In Poul Anderson's 1970 novel Tau Zero, a starship crew seeks to travel to the star Beta Virginis in hopes of colonizing a new planet. The ship's mode of propulsion is a "Bussard ramjet," an actual (though hypothetical) means of propulsion that had been proposed by physicist Robert W. Bussard just a decade earlier. Now, physicists have revisited this unusual mechanism for interstellar travel in a new paper published in the journal Acta Astronautica, and alas, they have found the ramjet wanting. It's feasible from a pure physics standpoint, but the associated engineering challenges are currently insurmountable, the authors concluded. This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more.
Last year, Voyager 2finally broke through into interstellar spaceafter traveling more than 11.2 billion miles. This epic mission was made possible by nuclear power, the technology that has powered spacecraft for decades. Spacecraft like the Voyager pair are powered with radioisotope thermoelectric generators, or RTGs. These engines rely on the fact that radioactive substances release heat as they break down. By converting the heat generated by the decay of plutonium-238 (P-238) into electricity, spacecraft keep going long after the sun's rays are a distant glimmer.
Our galaxy may contain billions of habitable worlds that don't host any life. Should we attempt to change that? Claudius Gros at the Goethe University Frankfurt, Germany, thinks we should. He believes in directed panspermia: deliberately seeding life throughout the cosmos. And to do that, he proposes we use a laser propulsion system that may not be technically out of reach.
It was a warm afternoon in July, and Hal Fearn was sitting in his camouflage jeep in the parking lot of a mostly empty IHOP in Southern California. Fearn, a physicist at California State University, Fullerton, bided his time by singing along to the a cappella covers pumping through his stereo. He hadn't loitered long before he spotted a silver minivan easing into the lot. Behind the wheel was Jim Woodward, large gold-framed glasses and a surgical mask adorning his gaunt face. Woodward, a physics professor emeritus at Fullerton, slid his van beside the jeep and rolled down his window to pass a box to Fearn.