[ti:Scientists Testing Space Propulsion by Light] [ar:Jonathan Evans] [al:Science In The News] [by:www.51voa.com] [00:00.00]Can the sun provide power for a spaceship [00:03.34]to travel to the edge of our solar system? [00:06.40]The answer may come from a small satellite. [00:10.50]A Delta V rocket carried the satellite into space earlier this (last) month. [00:16.93]The rocket was launched from Cape Canaveral Air Force Station in Florida. [00:22.29]The satellite is designed to test the effectiveness [00:26.89]of what is called solar sail propulsion. [00:30.16]Its large sail will catch solar wind and slowly reach [00:35.83]what scientists hope to be an extreme speed. [00:39.83]The satellite is called CubeSat. [00:43.48]It is about the size of a loaf of bread. [00:47.27]CubeSat was designed by a non-profit group, The Planetary Society. [00:53.41]Bill Nye is the chief executive officer of the society. [00:58.67]He says the satellite will test [01:01.76]whether sunlight can be used as a propulsion force for space travel. [01:07.00]"This may seem incredible at first, but it is nevertheless true that sunlight, [01:13.30]or light, has momentum even though it has no mass. [01:18.32]Photons have no mass but they still impart momentum [01:21.93]when they strike an object...it's a tiny, tiny amount of momentum. [01:27.40]Nevertheless, if you have a big enough sail, as we call it, [01:30.80]and [a bus or spacecraft with] a low enough mass, it will get a push." [01:34.43]Scientists believe that this method of propulsion [01:38.44]will reduce the cost of space exploration [01:42.21]for universities and even private individuals. [01:46.20]The sail is 32-square meters long. [01:49.99]It is made of Mylar, a material that is only one fourth as thick as human hair. [01:56.89]Bill Nye says laboratory tests of the sail were successful. [02:02.25]But he says testing the sail in space will be critical. [02:07.43]"This first time out is a test. [02:09.74]The big question, from an engineering standpoint not a physics standpoint, [02:14.98]is getting the sails to deploy. [02:17.40]This is where everything goes wrong." [02:19.88]The Planetary Society reported that the satellite reached its orbit [02:25.03]and that all of its systems appeared healthy. [02:28.50]The group says the solar sail can be seen from the earth in the middle of June. [02:35.04]I'm Jonathan Evans. [02:37.22]¸ü¶àÌýÁ¦Çë·ÃÎÊ51voa.com