The greatest barrier to human exploration of space is undoubtedly the vast distances and time lengths required to travel from one stellar body to the next. This post will outline some potential modes of interstellar propulsion:

Magnetoplasmadynamic (MPD) Thrusters

As described by NASA, MPD thrusters are the most powerful form of electromagnetic propulsion. They use charged particles from ionized gas as fuel (xenon, lithium, neon), feed them into an acceleration chamber and out a nozzle to produce thrusts of up to 200,000 MPH. Unfortunately, these thrusters require hundreds of kilowatts to generate acceleration, requiring power generation on the scale of nuclear power plants.

Bussard Interstellar Ramjet

The Bussard Interstellar Ramjet propulsion system draws its fuel from space itself. Developed in 1960 by Dr. Robert Bussard, this “ramjet” uses an electromagnetic field to collect interstellar hydrogen, which is compressed in the craft’s cylinder shaped body and expelled as propellant for a fusion rocket. The speed of the craft is mostly dependent on the density of hydrogen in front of the vacuum-like Bussard Collector. Some estimate that the Bussard Ramjet could move at 77% the speed of light. (The EnterpriseD has two “Bussard Collectors” that were used as emergency fuel sources for the warp drive).

Solar Sail and Beamed Solar Sail

This technology is true to its name and very real. Solar sails use solar photons to push a hair-thin reflective carbon-fiber fabric in a fashion similar to using wind against sails to move across water. This technology has been successfully created by NASA and put to use by the Japanese. IKAROS, a Japanese solar sail, traveled to Venus in 2010, proving the technology for intrasolar missions. Solar sails to not need fuel, but are propelled via solar pressure or self-generated lasers. Because of its sail mechanics, this craft takes years to build up speed, but can reach velocities of 100,000 MPH and more. – Latest solar sail project from my hometown!