The VASIMR engine is an electric propulsion system that has been lauded for its ability to cut down on interplanetary transfers. While it requires a high power source (in the range of 200kW), it is a relatively efficient system that offers long duration acceleration. Assuming that we can develop a nuclear reactor capable of 200 kW power delivery in space, the major drawback of VASIMR is the relatively low thrust-to-weight ratio, which would make orbital transfers slow for a large spacecraft.


If there was a manned spacecraft in orbit X around Earth, it appears that transferring to orbit Y would take longer compared to a chemical propulsion rocket. If a more rapid orbital transfer was desired, would an entirely separate rocket engine be required? Would this hypothetical spacecraft require a separate chemical propulsion system? Are there other options that could leverage the nuclear reactor, such as an Arcjet augmented nuclear thermal engine?

In response to some feedback, assume that the weight of the spacecraft is 500 metric tons. If the weight were to change to 5,000 metric tons, is the power requirement increased by a factor of 10?

Thank you.

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    $\begingroup$ At the moment answering this question involves designing a whole spacecraft and it all getting a bit nebulous- recommend picking some thrust and weight numbers that suit and editing them in (ISS is a good starting point for a Manned Mars craft)- there is an answer somewhere on the minimum thrust for an earth departure below which the moon gets in the way. $\endgroup$ Jan 6, 2022 at 0:20
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    $\begingroup$ Also these are two separable questions and as such, should probably be asked separately. $\endgroup$ Jan 19, 2022 at 19:05
  • $\begingroup$ Thanks - I've modified the question $\endgroup$
    – FontFamily
    Jan 19, 2022 at 20:49
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    $\begingroup$ Cost and complexity of going anywhere in the Solar System is generally minuscule to the cost and price of going to orbit. It is like exploring a farm from the bottom of a deep well. This is the main reason, why VASIMR is not widely used. Second reason is that it needs likely nuclear energy, making politicians itchy. Third reason is that it is too good. A plan of having a little bit better space exploration for ten billion dollar, has some chance. A plan of having stellar results for 100million is unbelievable, so it does not get the 100million. $\endgroup$
    – peterh
    Jan 21, 2022 at 20:02


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