Sailing to the Stars

Hop aboard a ship and sail to another galaxy? It may one day be possible in a spaceship powered by solar sails.

To travel into deep space, we'll need to go far and fast. Fuel-powered rockets have taken us to the Moon and may take us to Mars, but there are two problems with fuel: it's heavy, which slows the spacecraft, and it runs out.

Enter solar sails. Thin as notebook paper and 1/3 of a mile wide, these mirrorlike panels capture the Sun's rays. Like raindrops hitting a leaf, particles of light hit the sails, pushing the spacecraft forward.

The force of light is gentle, giving solar sails a slow start. However, unlike rockets, which coast after a quick blast of fuel, solar sails are constantly pushed by particles of light. Over time, solar sails will zip faster than any rocket, traveling 3,000 miles—the distance from New York to Los Angeles—in under a minute. That's 10 times faster than the space shuttle. Beyond Jupiter, where the Sun's rays weaken, solar sails could be powered by microwave or laser beams from other spacecraft.

This fall, a test spacecraft powered by small solar sails will begin orbiting our planet. Around 2010, a solar-powered craft called the Interstellar Probe is scheduled to launch, the first mission planned beyond our solar system! And apart from science, some companies have shown a commercial interest in solar sails. One already plans to send customers' photos, messages, and DNA into interstellar space—for just $50. So get those “Dear Alien” letters ready.


Between or among the stars.

An energy wave that is shorter than a radio wave and longer than a light wave. Microwaves are used in radar and in microwave ovens.

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  1. What kind of energy is released when a rocket blasts off?
    [anno: Thermal energy is released when a rocket blasts off.]
  2. What would happen if a rocket engine were used to power a solar sail?
    [anno: The heat released from the rocket engine would probably destroy the solar sail.]
  3. A solar sail is powered by sunlight. Do you think light energy could be used on Earth to move things? How are the conditions on Earth different than those in space? Write a sentence or two to explain why you think light energy could or could not be used to move things on Earth.
    [anno: Answers will vary but may include that sunlight could not be used on Earth to move things because the pull of gravity would be stronger than the sunlight. In space, there is no gravity.]