The flying vessel takes off, its jets straining against the atmosphere to eke out every Newton of force they can until, suddenly, its long wings seem to flow together, sweeping backwards as the ramjets take over.

Once sufficient height is gained, the vessel taps into the Earth's magnetic field and raises itself into a low Earth orbit.

Low Earth orbit is cluttered with the collected junk of the space age, but the pilots and passengers of the spaceship are safe. The ship's artificial intelligence would know if anything went wrong, and in the unlikely event that the hull was breached, it could reseal itself anyway.

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What sounds like science fiction may soon be science fact. In truth, the technologies for the aforementioned space vessel all exist and are being further developed today.

Science fiction writers have been speculating about space travel since Jules Verne's From the Earth to the Moon, published in 1865, and have thought of many ways to attack the problem.

Many of today's new technologies were thought of by sci-fi writers decades ago. Verne wrote about heavier-than-air vehicles in the 1800s; Dick Tracy used a wristwatch with a built-in camera and walkie-talkie, and Craig Thomas' Firefox had stealth technology,. All were fiction at the time of creation, but are now fact.

The trouble with the current space system stems from the extremely high cost involved; currently, it costs $10,000 for each pound lifted into low Earth orbit. NASA's Advanced Space Transportation Program (ASTP) intends to reduce the cost of space travel to 1 percent of its current price by 2025.

Low Earth orbit is the lowest stable Earth orbit and the stepping-stone to outer space. Although satellites in low Earth orbit are in the last fringes of the atmosphere, drag is minimal, objects are weightless and an orbit can be maintained.

Objects in low Earth orbit can both see Earth and peer into the depths of space. Low Earth orbit is the favored orbit for communications and remote sensing satellites as less energy is required to place them in orbit and higher detail from the surface can be gained.

The only trouble with placing satellites in low Earth orbit is that a network of satellites is required to acquire continuous Earth coverage.

Another troubling factor to space exploration, as recently highlighted by the Columbia disaster, is safety. Along with lower costs, the ASTP wants space travel to be as safe and reliable as today's air travel. To overcome the obstacles to cheap, safe and efficient space travel, several technologies have been developed.

Modern Materials

Among the contributions material science has forwarded toward the space age, the latest include advanced piezoelectric materials, shape-memory alloys, carbon nanotubes and self-healing metals.

Piezoelectric Materials Piezoelectric materials are hardly new; in fact, the quartz crystals that regulate the time on modern watches rely on piezoelectric effects to keep time.

A piezoelectric material changes shape in response to an electric current or conversely, if deformed or compressed, generates an electric current.

In a watch, the oscillation of a quartz crystal produces a measurable voltage, which is amplified and converted into steady pulses that drive the digital circuitry of a watch and keep time.

Modern piezoelectric materials are used for purposes other than time keeping.

Currently, aircraft use hydraulics to control the leading and trailing edges of their wings, moving flaps up and down. New smart wing aircraft will use piezoelectric materials to flex the leading and trailing edges, keeping the wings continuous and unbroken, improving structural integrity.

Piezoelectric sensors can be attached to machines to perform similar duties to our nerve sensors. If a part of the machine is "touched" and deformed in any way, an electric signal will be sent to the controlling computer, indicating possible damage.

Shape Memory Alloys Scientists have discovered alloys that can be "trained" to a specific shape.

At room temperatures, the alloy exists in one shape, but, when heated, shifts into its trained shape.

Current uses involve making non-hydraulic electric clamps that contract at room temperatures and open only when plugged in.

Nanotubes - Space Elevator Since the late 19th century, authors have speculated about a bridge or elevator into space. One end of the space elevator would be placed on the Earth, near the equator, and the other anchored to an asteroid in geosynchronous orbit around the Earth.

The main problem inherent in building the fanciful elevator is finding building materials that wouldn't collapse. The cable of the space elevator would face maximum strain at its orbiting end. The orbiting end of the elevator must be the thickest and taper as it moves toward the Earth.

Any building material can be characterized by its taper factor, the ratio between the cable's thickness in orbit and the thickness at the Earth's surface. For steel, the factor is measured in the tens of thousands range, so steel is clearly impractical to use.

Diamond's taper factor, including a safety factor, was found to be only 21.9 by Tom McKendree and presented at the Fourth Foresight Conference on Molecular Nanotechnolgy.

Unfortunately, along with being rare, diamond is brittle and would easily propagate cracks. Carbon nanotubes have a similar strength to diamond, but bundles of the tiny tubes would not propagate cracks as easily.

Nanotubes - Computing Moore's Law (an observation, not a physical law) states that the size of the circuits within a microchip decreases exponentially with time and predicts circuits on the atomic scale in the next few decades.

Computer simulations are already underway to grow 3-D circuits on the atomic scale. Depending on the atomic structure, or helical winding of carbon nanotubes, different properties are displayed.

Depending on the helical winding, scientists have theorized that single-walled carbon nanotubes, nanotubes with walls one atom thick, could have either metallic or semiconductor properties, allowing circuits hundreds of times smaller than current silicon technology allows.

Nanotubes - Lightweight Materials Alloys made with carbon technology promise to be lighter and stronger than materials now on the market. Lighter spacecraft would allow cheaper launches since less fuel would be needed.

Propulsion Systems

Chemical The chemical propulsion systems that are prevalent today are highly inefficient. In order to cross any interstellar distance, chemical rockets are burned on the spacecraft's initial leg, providing a huge push. There is no resistance in space and, thanks to Newton's laws of momentum, the craft can just coast to its destination.

Unfortunately, for interstellar distances, the initial burst required would consume more fuel than could possibly be provided.

Advances in the chemical propulsion field include the development of monopropellants, a propellant that does not require oxygen to burn, reducing engine complexity and advanced hydrocarbon fuels.

Fission Propulsion Fission power, our current nuclear power, has benefited the United States for almost 60 years and is a tried-and-true method of generating energy.

Fission uses relatively small volumes of fuel to achieve great results. One kilogram of plutonium can yield up to 300,000 kilojoules of energy.

The reactor could provide the ship with electricity as well as thrust.

Plasma Plasma propulsion involves high-powered reactions. The benefit of using a plasma system is that the plasma can be magnetically manipulated and can provide thrust directly, without having to convert it into electricity first, as in fission systems.

Anti-matter Anti-matter consists of atoms with an opposite charge and electron spin from the atoms in regular matter. When an anti-matter particle meets with a particle of normal matter, both annihilate each other and their mass is converted completely into energy.

Anti-matter can potentially provide more power than both fission and fusion and store at high densities.

Laser Lightcraft Laser-powered spaceships do not need to carry their own fuel as the energy source for a laser-propelled ship is based on Earth.

A high-powered ground-based laser beams at the lightcraft, which reflects the beam to a predetermined point. The heat of the concentrated beam expands the air explosively and propels the lightcraft upward.

The lightcraft has a store of hydrogen on board for higher altitudes, where the atmosphere is thin or nonexistent.

The best use for a lightcraft is to move payloads into Low Earth Orbit.

Ion Power Deep Space 1 was the first ion-powered spaceship launched. Magnifiers focused the Sun's rays onto solar panels providing electricity. The electricity was used to charge xenon atoms and propel the charged atoms out of the thrusters at 30 kilometers per second.

The force of the ion engine used on Deep Space 1 was very slight, about that of a piece of paper on a person's hand, but over time Deep Space 1's speed mounted.

Chemical propulsion imparts significantly higher initial acceleration to a spacecraft; a chemically propelled craft expends its fuel in one initial burst at the beginning of its journey.

If rapid acceleration is not required, ion propulsion wins out. The fuel lasts longer, and over time, higher speeds can be obtained, allowing large distances to be crossed more quickly than with chemical propulsion.

The speed of a craft using ion propulsion is only limited by the amount of propellant it carries. Deep Space 1's 81.5 kg payload lasted over three years.

Magnetic Powered Propulsion NASA is currently testing magnetic tethers. Tether propulsion is propellant-free and draws power from the Earth's magnetically-charged atmosphere.

Tethers will be used to transfer energy to satellites or other objects to raise or lower their orbits.

For the long haul, tethers could be used as permanent space tugboats.

NASA has also envisioned a spacecraft that surrounds itself in a magnetic field similar to the Earth's Van Allen belts and uses solar wind to accelerate and push it out of the solar system.

An advantage of this type of system is that, like the Van Allen belts, the spacecraft's magnetic field would protect the ship from radiation.

Solar Sails Mankind used sails to conquer the Earth's oceans, and with solar sails, mankind has invented another method of conquering the vistas of space.

Spacecrafts using solar sails, like those using laser power, require little to no onboard fuel.

Solar sails utilize light to provide acceleration. As photons of light impact the sails, they transfer some of their momentum to it, similar to wind blowing against a terrestrial sea vessel's sail.

The sails are made of a large, lightweight, durable material and typically cover large areas. The sail of Cosmo-1, the first spacecraft launched with a solar sail, was made of aluminum-coated Mylar, 5 microns thick (Saran wrap is 25 microns thick) and covered an area of 6,415 square feet.

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With all the technology available and under development, space travel soon will become affordable to everyone. Space tourism may become a booming industry, and the world of the Jetsons may no longer seem so far-fetched.