How a Beam of Pellets Could Blast a Probe Into Deep Space
upstart writes:
If you want a spacecraft that can explore beyond the solar system-and you don't want to wait decades for it to get there-you need one that can really move. Today's chemical rockets and solar-powered probes are downright poky on interstellar scales. Artur Davoyan has a completely different idea for how to accelerate a spacecraft to extreme speeds: pellet-beam propulsion.
Here's the gist of how it would work: First, you actually need two spacecraft. A probe blasts off on a one-way trip to deep space, while a second vehicle remains locked in an Earth orbit and fires thousands of tiny metallic pellets at its partner every second. The orbiting craft also either fires a 10-megawatt laser beam at the retreating probe, or aligns a laser fired from the ground at it. The laser hits the pellets, heats them, and ablates them, so that part of their material melts and becomes plasma-a hot cloud of ionized particles. That plasma accelerates the pellet remnants, and this pellet beam provides thrust to the spacecraft.
Alternatively, Davoyan thinks the probe could get thrust from the pellet beam if the craft were to deploy an on-board magnetic field-generating device to deflect the pellets. In this case, that magnetic action would push the craft forward.
Such a system could boost a 1-ton probe to speeds up to 300,000 miles per hour. That's slow compared to the speed of light, but more than 10 times faster than conventional propulsion systems.
It's a theoretical concept, but realistic enough that NASA's Innovative Advanced Concepts program has given Davoyan's group $175,000 to show that the technology is feasible. "There's rich physics in there," says Davoyan, a mechanical and aerospace engineer at UCLA. To create propulsion, he continues, "you either throw the fuel out of the rocket or you throw the fuel at the rocket." From a physics perspective, they work the same: Both impart momentum to a moving object.
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