Space Traveler’s Guide to the Universe

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Methods of Space Travel

We Might See One Day

Traveling to far away planets has been a dream of humanity and a staple of science fiction for over a century. In reality, there are many problems holding us back from these quests, including a lack of adequate technology. But that hasn’t stopped scientists from theorizing how advanced space travel could one day be possible.

10. Ion Thrusters


Ion thrusters shouldn’t be a new concept to Star Wars diehards, because they power TIE Fighters. They’re a real thing that was used on NASA’s Dawn probe that was launched in September 1997 to study the dwarf planets Vesta and Ceres.

Ion thrusters work when xenon atoms are hit with electrons, forming ions. At the back of the engine, there are metal grids charged to about 1,000 volts that shoot out ions at 90,000 miles per hour. The thrust is quite small, but since space is a frictionless environment with zero gravity it gradually builds up. The top speed of Dawn is 24,000 miles per hour.

Ion thrusters require minimal fuel. In fact, they’re 10 times more effective than chemical fuels. They gets their power from large solar panels, so there’s no need to build storage for fuel. That also gives them an inexhaustible source of energy. The current problem with ion thrusters is that they’re a bit too slow to transport humans. With that being said, they could be used to transport supplies to, say, a settlement on Mars.

9. Bussard Ramjet


As alluded to above, one of the biggest problems facing space travel is the amount of fuel needed. One attempt to overcome this came from the 1960s and was called the Bussard Interstellar Ramjet. The idea is that the spacecraft would pick up protons in the universe while traveling. If these protons could then be fused together, the spacecraft could use nuclear rockets.

However, there are a number of problems with the Ramjet. Only a certain amount of protons could be picked up, and a lot of drag would be generated when the vessel would collect protons. Also, there’s the little matter of getting a stable nuclear fusion device functioning.

8. Nuclear Pulse Propulsion


The idea of using nuclear power to launch spaceships dates back to the 1950s. Project Orion was an endeavor by NASA that entailed a ship the size of the Empire State Buildingbeing launched by exploding a nuclear bomb under it. You can probably guess some of the problems with this. For starters, this method would leave a tremendous amount of radiation behind and give the astronauts radiation poisoning. When the bomb went off, it would create an electromagnetic pulse that would wipe out all the on-board electronics. That’s if the launch was successful and didn’t result in a deadly accident. Despite all of this, Project Orion was actually considered because it could travel to Mars and back in three months, while it would take a spacecraft using normal propulsion 18 months to do the same trip.

Orion was abandoned, but ideas from the project lived on. Voyager 1, Voyager 2 and theCassini spacecraft use a form of nuclear power that takes decaying plutonium and converts it to electricity.

7. Laser Beamed-power Propulsion


Aerospace engineer and awesomely named Leik Myrabo got the idea of using laser beamed-power propulsion in 1988 when he was working on the Star Wars missile defense project. Myrabo’s craft would be conical. A powerful laser beam would be fired into the narrow end of the cone, which would contain a parabolic reflector. This would heat the air inside to about 30,000 degrees, which would cause explosions that would create thrust. Myrabo believes that he could have a spacecraft ready in 20 years, but his peers are skeptical as to whether laser technology will be adequate.

6. Daedalus Interstellar Spacecraft


The British Interplanetary Society conducted a five year study beginning in 1973 to see if it was possible for humans to travel to Barnard’s Star, which is about six light years away. Their solution was the Daedalus Interstellar Spacecraft. The Daedalus was a huge spacecraft, also nearly the size of the Empire State Building, and would need to beconstructed in the Earth’s orbit.

Similar to Project Orion, it would use fusion engines. Pellets of fuel would be injected at high velocity into a reaction chamber, where high-energy electron beams would ignite them. The first stage would launch from Earth with 46,000 tons of fuel, and then once in space it would launch a smaller part of the ship that would carry 4,000 tons of fuel. The fuel needed was Helium-3. Helium-3 is incredibly rare on Earth, but it’s believed there’s quite a bit on the moon, and there are also clouds of it in space. Collecting enough could take 20 years. Helium-3 is also the most difficult fusion fuel to ignite because of the incredible amount of heat needed. However, if it worked, the spacecraft would eventually travel at 12.2 percent of the speed of light, meaning it would get to Barnard’s Star in 50 years.

In 2009, an update called Project Icarus began its five year study to see how interstellar travel might now be done after years of scientific advancement. Hopefully they’re putting more thought into the science than the name.

5. Asteroid Hopping


One of the big problems with traveling in space is exposure to cosmic rays. If a person were to do a 1,000 day round trip to Mars, they would be exposed to so much radiation that it would increase their chances of getting cancer from one to 19 percent. Spacecraft are made of light material, and radiation shields are too heavy. That’s why a professor of physics at MIT believes the best way to travel would be to land on an asteroid and then tunnel below its surface.

The asteroid would need to be 33 feet wide and pass within a couple million miles of both Earth and Mars for the plan to work. There are five known asteroids that would be excellent candidates that will pass by Earth before 2100. The trip would only be one way, because there isn’t an asteroid that would make a round trip feasible. However, new discoveries are being made all the time, so it’s possible there’s an asteroid that will head back towards Earth that we haven’t discovered yet.

4. Solar Sail


While sails are low-tech by today’s standards, they’re getting a modern update in space travel. Instead of using wind, these sails would use the power of the sun. Solar sails would only give a spacecraft a small push, but since there’s no friction in space the sails would continually build up speed. For example, a solar sail that’s 1,300 feet wide could travel 1.3 billion miles per year. That’s faster than a vessel using chemical propulsion. That would also be relatively cheap compared to fuel use.

There are currently a number of projects using solar sails. One comes from NASA and is called the Sunjammer, after a short story by Arthur C. Clarke. The Sunjammer sail would be made out of a material called Kapton and be just five microns (about 0.0002 inches) thick, weigh less than 70 pounds and be about the size of a dishwasher when packed up.

It’s suggested that, while it make take a few centuries to develop, a solar sail could be used to carry a spacecraft into another solar system. This sail would need to be the size of Texas, and a strong laser would need to shine on it as it got further away from the sun.

3. Magnetic Sail


The sun releases mostly protons and electrons at speeds that range from 248 to 370 miles per millisecond. A magnetic sail would use this energy and push against it. A loop of conducting material would produce a magnetic field that’s perpendicular to the solar wind, and this would push the craft to the desired location. The problem is that in order to do this, the sail would need to be 62 miles long. The technology to make the superconducting material for a sail of that size, and keep it at the right temperature, just isn’t available right now. Magnetic sails are just a theory until better technology is developed.

2. Wormhole


A staple of science fiction, wormholes have fascinated people ever since they were first theorized in 1921. While they’re believed to exist, there’s no visible evidence. Wormholes are essentially tunnels in space, which objects could theoretically travel through. But wormholes are unstable — if someone were to travel through them, the walls would probably collapse. In order to safely travel through, the craft would to use an anti-gravitational force. Physicists say we most likely wouldn’t be able to collect enough energy. If there was a wormhole humans could travel through, it wouldn’t naturally occur; it would have to be constructed by an advanced civilization. So until we either get to that point or someone constructs a wormhole for us, it will remain in the realm of science fiction.

1. Warp Drive


Made popular by Star Trek, a warp drive allows for faster than light travel. It’s often thought to be impossible because of the incredible amount of energy needed to run a drive. However, researchers believe that they’ve found a way. The first idea was to use a design by physicist Miguel Alcubierre, who proposed a spacecraft shaped like an American Football with a flat circular ring around it. But in order to power that design, you would need a ball of antimatter the size of Jupiter.

To make the spacecraft more feasible, NASA’s Dr. Harold White tweaked the design. In theory, the modified ship would require much less antimatter, about 500 kilograms. The proposed spacecraft would warp space-time and reach speeds 10 times the speed of light. It would make trips to the closest star about four or five months long.

Unfortunately, antimatter is incredibly volatile. Just one third of a gram could release the same amount of energy that was released during the bombing of Hiroshima. The amount of antimatter that White’s design needs would be the equivalent of 1.5 million Hiroshimas, enough to destroy the Earth.

Space Traveler’s

Guide to the Universe

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