Talk:Fission sail

Steering
Why can't the sail be steered by rotating it (using momentum wheel or attitude jets or whatever)? njh 05:34, 31 December 2005 (UTC)

forwards fragments adding to thrust?
Why do forward fragments contribute to thrust? Unless I've misunderstood the structure (in which case this is a request for clarification ;) the radioactive layer and the absorbtion layer are bonded together, so any forwards moving fragment will simply work to heat the sail as a whole. The fragment will generate a tiny pulse of thrust backwards as it is emitted, but exactly the same pulse forward as it is absorbed. The material will then emit a photon in a random direction contributing nothing on average. njh 05:38, 31 December 2005 (UTC)

Bad Physics
The physics in this article make no sense. Forward was a respectable physicist however, so I don't think these are flaws with the concept, merely the article. Without some sources from Howard or other physicists I don't think we can make this article what it should be. A web search finds no mention of this technology outside of Wikipedia.

To go over the mistakes:

NathanHurst is right, steering would work fine.

To answer NathanHurst's other question: You can think of *either* the backwards moving fragment providing thrust (like the propellent in a rocket) and the forward fragment remaining attached to the sail, or the forward moving fragment as colliding with the sail and accelerating it, and the backwards moving fragment flying away.

Size would be irrelevant to insuring it works with fragments that do not fly directly forward or back. They are reacting on a surface, so one of the fragments will always collide with it, the other flying away.

There are no calculations as to feasibility. I find it likely that the added mass of the nuclear material and the absorber would reduce the acceleration due to the solar wind on the sail more than the later nuclear reactions will make up later. —Preceding unsigned comment added by 66.9.12.138 (talk) 22:55, 19 March 2008 (UTC)

Questioning such a radical-sounding stub which has no references is absoultely good practice. I have searched for good references and may have found one. The paper is titled "Fission thrust sail as booster for high Δv fusion based propulsion" and has been published in Acta Astronautica, you can find a freely available version online. These academics conclude that a fission sail would indeed be a viable method of propulsion Ramiel~enwiki (talk) 03:45, 7 May 2018 (UTC)

another question
Why would the sail need to be several kilometres across? Why can't it simply be hemispherical in shape and closer to the source? — Preceding unsigned comment added by 77.99.147.149 (talk) 21:10, 24 September 2014 (UTC)