While most of the fuel was used in getting the rocket into orbit, the limitations are apparent: It takes a lot of heavy fuel to get anywhere.Įlectric propulsion systems generate thrust using electricity produced from solar panels. The Saturn V rocket that took astronauts to the Moon produced 35 million Newtons of force at liftoff and carried 950,000 gallons of fuel. Today, the most common propulsion systems in use are chemical propulsion – that is, regular fuel-burning rockets – and solar-powered electric propulsion systems.Ĭhemical propulsion systems provide a lot of thrust, but chemical rockets aren’t particularly efficient, and rocket fuel isn’t that energy-dense. Energy density – how much energy a given amount of fuel can produce.Mass efficiency – how much thrust a system can produce for a given amount of fuel.Thrust – how fast a system can accelerate a ship.Once a ship has escaped Earth’s gravity, there are three important aspects to consider when comparing any propulsion system: Mike Jetzer/, CC BY-NC-ND Systems of today The Saturn V rocket was 363 feet tall and mostly just a gas tank. If Voyager-2 had a faster propulsion system, astronomers could have had those photos and the information they contained years earlier. It took Voyager-2 12 years just to reach Neptune, where it snapped some incredible photos as it flew by. As space agencies probe farther out into space, it is important to get data from unmanned missions as soon as possible. A better way to reduce radiation exposure is to simply get where you are going quicker.īut human safety isn’t the only benefit. Radiation shielding can help, but it is extremely heavy, and the longer the mission, the more shielding is needed. There are two reasons faster rockets are better for long-distance space travel: safety and time.Īstronauts on a trip to Mars would be exposed to very high levels of radiation which can cause serious long-term health problems such as cancer and sterility. Space is massive, and everything is far away. If astronauts want to explore anything farther than the Moon and perhaps Mars, they are going to need to be going very very fast. This is where nuclear systems come into play. To escape Earth’s gravity and reach deep space destinations, ships need additional acceleration.
It is once a ship reaches space that things get interesting.