<story><title>First images from James Webb telescope exceed expectations</title><url>https://cosmosmagazine.com/space/exploration/first-photos-james-webb-telescope/</url></story><parent_chain><item><author>jcadam</author><text>Any indication how many of those actuators they can lose and still maintain functionality (i.e., are any of those &amp;quot;spares&amp;quot;)?</text></item><item><author>chasil</author><text>I really and truly hope for longevity.&lt;p&gt;&amp;quot;The Webb telescope will use 132 small motors (called actuators) to position and occasionally adjust the optics as there are few environmental disturbances of a telescope in space. Each of the 18 primary mirror segments is controlled by 6 positional actuators with a further ROC (radius of curvature) actuator at the center to adjust curvature (7 actuators per segment), for a total of 126 primary mirror actuators, and another 6 actuators for the secondary mirror, giving a total of 132. The actuators can position the mirror with 10 nanometer (10 millionths of a millimeter) accuracy.&lt;p&gt;&amp;quot;The actuators are critical in maintaining the alignment of the telescope&amp;#x27;s mirrors, and are designed and manufactured by Ball Aerospace &amp;amp; Technologies. Each of the 132 actuators are driven by a single stepper motor, providing both fine and coarse adjustments. The actuators provide a coarse step size of 58 nanometers for larger adjustments, and a fine adjustment step size of 7 nanometers.&amp;quot;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;James_Webb_Space_Telescope&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;James_Webb_Space_Telescope&lt;/a&gt;</text></item><item><author>MontagFTB</author><text>I really appreciate how NASA is handling the James Webb. Instead of waiting for everything to be _done_ done, they’re bringing us all along for the setup, giving us “alpha” and “beta” images (if you will), and in so doing keeping interest in the telescope. I know it’ll continue, and I’m all hype about it.</text></item></parent_chain><comment><author>infogulch</author><text>The actuator is a genius flexure design that is both mechanically simple and accurate. &lt;i&gt;Breaking Taps&lt;/i&gt; 3d-prints a working replica and describes the design. I highly recommend: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;youtu.be&amp;#x2F;5MxH1sfJLBQ&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;youtu.be&amp;#x2F;5MxH1sfJLBQ&lt;/a&gt;&lt;p&gt;The actuator breaking wasn&amp;#x27;t as concerning after seeing the design.</text></comment>
<story><title>First images from James Webb telescope exceed expectations</title><url>https://cosmosmagazine.com/space/exploration/first-photos-james-webb-telescope/</url></story><parent_chain><item><author>jcadam</author><text>Any indication how many of those actuators they can lose and still maintain functionality (i.e., are any of those &amp;quot;spares&amp;quot;)?</text></item><item><author>chasil</author><text>I really and truly hope for longevity.&lt;p&gt;&amp;quot;The Webb telescope will use 132 small motors (called actuators) to position and occasionally adjust the optics as there are few environmental disturbances of a telescope in space. Each of the 18 primary mirror segments is controlled by 6 positional actuators with a further ROC (radius of curvature) actuator at the center to adjust curvature (7 actuators per segment), for a total of 126 primary mirror actuators, and another 6 actuators for the secondary mirror, giving a total of 132. The actuators can position the mirror with 10 nanometer (10 millionths of a millimeter) accuracy.&lt;p&gt;&amp;quot;The actuators are critical in maintaining the alignment of the telescope&amp;#x27;s mirrors, and are designed and manufactured by Ball Aerospace &amp;amp; Technologies. Each of the 132 actuators are driven by a single stepper motor, providing both fine and coarse adjustments. The actuators provide a coarse step size of 58 nanometers for larger adjustments, and a fine adjustment step size of 7 nanometers.&amp;quot;&lt;p&gt;&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;James_Webb_Space_Telescope&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;James_Webb_Space_Telescope&lt;/a&gt;</text></item><item><author>MontagFTB</author><text>I really appreciate how NASA is handling the James Webb. Instead of waiting for everything to be _done_ done, they’re bringing us all along for the setup, giving us “alpha” and “beta” images (if you will), and in so doing keeping interest in the telescope. I know it’ll continue, and I’m all hype about it.</text></item></parent_chain><comment><author>skykooler</author><text>None of them are spares per se; if any of them fail they will have to use the other four on that segment to point it away from the sensor and disable that segment.</text></comment>