<story><title>A dwarf planet coming within 11 AU of the sun over the next 10 years</title><url>https://groups.io/g/mpml/topic/83645454#36493</url></story><parent_chain><item><author>jessriedel</author><text>Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it.  You can&amp;#x27;t be captured by a planet&amp;#x27;s gravity alone.  If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured).  The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit around a planet and spontaneously be ejected.&lt;p&gt;Now, something like this can work if you use an &lt;i&gt;irreversible&lt;/i&gt; interaction like aerobreaking, but this dwarf planet has negligible atmosphere.  You could also use the dwarf planet for a gravitational assist (basically bouncing off it like a billiard ball), but I think gravitational assists from the other planets are almost always more convenient and effective.</text></item><item><author>tonmoy</author><text>Is that really true? If we manage to get a spacecraft get captured by the dwarf planet&amp;#x27;s gravity and orbit it, would that not be a lot less delta-V compared to if we made the spacecraft achieve the dwarf planet&amp;#x27;s orbit around the sun just by itself?</text></item><item><author>jessriedel</author><text>If you launch your telescope on a spacecraft and get it to match speed with the dwarf planet (which is necessary for a soft landing), there&amp;#x27;s not much point in actually attaching it to the dwarf planet.  That just blocks the view of half the sky.&lt;p&gt;Also, there will be nothing to see out there other than the dwarf planet itself.</text></item><item><author>Meerax</author><text>Is this something we could plan and manage to launch an orbiter&amp;#x2F;lander to in time? Has anyone thought about the possibility of slapping something like a telescope on that and letting it beam back data and images from veryyyyy far out eventually?</text></item></parent_chain><comment><author>azernik</author><text>It can &lt;i&gt;reduce&lt;/i&gt; the delta-V requirements, though - by the same principles as a gravity assist, a capture burn (especially into a loosely-bound planet-centric orbit) often takes less work than burning into the equivalent heliocentric orbit on your own.</text></comment>
<story><title>A dwarf planet coming within 11 AU of the sun over the next 10 years</title><url>https://groups.io/g/mpml/topic/83645454#36493</url></story><parent_chain><item><author>jessriedel</author><text>Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it.  You can&amp;#x27;t be captured by a planet&amp;#x27;s gravity alone.  If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured).  The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit around a planet and spontaneously be ejected.&lt;p&gt;Now, something like this can work if you use an &lt;i&gt;irreversible&lt;/i&gt; interaction like aerobreaking, but this dwarf planet has negligible atmosphere.  You could also use the dwarf planet for a gravitational assist (basically bouncing off it like a billiard ball), but I think gravitational assists from the other planets are almost always more convenient and effective.</text></item><item><author>tonmoy</author><text>Is that really true? If we manage to get a spacecraft get captured by the dwarf planet&amp;#x27;s gravity and orbit it, would that not be a lot less delta-V compared to if we made the spacecraft achieve the dwarf planet&amp;#x27;s orbit around the sun just by itself?</text></item><item><author>jessriedel</author><text>If you launch your telescope on a spacecraft and get it to match speed with the dwarf planet (which is necessary for a soft landing), there&amp;#x27;s not much point in actually attaching it to the dwarf planet.  That just blocks the view of half the sky.&lt;p&gt;Also, there will be nothing to see out there other than the dwarf planet itself.</text></item><item><author>Meerax</author><text>Is this something we could plan and manage to launch an orbiter&amp;#x2F;lander to in time? Has anyone thought about the possibility of slapping something like a telescope on that and letting it beam back data and images from veryyyyy far out eventually?</text></item></parent_chain><comment><author>shkkmo</author><text>&amp;gt;  You can&amp;#x27;t be captured by a planet&amp;#x27;s gravity alone&lt;p&gt;Technically, this isn&amp;#x27;t completely true. There are gravity assist techniques that will allow you to dump speed by essentially adding your momentum to the object you are trying to orbit. The is basically an anti-slingshot manuever.&lt;p&gt;In practice, I believe the range of scenarios when this is possible with a dwarf planet is so small as to be practically useless.</text></comment>