Editing Rocket engine (section)

====Nuclear thermal====

{| class="wikitable"
|-
! Type
! Description
! Advantages
! Disadvantages
|-
! [[Radioisotope rocket|Radioisotope rocket/"Poodle thruster"]] (radioactive decay energy)
| Heat from radioactive decay is used to heat hydrogen
| About 700–800 seconds, almost no moving parts
| Low thrust/weight ratio.
|-
! [[Nuclear thermal rocket]] (nuclear fission energy)
| Propellant (typically, hydrogen) is passed through a nuclear reactor to heat to high temperature
| [[Specific impulse|''I''<sub>sp</sub>]] can be high, perhaps 900 seconds or more, above unity thrust/weight ratio with some designs
| Maximum temperature is limited by materials technology, some radioactive particles can be present in exhaust in some designs, nuclear reactor shielding is heavy, unlikely to be permitted from surface of the Earth, thrust/weight ratio is not high.
|}