New Nuclear Thermal Rocket testing planned - decided not to use bomb grade U

[_Augustus_]

On 12/9/2016 at 11:11 AM, TheSaint said:

Fun Fact: One of them already has.

Yup! Apollo 13.

[DBowman]

7 hours ago, wumpus said:

Reusable nuclear rockets are likely going to be trickier than reusable chemical rockets.  Even once you throttle nuclear reactors they are still producing a lot of heat, for quite some time.  And all you have are consumables (that kill your ISP efficiency) and [black body] radiators.

The original prototypes were restartable, and I think the amount of propellant you have to use to flush 'decay heat' is pretty minimal - you have to budget for that non linearly decaying isp / deltav though as part of manoeuvre planning. The need for radiators with nukes in KSP is 'game balance' driven not reality driven.

Anytime you want high thrust (compared to ions, enough to do reasonable Pe kicks like >= 0.1 m/s^2 say) and high delta-v then nukes are good. If it just did the trans Mars injection (say) then you might as will take it with you to use for insertion at the other end - per NASA DRA5 nuke option (which even with extra insulation and cryo chillers is lighter than the chemical option).

Apparently a significant problem with solar ion as a LEO - HEO tug is that the Van Allen Belt radiation will 'quickly' degrade the solar arrays, I guess the avionics can be adequately shielded. I'm not sure what quickly means. Tethers Unlimited  has a plan to 'drain the electron radiation out of the inner belt' using tethers ...

Edited December 22, 2016 by DBowman

[wumpus]

7 hours ago, DBowman said:

Apparently a significant problem with solar ion as a LEO - HEO tug is that the Van Allen Belt radiation will 'quickly' degrade the solar arrays, I guess the avionics can be adequately shielded. I'm not sure what quickly means. Tethers Unlimited  has a plan to 'drain the electron radiation out of the inner belt' using tethers ...

That's pretty scary (especially since LEO-HEO would be where a tug would spend most of its time).  I'll have to look into that (and wonder if the Earth would fry without those belts... although I think it is simply the residue of "stuff that would fry the Earth" trapped by the magnetosphere).