Sailing Through Space | Out Of This World Weekly


The concept of a solar sail was introduced when astronomers first noticed in 1610 that solar wind caused the tails of comets to blow away from the Sun.  Since then, many have dreamed of being able to sail through space using the solar wind as propulsion.  In fact, this technology has been successfully used to propel craft between planets.  In 2010, Japan launched the Ikaros probe to test solar sail technology on a trip to Venus.  It did this successfully and Japan is planning on launching another sail to Jupiter and the Trojan Asteroids late in this decade.  NASA is also trying to get in on this propellant less technology, testing a small sail in orbit for a limited time in 2011.  After NASA did confirm that this technology is feasible, they thought up their next solar sail project:  Project Sunjammer.  As early as 2014, this large scale solar sail project is set to fly through interplanetary space to test more advanced control schemes, attitude control, and sail stability to further prove the technology. 

Why are solar sails so useful, when we have big, powerful rockets that can get us where we want to go as fast as possible?  Not everything needs to be there as fast as possible when cost is a consideration.  Solar sails would be very useful in several applications where conventional rockets would need to be either huge, prohibitively expensive, or both.  A solar sail could keep a satellite in Low Earth Orbit indefinitely, even recharging either attitude control or communications equipment from solar panels that could be built into it.  For deep space travel, a solar sail would allow for a continued acceleration that would eventually enable the high speeds needed to reach far distant targets.  Solar sails would also be ideal for missions like space junk control, catching space junk and de-orbiting it without having to use limited and expensive propellant.  Solar sails do offer many advantages that simply cannot be recreated using conventional or Hybrid rocket engines. 

Imagine the force of a packet of sweetener pressing down on your hand.  That is the kind of acceleration that a moderate sized solar sail can achieve but that acceleration is constant for every second of every day.  While this may seem small, some of the newest and best ion engines actually produce less acceleration while using limited propellant.  Over time, this acceleration can build to extremely high speeds for a small craft, or even enable large objects like asteroids to be moved slowly in a controlled fashion.  These solar sails do suffer from the idea that they are out of date relics, like so many large sailing ships of the past yet even today sailboats can be found in every single port because of their ability to enable travel without needing expensive fuel.  With these upcoming missions by NASA and JAXA, solar sails are primed to once again show the world the power of the sail. 

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