PIONEERS of the space race yesterday paid tribute to the crew of Columbia and called for their work to continue, as US President George W. Bush announced he would attend a NASA memorial service tomorrow in Houston, Texas, for the seven men and women who died. "It's a horrible thing to have happen, and our thoughts go out to the crew's family and friends," said former senator John Glenn, the first US astronaut to orbit the Earth in 1962. "It's important to remember we're not up there to just joyride around, we are up there to do things on Earth."...