Question Sheet: Riding Sunlight


Before reading:

  1. Why would scientists want to use solar power to propel a spaceship?
  2. How is space travel like sailing a ship?

During reading:

  1. Why does Louis Friedman compare the flight of Cosmos 1 to the Wright brother’s first flight?
  2. What is the solar wind?
  3. How is Newton’s third law of motion involved in solar sailing?
  4. Why must the sails of a solar spacecraft be large and lightweight?
  5. How does a spacecraft driven by solar sails change direction?
  6. When is Cosmos 1 scheduled to be launched?

After reading:

  1. Why does solar sailing make sense in space but not on Earth?
  2. Does solar sailing make sense for transporting people to other planets? Why or why not?
  3. Find pictures of a jet airliner and a space ship. In what ways are the designs of these vehicles different? In what ways are they similar?
  4. Design an experiment that illustrates Newton’s third law of motion. For examples, see

    (Reeko’s Mad Scientist Lab) or Institute of Technology).

  5. Cosmos 1 is scheduled to be launched from a submarine. In what other ways could the spacecraft be put into Earth orbit?
  6. Space travel tends to be very expensive. Do you think using solar power would make it cheaper? Why or why not?


  1. Nearly 400 years ago, Johannes Kepler proposed the idea of exploring the galaxy using sails. Who was Johannes Kepler? Why is he important in the history of astronomy? For biographical information about Kepler, see
  2. Several weeks before launch, Cosmos 1 will be delivered to the naval base at Severmorsk, near the port city of Murmansk. In what country is Murmansk? How far away is Murmansk from your home? For information about Murmansk, see (Wikipedia).


  1. Suppose that you are a reporter witnessing the launch of Cosmos 1. If the launch were a failure, how would you start off your article? Write the first paragraph that you would use.
  2. Come up with five questions that you would like to ask Friedman and his team about solar sailing and Cosmos 1.


The farther away you are from the sun, the weaker the sunlight is. In fact, if you were to double your distance from the sun, the sunlight intensity would be just one quarter of what it was at your original location. Mathematicians call such a relationship an inverse square (1/d2, where d is the distance). The distance from the sun to Earth is 1 Astronomical Unit (1 AU). Compared to Earth, how much sunlight would a spacecraft receive if it were three times as far from the sun as Earth? Mars is at a distance of 1.5 AUs from the sun. Compared with Earth, how much sunlight does it receive?