After the Columbia disaster on Saturday, President Bush spoke to the nation, reassuring the country that "our journey into space will go on."

Although Bush's words are a comfort for space enthusiasts, the question remains: How will NASA salvage space exploration?

On Friday, one day before the space shuttle Columbia was lost, President Bush outlined the new budget and structure for the Space Launch Initiative, the plan to upgrade existing space shuttles and build next-generation spacecraft to eventually replace them.

An aging but youthful fleet

"There are different parts of my program, and different parts of NASA, that are already looking at the long term for the International Space Station, how will we cope with this tragedy, and what will be our plan ahead," said General Mike Kostelnik, head of the combined International Space Station and space shuttle office.

Columbia was 22 years old when it broke up over East Texas on Saturday morning. The remaining three shuttles, Atlantis, Discovery, and Endeavour, are also aging.

"I know there are a lot of issues now about aging... and service life," Kostelnik said. But, he added, people don't have all the facts.

"An orbiter that's 20 years old that has just been through this 18-month program to refurbish, repair, 'refix,' upgrade, and modernize is not the same vehicle that went in, and is clearly not something that's 20 years old," he said.

Retrofits add spunk to shuttles

There are three stages to the Space Launch Initiative. The first stage was the recent retrofit of the four space shuttles. During the retrofit, NASA installed new 'glass' cockpits with modern avionics that give the crew easier-to-read and more detailed information about the spacecraft and its condition during flight. High tech sensors are now networked throughout each shuttle, giving diagnostic and telemetry data for the pilots in the shuttle and the crew on the ground.

The shuttles were also given newer, safer engines that are lighter and more efficient. NASA even added lighter astronaut seats and other new features to lighten the shuttle and make more room for cargo.

Still, those technologies didn't prevent the loss of the Columbia, which was on just its second flight since its retrofit.

Safety is a main reason why NASA is focusing on the second stage of the Space Launch Initiative, the Orbital Space Plane. The plan calls for NASA to have the new vehicle as a taxi for astronauts to and from the space station in seven years. It's slated to be at least 100 times safer than the shuttle, which NASA would keep as its U-Haul in the sky for heavy cargo.

Next-generation spacecraft

Lockheed Martin, Boeing, and a combined Orbital and Northrop Grumman team are all hoping to build the space plane.

Boeing has been extensively testing the X-37, which is not a prototype, but merely a test bed for new technologies. Boeing is testing new automation software to safely fly the craft and new thermal technology to protect against the heat of re-entry. It's also testing the body shape to see if it can provide lift during the glide back to earth.

The third stage of the Space Launch Initiative involves research for the Next Generation Launch Technology, something that gets science fiction writers excited. NASA confirms that it's looking at scramjets, which can take off and land like an airplane, but with a brief stopover in orbit. Such a plane would be able to circle the globe in fewer than 90 minutes.

Other technologies include magnetic levitation and other advanced propulsion technologies. Also, last month President Bush endorsed space-based nuclear propulsion, which would give NASA another futuristic way to get into orbit.

Looking ahead, to safety

Space industry contractors were reluctant to talk on camera about what Saturday's disaster means for their proposals for the Orbital Space Plane, but they and NASA appear to be doing some serious thinking.

The budget proposal President Bush sent to Congress before the Columbia tragedy included an increase in funding to $15.5 billion in 2004. Many lawmakers now say they'll seek to add to that so as to provide for increased safety measures.

NASA says it will not build a replacement shuttle for Columbia as it did after the Challenger disaster. Instead, it says, it remains focused on the next orbiter.

"Mankind is led into the darkness beyond our world by the inspiration of discovery and the longing to understand," Bush said in his address to the nation after the Columbia disaster on Saturday.

The question now is which vehicle will get us there most safely.