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WonderSpace technology fact

A solar sail is a huge, ultra-thin mirror that lets a spacecraft travel on the faint push of sunlight. It needs no fuel, and the tiny push keeps adding speed for as long as light falls on it.

Solar sail

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The story behind the card

Light has no mass, but it carries momentum, so when it bounces off a mirror it gives it a tiny push. The idea goes back to Johannes Kepler, who noticed in the early 1600s that comet tails point away from the Sun and imagined ships sailing on a heavenly breeze. In 2010 Japan's IKAROS became the first spacecraft to use a solar sail in interplanetary space, on its way past Venus. In 2019 the Planetary Society's LightSail 2, partly funded by public donations, showed that a small satellite could raise its orbit using sunlight alone; it burned up in the atmosphere in 2022. The push is tiny, but it never runs out, so over months it adds up.

Türkçe oku
Güneş yelkeni, çok ince ve dev bir aynadır; uzay aracı onunla güneş ışığının hafif itişiyle yol alır. Yakıt gerektirmez; üzerine ışık düştükçe bu küçük itiş aracı durmadan hızlandırır.

Işığın kütlesi yoktur ama momentumu vardır; bu yüzden bir aynaya çarpıp yansırken ona küçük bir itme uygular. Fikir Johannes Kepler'e kadar uzanır: Kepler 1600'lerin başında kuyruklu yıldızların kuyruğunun hep Güneş'in ters yönünü gösterdiğini fark etmiş ve göksel bir rüzgârla yol alan gemiler hayal etmişti. 2010'da Japonya'nın IKAROS aracı, Venüs'e doğru giderken gezegenler arası uzayda güneş yelkeni kullanan ilk uzay aracı oldu. 2019'da The Planetary Society'nin kısmen bağışlarla finanse ettiği LightSail 2, küçük bir uydunun yalnızca güneş ışığıyla yörüngesini yükseltebileceğini gösterdi; araç 2022'de atmosfere girerek yandı. İtme çok küçüktür ama hiç tükenmez; aylar içinde birikerek büyür.

Sources and further reading

Background reading: Solar sail
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