Steps of the journey



Target selection

No SGL mission exists without picking a target first. The SGL spacecraft needs to fly a great distance in the opposite direction, to find the focal region that represents the target.

The spacecraft

The SGL spacecraft will be extraordinary instruments. They will have to survive a close flyby near the Sun, spend 25 years traveling in deep space, and then continuously operate for several years, navigating with unprecedented precision while collecting data.

Solar sailing

To get to the SGL focal region within a human lifetime we need spacecraft that are much faster than any spacecraft to date. The only currently available technology to do this is solar sailing, combined with a close flyby of the Sun.

The cruise

Voyager 1 has traveled a over 150 astronomical units in deep space. The SGL spacecraft will have to top that and reach 650 AU or beyond in 25 years, all the while navigating and maintaining communications with the Earth.


At the SGL focal region, the image of the targeted exoplanet will be a moving target. The SGL spacecraft will need to follow this image and stay "on pixel" to avoid motion blur and collect data to construct a meaningful image. This requires unprecedented navigational accuracy.

Data collection

The Sun projects the image of an Earth-like exoplanet in our galactic neighborhood to an area that is several kilometers across in size. Imaging the exoplanet amounts to sampling this "image plane", essentially one (very large) pixel at a time.

Building images

The Sun is an imperfect lens. The images it produces are heavily blurred. Sharp images can be reconstructed but only at the expense of increasing noise, so there are limits. Science requirements may lead to trade-offs between spatial and spectral resolution.


Ultimately, an SGL mission is aimed at discovering, or confirming the existence of life on a sister planet. Perhaps we will be able to confirm the presence of higher-order life, such as photosynthesizing plants. And who knows? Maybe we will be able to see signs of an industrial civilization, leading to the most momentuous discovery in the history of humanity.

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