Russia to Build Nuclear Space Engine by 2017

[My2Cents]

For manned missions you would want to minimize the total travel time rather than maximize peak velocity. I think in the case of nuclear powered travel, water propellant is more practical than inert gas propellant. Significantly faster acceleration/deceleration means significantly faster average velocity which is the key in this case.

Ion thrusters' advantages are practically realized in unmanned missions where you don't have to worry about food and life support running out or astronauts/cosmonauts losing bone mass and getting older.

• Higher acceleration does not equate to higher average velocity except for short trips. On a trip from the Earth to the Moon, the nuclear steam thruster would be quicker. Earth to Mars the ion drive might be quicker. On Earth to Jupiter Ion drive will be quicker. The difference is that while the nuclear steam drive may allow higher accelerations, the ion drive can produce much greater delta-V for the same mass fraction (engine+fuel), if the voyage is long enough to exploit this advantage.
  
• At the temperatures common in space, most bulk gases will be handled either as liquids or solids.
  
• Water has its advantages and disadvantages as a propulsion media in space. One big disadvantage is that it freezes at the temperatures you will normally experience in space, so the tank needs to be insulated and heated. Another is the high heat of vaporization, which is essentially lost energy.
  
  For a short to mid range trip hydrogen is a better choice. It is a pumpable liquid at reasonably low temperatures, and it only takes 1/5th the energy of water to vaporize. It does however has some unique long term storage issues.

 

[My2Cents]

I have a question if we were in space could you use a planet or moons gravity field to sort of give your self a boost . If so could we use that to get to the moon or any planet using less fuel.

What you are talking about is a ‘gravity assist’ maneuver, where a space vehicle uses a partial orbit through a passing gravity well to transfer orbital momentum from the object generating the gravity well to/from the vehicle.

• Geometry is critical. This is only possible when the objects are in the correct orbital aligned
• The momentum transfer must be in line with the orbital plane of the object that is providing the assist.
• This also means that the object providing the assist cannot be the immediate point of origin or destination.

In short, you cannot use a gravity assist maneuver to get from the Earth to the Moon. I believe that gravity assist maneuvers have been used for every flight to the outer planets (Mars, Jupiter, Saturn, etc.), has included at least 1 such maneuver.