Spaced out! A high-tech race could make space tourism more affordable

Science World, Jan 24, 2005 by Kathryn Kukula

Hoping to vacation in outer space one day? Once the plot of science-fiction movies, space tourism just took one giant leap closer to reality.

In the past, only governments with bulging wallets could send astronauts into space. But last fall, Mike Melvill and Brian Binnie became the first pilots to guide a privately built craft into space.

Launched from the belly of a specially designed jet airplane, SpaceShipOne soared to a dizzying height of more than 110 kilometers (68 miles) above the planet's surface. Just minutes after cruising into outer space, the craft touched down again safely in Mojave, California.

A series of high-flying journeys earned SpaceShipOne's creators a $10 million award called the Ansari X Prize. An even bigger reward? Their feat cracked open the door to affordable space travel.

SPACE RACE

The X Prize was the beginning of a new kind of space race--one that rewards private companies for thinking outside the box to build lower-cost, innovative spacecraft. The latest contest: America's Space Prize. The first company to build a craft that can carry five to seven astronauts into two orbits (revolutions) around Earth will nab $50 million.

Not to be outdone, even NASA is getting onboard. Their new Centennial Challenges office plans to announce contests that are open to private cosmic contenders.

One hopeful in the race to space is the company Interorbital Systems. Interorbital has designed a space capsule called Neptune that will blast off from a platform in the ocean and then soar into orbit around Earth. "It will launch like a missile from a submarine," says Randa Milliron, CEO and cofounder of Interorbital.

A rocket will boost Neptune 297 km (185 mi) into Earth's atmosphere, or the protective layer of gases surrounding a planetary body (see Nuts & Bolts, p. 15). Once in the thermosphere (outermost layer of the atmosphere), the craft will try to maintain a speed of 28,163 km (17,500 mi) per hour--much faster than SpaceShipOne's 4,043 km (2,512 mi) per hour.

Why will it have to go so fast? Unlike SpaceShipOne, which dipped into space and then quickly turned Earthbound, Neptune aims to remain in orbit. To stay aloft, a spacecraft has to play a masterful game of tug-of-war with Earth's gravity, the force that pulls two objects together. If the craft were to zoom around the planet too quickly, it would go reeling into space. But were it to fly too slowly, the pull of Earth's gravity would cause the craft to plow into the planet.

TOUGH CHALLENGES

If a spacecraft manages to maintain orbit around Earth, the high speeds involved will create daunting challenges for the craft during reentry. That's because a homebound spacecraft hurtles down through the layers of Earth's atmosphere. With each passing layer, the craft smashes against more and more gas molecules (particles of two or more atoms, or the smallest units of an element, joined together), until it finally punches through the jam-packed troposphere, the atmosphere's lowest level. This collision course between the spacecraft and the gas molecules causes friction (resistance to movement when two surfaces rub together), which raises the temperatures around the craft to up to 1,649[degrees]C (3,000[degrees]F). "You come in like a ball of fire," says Milliron.

How will a spacecraft survive reentry's barbecue? To succeed, a craft will need a protective heat shield and a special coating to help it withstand the sizzling trip back to the planet.

YOUR TURN?

Which contenders will be ready to face the heat first? Milliron hopes to launch Neptune's first trained crew in 2006. After that, the craft could carry space tourists.

Seventeen-year-old Justin Houchin, who hopes to be the first teen in space, has already made a down payment for a trip. Now he's raising funds for the hefty airfare: $2 to $4 million. With price-slashing predicted for the future, maybe you'll be next.

Nuts & Bolts

Scientists divide Earth's atmosphere into four main layers: troposphere, stratosphere, mesosphere, and thermosphere. They further divide the thermosphere into the ionosphere and the exosphere.

THERMOSPHERE

Above 80 km (50 mi)

This layer has no definite outer limit. Space is said to start at about 350 km (217 mi).

MESOSPHERE

50 to 80 km (30 to 50 mi)

Most meteoroids burn up in this layer causing meteor showers.

STRATOSPHERE

12 to 50 km (7 to 31 mi)

Ozone gases in this layer absorb dangerous sunrays.

TROPOSPHERE

0 to 12 km (0 to 7 mi)

The layer in which you live contains over 75 percent of all the atmosphere's gases.

EXOSPHERE

Above 550 km (342 mi)

In this outermost layer, gases drift off into space.

IONOSPHERE

80 to 550 km (50 to 342 mi)

Radio waves bounce off this layer; aurora displays occur here.

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BLAST OFF: One day, these reusable spacecraft that take off like planes could replace NASA's aging shuttle fleet.

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COUNTDOWN: Modeled after SpaceShipOne, this Virgin Galactic ship could carry space tourists as soon as 2007.

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GOING UP: SpaceShipOne was towed up over 14 km (9 mi) by the carrier craft White Knight.