<story><title>The US military is getting serious about nuclear thermal propulsion</title><url>https://arstechnica.com/science/2020/06/the-us-military-is-getting-serious-about-nuclear-thermal-propulsion/</url></story><parent_chain><item><author>Knufen</author><text>The idea was considered before and showed great promise:
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Project_Orion_(nuclear_propulsion)&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Project_Orion_(nuclear_propu...&lt;/a&gt;
Of course there is always the backside, imagine a rocket exploding in the upper atmosphere leaving nuclear waste and rocket parts over vast areas of land.</text></item></parent_chain><comment><author>jjoonathan</author><text>NERVA &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;NERVA&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;NERVA&lt;/a&gt;  was way more practical. They actually built these things and experimentally confirmed specific impulse, they just never launched them.&lt;p&gt;It&amp;#x27;s so sad to listen to the documentaries and hear how NERVA &amp;quot;is on track to propel mankind to mars by the late 1970s or early 1980s.&amp;quot; Ah well. At least we&amp;#x27;re starting to care about space again!</text></comment>
<story><title>The US military is getting serious about nuclear thermal propulsion</title><url>https://arstechnica.com/science/2020/06/the-us-military-is-getting-serious-about-nuclear-thermal-propulsion/</url></story><parent_chain><item><author>Knufen</author><text>The idea was considered before and showed great promise:
&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Project_Orion_(nuclear_propulsion)&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.m.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Project_Orion_(nuclear_propu...&lt;/a&gt;
Of course there is always the backside, imagine a rocket exploding in the upper atmosphere leaving nuclear waste and rocket parts over vast areas of land.</text></item></parent_chain><comment><author>proaralyst</author><text>Nuclear pulse propulsion (Project Orion) is a different concept to nuclear thermal. Pulse works by using bombs to generate your energetic reaction mass in bursts, whereas thermal uses a more normal fission reactor to superheat some reaction mass that then passes through an ordinary rocket nozzle.&lt;p&gt;You&amp;#x27;re right that both are worrying until they&amp;#x27;re out of atmosphere.</text></comment>