1. Nuclear vasimr for mars transport/deep space propulsion stage?2. Solar vasimr for mars transport/deep space propulsion stage?3. Commercial applications4. Deep space probe applications 5. EELV upper stage applications6. National Security applications
We're going to need to get over our nuclear phobia in order to power a manned surface outpost on Mars. I don't think solar would cut it on the surface, especially if we're going to the high latitudes where water ice is more likely to be found.In my view, we have to do the robotic Mars sample return mission as a precursor to the manned mission, and for that, SEP makes the most sense, certainly between EML and LMO if not also direct from/to LEO.From this technology base, it then makes sense to continue with the manned mission by sending the surface hardware and ascent vehicle to LMO via SEP. Using hydrolox only for the manned orbital transport vehicle to and from LMO may not be so bad in terms of total mission IMLEO.Then we can work toward an NEP (and/or NTP) solution for the MTV to improve the economics if and when that becomes possible.
We're going to need to get over our nuclear phobia in order to power a manned surface outpost on Mars. I don't think solar would cut it on the surface, especially if we're going to the high latitudes where water ice is more likely to be found.
the ideal VASIMR ship would be powered by polywell fusion reactors... their lightweight and 100 MW of power for each would be the perfect match for VASIMR... 2 polywells (200 MW) and you get to Mars in 39 days... I wonder about the calculations for 4 Polywells (400MW)... how long to Mars or Jupiter...
VASIMR, if it to be considered fairly, needs to be considered in isolation from its power source, since any electric thruster can benefit from a low-mass power source.VASIMR's performance coefficients, thruster alpha, and other parameters would need to be known so they could be compared to other electric thruster (gridded ion, Hall ion, MPD, pulsed-inductive, etc.)
Quote from: kfsorensen on 06/15/2010 06:14 pmVASIMR, if it to be considered fairly, needs to be considered in isolation from its power source, since any electric thruster can benefit from a low-mass power source.VASIMR's performance coefficients, thruster alpha, and other parameters would need to be known so they could be compared to other electric thruster (gridded ion, Hall ion, MPD, pulsed-inductive, etc.) If you are only comparing electric propulsion systems and cost isn't an issue this is true. However if the comparison is with solar thermal/electric the fact that solar thermal does not require sunlight to be converted into electricity first, but rather can use it directly and thereby have lower mass( no conversion equipment required ) and higher efficiency. If electric propulsion is added to solar thermal, high efficiency high specific power concentrator type PV can be used to power it. Solar thermal has lower Isp, but can take advantage of the Oberth effect when going from low orbit to escape velocity to largely compensate for this vs. SEP and take a week or two as opposed to weeks or months with SEP. For Mars electric can then be used to speed things up, but need not have the kind of power levels that any all-electric needs to be useful. An all-electric has to have enough electricity to go from LEO to escape at fairly high Isp ( to compensate for its need to spiral out and the high mass of its power source ) and would need a source of electric power production far beyond anything reasonably available in the near future. VASIMIR's advantage is that it can operate at a large range of exhaust velocities. Solar thermal/electric may use two separate engines to do the same thing, but they both use the same large concentrator and solar thermal engines are low in mass for their thrust vs. electric. VASIMIR is more complex and heavier than MPD as well. Sol