Cuts in Nasa’s budget
mean deep-space travel may remain science fiction
By Ian Brown
The cutting-edge Breakthrough Physics Propulsion (BPP) project was established in 1996 as a clearing house for research to push back the boundaries of current knowledge and enable mankind to hurl a spacecraft beyond the shallows of our solar system into interstellar deep space.
However, it will run out of funding this month having fallen victim to costcutting at the troubled space agency. Though the project’s funding only totalled $15.5m (£9.7m) over seven years, Nasa – which faces declining budgets exacerbated by the Columbia shuttle dis aster – says its budget has been “deferred”.
But “deferred” could mean cut indefinitely, scientists working on the project fear. The BPP’s founder and manager, Marc Millis, admits that no firm commitments have been made to continue the project in 2005.
Yet what the project stands for is the most visionary end of the possibilities of space flight, Millis argues. Without it, deep space flight will remain in the realm of science fiction.
The potential for interstellar space flight is restricted not just by the limitations of existing technology, but by our understanding of science itself, and physics in particular.
Millis claims the task of building space shuttles and space stations is fine, but not what Nasa should be doing. “They could as easily have been built by the military or private industry,” he said. “If future space flight were constrained to only emerging technology – technology based on the physics known today – then practical ‘star flight’ would be impossible. The only way to overcome these limits is if some breakthrough propulsion physics could be discovered.”
The project, based at Nasa’s Glenn Research Center in Ohio, has identified three key breakthroughs: propulsion requiring no propellant; propulsion that attains the maximum speeds physically possible; and the production of sufficient energy to power such devices.
Even emerging technologies, including rocket applications like ion-drives and anti-matter thrusters, will never take us to the stars. These breakthroughs are within our grasp, but not enough to bridge the gulf between ourselves and even our nearest stellar neighbour, Proxima Centauri.
Light itself, travelling at 185,000 miles a second (5.9 trillion miles a year) takes over four years to get there. Apollo 11, if it had bypassed the moon, would have millenia to reach it.
To send even a small starship to Proxima Centauri, a rocket powered by nuclear fusion would need 1000 supertanker-size propellant tanks just to get there in 900 years – and that’s not including the propellant needed for braking.
Tau Ceti, Epsilon Eridani and 61 Cygni, the nearest sun-like stars , are more than twice as far again. That’s why the ideal “breakthrough” would be a form of propulsion that doesn’t need propellant. Perhaps light sails “pushed” by giant laser beams based on earth or the moon, or by sucking up the gases in space for fuel.
But even these could mean voyaging for centuries. This is why science fiction writers have imagined “space arks”, perhaps carrying humans from a dying earth to a new beginning in the stars, with generations living and dying and reproducing during the epic journey.
The BPP was aiming for more than this. To reach other stars within the lifetime of a human crew, a craft would have to attain faster-than-light velocities. And that is where the breakthrough is needed.
According to Albert Einstein, nature has imposed its own absolute speed-limit, the speed of light (C). The closer you come to it, the more mass you attain, so the more power you need to accelerate. It becomes a losing battle. The curve on the graph eventually goes vertical before C can be reached: it’s called the Lorentz Factor. To cheat the Lorentz Factor, it has even been proposed that, like Star Trek’s USS Enterprise, we might scrunch-up or “warp” the fabric of space-time to negate distance. Some physi cists, including Miguel Alcu bierre and Kip Thorne, believe such apparent science fiction is theoretically possible, although it would take staggering amounts of energy to achieve.
Concepts such as warp drives, wormholes, gravity control and inertial modification have also been investigated. They may sound fantastic, but this is the kind of science that is within the scope of the BPP project, said Millis. “What’s critically important is finding the increments of credible and affordable research that can lead us closer to these goals,” he said.
Arthur C Clarke predicts in his latest book that interstellar travel will be achieved by the 2060s. Clarke’s prophecies have a habit of coming true, but Millis is more cautious. “I think we stand to gain far more by trying than we would by giving up,” he said. “In all fairness, we must honestly confront the possibility that such breakthroughs might simply not exist to be discovered. But I opt for reaching for the outward challenges, and in the attempt, developing the tools to make life better on earth. If we achieve star flight in the process, all the better.”
14 September 2003
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