VOA慢速英語:科學(xué)家用光來探測飛船推動力

Can the sun provide power for a spaceship to travel to the edge of our solar system? The answer may come from a small satellite. A Delta V rocket carried the satellite into space earlier this (last) month. The rocket was launched from Cape Canaveral Air Force Station in Florida.

The satellite is designed to test the effectiveness of what is called solar sail propulsion. Its large sail will catch solar wind and slowly reach what scientists hope to be an extreme speed.

The satellite is called CubeSat. It is about the size of a loaf of bread. CubeSat was designed by a non-profit group, The Planetary Society. Bill Nye is the chief executive officer of the society. He says the satellite will test whether sunlight can be used as a propulsion force for space travel.

"This may seem incredible at first, but it is nevertheless true that sunlight, or light, has momentum even though it has no mass. Photons have no mass but they still impart momentum when they strike an object...it's a tiny, tiny amount of momentum. Nevertheless, if you have a big enough sail, as we call it, and [a bus or spacecraft with] a low enough mass, it will get a push."

Scientists believe that this method of propulsion will reduce the cost of space exploration for universities and even private individuals.

The sail is 32-square meters long. It is made of Mylar, a material that is only one fourth as thick as human hair. Bill Nye says laboratory tests of the sail were successful. But he says testing the sail in space will be critical.

"This first time out is a test. The big question, from an engineering standpoint not a physics standpoint, is getting the sails to deploy. This is where everything goes wrong."

The Planetary Society reported that the satellite reached its orbit and that all of its systems appeared healthy. The group says the solar sail can be seen from the earth in the middle of June.

I'm Jonathan Evans.

VOA's George Putic reported on this story from Washington. Jonathan Evans adapted it for Learning English. George Grow was the editor.

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Words in This Story

critical – adj. extremely important

momentum – n. the force that something has when it is moving

photon – n. a tiny particle of light or electromagnetic radiation

propulsion – n. the force that moves something forward; the force that propels something