| | Category | PH | P31 | Solar Sails: Which Design is Best? |
| | Abstract | With today’s growing use of satellites and other spacecraft for |
| | exploration, much research is being done to develop faster, lighter, and |
| | more efficient space vehicles. One of the avenues being explored |
| | involves the use of large reflective “solar sails” to propel a spacecraft |
| | using thrust from sunlight. James Clerk Maxwell proposed in 1873 that the |
| | photons which make up sunlight exert force on objects. This was |
| | confirmed in the early 20th century by the experiment of Nichols and Hull. |
| | Today, multiple countries are developing solar sails; NASA hopes to launch |
| | its NanoSail-D in 2010. However, no solar sails have been successfully |
| | flown so far. Over the course of solar sail history, different |
| | configurations have been tested to develop maximum efficiency. This |
| | experiment was formulated to research the ability and efficiency of flat, |
| | concave, and convex sails to propel a payload. The three sail types |
| | would be tested with a light source shining directly on them, and then at a |
| | forty-five degree angle. Thus, the best sail for sailing directly away from |
| | the sun, and the best for sailing at an angle would be determined. Ray |
| | tracing was performed for each sail in an attempt to predict which sail |
| | would perform the best for each part of the experiment. It was |
| | hypothesized that, if the force on the sail was great enough to be |
| | measured, the flat sail would perform best when struck directly, followed |
| | by the concave and convex sails. When struck at a forty-five degree |
| | angle, the convex sail would be most effective, followed by the concave |
| | and flat sails. To perform the experiment, a device based on the one |
| | Nichols and Hull used was constructed. A sail was placed in the device, |
| | and a bright LED spotlight was shone on it. However, no movement was |
| | detected which could be attributed to the light, even when modifications |
| | were made to increase the sensitivity of the device. The torsion |
| | coefficients of various fibers were calculated to determine a more |
| | sensitive material and a laser-based measurement system was devised in |
| | order to further increase the sensitivity. It was concluded that the light |
| | force was not significant enough to be measured in this manner. |
| | However, the experiment did not disprove the existence of this force, but |
| | only demonstrated that it is very small indeed. A very large sail would be |
| | needed to propel a small mass. This experiment was enjoyable, though, |
| | as well as being educational about the principles behind solar sailing. |
| | Bibliography | Books: |
| | Taylor, P., Hendrickson, N. (1995). Beginner’s Guide to the Sun. |
| | Waukesha, WI: Kalmbach Books. |
| | |
| | Urone, P. (2001). College Physics Second Edition. Pacific Grove, CA: |
| | Brooks/Cole. |
| | |
| | Articles: |
| | Carlson, S. (2006) Homebrew Magnetometer: Build a Torsion Balance to |
| | Measure Tiny Changes in the Earth’s Magnetic Field. Make Magazine |
| | Volume 08. |
| | |
| | Jensen, T. (2005) Measuring the Pressure of Light: Pure Science at |
| | Dartmouth. Dartmouth Science History. |