NTP for Persephone mission

[oscarddt]

First time posting here,

I was reading this post in Space Flight Now (https://spaceflightnow.com/2020/07/14/five-years-after-new-horizons-flyby-scientists-assess-next-mission-to-pluto/) and makes me wonder if a smaller version of a nuclear thermal propulsion rocket (https://www.nasa.gov/directorates/spacetech/game_changing_development/Nuclear_Thermal_Propulsion_Deep_Space_Exploration) should be considered. What I don't know is how much this rocket could make the journey shorter.

[Vahe231991]

First time posting here,

I was reading this post in Space Flight Now (https://spaceflightnow.com/2020/07/14/five-years-after-new-horizons-flyby-scientists-assess-next-mission-to-pluto/) and makes me wonder if a smaller version of a nuclear thermal propulsion rocket (https://www.nasa.gov/directorates/spacetech/game_changing_development/Nuclear_Thermal_Propulsion_Deep_Space_Exploration) should be considered. What I don't know is how much this rocket could make the journey shorter.

To answer this question, a May 2018 report from Iowa State University's Department of Aerospace Engineering explains on page 46 the disadvantages of using a nuclear thermal rocket for the proposed Persephone mission:

While an NTR engine provides better efficiency, the mass that the system adds to the spacecraft significantly inhibits its performance unless high arrival velocities are reached. With either system, it is obvious that both require a high propellant fraction to enable POI. While this is certainly doable, it is not necessarily ideal as it requires increased system mass and complexity.

In other words, the writers of this paper selected the chemically-fueled Butek BHT-600 engine for the Persephone due to it offering greater arrival velocity than the nuclear thermal rocket.

[ccdengr]

the writers of this paper selected the chemically-fueled Butek BHT-600 engine for the Persephone...

The Busek (misspelled in the report linked upthread, not a good sign) BHT-600 is an Hall-effect ion thruster, not chemical.

I hate to be a downer, but there's no way this mission will be flown any time soon regardless of the details of the propulsion system.