Japanese space agency (Jaxa) scientists want to detect a measurable acceleration in the spacecraft as photons - the particles of light - from the Sunfall on the roughly 200-sq-m, ultra-thin sheet.
Some people may wonder why we in the Northern Hemisphere have our spring and summer when our planet is far away from the sun. (Equally confusing: our fall and winter come when we are near to the sun.) Shouldn't proximity to that nice warm ball of sunshine predict our seasons?
This shield does not stop all the cosmic rays from getting though, and its effectiveness varies with the long-term changes in the activity of the Sun, which can rise and fall on a timescale of centuries.
It is as if some politicians seem so full of hubris they cannot resist flying so close to the sun and then seem surprised when, like Icarus, they fall to the ground.
Even if they fall short of that grand claim, its clients probably won't risk changing horses unless Sun's rivals present an overwhelming technological or economic case to do so.