms at 706 am ET 4:06 am Pacific time. It fell sharply over the Indian Ocean for forty minutes and entered Earth's atmosphere over the Pacific. As the infra-red camera was tracking its reentry in the pre-dawn darkness, Discovery glowed to incandescence with a temperature of 1630 degrees in her heat shields, traveling through the ocean of air molecules at 27,360 km/hour, at an inclination of 40 degrees. Once inside the atmosphere, the space-craft became an aircraft, gliding through its fly-path that took it to the Mojave desert north of Los Angeles in California. 3 minutes before landing, two sonic booms, hallmark of a shuttle's landing, heralded its advent on the horizon, giving rise to lots of whoops and cheers before it finally landed on runway 22 of the Edwards Airforce Base, at 8-11 am ET 5:11 am Pacific Time. By then it had completed 219 orbits around around the world and traveled 9.3 million kilometers.

As the shuttle turned absolutely white in the thermal images that Mission Control were watching on their monitors, a gentleman named Dr. John Clark was lost in his own thoughts in the Kennedy Space Centre. He is the NASA neurologist and husband of astronaut Laurel Clark. Laurel died on the first of February 2002, when Columbia burnt out while entering Earth's atmosphere.

"I thought, 'This is when the tire light went on,'" Clark said from Kennedy Space Center, referring to an initial sensor reading that Columbia was breaking up. "I was paralleling the two missions."

It was not Clark alone who was paralleling the two missions. Thousands of miles away, in India, the mother of Kalpana Chawla, the deceased Indian astronaut of Columbia, was earnestly praying for

Discovery's safe return. When she heard that Discovery had made a safe landing, she said: "It is like my daughter coming back alive."

From the days of Apollo 1, the saga of space flight has been strewn with tragedies. On January 27, 1967, a fire in the cockpit of Apollo 1 killed all three astronauts who were carrying out the final tests and it happened on the launch pad. Though Apollo 13 finally managed to come back home safely, it had the closest brush with destruction due to loss of oxygen while in space. Very brilliantly re-created by two great actors, Tom Hanks and Ed Harris, one on the Earth and the other in space, Apollo 13 was a movie revealing the human story behind every space venture.

On January 28, 1986, Challenger blew up 73 seconds into its fateful flight. The first teacher en route to space, Sharon Christa McAuliffe, working under TISP -- Teacher In Space Program -- died along with 5 other men and 1 woman.

Investigation reports revealed that the disaster was due to the failure of an O-ring seal in the solid-fuel rocket on Challenger's right side, that allowed hot gases to pass and damage the attachment of one of the booster rockets. It broke loose, hit and pierced the liquid oxygen tank, combining raw liquid oxygen and hydrogen into a raging fire that finally engulfed Challenger, burning its crew alive.

Columbia burnt off into ashes over the Pacific ocean on February 1, 2002, killing 5 men and two women. This was caused by the same type of falling debris during lift off as Discovery's. Ironically, Discovery was sent up after a protracted period during which modifications and improvements were made after the Columbia disaster. It also was meant to carry out repairs with techniques that had been devised after the Columbia disaster to handle damages that may occur due to similar causes. The astronauts never realised that they would be in the same situation as Columbia itself, and would have to count on luck while passing through the atmospheric resistance of mother Earth during re-

entry.

The Russian history of space flight is also full of trials and errors with resulting tragedies attached. During the cold war era, in a bid to beat the Americans,the Russians stretched themselves to the limit where the parameter called safety was totally ignored. The astronauts used to be treated as secret service agents, their whereabouts and movements clandestine and their disappearances un-disclosed. The first man ever to go into orbit was Yuri Gagarin and his death is apparently attributed to an aircraft crash. But there is suspicion that he died in a rocket mishap. Many of the accidents and deaths went unreported or were attributed to false causes.

With the space shuttle program that originated during President Nixon's time in early 70s, and succeeded in launching the first space shuttle, Columbia, in 1981, the Russians became increasingly uncomfortable. Primarily, the shuttle program was poised to carry payloads to space for research activities but its military capability was potentially diverse and that influenced the Russians in an adverse way. They raced for a match, developing BORAN, a similar space vehicle that could glide back to Earth and be reused, retaining the same look as the American shuttles. The first flight of Boran almost ended in a disaster but escaped with sheer luck. Part of the launch pad was gutted by the hot exhaust gas that strayed from the exhaust bunker as the spaceship tilted badly during lift off. However, the space craft performed its journey and return from space safely.

In these days of post cold-war era, where transparency, safety and care for environment take precedence over everything else, including mastery of technology and power, it is obvious that NASA will have to weigh many of its old paradigms in the light of the imperatives of a new world and revamp and modernise its space program .

Golam Kibria is Manager, Dhaka Office, Bureau Veritas (Bangladesh) Pvt. Ltd.