Atlantis - the final countdown

 

Nasa’s last shuttle space flight will take place next week and will mark the end of a pioneering adventure story that brought magnificent highs and terrible lows, writes Science Editor DICK AHLSTROM

THE HUMAN adventure in space is about to lose much of its razzmatazz.

July 8th sees the lift-off of the space shuttle Atlantis, the very last shuttle flight to be made.

Its departure on a 12-day trip to the International Space Station (ISS) brings to a close 30 years of space-shuttle travel and marks the beginning of an uncertain future for manned space flight.

The shuttle programme has brought us tremendous highs, watching as space-walking astronauts carried out essential running repairs to the wonderful Hubble Space Telescope, or as the shuttle’s robot arm manoeuvred another chunk of the space station into place.

It also brought us the deepest lows, with the loss of the shuttles Challenger and Columbia and the deaths of 14 flight crew. They died invisibly, far overhead, but the cameras rolled, allowing us watch as the reality of loss overwhelmed the horrified crews’ family members.

One could argue that the second great age of manned space travel comes to a close as Atlantis finally touches down. This was the age of the reusable space workhorse, a vehicle carried aloft by rocket but able to land like an airplane.

The space shuttle and the space stations it visited, including Mir and the ISS, sought to make travel into space routine. The shuttle was portrayed as the bus service that got you into orbit where satellites were dropped off or repaired and research in zero gravity was conducted before heading home.

The US National Aeronautics and Space Administration (Nasa), which developed plans for the shuttle even as the first manned Apollo flights took off in the 1960s, was perhaps a bit too effective at making manned flight routine, even boring.

Gone was the sense of excitement and adventure that gripped the world during the first great age in space travel that began in 1961, as Russian cosmonaut Yuri Gagarin became the first human to orbit the Earth.

The Americans quickly followed with the sub-orbital flight on May 5th, 1961 of Mercury Freedom-7 piloted by Alan Shepard, and then nine months later a three-orbit Mercury flight by John Glen.

As the US and Soviet Union space programmes developed, each new step into space represented high drama, with each returning pilot becoming another hero treated to a tickertape parade.

The early flights were short, with an orbit taking just 90 minutes. I remember as a child in primary school how a television would be set up at the front of the classroom so we could watch history unfold before our eyes. Needless to say, astronaut quickly joined train engineer and fireman as the most coveted jobs to aspire to by the boys in the class.

The drama continued on July 20th, 1969, when the Apollo 11 flight landed the first humans on the Moon. It was a moment of huge triumph during the dark days of the Cold War and the grinding tragedy of the Vietnam War.

Apollo 13 also caused a stir in 1970 when an explosion cut short its trip to the moon. After that, however, we quickly got used to successful flights and public interest waned.

During this time, however, planning for the shuttle was already under way. While the manned flights of the 1960s and 1970s were all about human adventure, the Skylab orbiting space station failed to capture the public imagination in the US.

This also meant, however, that there was little to compete with the space shuttles when they approached their first manned launch in 1981.

They were portrayed as a new kind of spacecraft and patently they were. They were the only winged manned spacecraft that could reach orbit but land like a plane on a runway. They were also the first reusable space vehicle, specifically designed to make multiple flights. They had an assumed life of 10 years and 100 flights on paper.

They were also the first manned spacecraft to have liquid fuel engines fed by a large detachable tank, but also twin solid-fuel boosters to help propel the heavy vehicle into orbit.

This new kind of human flight into low-Earth orbit again captured the public imagination, so the scene was set for a triumphant return to space.

Construction began on the first shuttle, Columbia, in 1975 and its lift-off on April 12th, 1981, initiated the age of the shuttle. Planners had assumed that with a full complement of five shuttles, Nasa could deliver four flights a month, very much providing a bus service into space.

Another 23 uneventful flights followed the first and public interest once again flagged as space travel became routine. This all changed however when flight STS-25 took off on January 28th, 1986.

Shuttle Challenger was only 73 seconds into its planned mission when a solid-fuel booster failure caused the huge liquid-fuel tank to detach. Explosive and aero-dynamic forces literally tore the shuttle apart, causing the deaths of all seven crew.

The accident showed that space travel was anything but routine and remained a highly dangerous endeavour. It took more than two years for the shuttle programme to recover, improve safety and get flying again.

Things once again fell into a comfortable pattern with flight after flight returning home safely. There were highs, for example flight STS-35 in April 1990, which saw the deployment of the Hubble Space Telescope.

Tragedy was to strike once again, however. Seven more astronauts were to die when flight STS-113 failed to come home, shuttle Columbia disintegrating during re-entry due to the failure of heat-shielding tiles. The loss of Columbia effectively delivered the death knell for the shuttle programme. Another two-and-a-half years passed before flights resumed and so they have continued until now.

Most of the last 20 have been essential delivery and servicing flights to the ISS. The heavy-lift capacity of the shuttle was essential to the building of the ISS and now the last large module, Raffaello, will be carried aloft on the final flight STS-135 on board Atlantis.

Water, water, everywhere

If you’ve ever run out of water while on Earth, you’ll know what a disaster that can be. Now imagine the water runs out when you are in space. You could be a little stuck.

So a crew member on the last shuttle mission, STS-135, will be testing technology that can filter “dirty” liquids such as wastewater and provide something drinkable. The technology, which is already available on Earth, uses forward osmosis to filter out the undesirable bits.

“Forward osmosis is the natural diffusion of water through a semi-permeable membrane,” says Michael Flynn, scientist at Nasa’s Ames Research Center. “The membrane acts as a barrier that allows small molecules, such as water, to pass through while blocking larger molecules like salts, sugars, starches, proteins, viruses, bacteria and parasites.”

The experiment will take place on board the Atlantis when it undocks from the ISS for the return home, and will use six slightly modified osmosis kit bags to see how they fare filtering water in microgravity. A crew member will knead and shake some of the bags to see how this affects the filtering process.

According to the article, if manipulating the bag helps, one idea could be to put the system in a spacesuit: moving around during a spacewalk could then enhance the water cleansing.

Claire O'Connell

And the Irish connection?

HOW NIFTY does this sound: an experiment that runs only while you snooze. Soon, as the crew members on the International Space Station sleep, an onboard experiment will be helping to figure out how gravity (or the lack of it) affects how materials solidify – with the aim of informing how we manufacture a range of products back on Earth.

On its final mission, space shuttle Atlantis will ship alloy materials up to the ISS, explains Dr David Browne from University College Dublin, a co-investigator on the European Space Agency CETSOL project, which also involves centres in France, Germany and the US.

“The experiments are to be performed on the Materials Science Laboratory, which is already installed on the ISS,” explains Browne. “This is a furnace capable of melting and solidifying aluminium alloys – which are of significant industrial importance – in zero gravity conditions.”

But why do the crew members in space have to be asleep? “The astronauts moving around the ISS cause vibrations which can spoil the zero-g conditions, so they turn on the experiments before they all go to bed – the samples have then been processed automatically when they wake up again.”

A ground support centre in Cologne will track the experiments as they happen, but the proof of the pudding will be the analysis when the samples are returned to terra firma, explains Browne, who describes how an initial batch of experiments on the ISS has already shown good agreement with computer simulations.

And by comparing the results collected in space with results from the same experiments carried out on Earth, the researchers have been isolating the effects of gravity: “This is leading to more accurate simulation models for alloy solidification which is a high-value process used to cast components as diverse as artificial knee implants and aircraft turbine blades.”

Claire O'Connell

What next for the US space programme?

IT IS ALL change for US-funded human space flights in the coming two decades. Gone is the notion of building a base on the Moon. And now companies rather than Nasa will take over launch activity into low-Earth orbit.

US president Barack Obama mapped out the changes in an address at the Kennedy Space Center in April last year. The Constellation programme, which got under way while the shuttles were still flying, is now gone.

It included Ares, a heavy-lift rocket, and Orion, a crew module. These were to be used to ferry crew and equipment up to the International Space Station, then support flights to the Moon, to asteroids and finally to Mars .

Now this service will be provided by private contractors. Four firms are working on competing rockets and crew modules. Nasa will be partly involved in a modified version of Orion but it will only be used as an emergency escape vehicle to retrieve crew at short notice from the station. Ambitious manned missions will remain but with such long lead times that they are certain to change as future fiscal and political factors demand.

One goal involves development of an alternative to Ares, large enough to carry crew all the way to Mars. It envisages rocket test flights by 2015 and then missions to Mars by 2030.

Dick Ahlstrom