由太阳光驱动的宇宙飞船将从SpaceX火箭上发射

Sunlight-Powered Spacecraft Set to Launch Aboard SpaceX Rocket

A major experiment in solar sailing is set to launch this month.

Solar sailing is a method that can push, or propel, a vehicle through space. A spacecraft is attached to a large solar sail to capture wind pressure from sunlight. This pressure is the force for movement.

A small spacecraft is set to demonstrate this technology after being launched from a rocket on June 22. The spacecraft, called LightSail 2, will launch from a Falcon¹ Heavy rocket built by American aerospace² company SpaceX. The rocket will launch from Florida’s Kennedy Space Center.

LightSail 2 is a small spacecraft that weighs about five kilograms. It was designed by a not-for-profit group, The Planetary Society. Such small spacecraft are known as CubeSats. These provide a low-cost way for scientists, governments and private organizations to carry out space experiments.

LightSail 2 will be part of a U.S. Department of Defense³ operation that will also launch about 24 satellites. The Planetary Society launched a similar spacecraft in 2015 called LightSail 1. That spacecraft successfully tested the sail deployment⁵ system.

American scientist, writer and television star Carl Sagan, along with others, created the Planetary Society. Bill Nye currently leads the organization. Nye says the operation will attempt to raise the first solar sail spacecraft to orbit Earth.

In a statement, Nye added that this month’s launch could complete one of Sagan’s major goals. "Forty years ago, my professor Carl Sagan shared his dream of using solar sail spacecraft to explore the cosmos⁶. The Planetary Society is realizing the dream," he said.

The Planetary Society said citizen donations have paid for the project. Nye said thousands of people from all over the world came together to support it. He said the society was created to “empower people everywhere to advance space science and exploration.” Now, he said: “We are go for launch!"

A main goal of the operation is to demonstrate the power of sunlight to propel spacecraft without the need for costly⁷ rocket fuel.

Light is made up of particles called photons. Photons themselves do not have any mass. But when they travel through space they can pick up momentum⁸.

The sail used with LightSail 2 has a very bright surface that can reflect light. When the photons in the light hit the solar sail, it creates momentum. This momentum results in small pushes as the photons repeatedly strike the sail.

Once in space, LightSail 2 will deploy⁴ its solar sail system, which covers a total area of about 32 square meters. Over time, it will seek to raise its orbit using the small, continual pushes from solar photons.

The sail will turn towards the Sun for half of each orbit, “giving the spacecraft a tiny push no stronger than the weight of a paper clip,” the Planetary Society said in a statement. “For about a month after sail deployment, this continual thrust should raise LightSail 2's orbit by a measurable amount.

Project officials say they expect LightSail 2 to fly to an orbit of 720 kilometers high. The spacecraft might be able to be seen in the night sky to observers within 42 degrees of the equator, they added.

“This will be the first time navigating⁹ by light in Earth orbit,” Nye told the NBC’s Mach website. He noted¹⁰ that the amount of orbital energy needed to move LightSail 2 forward can be increased by changing the position of the sail.

When a solar sail faces the Sun directly, photons push the spacecraft forward, away from the Sun. But the sail can move in other directions permitting control over where it travels, the society said on its website.

I’m Bryan Lynn.

Words in This Story

cosmos – v. the whole universe

advance – v. develop or progress

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

reflect – v. send back or bounce off

paper clip – n. small piece of metal used to hold pieces of paper together

thrust – n. upward push or force

navigate¹¹ – v. find the right direction to travel by using maps or other equipment

1 falcon   

n.隼，猎鹰

参考例句：

• The falcon was twice his size with pouted feathers.鹰张开羽毛比两只鹰还大。
• The boys went hunting with their falcon.男孩子们带着猎鹰出去打猎了。

2 aerospace   

adj.航空的，宇宙航行的

参考例句：

• The world's entire aerospace industry is feeling the chill winds of recession.全世界的航空航天工业都感受到了经济衰退的寒意。
• Edward Murphy was an aerospace engineer for the US Army.爱德华·墨菲是一名美军的航宇工程师。

3 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

4 deploy   

v.（军）散开成战斗队形，布置，展开

参考例句：

• The infantry began to deploy at dawn.步兵黎明时开始进入战斗位置。
• The president said he had no intention of deploying ground troops.总统称并不打算部署地面部队。

5 deployment   

n. 部署,展开

参考例句：

• He has inquired out the deployment of the enemy troops. 他已查出敌军的兵力部署情况。
• Quality function deployment (QFD) is a widely used customer-driven quality, design and manufacturing management tool. 质量功能展开(quality function deployment,QFD)是一个广泛应用的顾客需求驱动的设计、制造和质量管理工具。

6 cosmos   

n.宇宙；秩序，和谐

参考例句：

• Our world is but a small part of the cosmos.我们的世界仅仅是宇宙的一小部分而已。
• Is there any other intelligent life elsewhere in the cosmos?在宇宙的其他星球上还存在别的有智慧的生物吗？

7 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

8 momentum   

n.动力，冲力，势头；动量

参考例句：

• We exploit the energy and momentum conservation laws in this way.我们就是这样利用能量和动量守恒定律的。
• The law of momentum conservation could supplant Newton's third law.动量守恒定律可以取代牛顿第三定律。

9 navigating   

v.给（船舶、飞机等）引航，导航( navigate的现在分词 )；（从海上、空中等）横越；横渡；飞跃

参考例句：

• These can also be very useful when navigating time-based documents, such as video and audio. 它对于和时间有关的文档非常有用，比如视频和音频文档。 来自About Face 3交互设计精髓
• Vehicles slowed to a crawl on city roads, navigating slushy snow. 汽车在市区路上行驶缓慢，穿越泥泞的雪地。 来自互联网

10 noted   

adj.著名的，知名的

参考例句：

• The local hotel is noted for its good table.当地的那家酒店以餐食精美而著称。
• Jim is noted for arriving late for work.吉姆上班迟到出了名。

11 navigate   

v.航行，飞行；导航，领航

参考例句：

• He was the first man to navigate the Atlantic by air.他是第一个飞越大西洋的人。
• Such boats can navigate on the Nile.这种船可以在尼罗河上航行。