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Mars in 40 Days
Aug. 5th, 2009 11:23 amWhen I wrote my (in my own mind) epic The Mars Run, I postulated a trip to Mars using ionic engines. Ionic engines use ionized particles to generate very low but continuous thrust with very low fuel consumption. They are a good near-future interplanetary propulsion system. Not having good data about the reasonable travel times available from ionic engines, I looked at current, rocket-based, technology. Current, rocket-propelled ships could make the journey in about six months, so I figured six months was a safe figure for my book.
Since then, I've discovered the VASIMR concept for ionic engines. Well, this article, which I found via Jerry Pournelle, suggested a VASIMR-type ionic engine could make the trip in 40 days! My interest was piqued, to say the least. After all, extrapolating from this table, that's almost a .01 G continuous thrust.
The problem is, to make that rapid a journey requires a power plant generating in the neighborhood of 200 MW. So how big is a 200 megawatt nuclear power plant? Well, depends on how you define "big." Per this site, your larger nuclear submarine has a power plant in the neighborhood. Of course, said power plant is probably a thousand tons or so, and requires several crewmembers to operate. And the original article had no data on the assumed weight / thrust ratio of this Mars-in-40-days ship.
So, don't look for a 40 day cruise to Mars showing up on travelocity any time soon. But, from a science fiction writer's perspective, all these problems are mere engineering details, fixable with a few keystrokes!
Since then, I've discovered the VASIMR concept for ionic engines. Well, this article, which I found via Jerry Pournelle, suggested a VASIMR-type ionic engine could make the trip in 40 days! My interest was piqued, to say the least. After all, extrapolating from this table, that's almost a .01 G continuous thrust.
The problem is, to make that rapid a journey requires a power plant generating in the neighborhood of 200 MW. So how big is a 200 megawatt nuclear power plant? Well, depends on how you define "big." Per this site, your larger nuclear submarine has a power plant in the neighborhood. Of course, said power plant is probably a thousand tons or so, and requires several crewmembers to operate. And the original article had no data on the assumed weight / thrust ratio of this Mars-in-40-days ship.
So, don't look for a 40 day cruise to Mars showing up on travelocity any time soon. But, from a science fiction writer's perspective, all these problems are mere engineering details, fixable with a few keystrokes!
