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SHUTTLE: REPAIR MISSION TO ISS

It was in a spectacular night landing that the Atlantis space shuttle touched down at 2.20 a.m. local time on 29 May on floodlit runway 15 of the Kennedy Space Center in Florida, to the delight of NASA. "Atlantis and its crew did a wonderful job," said space station flight director Paul Hill. Shuttle programme manager Ron Dittemore was even more positive. "It never ceases to amaze me how wonderful a machine the space shuttle really is. We had a wonderful mission, everything worked just right."

The jubilation was understandable, since Atlantis had not been in space for almost three years. In the interim it had undergone a complete overhaul, part of a major upgrade by NASA which is planned to include the other three shuttles, Colombia, Discovery and Endeavour, as well.

So when Atlantis took off on 19 May it was the first updated shuttle, with a digital cockpit similar to the one on the Boeing 777. The engines and other components had also been upgraded, so the ground teams were especially interested in seeing how the shuttle would operate after being grounded for such a long time.

Launching the Atlantis and its crew of seven astronauts turned out to be far from plain sailing. Originally planned for 24 April, the launch had to be postponed twice due to bad weather at Cape Canaveral. And when the sky finally cleared over the John F. Kennedy Space Center, cloud cover over two emergency landing fields in Africa and Spain foiled the third attempt at lift-off, on 26 April.

But then, on 19 May, the weather conditions were finally right and the Atlantis was able to lift off at last. At 6.11 a.m. local time, before dawn and with an almost full moon in the sky, Atlantis set off for the dark skies above. As it slowly became transformed into a morning star, and with all still dark below, the first rays of sunshine from on high caught the smoke from its engines in a kind of Bengal light.

After all the delays the entire mission ran like clockwork, so it was easy to forget that it was actually never planned but borne out of an emergency. The $400 million undertaking was required because, due to lack of funds, the Russians were almost scandalously late in delivering their assigned components for the International Space Station.

In December 1998 the Zarya (Russian for "dawn") module was hauled up into space, followed a month later by the American node module Unity. Additional modules should have been connected up to these modules long ago, but instead nothing happened. In particular, one of the cornerstones of the station, the large Russian service module Zvezda (Russian for "star") has fallen more than two years behind schedule.

It was because of these delays that the alarm sounded at the end of last year. The first two modules were losing altitude, by around 2.5 km (1.5 miles) per week. One of the functions of the Russian Zarya module was to prevent this quite normal loss of altitude. But there were only enough fuel and other resources to last until the spring of 2000.

This meant that NASA had to jump in and undertake a mission which should really have taken place only considerably later, and with different objectives. The Atlantis completed its most important task and boosted the orbit of the unfinished complex by 43 km (27 miles) to 374 km (232 miles). Otherwise the two ISS modules would have continued their downward trajectory and would eventually have burned out.

The rest of the mission was also taken up with work which was never included in the plan for assembly of the space station. It is only a slight exaggeration to say that the crew were having to spend their time on repair work before the ISS has even entered service.

This work began when the Atlantis commander, 43 year-old USAF Colonel James Halsell from Lousiana, and his team ventured forth into the Russian Zarya module, whose stale air had heated to over 25* C, armed with only ear plugs and their personal fans.

When the module was inspected by American astronauts a year earlier, the air conditioning had been malfunctioning, so that the visitors got sick and returned to Earth unwell. Again, the Russian units had been making such a noise that the Americans were subjected to a sustained acoustic loading at a constant frequency range and feared that their hearing would suffer, so while they were there they had installed some isolation material to reduce the noise.

Some of the repairs which had since become necessary are astonishing. Thus, 42-year-old astronaut Susan Helms and the experienced Russian cosmonaut Yuri Usachev had to replace four out of a total of six battery sets on board the Russian module. They had been overloaded out of carelessness by the Russian ground teams, resulting in damage if not permanent failure.

One battery charger had also failed and had to be replaced. Then no fewer than three fire extinguishers, four fans and ten smoke alarms had to be replaced, along with a faulty antenna and a camera cable. On top of this eight new handrails had to be installed for the astronauts.

Even before Atlantis lifted off, one American critic had complained, "The Russian module, which, to add insult to injury, was financed entirely with American funds, is already in such a dismal state that we now have to fit in an extra shuttle flight solely to lick it back into shape."

Admittedly, not all the repairs were to Russian equipment: astronauts James Voss and Jeffrey Williams also had to reattach a cargo boom which had been installed by the Americans in the spring of 1999 because it had come loose. They also installed a 15 m (49 ft) Russian crane which amongst other things should assist with assembling the rest of the space station. Finally, their colleague Mary Ellen Weber had to transfer almost 500 kg (1,100 lb) of supplies and equipment to the rudimentary station, including computers, clothing, an exercise bicycle, a treadmill and 180 litres of water.

As the shuttle set back towards Earth with shuttle pilot Scott Horowitz at the controls, it left behind an ISS which, although still very basic, is now fully functional, on the right orbit and ready to finally receive the long-awaited Russian service module. Latest reports from Moscow suggest that Zvezda will lift off on a Russian Proton launcher in Baikonur some time between 8 and 12 July.

Once Zvezda is attached, station assembly will resume with a succession of further shuttle deliveries. NASA is planning another three shuttle flights in the second half of 2000 to take further equipment and supplies to the station. Atlantis itself will head back there on 8 September, followed by Discovery on 28 September and Endeavour on 30 November. The Russians for their part are planning to finally set down the first three long-term visitors, one American and two Russians, at the beginning of November.

The team has been selected and fully trained for some time and will comprise the 50-year old American astronaut William Sheperd and the two Russian cosmonauts Yuri Gidzenko (38) and Sergej Konstantinovitch Krikalev, born in St. Petersburg in 1958 - all three veteran astronauts.

After difficult negotiations with the Russians, the Americans succeeded in getting their way and appointing Sheperd, who has already flown several space missions with the shuttle, as the first commander of the - still rudimentary - ISS. One of the cosmonauts who was planned to fly on the mission has withdrawn because he felt the first commander on board the ISS should be a Russian. It has been agreed that American and Russian commanders will alternate thereafter.

From page 56 of FLUG REVUE 8/2000