solar sails

Harnessing the power of the Sun to propel a spacecraft may appear somewhat ambitious and
the observation that light exerts a force contradicts everyday experiences. However, it is an
accepted phenomenon that the quantum packets of energy which compose Sunlight, that is to
say photons, perturb the orbit attitude of spacecraft through conservation of momentum; this
perturbation is known as solar radiation pressure (SRP). To be exact, the momentum of the
electromagnetic energy from the Sun pushes the spacecraft and from Newton’s second law
momentum is transferred when the energy strikes and when it is reflected. The concept of
solar sailing is thus the use of these quantum packets of energy, i.e. SRP, to propel a spacecraft,
potentially providing a continuous acceleration limited only by the lifetime of the sail
materials in the space environment. The momentum carried by individual photons is
extremely small; at best a solar sail will experience 9 N of force per square kilometre of sail
located in Earth orbit (McInnes, 1999), thus to provide a suitably large momentum transfer the
sail is required to have a large surface area while maintaining as low a mass as possible.
Adding the impulse due to incident and reflected photons it is found that the idealised thrust
vector is directed normal to the surface of the sail, hence by controlling the orientation of the
sail relative to the Sun orbital angular momentum can be gained or reduced. Using
momentum change through reflecting such quantum packets of energy the sail slowly but
continuously accelerates to accomplish a wide-range of potential missions.solar sails may also be used in deciding the attitude of a spacecraft while in flight.

career in aerospace

Careers in Aerospace Technology A new century has begun. As a student you will be spending your life in the 21st century and the future may offer many unpredictable opportunities. It will be a time of space stations and robotic probes. Manned missions to other planets and moon outposts are future possibilities. All this, and more scientific accomplishments that have not even been dreamed of, will happen because Americans wants to live and work in space. Where Will You Be in 10 Years? The world will continue to need aerospace scientists, engineers, technologists and technicians to be ready for the 21st century. What Could An Aerospace Technology Career Mean for You? Aerospace workers are professionals who work independently or as part of a team. They conduct research, and de-sign and develop vehicles and systems for atmospheric and space environments. Individuals who are successful in aerospace careers have the proper educational background, possess good communications skills, and are committed to being part of a team. A wide variety of aerospace career fields offers opportunities for high job satisfaction and excellent compensation. What Education Will You Need Beyond High School? A career in aerospace as a scientist or engineer requires four to seven years of college study following high school. A bachelor’s degree requiring four years of study is the minimum necessary to enter this field. Colleges and universities also offer graduate programs where students can obtain master’s and doctoral degrees. The master’s program usually takes two years. An additional two to four years is needed to earn a doctorate. A starting position as an engineer, mathematician, physical scientist, or life scientist requires a bachelor’s degree. (A master’s and/doctoral degree is highly desirable in life sciences.) Some examples of engineering degrees required are electrical/electronics, aerospace, and mechanical. Other types of bachelor’s degrees that may lead to aerospace careers are: physics, chemistry, geology, meteorology, mathematics, experimental psychology and biology. Engineering technicians typically earn a two-year Associate of Science degree. Some may continue for two additional years and obtain a bachelor’s degree in engineering technology. Others may earn a bachelor’s degree in engineering or one of the physical sciences. A few complete a five-year apprenticeship program offered at some NASA field centers. How Do You Know if You Want An Aerospace Career? If you think you would be interested in a career in aerospace technology, check your potential for success by answering these questions: Do you enjoy math and science? Do you have an inquisitive and searching mind? Are you interested in knowing what makes things work? Do you like to solve problems and puzzles? Do you like to create things? Do you enjoy learning? Do you enjoy working with computers? Do you like to build things? Are you prepared to study hard and do homework? Do you achieve good grades? If you answered yes to most of the questions, you may want to consider an aerospace career. Some of the recom-mended high school courses are listed on the reverse side. http://www.nasa.gov/centers/langley/news/factsheets/FS-2001-09-68-LaRC.html