Monday, July 28, 2014


Set to launch atop a SpaceX Falcon Heavy rocket in 2016, a solar craft belonging to the Planetary Society aims to journey around to solar system.
Cool in so many ways; for one it is a privately funded project paid for by private donors of the society which Carl Sagan co-founded. Another fact that lends it coolness is their current leader, Bill Nye.
It won’t be the first solar sail. Later this year NASA has plans for their solar sail named Sunjammer to take off. If Sunjammer sounds familiar it’s because it should. Arthur C. Clarke wrote a Science Fiction story that was published in 1964 of the same title. In the story the solar sails lead to a sun-yacht racing craze.

Of course NASA won’t be the first either. In May of 2010 the Japanese Space Agency (JAXA) sent up IKAROS. They were able to successfully demonstrate solar-sail technology within interplanetary space. Although all the planned experiments were completed in 2010, the mission continued through 2013 after a brief hiatus in contact.
Japan has an additional solar sail demonstration planned for some time prior to 2020. This sail will also have an integrated ion propulsion and will launch off to Jupiter and some of the Trojan asteroids.
Japan sent up a previous attempt as a test of the concept in 2005 but due to a failure with a Russian booster, the attempt was unsuccessful.
Solar sails are one of the forms of propulsion that are building up excitement for those who hope for or even expect travel to other planets, stars, even galaxies to be a part of our future. The lack of a need for fuel makes this method a promising one.
BUT if you are thinking that maybe this is the answer for going to Mars, you not right, or not 100%. Solar sails offer the slowest of accelerations and so offer no advantage of a chemical rocket. At least, no advantage of a current day chemical rocket if people are being transported; conversely, if transporting supplies for an outpost, and there’s no hurry, this method is alluring.
A comment – if you have read my earlier writing I have spoken the se of a solar sail for getting supplies to an outpost on the Moon. First they get SpaceX to rocket the supplies to space, then deploy the parachute, then have LiftPort’s space elevator on the Moon will grab the parachute/supplies and bring it down to the Moon’s surface. Not to mention the opportunities of science and missions in our own orbit – weather missions, sampling of the atmosphere etc.
But there are other missions and other uses planned for Solar Sails. Cleaning up Earth’s orbit is of concern to every nation spacefaring or hopeful and those who have no current ambitions for space as well. One of the ESA plans, and like NASA they have several, named “Gossamer”. The intention is to deorbit small artificial satellites from low Earth orbit.

There are many methods and types of Solar sails. It is not just simple opening up a parachute in space.
First there was the design that utilized rotating blade and ring sails - designed to stiffen the structures using angular momentum, eliminate the need for struts and thus lessen the mass but control was more difficult. Another design uses plastic film blades deployed from a roller – basically thanks to centrifugal forces the blades managed similar to a helicopter. Again it offered no significant advantages other than the fact that this style was simpler to deploy. There were many others as well but ultimately the design has remained the same…mostly.
There is the electric solar wind sail although it isn’t the traditional design format; the sails are gone replaced with straightened conducting wires placed radially around the host ship. Then the electrical wires are charged to create an electric field that extends into the plasma of the solar wind. The solar electrons are reflected by the electric field as a traditional sail would reflect them. Additionally there is a magnetic sail which also employs the solar wind.
Many are misled, thinking that solar sails are ‘pushed’ be solar wind much like sails of a sailboat in the bay is pushed by the wind here on Earth. Not exactly. The propulsion from a solar sail comes from the pressure of photons from the Sun’s light (or lasers).
While perhaps sails present a problem the further they are from the Sun or perhaps with tacking (coming about) is a maneuver where the sailboat turns it’s bow through the wind allowing ultimately allowing the wind to change from blowing from one direction to the complete opposite.  
So back to the Planetary Societary’s plan LightSail. LightSail will be stored inside of another spacecraft which is named Prox-1. It will be expulsed and then a few weeks after it reaches orbit it will have expanded its reflective wings to about 32 square meters. Cool part is once this is done, it will be visible from Earth.
There is a slight wrinkle with LightSail-A, the planned test vehicle for 2015; it has a blown radio amplifier and while this should propose no problem for the 2016 flight timetable, it does throw a wrinkle into its test flight and speaking to the ground stations.

So come 2016 keep your eyes skyward and check out the flight of LightSail brought to you by the planetary society. (

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