The most important reason to get Americans into space is to maintain our nation's industrial leadership. He said more than 30,000 products have been developed directly or indirectly using technology from the space program.
There's also pure science.
"For instance, I've worked in planetary geology," said Gruener. "There are four disciplines in planetary geology ? volcanism, impact, mass wasting (like erosion) and tectonics. If you have only one data point, Earth, you can only get so far."
Then, he said, there's the examples of the dinosaurs.
"Eventually, something is going to smack into the Earth," he said. "So some people are thinking we need to survive by getting off-planet."
Gruener also stated that what makes people want to go into space is the desire to explore unknown territory. It's "whatever made Columbus sail west," he said, "whatever made Lewis and Clark search for a route to the Pacific Ocean ? that sense of adventure."
The first challenge
John Kohl is a propulsion engineer. He's been with NASA for more than four decades, having worked on the gigantic Saturn rocket that lifted the Apollo moon lander into space.
Now Kohl works with NASA Institute for Advanced Concepts at the Marshall Space Flight Center, outside of Huntsville, Ala. He said commercial space flight is no longer a dream for the future. Space passengers have already been to space. For $20 million each, Russian space officials have already flown California businessman Dennis Tito to the International Space Station in 2001 and South African businessman Mark Shuttleworth a year later. New Jersey businessman Gregory Olsen is scheduled to be the third space tourist, perhaps as early as October.
With current technology ? chemical-based, single-use rockets ? getting people and material into space requires enormous amounts of power, Kohl said. And that costs a lot of money. To reduce costs, many experimental and hypothetical power sources are being looked over by NASA.
One of the most simple of these propulsion advances would be to create a reusable launch technology, instead of building expensive new rockets for each launch ? something like building a new airplane for every airliner flight.
Another launch technology under development is electro-magnetic launching. In this scenario, the shuttle would be magnetized, and a large electro-magnet catapult would shoot the spaceship into the air.
Then there's the space elevator ? yes, an actual elevator to space. The idea is that a 1,000-mile cable would reach from the surface of the Earth into space, attached to a very large weight in orbit. This weight would allow centrifugal force to keep the cable extended into space. Then, cars could ascend into space much as one might go up Hershey Park's Kissing Tower.
Problem: There are no currently feasible cable materials strong enough to go such a distance and remain intact. Another problem: Dodging satellites.
The second challenge
NASA doesn't deal with tourism ? that's for private enterprise. NASA focuses on research and technology.
Gruener spoke of an orbiting facility that had 50 to 100 people ? maybe a dormitory of sorts, an industrial facility or a permanent outpost on the way to the moon.
However, Gruener said once people are in space, "keeping them alive is the second challenge." Humans need air to breathe, water and food to consume, a place to sleep and a way to deal with waste.
Gruener suggested a regenerative life-support system ? recycling as much air, water and food as possible. He also said that radiation wouldn't be so much a problem in low Earth orbit because electromagnetic bands surround the Earth and block a huge portion of space radiation.
But if humans travel to the moon or Mars, radiation will be a huge problem, with the ship being hit with waves of radiation ceaselessly.