Free Republic

Figure 9 from “A Roadmap to Interstellar Flight”Guest essay by Eric WorrallAn American scientist has made a remarkable conceptual breakthrough, a design for a non nuclear relativistic launcher, capable of accelerating thousands of deep space probes per year to 0.25C; fast enough to reach the nearest stars in 15 years. The system is extremely scalable – you could start with a small, low cost proof of concept launcher, and work up to bigger devices, capable of launching substantial probes into interstellar space. The system also has a practical alternative use – the full size version is powerful enough to deflect...

Piloted spaceships, planetary probes, and space telescopes fascinate people. That’s easy to understand since these spacecraft make the discoveries of our time. Nevertheless, this is only the proverbial “tip of the iceberg” since they account for less than 10% of all spacecraft ever launched. What are the other 90% for? Who launched them and for what purpose? It’s worth noting that it is impossible to establish a definitive number of spacecraft launched since it depends of how you count them. Answering these questions tells us a lot about what’s going on in space. For example, more than a quarter of...

Mysteriously, five spacecraft that flew past the Earth have each displayed unexpected anomalies in their motions. These newfound enigmas join the so-called "Pioneer anomaly" as hints that unexplained forces may appear to act on spacecraft. A decade ago, after rigorous analyses, anomalies were seen with the identical Pioneer 10 and 11 spacecraft as they hurtled out of the solar system. Both seemed to experience a tiny but unexplained constant acceleration toward the sun. A host of explanations have been bandied about for the Pioneer anomaly. At times these are rooted in conventional science — perhaps leaks from the spacecraft have...