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Mini guidance satellites could be used to position telescopes in space

When it comes to launching telescopes, a recent development is to use “segmented” telescopes which include multiple small mirrors that can be combined or unfurled to create one much larger mirror once the telescope has made it into space. The unfortunately delayed James Webb Space Telescope is one such segmented telescope that will have a total diameter of over 21 feet of mirror created by 18 hexagonal segments. In the future, telescopes could use over 100 mirror segments to create a size of nearly 50 feet.

These segmented telescopes are easier to launch as the mirror segments take up much less space than a full unsegmented mirror would. However, there are challenges with using a segmented design: in particular, how each segment of the mirror can be held stably in the correct position and how the mirror as a whole can be pointed towards the exoplanetary system that the telescope is collecting data from.

Now a team from the Massachusetts Institute of Technology (MIT) has published a paper in Astronomical Journal which suggests a fix for this challenge: using a miniature satellite the size of a shoebox which could guide the telescope into place. This could be achieved using technology already available today like a simple laser which could provide a steady, bright light for the telescope to use as a reference point when moving through space.

The advantage of this concept is that it would allow telescopes to be built in a more flexible way as they would not need such a very high level of precision in their manufacture. “This paper suggests that in the future, we might be able to build a telescope that’s a little floppier, a little less intrinsically stable, but could use a bright source as a reference to maintain its stability,” Ewan Douglas, an author of the paper and a postdoc in MIT’s Department of Aeronautics and Astronautics, explains. “If imperfections in the telescope motor or gears were causing your telescope to track slightly faster or slower, you could watch your guide star on a crosshairs by eye, and slowly keep it centered while you took a long exposure.”

This development could help build telescopes in the future which are both cheaper and more accurate.

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